Printer Friendly

Developing an in vitro optimized protocol to sweet potato landraces conservation/Desenvolvimento de um protocolo otimizado para a conservacao in vitro de variedades locais de batata-doce.

Introduction

The sweet potato is considered the seventh most important crop in the world and the fifth most important in developing countries (Loebenstein, 2009). In Africa and Asia, thousands of people depend on sweet potato for food safety (Zhang, Wang, Liu, & Wang, 2009). On the Latin American continent, Brazil is the main producer, with an estimated annual production of 505,000 ton. (Reetz, 2014).

This vegetable crop can be used in home cooking or as a raw material in industrial processes for the production of sweets, flour, flakes, and starch, in addition to the production of biomass for biofuel (Ferrari, Guigou, & Lareo, 2013; Wang, Shi, Xia, Li, & Chen, 2013; Zhang et al., 2013).

In several areas of production, the sweet potato is a typical crop for small rural producers who are responsible for the maintenance of high genetic variability through the conservation of local varieties on their farms. However, some factors have jeopardized this so-called important form of conservation of genetic resources, e.g., the modernization of agriculture, which leads to rural exodus and contributes to the loss of genetic diversity of crops that were traditionally farmed by small farmers, such as the sweet potato. Another factor is the change in the eating habits of populations brought about by the emergence of new consumption options. In addition, landraces have been replaced by commercial varieties (Rodrigues & Santos, 2011). To prevent this loss of diversity, it is essential to preserve the germplasm so that it can be available for future use (Sa, Ledo, & Ledo, 2011).

In vitro plant culture is an alternative method for the conservation of germplasm, especially vegetatively propagated species, such as the sweet potato. This technique offers many advantages over the germplasm conservation process in the field. In vitro plant material is free from pathogens and weather conditions and risks present in the field such as theft, predation, attacks by pests and diseases, floods and droughts. In addition, the technique allows the maintenance of a large number of accessions in a small physical space, contributing to the reduction of financial costs (Withers & Williams, 1998; Cid, 2001).

One of the ways to preserve plant material in vitro is through the slow-growth or minimal-growth technique, in which the plant metabolism is reduced, thereby increasing the interval between subcultures. To this end, alterations are made in the chemical conditions of the growth medium, such as the addition of growth regulators or a reduction in the concentrations of salt and organic components of the growth medium, as well as a reduction in the light intensity or temperature in the growth room. In this way, the labor and space necessary for the maintenance of the germplasm are reduced (Tahtamouni, Shibli, & Ajlouni, 2001; Islam, Leunufna, Dembele, & Keller, 2003; Sarwar & Siddiqui, 2004; Divakaran, Babu, & Peter, 2006; Santos, Ledo, Ledo, Souza, & Junior, 2011). Sweet potato subculture is performed on average every 90 days, and this is one of the most time- and cost-consuming factors in the maintenance of in vitro collection (Teixeira & Nascimento, 1999).

Published studies on the preservation of sweet potato by minimal in vitro growth report an evaluation period of up to 90 days (Teixeira & Nascimento, 1999). However, for the creation of an in vitro sweet potato germplasm bank, several unanswered questions arise in the literature: (1) How will in vitro conditions, such as salt and sucrose concentrations and temperature, influence plant growth after these 90 days of minimal growth? (2) How long can I maintain this material in vitro? (3) What happens to the plant material after subculture? (4) What is the maximum period between subcultures? (5) How will the in vitro conditions affect the ex vitro response of plants after preservation?

This study describes a protocol to optimize the in vitro conservation of landraces of sweet potato by increasing the period between subcultures for this species.

Material and methods

Plant material

Twenty-eight accessions of sweet potato were collected from small farms in the northern region of Rio de Janeiro State (Brazil) and characterized by Moulin et al. (2012a and 2012b), were established in vitro, kept in a growth room at a temperature of 27 [+ or -] 2[degrees]C and irradiance of 25 [micro]mol [m.sup.-2] [s.sup.-1], provided by fluorescent lamps (OSRAM[R], daylight), under a photoperiod of 16:8 hours of light:darkness, for 90 days. Two commercial genotypes developed by Empresa Brasileira de Pesquisa Agropecuaria (Embrapa), i.e., 'Brazlandia Rosada' (UENF 1997) and 'Princesa' (UENF 1994), were also used (Table 1).

For the in vitro establishment of the material, nodal segments of branches of sweet potato containing one bud each were utilized. A semisolid growth medium was used containing mineral salts of MS medium (concentration of 100%) and White's vitamins (Murashige & Skoog, 1962), 100 mg [L.sup.-1] myo-inositol, sucrose at a concentration of 3%, and pH adjusted to 5.7. Next, the medium was solidified with 8.0 [L.sup.-1] bacteriological agar Vetec[R] and autoclaved for 15 min. at 121[degrees]C and 105 kPa.

