稻米营养品质对大气[CO2]升高响应的调控机制

Climate change will bring the opportunities and challenges for food security in future. The past research indicated that, although elevated [CO2] enhances the yield of rice, nutrient quality (protein, iron and zinc) is markedly decreased. To date, the regulation mechanism for rice nutrient response to elevated [CO2] is not initiated. Based on the previous studies, the decrease of transpiration rate ability under high [CO2] might play the important role for the decline of rice nutrient. Hence, it is assumed that the nutrient uptake capacity can be efficiently enhanced by adjusting the rice transpiration, to alleviate the decline of rice nutrient. To test the hypothesis, we will use the following rice material: wild type, mutants with up-regulation of transpiration under the simulated atmospheric CO2 concentration condition in the future (ambient + 200 μmol mol-1) using the FACE (Free Air CO2 Enrichment) platform in paddy field. Under elevated [CO2], compared to conventional rice, we study how the mutant with enhancing transpiration promote absorbing process for N, Fe and Zn and the possibility of mitigating the decline of rice nutritional quality, and its related mechanisms. This prospective study will not only provide the security for food nutrition in future, but also provide the opportunity to lead this direction of research for China FACE.

气候变化为未来粮食安全带来了机遇和挑战。前人发现高[CO2]增产稻米的同时，也会降低其营养品质（蛋白质、铁和锌）。目前为止，稻米营养品质对大气[CO2]升高响应的调控机制研究几近空白。基于前人研究，可知高[CO2]条件下，水稻蒸腾速率吸收能力的降低可能在稻米养分下降过程中扮演重要的角色。由此假设可通过调节水稻蒸腾，来提升养分吸收能力，从而缓解稻米养分下降。为验证假设，使用水稻材料：野生型（中花11），上调蒸腾突变体；利用大田开放式空气[CO2]升高平台，模拟未来大气[CO2]升高200 μmol mol-1条件下，提升蒸腾的水稻遗传材料是否能够有效促进N、Fe和Zn吸收及转运，从而有效缓解稻米营养品质下降，并阐明其响应相关机制。这一前瞻性研究不仅为未来的粮食营养安全提供保障，也为中国FACE率先开展并引领该方向的研究提供了机遇。

气候变化为未来粮食安全带来了机遇和挑战，前人发现高[CO2]增加稻米的同时，也会降低其营养品质（蛋白质、铁和锌）。本项目开展多年FACE试验比较野生型水稻品种(Zhonghua11,与相关突变体 [增大根系(ERF3-7 ERF3-12)和上调蒸腾 (ZmK2.1-15, ZmK2.1-20, OsKAT3-26 OsKAT3-30)]；并进一步研究了FACE条件下野生型Nipponbare和突变体（NRT1.1B-Indica等位基因增强硝酸盐吸收），以确定产量和营养品质对[CO2]升高的反应。结果表明高[CO2]条件， Zhonghua11和Nipponbare产量分别增加18%和8%，而蛋白、铁和锌营养总体下降，且精米降幅低于糙米；与野生型相比，突变体增产幅度明显上调，ERF3过表达系增产38-40%，ZmK2.1/OsKAT3过表达系增产24-29%，NIL增产19%；ERF3和ZmK2.1/OsKAT3过表达株系均缓解了籽粒养分下降，ERF3过表达株系对糙米和ZmK2.1/OsKAT3过表达株系对精米的缓解作用更大，携带NRT1.1B-indica等位基因的突变体糙米和精米蛋白下降的缓解效应几乎相同。本研究证实，通过分子生物技术提高根系、增加气孔开度、增加光合作用、提高蒸腾驱动的质量流量、促进硝酸盐吸收是提高粳稻产量、缓解CO2升高对水稻营养威胁的有效途径。此外，未来 CO2 浓度升高条件下，通过基因改良促进水稻蒸腾作用和硝酸盐吸收是提升稻米外观与加工品质的有效途径之一。