A cDNA encoding chalcone isomerase from aged pea epicotyls.

Abstract

One of the defense mechanisms employed by plants in response to stress stimuli involves the accumulation of protective molecules, such as flavonones, around the affected regions (Schmelzer et al., 1989). Flavonoids represent an important class of inducible compounds and function as pigments, UV absorbants, and phytoalexins (Hahlbrock and Griesbach, 1979). An enzyme involved in the synthesis of flavonoids is CHI. CHI genes have been isolated from Pefunia hybrida (van Tunen et al., 1988) and Phaseolus vulgaris (Blyden et al., 1991). The expression and accumulation of CHI mRNA is induced by UV irradiation (van Tunen et al., 1988), phytopathic infection, funga1 elicitor, and wounding (Mehdy and Lamb, 1987). We report the sequence of a cDNA clone (Table I) isolated from a library constructed from mRNA of aged pea (Pisum safivum L. var Alaska) epicotyls. The cDNA is 986 bp long and contains an open reading frame encoding a protein of 233 amino acids. The predicted amino acid sequence shows high homology to CHI from P. vulgaris (Blyden et al., 1991) and P. hybrida (van Tunen et al., 1988). We are studying pea epicotyls in an attempt to understand both local and distant wound-inducible gene expression. Wounding of aged pea epicotyls generates a bidirectional wound signal (Davies and Schuster, 1981) and elevates the leve1 of about 20 translatable mRNAs (Schuster and Davies, 1983). Information on the expression of wound-inducible genes may allow dissection of the wound response.