The experiments were conducted in the Setor de Horticultura of the Laboratorio de Fitotecnia, in the Centro de Ciencias e Tecnologias Agropecuarias of Universidade Estadual do Norte Fluminense Darcy Ribeiro, located in Campos dos Goytacazes, Rio de Janeiro State, Brazil.

Establishment of in vitro minimal growth conditions

A preliminary trial was conducted to establish the conditions for in vitro minimal growth, randomly using accession UENF 1931 as the model plant. In this experiment, nodal segments containing one bud from accession UENF 1931 obtained from plants established in vitro and maintained in a growth room under the afore-described conditions were used as explants. The experimental design was completely randomized, with a 4 X 4 factorial arrangement, which consisted of four concentrations of the mineral salts from the MS medium (0, 10, 50, and 100%), and four concentrations of sucrose (0, 1, 2, and 3%), at two temperatures (18 [+ or -] 2[degrees]C and 27 [+ or -] 2[degrees]C), resulting in a total of 16 treatments with three replicates. Each replicate consisted of three test tubes (25 X 150 mm) with 10 mL of medium containing one explant each.

After the explants were inoculated, test tubes were sealed with PVC film. Half of the tubes were kept in a B.O.D. growth chamber and the other half in a growth room, both under a photoperiod of 16:8 hours of light:darkness and irradiance of 25 [micro]mol [m.sup.-2] [s.sup.-1] provided by fluorescent lamps (OSRAM[R]) similar to daylight. The temperature in the growth chamber was maintained at 18 [+ or -] 2[degrees]C and that in the growth room at 27 [+ or -] 2[degrees]C. Assessments were made every 30 days, for 12 months; plant height (mm), number of leaves, and survival rate were measured.

At 360 days, the plants of accession UENF 1931 in the treatment with 100% MS medium and 2% sucrose at both temperatures were explanted, and nodal segments containing one bud were transferred to a new medium with the same concentrations of salts and sucrose. Plant survival rate was measured after 90 days.

In vitro minimal growth of sweet potato accessions

The combination that allowed the in vitro conservation of accession UENF 1931 for the longest period was that which contained mineral salts from the MS medium at 100% concentration and 2% sucrose. This combination was then tested using all other accessions. For this purpose, nodal segments containing one bud each from plants retained in vitro under the previously described conditions were used.

The experimental design in this phase of the study was completely randomized, with 30 genotypes of sweet potato plants at two temperatures (18 [+ or -] 2[degrees]C and 27 [+ or -] 2[degrees]C), totaling 30 treatments, with three replicates. Each replicate consisted of three test tubes (25 X 150 mm) with 10 mL of medium containing one explant each.

After the inoculation of the explants, the test tubes were sealed with PVC film. Half of the test tubes were maintained in a B.O.D. growth chamber at a temperature of 18 [+ or -] 2[degrees]C, and the other half in a B.O.D. growth chamber at a temperature of 27 [+ or -] 2[degrees]C, both under a photoperiod of 16:8 hours of light:darkness and irradiance of 25 |Jmol [m.sup.-2] [s.sup.-1] provided by fluorescent lamps (OSRAM[R]) similar to daylight.

Evaluations were carried out every 30 days for 12 months; plant height, number of leaves, and survival rate were measured to determine the performance of the other sweet potato accessions in the treatment that was previously established with accession UENF 1931.

At 360 days, the plants of the surviving accessions at both temperatures were explanted, and nodal segments containing one bud were transferred to a new medium with the same concentrations of salts and sucrose and the same experimental design. Plant survival rate was measured after 90 days.

Acclimatization of plants

The experimental design in this phase was completely randomized, consisting of 30 genotypes of sweet potato plants, totaling 30 treatments, with two replicates. Each replicate consisted of three test tubes (25 X 150 mm) with 10 mL of medium containing one explant each, maintained at 27 [+ or -] 2[degrees]C. The medium contained 100% MS mineral salts and 2% sucrose.

After 180 days of in vitro conservation, plants of all 30 accessions tested that were approximately 9.0 cm in height were removed from the test tubes and placed in pots containing 1.5 L of the substrate Basaplant Hortalicas[R]. Two pots were used for each accession, and each pot contained three plantlets. Next, plantlets were transferred to a greenhouse with a plastic cover (100 pm) and shade net 50% (Sombrite[R]). The temperature was monitored daily, and it ranged from 21 to 33[degrees]C. Plant survival was assessed every 30 days, for 360 days.

Statistical analysis

To determine whether the data would meet the assumptions of analysis of variance (ANOVA), they were subjected to preliminary analyses to determine the normality and homogeneity of variances among treatments, for each factor (plant height, number of leaves, and survival rate), based on the Lilliefors (1967) and Bartlett, Bobko, and Mosier (1978) tests. Subsequently, the data were subjected to analysis of variance, and the means were compared according to the F test at 5% probability, utilizing SAEG 9.1 (2007) software. The variation in the parameters analyzed over time was evaluated using regression analysis.

