Abstract
Mungbean (Vigna radiata (L.) Wilczek) is commonly used as human food. However, the genomic resources of this species available in databases are limited. This study has two sections, the expressed sequence tags (EST) related to early seedling development and chilling response are developed in the first part. Two mungbean varieties NM94 and VC1973A were obtained from the Asian Vegetable Research and Development Center-The World Vegetable Center (AVRDC). They differ in disease resistance and susceptibility to chilling temperatures. NM94 can maintain a better membrane integrity than VC1973A during seedling stage exposed to 4 degree C. To investigate the molecular mechanisms of the inherent chilling-susceptibility, the gene expression patterns in young seedlings of NM94 and VC1973A were compared in the second part of this thesis. A cDNA microarray containing 735 uniESTs was employed to profile the transcriptional changes during chilling stress and after recovery from chilling. The results show that a chilling exposure triggered the expression of a common set of CORs (cold regulated genes) in both NM94 and VC1973A. These CORs encode proteins that are involved in restructuring the protein synthesis apparatus, participating in protein trafficking and degradation, and synthesizing the stress protectants. The comparative expression profile indicates that the photosynthetic capacity and the cryoprotective proteins may be the key regulators of comparative toler55ance to chilling in NM94. Our data support the role of LTPs (lipid transfer proteins) in cryoprotection during chilling stress and resumption of plant growth after recovery from chilling.