低磷胁迫下水稻根系的发生及生长素的响应

摘要

The biomass of rice plant and the initiation and elongation of seminal, adventitious and lateral roots were recorded under five P concentrations (0. 10, 50, 100. 300 μmol/L). And auxin concentration and relative expression level of OsPlN genes were also investigated under 10 and 300 μmol/L P concentrations. Rice shoot biomass decreased with decreasing P concentration, finally resulting in significant increase in root/shoot ratio. Compared with thai under 300 μmol/L P concentration, the root/shoot ratio increased by 100% under 10 μmol/L P concentration. The length of seminal, adventitious and lateral roots increased significantly with decreasing P concentrations. However, compared with that under 300 μmol/L P concentration, the number of adventitious roots and the density of lateral roots decreased with decreasing P concentrations. Compared with that under 300 μmol/L P concentration, auxin concentration increased in the first leaf from top, junction and roots by 85%. 161% and 86% under 10 μmol/L P concentration, respectively. And relative expression level of OsPIN5a in rice root markedly increased after exposure to low P stress for 24 and 96 hours as compared with that under 300 μmol/L P concentration. Knhanced auxin synthesis and polar transport from the shoot to root might be involved in the response of rice to low P stress.%研究了5个磷浓度下(0,10,50,100,300 μmol/L)水稻植株的生物量以及水稻根系发生和伸长,并测定正常供P (300 μmol/L)与低磷( 10 μmol/L)条件下水稻不同部位生长素浓度以及生长素外流蛋白OsPIN家族基因的表达情况.结果表明,与正常供P处理相比,随着供P浓度的降低,水稻地上部的干质量降幅显著,进而导致根冠比显著增加；与正常供P 处理相比,低P处理的水稻根冠比增幅约为100％.水稻种子根、不定根和侧根的长度随供P浓度降低而显著增加,而不定根数及侧根密度随着供P浓度的降低而降低.与正常供P处理相比,低P处理的水稻倒1叶、根茎结合处和根系的生长素浓度显著上升,增幅分别为85％、161％和86％,差异达显著水平.RT-PCR结果表明,与正常供P相比,低P处理24h和96h的水稻根系OsPIN5a表达上调.低P胁迫下水稻生长素合成和从地上部到根系极性运输的增强是水稻根系发生对低P 胁迫响应的重要生理机制之一.