Results

Establishment of in vitro minimal growth conditions

Overall, the temperature of 27 [+ or -] 2[degrees]C was more favorable for plant survival (66.29%) and provided the greatest height (2.20 cm) and lowest number of leaves (1.41) when the entire in vitro growth period was evaluated (Table 2).

The plants from the treatments with total suppression of mineral salts and sucrose in the growth medium grew less (0.20 cm), produced fewer leaves (0.16) and had one of the lowest survival rates (59.82%), irrespective of the temperature.

The treatments with 100% MS medium and 1%, 2%, and 3% sucrose simultaneously displayed a greater number of leaves, reduced growth, and high survival rate and were thus the most indicative of minimal growth for the accession under study for subculturing every 360 days (Figures 1 and 2).

After 360 days, the plants of accession UENF 1931 in the treatment with 100% MS medium and 2% sucrose at both temperatures were explanted, and nodal segments containing one bud were transferred to a new medium with the same concentrations of salts and sucrose. After 90 days of reculturing, it was observed that the plants at 18 [+ or -] 2[degrees]C showed only 10% survival, whereas those maintained at 27 [+ or -] 2[degrees]C had a survival rate of 100%.

In vitro minimal growth of sweet potato accessions

A temperature of 18 [+ or -] 2[degrees]C resulted in the highest plant survival rate (77.06%), whereas a temperature of 27 [+ or -] 2[degrees]C resulted in the tallest plant height (4.88 cm) and the greatest number of leaves (1.77) when the entire in vitro growth period was evaluated (Table 3).

Plants of accession UENF 1937 simultaneously exhibited the greatest height and number of leaves (not differing from UENF 1928) and the highest survival rate (not differing from UENF 1947), whereas accession UENF 1988 displayed the lowest height, lowest number of leaves (not differing from UENF 1920) and lowest survival rate.

For most accessions, the greatest plant height was observed from 150 to 270 days under in vitro minimal growth at both temperatures. The most representative accessions at temperatures of 18 [+ or -] 2[degrees]C and 27 [+ or -] 2[degrees]C were UENF 1925 and UENF 1953, respectively (Figure 3).

At both temperatures, the highest number of leaves was observed at 90 days of in vitro conservation. Accessions UENF 1932 and UENF 1962 were the most representative at the temperatures of 18 [+ or -] 2[degrees]C and 27 [+ or -] 2[degrees]C, respectively (Figure 3).

The percent survival was 100% for all accessions up to 180 days. After 180 days, the percent survival of most accessions started to decline, with accessions UENF 1922 and UENF 1917 being the most representative at the temperatures of 18 [+ or -] 2[degrees]C and 27 [+ or -] 2[degrees]C, respectively (Figure 3).

After 360 days of in vitro conservation, only some accessions survived: 11 at 18 [+ or -] 2[degrees]C (UENF 1917, UENF 1922, UENF 1925, UENF 1928, UENF 1931, UENF 1935, UENF 1937, UENF 1944, UENF 1947, UENF 1960, and UENF 1962), six at 27 [+ or -] 2[degrees]C (UENF 1922, UENF 1928, UENF 1937, UENF 1947, UENF 1987, and UENF 1990), and these were recultured. Four accessions survived at both temperatures (UENF 1922, UENF 1928, UENF 1937, and UENF 1947).

At 90 days of reculture of the accessions that survived, only four of the 11 accessions that were maintained at 18 [+ or -] 2[degrees]C showed survival rates greater than 50%: UENF 1917, UENF 1935, UENF 1944, and UENF 1947 (Figure 4).

Of the six accessions maintained at 27 [+ or -] 2[degrees]C, five showed survival equal to or greater than 90%, as follows: UENF 1922, UENF 1937, UENF 1947, UENF 1987, and UENF 1990 (Figure 4).

Plant acclimatization

The survival rate of the plants in the greenhouse was 100% for all accessions maintained at 27 [+ or -] 2[degrees]C (Figure 5).

Discussion

In the treatments with total suppression of mineral salts and sucrose in the growth medium, it was observed that the plants grew less, produced fewer leaves, and had the lowest survival rates irrespective of the temperature. Therefore, mineral salts and sucrose are essential components for the growth and survival of sweet potato plants in vitro and should not be totally suppressed in the growth medium.

The highest survival rate, the greatest height, and the highest number of leaves were observed in the treatments with MS salts at a concentration of 100%, at both temperatures (except for the treatments with complete suppression of sucrose). Other researchers working with in vitro conservation of sweet potato also utilized MS salts at a concentration of 100%, despite not having tested other concentrations, such as 10% and 50% (Jarret, 1997; Jarret & Gawel, 1991a; Jarret & Gawel, 1991b; Hirosse, Creste, Custodio, & Machado-Neto, 2012; among others). The reduction of the concentration of the salts in the present study did not benefit the in vitro conservation of the studied accessions.

