Effects of Pilosity on Rice Leaves on Photosynthesis, Transpiration and Drought Resistance.

为了提高旱稻的抗旱性，研究了旱稻种质叶片上的孢子数，特别参考了光合/蒸腾速率。irat109是一种多毛品种，叶子上有五种不同的毛发。其中，无毛品种JRAT212和所有日本品种均未检测到100 ~ 1000μm长的毛。在停止浇水后，IRAT109盆栽的土壤干燥延迟到IRAT212盆栽，表明IRAT109的蒸腾速率较低。通过对不同光湿条件下叶片光合作用和蒸腾作用的详细分析，揭示了长毛特性主要通过高边界层阻力降低光合作用的蒸腾作用，提高水分利用效率。有毛品种IRAT109与无毛品种IRAT212和IAC25互交培养的F1杂交种均具有长毛性状。F2植株的分离结果表明，长毛是由少数基因支配的显性性状。今后，我们将利用本研究培养的杂交种后代，通过QTL分析研究长毛性状，并鉴定相关基因，用于水稻抗旱性改良育种。

In order to improve the drought resistance of upland rice, the pilosity on leaves of rice germplasm were investigated, with special reference to photosynthesis/transpiration rates. IRAT 109, a hairy cultivar has five different kinds of hair on leaves. Among them, a 100 to 1000μm long hair was not detected in a non-hairy cultivar JRAT212 and all Japanese cultivars examined. In a pot grown with IRAT109 delayed soil drying to a pot grown with IRAT212 after the stop of watering, showing that low transpiration rates of IRAT109. With detail analysis of leaf photosynthesis and transpiration under several light and humidity conditions, it revealed that long hair characteristics were effective on reducing transpiration relative to photosynthesis and improving water use efficiency mainly by high boundary layer resistance. F1 hybrid plants raised by reciprocal crossings between hairy cultivar IRAT109 and nonhairy cultivars IRAT212 and IAC25 have all long hair characteristics. The segregation in F2 plants showed long hair was a dominant characteristics governed by a small number of genes. In the future, we will investigate long hair characteristics by QTL analysis with using the progeny of the hybrids raised in this study and identify the related genes to use rice breeding for improving drought resistance.