不同化感潜力水稻品种对低钾的生理与分子响应

Physio-biochemical and molecular response of rice(Oryza sativa L.) cultivars with different allelopathic potentials to potassium deficiency

选择国际公认的化感水稻品种"PI312777"和非化感水稻品种"Lemont"为材料,在K元素为5mg.L-1(低K)和40mg.L-1(正常K)2个水平的营养液中培养,通过水稻形态学指标(根长、株高、根冠比和生物量)、生理生化指标(SOD、POD、CAT、根系活力及植株中N、P、K含量),评价不同化感潜力水稻品种对低K胁迫的生理响应,并采用实时荧光定量PCR(Real time Fluorescent Quantitative PCR,FQ-PCR),分析了低K胁迫下水稻根和叶中与N、P、K吸收利用相关的12个关键酶的基因表达差异。结果表明,低K促进了化感水稻"PI312777"根的生长,根冠比加大,生物量增加,但对株高的影响不显著;而该条件下非化感水稻"Lemont"的上述指标均受到不同程度的抑制。低K对两种水稻的保护酶系(SOD、POD、CAT)和根系活力均有一定程度的抑制作用,植株中N、P、K含量降低,但非化感水稻"Lemont"受抑制的程度远大于化感水稻"PI312777"。FQ-PCR检测结果表明,低K胁迫下两种水稻根、叶中的12个关键酶的基因均呈现上调表达,而化感水稻"PI312777"的基因表达上调倍数均明显大于非化感水稻"Lemont"。低K胁迫下两种水稻品种的形态学差异、生理与分子响应均表明,化感水稻"PI312777"比非化感水稻"Lemont"具有更强的适应K匮乏的能力。

In order to explore physio-biochemical and molecular response of rice cultivar with different allelopathic potentials to potassium deficiency, allelopathic rice “PI312777” and non-allelopathic rice “Lemont” were studied. Two rice accessions were cultured respectively in Hoagland solution at 5 mg（ K）·L^-1 （ low potassium） and 40 mg（ K）·L^-1 （ normal potassium）. Morpholog- ical indexes （root length, shoot height, root-to-shoot ratio, and biomass） and physio-biochemical characteristics （ SOD, POD, CAT, root activity, and N, P, K contents） were investigated at two potassium levels. Additional twelve rice genes of correlative key enzymes for N, P, K absorption and utilization were determined by Real-time Fluorescent Quantitative PCR （FQ-PCR） to evaluate expressed change under low potassium. The results show stimulation in root length, root-to-shoot ratio and allelopathic rice “PI312777” biomass, but with insignificant influence on shoot height; whereas all the indexes show inhibition in non-allelopathic rice “Lemont”. The SOD, POD, CAT and root activity of the two rice accessions exhibit inhibition, while N, P, K content decreases. However, the rate of inhibition of the physio-biochemical characteristics and the degree of decrease in N, P, K contents are significantly higher in non-allelopathic rice “Lemont” than in allelopathic rice “PI312777”. Through FQ-PCR detection, all the twelve genes of the key enzymes are up-regulated at a significantly higher order of magnitude in allelopathic rice “PI312777” than in non-allelopathic rice “Lemont”. The findings reveal that allelopathic rice “PI312777” has better adaptability and endurance to K deficiency than non-allelopathic rice “Lemont”.