Plants in the treatment with 100% MS medium and 2% sucrose, at both temperatures, showed the highest survival rates and the largest number of leaves. Jarret and Gawel (1991b) analyzed the effect of different levels of sucrose on the minimal growth of sweet potato. Sucrose concentrations reduced to 1.5% and 2% also resulted in higher survival rates, corroborating the results observed in the present study. However, these authors evaluated the development of plants for 90 days, unlike the period evaluated in the present study (360 days).

Although the literature cites sucrose concentrations of 2.0 to 8.0% as being effective for the minimal growth of other crops such as potato (Gopal, Chamail, & Sarkar, 2004), Drosophyllum lusitanicum (Goncalves & Romano, 2007), Elettaria cardamomum (Tyagi et al., 2009), Malus domestica (Kovalchuk, Lyudvikova, Volgina, & Reed, 2009) and Manihot esculenta (Londe, Alves, & Ribeiro, 2012), lower concentrations in the range of 2.0% were more efficient for sweet potato.

Plants from the treatment with 100% MS medium and 2% sucrose showed a higher number of axillary buds; i.e., shorter internodes, which generates a larger number of nodes. A higher number of nodes results in a higher number of explants and consequently, greater efficiency with respect to in vitro minimal growth. Until now, no studies have been conducted on in vitro minimal growth of sweet potato that have reported shortening of plant internodes.

Some studies on the in vitro minimal growth of sweet potato utilized growth retardants such as abscisic acid (Arrigoni-Blank et al., 2014; Jarret & Gawel, 1991a), sorbitol, and mannitol (Jarret & Gawel, 1991b). Growth retardants were not utilized in this study, to reduce costs and to avoid somaclonal variation. Moreover, according to the obtained results, sweet potato requires mineral salts and sucrose in the growth medium for its survival in vitro. The reduction of these components and the use of growth retardants can result in increased mortality of sweet potato in vitro (Arrigoni-Blank et al., 2014).

The positive effect of the temperature decrease was not observed for the majority of the sweet potato accessions in this study after 360 days of in vitro growth. The temperature of 27 [+ or -] 2[degrees]C was more efficient compared with the temperature of 18 [+ or -] 2[degrees]C, since 90 days after the subculture of accession UENF 1931, the plants at 27 [+ or -] 2[degrees]C showed 100% survival, whereas those maintained at 18 [+ or -] 2[degrees]C showed 10% survival. Although Jarret and Gawel (1991b), who studied the effect of different temperatures on the minimal growth of sweet potato, reported a 50% decrease in plant growth with a temperature decrease from 21.1 to 15.6[degrees]C, the evaluated period was only 90 days, and no subculturing was performed. In the present study, the evaluation period was 360 days, followed by another subculture, evaluated after 90 days.

The recommended temperature regimes differ from culture to culture, with some more tolerant to cold than others. Some plants can well withstand a temperature decrease, e.g., Asparagus officinalis (Bekheet, 2000), Saccharum officinarum (Lemos, Ferreira, Alencar, Neto, & Albuquerque, 2002), Vanilla planfolia (Divakaran et al., 2006), Piper aduncum and P hispidinervum (Silva & Scherwinski-Pereira, 2011), and Vitis labrusca and V vinfera (Silva, Luis, & Scherwinski-Pereira, 2012), among others. Sweet potato develops better in regions or during times when the average temperature is higher than 24[degrees]C (Silva, Lopes, & Magalhaes, 2004), and in its natural environment (ex vitro conditions), it does not withstand low temperatures well, maintaining this characteristic when grown in vitro.

Plants of accession UENF 1931 maintained at 18 [+ or -] 2[degrees]C did not acclimatize after 360 days of in vitro conservation, resulting in plant death. However, the plants maintained at 27 [+ or -] 2[degrees]C had 100% survival (data not shown). For the plants of all accessions acclimatized after 180 days of in vitro growth in 100% MS medium and 2% sucrose at a temperature of 27 [+ or -] 2[degrees]C, there was 100% survival. According to Roesler, Gomes, Moro, Kummer, and Cereda (2008), sweet potato is a rustic, easily grown vegetable crop with great adaptation and high tolerance to drought. Moreover, the greenhouse temperatures (21 and 33[degrees]C) did not vary widely in relation to the temperature at which the plants were grown in vitro (27 [+ or -] 2[degrees]C), which is a factor that must have contributed to the high survival rate.

Although there were similar responses among all accessions studied, slight variations were observed among these genotypes. These different responses during the in vitro conservation of sweet potato may be related to the genetic traits of each accession. The results of different reactions of genotypes conserved in vitro were already reported in previous studies with Passifora giberti (Faria, Costa, Junghans, Ledo, & Souza, 2006), Aechmea fasciata and A. miniata (Moreira, Costa, Souza, Bastos, & Rocha, 2008), among others. However, few studies have reported such differences in sweet potato (Manrique-Trujillo, Diaz, Reano, Ghislain, & Kreuze, 2013; Arrigoni-Blank et al., 2014).

