Physiological and genetic analysis for lodging resistance in rice

倒伏是一个普遍的问题，尤其是水稻（Oryza sativa）。它会降低产量、产品质量和机械收获效率（Weber和Fehr, 1966; Kono, 1995）。从动力学的角度来看，植物的抗倒伏性主要由两个因素决定，即上部（穗和上部叶和茎）的重量和下部的抗推力（Mulder, 1954）。以抗压性作为玉米和水稻抗倒伏性的指标。本研究鉴定了水稻下部抗推能力增强的新基因座，并对其生理功能进行了分析，以了解如何提高水稻的抗倒伏能力。以日本粳稻×籼稻回交自交系为材料，剔除上部重量的影响，在40 cm处剪断，分析了控制下部抗压性的数量性状位点。检测到5个推阻qtl…只有Kasalath在5号染色体上的一个QTL （pr15）具有阳性作用。pr15的似然比值比曲线与台风抗倒伏的似然比值比曲线相呼应。我们选择了三个近等基因系（NILs），其中pr15染色体区域被Nipponbare背景下的Kasalath染色体区域所取代。各品种的干重、干密度和40 cm以下（下茎）茎中积累碳水化合物含量均显著高于日本裸。在产量、根系特征和上部重量方面，日本裸子与非氮肥品种无显著差异。NILs的下端推压阻力和倒伏阻力比Nipponbare高2倍。这些结果表明，pr15可能会影响NILs下部茎的特性，从而提高其抗倒伏能力。本研究结果强烈提示，推动下部抗倒伏能力可能成为提高水稻抗倒伏能力的新靶点。我们已经证明，pr15可以提高抗倒伏能力，而不会对其他性状（如产量和株高）产生负面影响；因此，它可能适合引入现代水稻品种。少

Lodging is a common problem especially in rice (Oryza sativa). It can reduce yield, quality of production, and mechanical harvesting efficiency (Weber and Fehr, 1966 ; Kono, 1995). From the point of view of dynamics, lodging resistance in a plant is determined by two main factors, the weight of the upper part (ears and upper leaves and stems) and the pushing resistance of the lower part (Mulder, 1954). Pushing resistance was used as the index of lodging resistance in maize and rice. We identified a new locus responsible for increased pushing resistance of the lower part of rice (Oryza sativa) and analyzed its physiological function to understand how to improve lodging resistance in rice. Quantitative trait loci (QTLs) controlling pushing resistance of the lower part were analyzed in a population of backcross inbred lines of japonica Nipponbare x indica Kasalath plants cut out at 40 cm to exclude the effect of the weight of the upper parts. Five QTLs for pushing resistance were detected … More ; only one QTL from Kasalath on chromosome 5 (pr15) had a positive effect. The likelihood odds ratio curve of pr15 echoed that for lodging resistance by typhoon. We selected three near-isogenic lines (NILs) in which the chromosomal region of pr15 was substituted with that of Kasalath in the Nipponbare background. The dry weights and densities and the contents of accumulated carbohydrate in stems below 40 cm (lower stems) in each NIL were significantly higher than those of Nipponbare. There was no difference between Nipponbare and the NILs in yield, root characteristics, or the weights of the upper parts. Pushing resistance of the lower part and lodging resistance in the NILs were up to twice as high as in Nipponbare. These results suggest that pr15 might affect the characteristics of the lower stems of the NILs, thus increasing lodging resistance. The results of this study strongly suggest that pushing resistance of the lower part could be a new target for improving lodging resistance in rice. We have shown that pr15 can improve lodging resistance without negative effects on other traits (e.g.yield and plant height); therefore, it might be suitable for introduction into modern rice cultivars. Less