Cotton Lea4 (D19) and LeaA2 (D132) Group 1 Lea Genes Encoding Water Stress-Related Proteins Containing a 20-Amino Acid Motif

LEA2 proteins are a diverse group of probable desiccation protectants that are developmentally induced during the post- abscission stage of late embryo development by ovule abscission and are environmentally induced, probably by a different mechanism(s), in cultured embryos by ABA, desiccation, and osmotic stress (7,8).Of the 18 Lea and LeaA mRNAs cloned from cotton (4), mRNAs of the two related genes (4) Lea4 (cDNA clone D19) and LeaA2 (cDNA clone D132) have the highest cross-hybridization with embryo RNAs ofother plants (K.S. Jakobsen, D.W. Hughes, G.A. Galau, unpublished ob- servations).A recent compilation of Group 1 Lea sequences confirms a very high conservation at the amino acid level in the cDNAs Em of wheat, Dl 9 of cotton, p8B6 of radish, EMB-1 of carrot, Emb564 of maize, and B19 of barley (2).Extensive work with a wheat Em gene has defined putative ABA-responsive elements and a leucine zipper-containing protein with an affinity for these elements (6), and there is some evidence that these elements may be common in other kinds of Lea and other environmentally responsive genes (6,10).