The results of the present study indicate it is possible to extend the period between subculturing of sweet potato from 90 (Teixeira & Nascimento, 1999) to 180 days, thereby reducing the working time of the curator and the amount of reagents utilized in the preparation of the growth medium, which can decrease the maintenance costs of the in vitro collection. The same growth medium can be utilized for all accessions because all of the accessions studied had a survival rate of 100% up to 180 days. In addition, the need for a temperature reduction may increase the maintenance costs of the collection, as this implies higher energy expenses to cool the environment, especially in tropical countries such as Brazil. For the sweet potato accessions evaluated in the present study, this temperature decrease was detrimental and is not necessary.

The main difference between this and other studies was that the in vitro conservation of sweet potato germplasm was evaluated for a longer time period (360 days). In addition, the survival rate after the first subculture of plants was maintained at 18 [+ or -] 2[degrees]C and 27 [+ or -] 2[degrees]C was presented. Although all accessions survived at both temperatures, after the subculture, the survival of explants at 18 [+ or -] 2[degrees]C was only 10%. Thus, a temperature decrease is not recommended for the sweet potato accessions studied here.

In conclusion, it was possible to establish and maintain in vitro minimal growth of the sweet potato accessions collected on small farms from the northern region of Rio de Janeiro State. This methodology contributed to the reduction in the loss of genetic diversity of sweet potato in this region.

Conclusion

The recommended in vitro minimal growth conditions for the studied accessions are MS medium with 100% concentration of mineral salts and 2% sucrose, at a temperature of 27 [+ or -] 2[degrees]C, with subculturing performed every 180 days. The results obtained in this study provide a technical basis for the establishment of a new in vitro germplasm bank of Ipomoea batatas.

Doi: 10.4025/actasciagron.v39i3.32700

References

Arrigoni-Blank, M. D. F., Tavares, F. F., Blank, A. F., Santos, M. C. D., Menezes, T. S. A., & Santana, A. D. D. D. (2014). In vitro conservation of sweet potato genotypes. The Scientific World Journal, 2014. doi: 10.1155/2014/208506

Bartlett, C. J., Bobko, E, & Mosier, S. (1978). Testing for fairness with a moderated multiple regression strategy: An alternative to differential analysis. Personnel Psychology, 31(2), 233-245.

Bekheet, S. A. (2000). In vitro preservation of Asparagus officinalis. Biologia Plantarum, 43(2), 179-183.

Cid, L. E B. (2001). A propagacao in vitro de plantas. O que e isso? Biotecnologia, 19(1), 16-21.

Divakaran, M., Babu, K. N., & Eeter, K. V (2006). Conservation of Vanilla species in vitro. Scientia Horticulturae, 110(2), 175-180.

Faria, G. A., Costa, M. A. E C., Junghans, T. G., Ledo, C. A. S., & Souza, A. S. (2006). Efeito da sacarose e sorbitol na conservacao in vitro de Passiflora giberti N. E. Brown. Revista Brasileira de Fruticultura, 28(2), 267-270.

Ferrari, M. D., Guigou, M., & Lareo, C. (2013). Energy consumption evaluation of fuel bioethanol production from sweet potato. Bioresource Technology, 136(1), 377-384.

Gopal, J., Chamail, A., & Sarkar, D. (2004). In vitro production of microtubers for conservation of potato germplasm: effect of genotype, abscisic acid, and sucrose. In Vitro Cellular and Developmental Biology, 40(5), 485-490.

Goncalves, S., & Romano, A. (2007). In vitro minimum growth for conservation of Drosophyllum lusitanicum. Biologia Plantarum, 51 (4), 795-798.

Hirosse, E. H., Creste, J. E., Custodio, C. C., & Machado-Neto, N. B. (2012). In vitro growth of sweet potato fed with potassium phosphite. Acta Scientiarum. Agronomy, 34(1), 85-91.

Islam, M. T., Leunufna, S., Dembele, D. E, & Keller, E. R. J. (2003). In vitro conservation of four mint (Mentha spp.) accessions. Plant Tissue Culture, 13(1), 37-46.

Jarret, R. L. (1997). Effects of chemical growth retardants on growth and development of sweet potato (Ipomoea batatas (L.) Lam.) in vitro. Journal of Plant Growth Regulation, 16(4), 227-231.

Jarret, R. L., & Gawel, N., (1991a). Abscisic acid-induced growth inhibition of sweet potato (Ipomoea batatas L.) in vitro. Plant Cell, Tissue and Organ Culture, 24(1), 13-18.

Jarret, R. L., & Gawel, N., (1991b). Chemical and environmental growth regulation of sweet potato (Ipomoea batatas (L.) Lam.) in vitro. Plant Cell, Tissue and Organ Culture, 25(2), 153-159.

Kovalchuk, I., Lyudvikova, Y., Vblgina, M., & Reed, B. M. (2009). Medium, container and genotype all influence in vitro cold storage of apple germplasm. Plant Cell, Tissue and Organ Culture, 96(2), 127-136.

