Abstract
We already found the desiccation-responsible genes from a terrestrial cyanobacterium Anabaena sp. PCC7120 using DNA segment array. To clear these genes function, the genes selected in typical gene-expression patterns were disrupted and desiccation tolerance of the gene-disruptants was tested. Although selected genes were expressed in nitrogen-rich condition, the gene-disruptants decreased desiccation tolerance in nitrogen-free condition. In cell growth, some of the gene-disruptant decreased growth rate in nitrogen-free condition. In accumulation of trehalose and sucrose known as desiccation-protectant, the gene-disruptants were almost the same tendency as wild-type irrespective of nitrogen content, suggesting that desiccation-responsible genes were larger influence than desiccation-protectant. These results may suggest that 1) desiccation-tolerant genes are containing nitrogen fixation relating genes, 2) many of the genes are expressed irrespective of nitrogen content to protect desiccation sensitive nitrogen fixing heterocyst and 3) complementary genes hide the mutant phenotype under desiccation in nitrogen rich condition.
