IMMUNOLOGICAL DETECTION OF POTENTIAL SIGNAL-TRANSDUCTION PROTEINS EXPRESSED DURING WHEAT SOMATIC TISSUE-CULTURE

An immunochemical approach was used to detect the expression of putati ve guanine nucleotide-binding proteins (G-proteins), arrestin, and nuc leoside diphosphate kinases during wheat (Triticum aestivum) tissue cu lture initiated from immature embryos. Both the soluble and membrane e xtracts from the immature embryos revealed bands of 58, 40, and 16 kD with antibodies to G-protein (alpha subunit), arrestin, and nucleoside diphosphate kinase, respectively. These proteins were overexpressed i n vitro in both nonembryogenic callus and embryogenic cultures. An add itional soluble protein (32 kD) was detected by anti-G alpha antibodie s in cultured tissues but not in immature embryos, suggesting a possib le function in cell multiplication. Moreover, somatic embryogenesis wa s associated with the appearance of a 29-kD protein reactive with anti -arrestin antibodies, both in soluble and membrane fractions. Tissue-c ultured genetic stocks of Chinese Spring wheat, including the disomic, 36 ditelosomic, and 6 nullisomic-tetrasomic wheat lines, were used to ascertain the chromosomal location of the genes encoding the 29-kD ar restin-like protein. The lack of a signal with the nonembryogenic dite losomic 3 D short chromosome arm line suggests that the 3 D long chrom osome arm possesses at least one gene involved in the expression of th e 29-kD protein. The putative role of the 29-kD protein in signal-tran sduction regulating embryogenesis is discussed.