日本神户大学2月26日发表公报称，其研究小组在世界上首次发现了调节植物淀粉合成的基因。这一成果将有助于通过改良品种，让作物产生更多淀粉，从而提高收获量。

大气中二氧化碳浓度不断升高已成为社会问题，而对植物来说，二氧化碳是光合作用合成淀粉的必要原料。此前研究显示，在二氧化碳浓度高的条件下培养的农作物，淀粉合成更多，农作物生长更旺盛，收获量也会增加。但是，植物如何在基因层面适应二氧化碳浓度的变化，淀粉的合成能力又是如何受到调节的则一直不清楚。

神户大学研究生院助教深山浩率领的小组在二氧化碳浓度很高的条件下培育植物，然后详细分析了植物体内的各种基因，发现有一种基因在二氧化碳浓度越高的情况下越活跃，他们将其命名为“二氧化碳响应CCT结构域基因（CRCT基因）”，并详细调查了其功能。

研究人员发现，通过基因操作降低水稻体内CRCT基因的功能，则水稻茎中积累的淀粉量降至正常水平五分之一以下，而加强这种基因的功能，水稻茎中的淀粉量急剧增加，达到正常水平的三至四倍，几乎达到了马铃薯的水平。因此证实，CRCT基因发挥了“主开关”功能，负责调节与合成淀粉有关的基因。

由于目前大气中二氧化碳浓度不断升高，这一成果将有助于开发能更多吸收二氧化碳的作物。例如，水稻收获时秸秆本来是无用的部位，如能增强水稻茎中CRCT基因的功能，使水稻茎大量积累淀粉，就有可能成为制造生物乙醇的原料。

深山浩指出：“很多植物都拥有CRCT基因，这种基因应该能应用到其他作物的品种改良上。”研究人员计划今后通过对该基因的进一步研究，改善作物生产效率，并开发出新型农作物。

相关论文已刊登在新一期美国科学杂志《Plant Physiology》上。（来源：新华社 蓝建中）

CO2 Responsive CCT protein, CRCT Is a Positive Regulator of Starch Synthesis in Vegetative Organs of Rice

A novel CO2 Responsive protein (CRCT) containing a CONSTANS, CONSTANS-like and TOC1 (CCT) domain but not Zinc finger motif is described which is up-regulated under elevated CO2 in rice (Oryza sativa). The expression of CRCT showed diurnal oscillation peaked at the end of light period and was also increased by sugars such as glucose and sucrose. Promoter GUS analysis showed that CRCT was highly expressed in the phloem of various tissues such as leaf blade and leaf sheath. Overexpression or RNAi knockdown of CRCT had no appreciable effect on plant growth and photosynthesis except that tiller angle was significantly increased by the overexpression. More importantly, starch content in leaf sheath which serves as a temporary storage organ for photoassimilates, was markedly increased in overexpression lines and decreased in knockdown lines. The expressions of several genes related to starch synthesis such as ADP-glucose pyrophospholylase and α-glucan phospholylase were significantly changed in transgenic lines and positively correlated with the expression levels of CRCT. Given these observations, we suggest that CRCT is a positive regulator of starch accumulation in vegetative tissues, regulating coordinated expression of starch synthesis genes in response to the levels of photoassimilates.

原文链接：

http://www.plantphysiol.org/content/early/2015/02/24/pp.15.00021.full.pdf+html?with-ds=yes