Coordinated regulation of photosynthesis in rice increases yield and tolerance to environmental stress.

Plants capture solar energy and atmospheric carbon dioxide (CO2) through photosynthesis, which is the primary component of crop yield, and needs to be increased considerably to meet the growing global demand for food. Environmental stresses, which are increasing with climate change, adversely affect photosynthetic carbon metabolism (PCM) and limit yield of cereals such as rice (Oryza sativa) that feeds half the world. To study the regulation of photosynthesis, we developed a rice gene regulatory network and identified a transcription factor HYR (HIGHER YIELD RICE) associated to PCM, which on expression in rice enhances photosynthesis under multiple environmental conditions, determining a morpho-physiological program leading to higher grain yield (GY) under normal, drought and high temperature stress conditions. We show HYR is a master regulator, directly activating photosynthesis genes, cascades of transcription factors and other downstream genes involved in PCM and yield stability under drought and high temperature environmental stress conditions. To assess the role of increased HYR expression in rice, whole-genome microarrays were used to generate gene expression profiles of rice cultivar Nipponbare transformed with an overexpression construct of the HYR gene (Loc_Os03g02650) under control of the CaMV 35S promoter, along with control wild-type (WT) lines. Two biological replicate samples each from the HYR and WT-control lines were profiled using rice whole-genome microarrays.

植物通过光合作用捕获太阳能与大气中的二氧化碳（CO₂），而光合作用是作物产量的核心组成部分，为满足全球日益增长的粮食需求，亟需大幅提升光合效率。随着气候变化加剧，环境胁迫日益频发，会对光合碳代谢（photosynthetic carbon metabolism, PCM）产生不利影响，并限制全球半数人口赖以生存的谷类作物产量，例如水稻（Oryza sativa）。为研究光合作用的调控机制，本研究构建了水稻基因调控网络，并鉴定出一个与光合碳代谢相关的转录因子HYR（HIGHER YIELD RICE）。该因子在水稻中表达后，可在多种环境条件下提升光合效率，调控一套形态生理程序，最终在正常生长、干旱及高温胁迫条件下均能提高籽粒产量（grain yield, GY）。研究表明，HYR是一类主调控因子，可直接激活光合相关基因、转录因子级联反应以及其他参与光合碳代谢的下游基因，从而在干旱与高温胁迫环境下维持作物产量稳定性。为评估HYR过表达在水稻中的功能，本研究采用全基因组微阵列技术，对携带HYR基因（Loc_Os03g02650）过表达载体（由CaMV 35S启动子调控表达）的水稻品种日本晴（Nipponbare），以及野生型（WT）对照株系进行基因表达谱分析。本研究通过水稻全基因组微阵列，对HYR过表达株系与野生型对照株系各两份生物学重复样本开展了表达谱检测。