Physiological and genetic analysis for lodging resistance in rice

倒伏是一个常见的问题，特别是在水稻（Oryza sativa）。它可以降低产量、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，植物的抗倒伏性由两个主要因素决定，即上部（穗和上部叶和茎）的重量和下部的推压阻力（Mulder，1954）。以推压阻力作为衡量玉米和水稻抗倒伏性的指标。为了研究水稻抗倒性的提高途径，我们鉴定了一个新的水稻下部抗倒性基因座，并对其生理功能进行了分析。以粳稻日本晴×籼稻Kasalath回交自交系群体为材料，分析了控制水稻下半部抗逆性的数量性状基因座（QTL）。检测到5个抗倒推性QTL ...更多信息 只有一个来自第5染色体上Kasalath的QTL（pr 15）具有正效应。pr 15的似然比曲线与抗台风倒伏的似然比曲线基本一致。我们选择了三个近等基因系（NILs），其中pr 15的染色体区域被取代的Kasalath在日本晴的背景。各近等基因系40 cm以下茎干重、密度和碳水化合物积累量均显著高于日本晴。日本晴和近等基因系在产量、根系特征和上部重量上没有差异。近等基因系的下部抗推性和抗倒性比日本晴高一倍以上。这些结果表明，pr 15可能会影响近等基因系的下部茎的特性，从而提高抗倒伏性。本研究结果表明，水稻下部抗倒性可能是提高抗倒性的新目标。我们已经证明pr 15可以提高抗倒伏性，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