Abstract
Auxin induces cell wall loosening, leading to elongation growth by water absorption. The molecular mechanism of the wall loosening has been speculated that some enzymes modified hemicellulosic polysaccharides. Xyloglucan endotransglycosylase/hydrolases (XTHs) are thought to participate in xyloglucan degradation and/or reconstruction, leading to wall loosening, particularly in dicot. However, the involvement of XTHs in auxin-induced elongation has not been extensively studied, partly because of the little effect of auxin on elongation of Arabidopsis (Columbia) hypocotyls. We examined the effect of auxin on the elongation growth of etiolated hypocotyls and expression of XTHs. IAA stimulated the elongation of hypocotyls within 2 hr either in the absence or presence of sucrose. Expressions of known 33 XTH genes were examined by RT-PCR. XTH 4, 15, 17, 18, 24, 27 and 30 were highly expressed in the etiolated hypocotyls. The early effects of IAA treatment and presence of sucrose on the expressions are reported.
