新华社东京8月5日电 水稻种植需要大量水，所以干旱天气是个大敌。日本研究人员日前通过基因改良开发出一种耐旱水稻，这种水稻的根部能够深深扎入土壤中吸收水分，因此在干旱条件下也能生长。
日本农业生物资源研究所宇贺优作率领的研究小组介绍说，水稻的根是横向伸展的，所以在土壤中扎根很浅，而旱稻的根则扎得很深。他们经过研究发现，旱稻拥有一种DRO1基因。这种基因感知重力后，可以使旱稻根部向下伸展。
研究小组在新一期《自然－遗传学》杂志上发表论文说，他们对一种名为IR64的水稻（属于籼稻）进行了基因研究，发现其DRO1基因有部分缺损。通过杂交，研究人员为IR64重新植入DRO1基因。结果发现其扎根深度达到以前的2倍以上。在IR64水稻几乎会绝收的严重干旱环境下，植入DRO1基因后，收获量能够达到通常水平的30％左右。
研究人员说，全球容易受干旱影响的水稻田面积达到2300万公顷。这一抗旱水稻新品种有助于对抗干旱对水稻种植区的影响。此外，玉米等其他作物也有类似基因，所以此次的研究成果也有望促进开发出其他作物的耐旱新品种。（生物谷 Bioon.com）
生物谷推荐的英文摘要
Nature Genetics doi:10.1038/ng.2725
Control of root system architecture by DEEPER ROOTING 1 increases rice yield under drought conditions
Yusaku Uga, Kazuhiko Sugimoto, Satoshi Ogawa, Jagadish Rane, Manabu Ishitani, Naho Hara, Yuka Kitomi, Yoshiaki Inukai, Kazuko Ono, Noriko Kanno, Haruhiko Inoue, Hinako Takehisa, Ritsuko Motoyama, Yoshiaki Nagamura, Jianzhong Wu, Takashi Matsumoto, Toshiyuki Takai, Kazutoshi Okuno & Masahiro Yano
The genetic improvement of drought resistance is essential for stable and adequate crop production in drought-prone areas1. Here we demonstrate that alteration of root system architecture improves drought avoidance through the cloning and characterization of DEEPER ROOTING 1 (DRO1), a rice quantitative trait locus controlling root growth angle. DRO1 is negatively regulated by auxin and is involved in cell elongation in the root tip that causes asymmetric root growth and downward bending of the root in response to gravity. Higher expression of DRO1 increases the root growth angle, whereby roots grow in a more downward direction. Introducing DRO1 into a shallow-rooting rice cultivar by backcrossing enabled the resulting line to avoid drought by increasing deep rooting, which maintained high yield performance under drought conditions relative to the recipient cultivar. Our experiments suggest that control of root system architecture will contribute to drought avoidance in crops.
