GGS : Vol. 75 (2000) , No. 4 p.179-188

New members of a cold-responsive group-3 Lea/Rab-related Cor gene family from common wheat (Triticum aestivum L.)

Kanako Tsuda¹⁾, Sergei Tsvetanov¹⁾, Shigeo Takumi¹⁾, Naoki Mori¹⁾, Atanas Atanassov²⁾ and Chiharu Nakamura¹⁾

1) Laboratory of Plant Genetics, Department of Biological and Environmental Science
2) Institute of Genetic Engineering

A Cor (cold-responsive) cDNA that belongs to the group-3 Lea (late embryogenesis abundant)/Rab (responsive to abscisic acid, ABA) family was isolated from a winter-hardy cultivar of common wheat (Triticum aestivum L.). Screening of a cold-acclimated cDNA library was performed using an ABA- and other stress-responsive barley cDNA clone, Hva1, as a probe. A wheat cDNA clone (designated as Wrab19) putatively encoded a basic (pI=10.3) and hydrophobic protein with 179 amino acids. The deduced protein showed characteristics of the group-3 LEA/RAB protein family. In contrast to the single copy barley Hva1, Wrab19 belonged to a multigene family in the hexaploid wheat genome and six loci were assigned to the homoeologous group 1 chromosomes. Using Wrab19 as a probe, four homologous cDNAs (designated as Wrab17) were isolated that encoded acidic (pI=4.6-4.7) and hydrophobic proteins, all with 166 amino acids. The deduced proteins showed high homology (a mean of 84% identity) with a barley gibberellic acid (GA₃)-inducible protein, ES2A, and several other group-3 LEA/RAB proteins. Wrab17 was considered to be a three-copy gene and each copy was assigned to chromosome 5A, 4B or 4D of hexaploid wheat. Transcripts of both Wrab19 and Wrab17 accumulated within 1 day of cold acclimation at 4°C. They were responsive to ABA and/or GA₃, but showed some cultivar differences in their response to these plant hormones. We conclude that the two genes are new members of the group-3 Lea/Rab-related Cor gene family in wheat.