IAA、GA_3和ABA对稻根负向光性和生长的影响

为探明稻根负向光性与内源植物激素含量的关系,以及外源激素对水稻根系生长的影响,以扬稻6号(籼稻)、日本晴(粳稻)和中花11(粳稻)的OsPIN1a超表达转基因水稻为材料,观察了根负向光性生长的过程,分析了负向光弯曲部位内源生长素(IAA)、赤霉素(GA3)和脱落酸(ABA)的含量,以及外源激素对水稻根系形态和解剖结构的影响。结果表明,扬稻6号和日本晴的根都具有负向光性,扬稻6号侧根和不定根的负向光性大于日本晴;2种材料中,IAA、GA3和ABA在发生负向光弯曲过程中的含量变化基本一致。光照引起3种激素的含量下降;向光侧的含量低于背光侧。单侧光照和外施IAA共同促进了籼稻根毛的大量发生;与普通水稻相比,OsPIN1a超表达稻株的根负向光性角度增大。外源GA3和ABA处理与稻根负向光性间无直接关系;外源ABA处理显著抑制了根的生长,单株根系总吸收表面积与根数均减少。10μmol L–1 ABA处理的水稻根尖生长异常,分生区和根冠发育不良,细胞伸长受抑,成熟区细胞变形使根局部膨胀,并改变了中央维管组织的发育。

Impact of IAA,GA3, and ABA on Negative Root Phototropism and Root Growth of Rice

The objective of this research was to investigate the relationship between rice roots negative phototropism and endogenous plant hormone levels, as well as the impact of exogenous hormones on rice root growth. The adventitious roots and primary roots of conventional cultivars Yangdao6 (indica), Nipponbare (japonica), Zhonghua11 (japonica) and its OsPIN1a over expressed transgenic seedlings were used to observe the process of root negative phototropism, measure contents of endogenous auxin (IAA), gibberellin (GA₃) and abscisic acid (ABA) in the bending part of root tips, and investigate the impact of exogenous hormones to rice root morphology and anatomy. Results indicated that seedling roots of both Yangdao6 and Nipponbare had negative phototropism, and the lateral roots and adventitious roots of Yangdao6 showed stronger negative phototropism. Plant hormones and negative phototropism of rice root and root development are closely linked. Under unilateral illumination, endogenous IAA, GA₃ and ABA levels declined. The content of these phytohormones in the irradiated side was lower than that in the shaded side. The treatment of unilateral light and exogenous IAA induced a large number of root hairs in Yangdao6. Compared with conventional rice, the angel of negative phototropism was lager in OsPIN1a transgenic plant. There was no direct relationship between exogenous GA₃ and ABA treatments and root negative phototropism of rice. Exogenous ABA inhibited root growth obviously. The total absorption surface area, root number and root length per plant were significantly reduced by ABA treatment. The treatment of 10 μmol L^-1ABA not only caused a dysplasia of both meristematic and elongation zone but also promoted the development of the central vascular tissue in root tips.