XVI International Botanical Congess
Leaf senescence is a genetically controlled developmental process. We have isolated a new class of senescence-associated mutant, hypersenescence1 (hys1), from Arabidopsis thaliana. In the hys1 mutant, leaf senescence began earlier than wild type during age-dependent and dark-induced senescence, when examined with such parameters of senescence as decrease in the contents of chlorophyll and protein and in photochemical efficiency. In addition, we found that the hys1 mutant is hypersensitive to sugar in regard to the elongation of hypocotyls when grown in the presence of sugar. These observations suggest that hys1 gene is an element controlling sugar-sensing mechanism that has a key role in the start of leaf senescence.