MAPPING OF ABSCISIC-ACID RESPONSIVE GENES AND VP1 TO CHROMOSOMES IN WHEAT AND LOPHOPYRUM-ELONGATUM

The plant hormone abscisic acid (ABA) affects developmental and physiological processes that can impact crop production. These processes include germination, environmental stress responses in vegetative tissue, embryo maturation, and dormancy. Identification and molecular tagging of ABA-responsive genes, as well as the vp1 gene, required for ABA sensitivity, may be valuable in developing breeding strategies designed for manipulating ABA-regulated traits. Using aneuploid genetic stocks and alien substitution lines the chromosomal location of vp1 and seven abscisic acid (ABA) responsive genes was determined in wheat and Lophopyrum elongatum (Host) Love. Clones (gene homology, if known, in parentheses) isolated from wheat hybridized to wheat and L. elongatum homoeologous chromosome groups as follows: pMA80 (dhn), chromosome 4; pMA1949 (group 3 LEA(II)), chromosome 3S; pMA1951, chromosome 5S; pMA1959 (Em), chromosome 1L; pMA2005 (group 3 LEA), chromosome 1S; and PKABA1, chromosome 2L. Clone pBS128, corresponding to an ABA-responsive gene from Bromus secalinus, hybridized to wheat chromosome 2S. The cDNA clone pcvp23 that is homologous to vp1, a gene required for ABA responsiveness and the prevention of precocious germination in maize embryos, did not hybridize well with wheat but hybridized to chromosomes 3L and 7 beta in L. elongatum. Three of the clones mapped previously in barley by other researchers, pMA1949, pMA1951, pMA1959, were found here to be on the corresponding homoeologous chromosomes in wheat.