Abstract
Expansins are proteins that function in cell enlargement, fruit tissue softening, abscission, pollen tube elongation and others and the α-expansin subfamily is composed of 26 genes in Arabidopsis. Based on the DNA microarray analysis we examined four α-expansins (AtEXPA1, AtEXPA4, AtEXPA6, AtEXPA15) which highly express in the elongating tissues such as hypocotyls and stems. The observation of T-DNA inserted mutants showed that the hypocotyls of atexpa1/atexpa15 double mutant significantly shorten compared with wild type. As a result of promoter GUS analysis, expression of AtEXPA15 was observed in the hypocotyls just after germination. Taken together it is suggested that AtEXPA15 involves in the elongation growth of the hypocotyls. We now analyze the expression pattern of AtEXPA1.
