In this work we compared the effect of the growth regulator content of the culture medium on the growth of in vitro shoot tips of five yam accessions belonging to four yam species (one Dioscorea alata, one D. rotundata, one D. cayenensis and two D. trifida). Medium S contained 0.6 μM benzyl adenine, 1.07 μM naphthalene acetic acid and 0.23 μM gibberellic acid while medium EBR contained 0.23 μM gibberellic acid and 0.1 μM 24-epibrassinolide. After 2 months of culture, oxidation level was significantly reduced on medium EBR compared to medium S for four of the five accessions tested. By contrast, medium EBR did not have any positive effect on shoot length since length of shoots produced after 2 months of culture on medium S and EBR were similar, except with accession 3-45T, for which shoot length was shorter on medium S compared to medium EBR. These results underline the potential of 24-epibrassinolide to reduce oxidation phenomena during in vitro culture and call for its utilization for regeneration of cryopreserved yam shoot tips, which is often impeded by oxidation phenomena.
[1] F. Engelmann, “Plant Cryopreservation: Progress and Prospects,” In Vitro Cellular & Developmental Biology— Plant, Vol. 40, No. 5, 2004, pp. 427-433.
[2] B. B. Mandal, K. P. S. Chandel and S. Dwivedi, “Cryopreservation of Yam (Dioscorea spp.) Shoot Apices by Encapsulation-Dehydration,” Cryo Letters, Vol. 17, No. 3, 1996, pp. 165-174.
[3] B. Malaurie, M. F. Trouslot, F. Engelmann and N. Chabrillange, “Effect of Pretreatment Conditions on the Cryopreservation of in Vitro Cultured Yam (Dioscorea alata and D. bulbifera) Shoot Apices by Encapsulation-Dehydration,” Cryo Letters, Vol. 19, No. 1, 1998, pp. 15-26.
[4] S. Leunufna and E. R. J. Keller, “Cryopreservation of Yam Using Vitrification Modified by Including Droplet Method: Effects of Cold Acclimation and Sucrose,” Cryo Letters, Vol. 26, No. 2, 2005, pp. 93-102.
[5] B. B. Mandal and S. Ahuja-Ghosh, “Regeneration of Dioscorea floribunda Plants from Cryopreserved Encapsulated Shoot Tips: Effect of Plant Growth Regulators,” Cryo Letters, Vol. 28, No. 5, 2007, pp. 329-336.
[6] B. B. Mandal, S. Ahuja-Ghosh and P. S. Srivastava, “Cryopreservation of Dioscorea rotundata Poir.: A Comparative Study with Two Cryogenic Procedures and Assessment of True-to-Type of Regenerants by RAPD Analysis,” Cryo Letters, Vol. 29, No. 5, 2008, pp. 399-408.
[7] P. Mukherjee, B. B. Mandal, K. V. Bhat and A. K. Biswas, “Cryopreservation of Asian Yam Dioscorea bulbifera and D. alata by Vitrification: Importance of Plant Growth Regulators,” Cryo Letters, Vol. 30, No. 2, 2009, pp. 100-111.
[8] Engelmann-Sylvestre and F. Engelmann, “Effect of Various Growth Regulators on Growth of Yam (Dioscorea trifida L.) in Vitro Shoot Tips,” African Journal of Biotechnology, submitted.
[9] A. Verma, C. P. Malik and V. K. Gupta, “In Vitro Effects of Brassinosteroids on the Growth and Antioxidant Enzyme Activities in Groundnut,” ISRN Agronomy, Vol. 2012, 2012, Article ID: 356485.
http://dx.doi.org/10.5402/2012/356485
[10] N. Nakajima, A. Shida and S. Toyama, “Effects of Brassinosteroid on Cell Division and Colony Formation of Chinese Cabbage Mesophyll Protoplasts,” Japanese Journal of Crop Science, Vol. 65, No. 1, 1996, pp. 114-118.
http://dx.doi.org/10.1626/jcs.65.114
[11] M. H. Oh and S. D. Clouse, “Brassinolide Affects the Rate of Cell Division in Isolated Leaf Protoplasts of Petunia hybrida,” Plant Cell Reports, Vol. 17, No. 12, 1998, pp. 921-924.
http://dx.doi.org/10.1007/s002990050510
[12] T. Iwasaki and H. Shibaoka, “Brassinosteroids Act as Regulators of Tracheary-Element Differentiation in Isolated Zinnia Mesophyll Cells,” Plant Cell Physiology, Vol. 32, No. 7, 1991, pp. 1007-1014.
[13] J. Li, P. Nagpal, V. Vitart, T. C. McMorris and J. Chory, “A Role for Brassinosteroids in Light-Dependent Development of Arabidopsis,” Science, Vol. 272, No. 5260, 1996, pp. 398-401.
http://dx.doi.org/10.1126/science.272.5260.398
[14] T. Murashige and F. Skoog, “A Revised Medium for Rapid Growth and Bioassays with Tobacco Tissue Cultures,” Physiologia Plantarum, Vol. 15, No. 3, 1962, pp. 473-497.
http://dx.doi.org/10.1111/j.1399-3054.1962.tb08052.x
[15] E. E. Uchendu, M. Muminova, S. Gupta and B. M. Reed, “Antioxidant and Anti-Stress Copmounds Improve Regrowth of Cryopreserved Rubus Shoot Tips,” In Vitro Cellular & Developmental Biology—Plant, Vol. 46, No. 4, 2010, pp. 386-393.
http://dx.doi.org/10.1007/s11627-010-9292-9