COMPARATIVE-ANALYSIS OF GENOMIC SEQUENCE AND EXPRESSION OF A LIPID TRANSFER PROTEIN GENE FAMILY IN WINTER BARLEY

Three genomic clones (gblt4.2, gblt4.6, gblt4.9) have been isolated from a barley (Hordeum vulgare L.) cv, Igri genomic library using a cDNA clone of the low temperature responsive gene blt4.1 as the probe. The genomic clones are closely related and from sequence homology are believed to be three further members of a barley gene family encoding lipid transfer proteins, One clone, gblt4.9, corresponds to a second cDNA clone (blt4.9). Northern blot analysis revealed that the three genes reported here are induced by low temperature and drought; however, the relative level of response to these stimuli was shown to differ between the genes. Further, the developmental response of gblt4.2 is different from that found for other members of the gene family. The degree of low temperature induction of the blt4 gene family appears to be cultivar-dependent. Comparative analysis of the putative promoter regions of the genomic clones indicates three regions that show over 80% sequence conservation between gblt4.9 and gblt4.6. Also identified are putative cis acting elements previously identified in ABA responsive genes and low temperature inducible genes. The possible functional significance of the conserved regions and elements is discussed in relation to the expression of the blt4 gene family.