Expression of different abscisic acid-responsive genes during somatic embryogenesis in sugarcane (Saccharum officinarum)

We have examined the expression of four genes during somatic embryogenesis in two cultivars of sugarcane, Saccharum officianrum, one drought resistant (JA-605) and the other one sensitive (C-8751), as well as in embryogenic a nd nonembryogenic tissues treated with abscisic acid (ABA) or after drought stress. Three of the cDNAs probed, from plasmids pMA1049, pMA2005 and CM1, were lea genes and the other one, from a barley hemoglobin gene, was induc ed in other species under stress conditions. Only transcripts homologous to the pMA2005 and CM1 clones were differentially accumulated during somatic embryogenesis; moreover, the CM1 clone only appeared in somatic embryos of the non-resistant variety. All the lea cDNAs were dramatically increased in the embryogenic tissues treated with ABA, but we observed differences amon g the accumulation of these mRNAs in the nonembryogenic tissues treated wit h ABA, and only the pMA2005 transcript appeared. The mRNA homologous to the barley hemoglobin gene appeared in the nonembryogenic tissue and the expre ssion increased after ABA treatment. The desiccation treatments had differe nt effects on the varieties, and the pMA2005 transcripts only appeared in t he sensitive variety.