Ethylenesynthesis, aerenchyma formation and expression of xyloglucan endotransglycosylase in roots of Vigna sps. under waterlogging condition
2010
Sairam, R.K. | Dharmar, K. | Chinnusamy, V.
The objective of this study was to examine the role of ethylene, aerenchyma formation ~and expression of xyloglucan endotransglycosylase (XET) in the waterlogging tolerance of contrasting mung bean (Vigna radiata) genotypes viz., T 44 (tolerant) and Pusa Baisakhi (susceptible), and a highly tolerant wild Vigna species Vigna luteola under pot-culture condition. Waterlogging resulted in decrease in relative water content (RWC) and chlorophyll (Chi) content in leaves, and membrane stability index (MSI) in root and leaf tissues. Waterlogging induced decline in RWC, MSI, and Chi was greater in Pus a Baisakhi (PB) than V. luteola and T 44. Ethylene production .in the roots increased in all the genotypes, however, the concentration was higher in V. luteola and T 44 than Pusa Baisakhi. Though the waterlogging induced XET expression in the roots was observed in case of V. luteola and T 44, aerenchyma formation was observed only in the roots of V. luteola. PCR band products were cloned and sequenced, and partial cDNAs of 455 and 456 bp were obtained for V. luteola and T 44, respectively. The partial cDNA sequences of cloned XET genes showed 98 % homology in V. luteola and T 44. T 44 and V. luteola showed 100 and 98 % homology with maize XET (Genbank Acc. No. ZMU15781), while in case of rice (Genbank Ace. No. Os06g0696600) the similarity was in the range of 87 and 86 %, respectively. The results suggest that one of the reasons of the waterlogging tolerance of V. luteola is its ability to develop aerenchyma. Further, besides XET some other factor may also be essential for aerenehyma formation in the roots, which might be absent in T 44.
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