Lemos, E. E. E., Ferreira, M. S., Alencar L. M. C., Neto C. E. R., & Albuquerque M. M. (2002). Conservacao in vitro de germoplasma de cana-de-acucar. Pesquisa Agropecuaria Brasileira, 37(10), 1359-1364.

Lilliefors, H. W. (1967) On the Kolmogorov-Smirnov test for normality with mean and variance unknown. Journal of the American Statistical Association, 62(318), 399-402.

Loebenstein, G. (2009). Origin, distribution and economic importance. In G. Loebenstein, & G. Thottappilly, G. (Eds.), The sweet potato (p. 9-12). Springer Netherlands. doi: 10.1007/978-1-4020-9475-0

Londe, L. N., Alves, K. A., & Ribeiro E. B. (2012). Efeito de concentracoes de sacarose e de meio de cultura sobre a taxa de crescimento de Mandioca variedade BGM, 0116 conservadas in vitro. Revista Tropica, 6(2), 67-78.

Manrique-Trujillo, S., Diaz, D., Reano, R., Ghislain, M., & Kreuze, J. (2013). Sweet potato plant regeneration via an improved somatic embryogenesis protocol. Scientia Horticulturae, 161(1), 95-100.

Moreira, M. J. S., Costa, M. A. E C., Souza, F. V D., Bastos, L. E, & Rocha, M. A. C. (2008). Germinacao de sementes in vitro de especies de bromelias ameacadas de extincao. Magistra, 20(4), 321-327.

Moulin, M. M., Rodrigues R., Goncalves L. S. A., Sudre C. E, Santos M. H., & Silva J. R. E (2012a). Collection and morphological characterization of sweet potato landraces in north of Rio de Janeiro state. Horticultura Brasileira, 30(2), 286-292.

Moulin, M. M., Rodrigues, R., Goncalves, L. S. A., Sudre, C. E, & Eereira, M. G. (2012b). A comparison of RAED and ISSR markers reveals genetic diversity among sweet potato landraces (Ipomoea batatas (L.) Lam.). Acta Scientiarum. Agronomy, 34(2), 139-147.

Murashige, T., & Skoog, F. (1962). A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiologia Plantarum, 15(3), 473-497.

Reetz, E. R. (2014). Anuario Brasileiro de Hortalicas. Santa Cruz do Sul, RS: Gazeta Santa Cruz.

Rodrigues, R., & Santos, M. H. (2011). Agrobiodiversidade, germoplasma e melhoramento de plantas. In D. L. Cardoso, L. N. Luz, & T. N. S. Eereira (Eds.), Estrategias em melhoramento de plantas (p. 121-129). Vicosa, MG: Arka.

Roesler, E V S., Gomes, S. D., Moro, E., Kummer, A. C. B., & Cereda, M. E (2008). Eroducao e qualidade de raiz tuberosa de cultivares de batata batata-doce no oeste do Parana. Acta Scientiarum. Agronomy, 30(1), 117-122.

Sa, A. J., Ledo, A. S., & Ledo, C. A. S. (2011). Conservacao in vitro de mangabeira da regiao nordeste do Brasil. Ciencia Rural, 41(1), 57-62.

Sistema para Analises Estatisticas [SAEG]. (2007). SAEG Versao 9.1. Vicosa, MG: UFV

Santos, M. C., Ledo, A. S., Ledo, C. A. S, Souza, F. V. D., & Junior, J. F. S. (2011). Efeito da sacarose e do sorbitol na conservacao in vitro de segmentos nodais de mangabeira. Revista Ciencia Agronomica, 42(3), 735-741.

Sarwar, M., & Siddiqui, S. U. (2004). In vitro conservation of sugar cane (Saccharum officinarum L.) germplasm. Pakistan Journal of Botany, 36(3), 549-556.

Silva, J. B. C., Lopes, C. A., & Magalhaes, J. S. (2004). Cultura da batata-doce (Sistema de producao, 6). Ponte Alta-Gama, DF: Embrapa Hortalicas.

Silva, T. L., & Scherwinski-Pereira, J. E. (2011). In vitro conservation of Piper aduncum and Piper hispidinervum under slow-growth conditions. Pesquisa Agropecuaria Brasileira, 46(4), 384-389.

Silva, R. C., Luis, Z. G., & Scherwinski-Pereira, J. E. (2012). Short-term storage in vitro and large-scale propagation of grapevine genotypes. Pesquisa Agropecuaria Brasileira, 47(3), 344-350.

Tahtamouni, R. W., Shibli, R. A., & Ajlouni, M. M. (2001). Growth responses and physiological disorders in wild pear (Pyrus syriaca Boiss) during slow-growth in vitro preservation on osmostressing media. Plant Tissue Culture, 11(1), 15-23.

Teixeira, D. M. C., & Nascimento, A. S. (1999). Reducao do crescimento in vitro de batata-doce pela diminuicao da disponibilidade de sacarose (Boletim Tecnico da Embrapa, n. 23). Brasilia, DF: Embrapa-CNPH.

