Role of Gibberellin-Induced Cell Division in First Internode Elongation of a Wheat Variety Tolerant to Deep-Sowing

Abstract

Seedlings of Hong Mang Mai, a wheat variety tolerant to deep-sowing conditions, emerge from much deeper in the soil than do other cultivars by elongating their first internode. Previously, we found that gibberellin (GA) extremely stimulate the elongation of the first internode in Hong Mang Mai, due to the higher GA sensitivity. As shoot elongation consists of two cellular processes, namely, cell division and cell elongation, we investigated the effects of GA on these processes during first internode elongation by monitoring the changes of cell length and mitotic index. We found that extensive shoot elongation occurs mainly at the basal region of the first internode. Moreover, GA promoted cell elongation only at the middle region, whereas GA promoted cell division at the basal region. Thus, in addition to cell elongation, GA-induced cell division might play an important role in the first internode elongation in Hong Mang Mai.