关键词: 脱落酸, 赤霉素, 赤霉素合成抑制剂, 地上部生长

Abstract: Abscisic acid (ABA) and gibberellic acid (GA) are both important plant hormones, which have important regulatory effects on rice growth. Previous studies have showed that the down-regulation of OsPK1 gene (encoding cytoplasmic pyruvate kinase) in rice results in the change of ABA/GA ratio, thus affecting the plant height. However, the molecular mechanism of shoot growth regulated by ABA and GA synergistically is still unclear. In order to reveal the relationship between ABA and GA in the regulation of shoot growth of rice seedlings, rice wild-type Hwayoung (HY) and IR29 were used as research materials, treated with plant hormones ABA, GA3 and GA synthesis inhibitor paclobutrazol (PAC), and shoot length and fresh weight were used as indicators to measure the growth and development of rice seedlings. The results showed that the inhibition of ABA on shoot growth of rice was relieved under gibberellin treatment. Subsequently, real-time fluorescence-based quantitative PCR (qPCR) was further used to detect the expression levels of key gibberellin synthesis genes (OsCPS1, OsKS1, OsKO2, OsKAO, OsGA20ox2 and OsSHB) in ABA-treated wild-type Nipponbare, and the results showed that ABA could inhibit the expression of OsCPS1, OsKO2 and OsSHB. The results have revealed that ABA could affect the expression of genes related to gibberellin biosynthesis through signal transduction, thus inhibiting the shoot growth of seedlings.

Key words: abscisic acid, gibberellic acid, gibberellin synthesis inhibitor, shoot growth