Tyagi, R. K., Goswami, R., Sanayaima, R., Singh, R., Tandon, R., & Agrawal, A. (2009). Micropropagation and slow growth conservation of cardamom (Elettaria cardamomum Maton). In Vitro Cellular and Developmental Biology, 45(6), 721-7299.

Wang, M., Shi, Y., Xia, X., Li, D., & Chen, Q. (2013). Lifecycle energy efficiency and environmental impacts of bioethanol production from sweet potato. Bioresource Technology, 133(1), 285-92.

Withers, L. A., & Williams, J. T. (1998). Conservacao in vitro de recursos geneticos de plantas. In C. A. Torres, L. S. Caldas, & J. A. Buso (Eds.), Cultura de tecidos e transformacao genetica de plantas (p. 297-329). Brasilia, DF: Embrapa-SPI/Embrapa-CNPH.

Zhang, L. M., Wang, Q. M., Liu, Q. C., & Wang, Q. C. (2009). Sweet potato in China. In G. Loebenstein, & G. Thottappilly (Eds.), The sweet potato (p. 325-358). Springer Netherlands. doi: 10.1007/978-1-4020-94750

Zhang, P, Chen, C., Shen, Y., Ding, T., Ma, D., Hua, Z., & Sun, D. (2013). Starch saccharification and fermentation of uncooked sweet potato roots for fuel ethanol production. Bioresource Technology, 128(1), 835-838.

Received on July 12, 2016.

Accepted on October 18, 2016.

Renato Gobbi Vettorazzi (1) *, Virginia Silva Carvalho (1), Claudia Pombo Sudre (2) and Rosana Rodrigues (2)

(1) Laboratorio de Fitotecnia, Centro de Ciencias e Tecnologias Agropecuarias, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Av. Alberto Lamego, 2000, Parque California, 28013-602, Campos dos Goytacazes, Rio Janeiro, Brazil. (2) Laboratorio de Melhoramento Genetico Vegetal, Centro de Ciencias e Tecnologias Agropecuarias, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Rio de Janeiro, Brazil. * Author for correspondence. Email: renato.g.v@hotmail.com

Caption: Figure 1. Height (cm), number of leaves, and percent survival of sweet potato accession UENF 1931 conserved in vitro in 100% MS medium with sucrose at concentrations of 1%, 2% and 3% and temperatures of 18 [+ or -] 2[degrees]C (left) and 27 [+ or -] 2[degrees]C (right) as a function of time (every 30 days).

Caption: Figure 2. Sweet potato plants (accession UENF 1931) conserved in vitro after 12 months. (A) Temperature of 18 [+ or -] 2[degrees]C and 100% MS medium with sucrose at concentrations of 1%, 2% and 3% from left to right; (B) Temperature of 27 [+ or -] 2[degrees]C and 100% MS medium with sucrose at concentrations of 1%, 2% and 3% from left to right. Bars= 13 cm.

Caption: Figure 3. Height (cm), number of leaves, and percent survival of sweet potato plants conserved in vitro in 100% MS medium with 2% sucrose, at temperatures of 18 [+ or -] 2[degrees]C (left) and 27 [+ or -] 2[degrees]C (right) as a function of time (every 30 days).

Caption: Figure 4. Percent survival of in vitro sweet potato plants 90 days after the first subculture, in 100% MS medium with 2% sucrose, at temperatures of 18 [+ or -] 2[degrees]C (left) and 27 [+ or -] 2[degrees]C (right).

Figure 5. Sweet potato plants originated from in vitro minimal growth, in a greenhouse. After 30 (A), 60 (B), 90 (C), 120 (D), 150 (E) and 180 (F) days of acclimatization.
Table 1. Origin and characteristics of roots of 28 accessions of sweet
potato collected in Rio de Janeiro State, Brazil, and two commercial
genotypes grown in vitro (Adapted from Moulin et al., 2012 a).

Accession        Provenance         Skin color        Flesh color

UENF 1917   Campos dos Goytacazes   Dark purple          Cream
UENF 1920   Campos dos Goytacazes      Cream             Cream
UENF 1922   Campos dos Goytacazes      White             White
UENF 1923   Campos dos Goytacazes      Pink       Strongly pigmented
                                                   with anthocyanins
UENF 1925   Campos dos Goytacazes      Cream             White
UENF 1927      Espirito Santo          White          Pale yellow
UENF 1928      Espirito Santo          Cream             White
UENF 1931   Campos dos Goytacazes   Dark purple          White
UENF 1932     Sao Joao da Barra        Cream      Intermediate orange
UENF 1935     Sao Joao da Barra     Dark purple          White
UENF 1937     Sao Joao da Barra        White             White
UENF 1939         Cabo Frio         Dark purple          Cream
UENF 1940      Espirito Santo       Dark purple          Cream
UENF 1941     Sao Joao da Barra        Pink              Cream
UENF 1942      Espirito Santo          Cream             Cream
UENF 1944      Espirito Santo       Dark purple          Cream
UENF 1945      Espirito Santo          Cream             Cream
UENF 1947      Espirito Santo       Dark purple          White
UENF 1949   Campos dos Goytacazes   Dark purple          Cream
UENF 1953     Sao Joao da Barra        Cream             Cream
UENF 1960   Campos dos Goytacazes      Cream             Cream
UENF 1962   Campos dos Goytacazes      Pink              Cream
UENF 1965   Campos dos Goytacazes      Cream             Cream
UENF 1969     Sao Joao da Barra        Cream             Cream
UENF 1970     Sao Joao da Barra        Pink              Cream
UENF 1987   Campos dos Goytacazes      Cream          Pale orange
UENF 1988   Campos dos Goytacazes      Cream             Cream
UENF 1990   Campos dos Goytacazes      White             White
UENF 1994         Brasilia          Dark purple          White
UENF 1997         Brasilia          Dark purple          White

Accession         Latitude                Longitude

UENF 1917   21 [degrees] 54'27.3"   41 [degrees] 02'30.2"
UENF 1920   21 [degrees] 57'08.5"   41 [degrees] 08'19.2"
UENF 1922   21 [degrees] 37'21.4"   41 [degrees] 13'12.2"
UENF 1923   21 [degrees] 37'21.4"   41 [degrees] 13'12.2"

UENF 1925   21 [degrees] 39'01.7"   41 [degrees] 11'20.2"
UENF 1927            --                      --
UENF 1928            --                      --
UENF 1931   21 [degrees] 46'30.8"   41 [degrees] 18'35.2"
UENF 1932   21 [degrees] 45'41.2"   41 [degrees] 17'26.7"
UENF 1935   21 [degrees] 45'29.3"   41 [degrees] 19'33.6"
UENF 1937   21 [degrees] 46'31.6"   41 [degrees] 19'11.1"
UENF 1939   21 [degrees] 45'38.8"   41 [degrees] 19'41.5"
UENF 1940   21 [degrees] 44'23.6"   41 [degrees] 21'04.4"
UENF 1941   21 [degrees] 44'56.7"   41 [degrees] 19'34.3"
UENF 1942   21 [degrees] 43'25.5"   41 [degrees] 19'15.8"
UENF 1944   21 [degrees] 42'58.4"   41 [degrees] 19'26.9"
UENF 1945   21 [degrees] 35'59.4"   41 [degrees] 19'01.2"
UENF 1947   21 [degrees] 45'43.2"   41 [degrees] 19'34.3"
UENF 1949   21 [degrees] 57'05.1"   41 [degrees] 03'45.7"
UENF 1953   21 [degrees] 56'03.2"   40 [degrees] 59'28.0"
UENF 1960   21 [degrees] 36'33.6"   41 [degrees] 18'59.2"
UENF 1962   21 [degrees] 38'08.6"   41 [degrees] 16'32.3"
UENF 1965   21 [degrees] 37'07.4"   41 [degrees] 13'23.4"
UENF 1969   21 [degrees] 43'48.1"   41 [degrees] 07'48.8"
UENF 1970   21 [degrees] 54'28.8"   41 [degrees] 05'46.6"
UENF 1987   21 [degrees] 58'43.6"   41 [degrees] 29'42.2"
UENF 1988   21 [degrees] 58'43.6"   41 [degrees] 29'42.2"
UENF 1990   21 [degrees] 58'28.8"   41 [degrees] 29'19.0"
UENF 1994            --                      --
UENF 1997            --                      --

Table 2. Mean values for height, number of leaves, and survival
of sweet potato accession UENF 1931 conserved in vitro for 12
months.

Temperature                 Height (cm)   Leaf number   Survival (%)

18 [+ or -] 2 [degrees]C     1.02 b        1.20 b        63.14 b
27 [+ or -] 2 [degrees]C     2.20 a        1.41 a        66.29 a

* Means followed by the same letter within a column do not differ
according to the F test at the 5% probability level.

Table 3. Mean values for height, number of leaves, and survival
of 30 accessions of sweet potato conserved in vitro for 12 months.

Temperature                 Height (cm)   Leaf number   Survival (%)

18 [+ or -] 2 [degrees]C     1.54 b        1.04 b        77.06 a
27 [+ or -] 2 [degrees]C     4.88 a        1.77 a        72.40 b

* Means followed by the same letter within a column do not differ
according to the F test at the 5% probability level.
COPYRIGHT 2017 Universidade Estadual de Maringa
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2017 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Vettorazzi, Renato Gobbi; Carvalho, Virginia Silva; Sudre, Claudia Pombo; Rodrigues, Rosana
Publication:Acta Scientiarum. Agronomy (UEM)
Date:Jul 1, 2017
Words:5965
Previous Article:Use of wild yeasts as a biocontrol agent against toxigenic fungi and OTA production/Uso de leveduras selvagens como agente de biocontrole contra...
Next Article:Nitrogen management effects on soil mineral nitrogen, plant nutrition and yield of super early cycle common bean genotypes/Nitrogenio mineral do...

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters