Mathan Jyotirmaya, Singh Anuradha, Jathar Vikram, Ranjan Aashish
National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India.
J Exp Bot. 2021 Oct 26;72(20):7119-7135. doi: 10.1093/jxb/erab313.
The importance of increasing photosynthetic efficiency for sustainable crop yield increases to feed the growing world population is well recognized. The natural genetic variation in leaf photosynthesis in crop plants is largely unexploited for increasing yield potential. The genus Oryza, including cultivated rice and wild relatives, offers tremendous genetic variability to explore photosynthetic differences and underlying biochemical, photochemical, and developmental traits. We quantified leaf photosynthesis and related physiological parameters for six cultivated and three wild rice genotypes, and identified photosynthetically efficient wild rice accessions. Fitting A/Ci curves and biochemical analyses showed that leaf photosynthesis in cultivated rice varieties IR 64 and Nipponbare was limited due to leaf nitrogen content, Rubisco activity, and electron transport rate compared with photosynthetically efficient wild rice accessions Oryza australiensis and Oryza latifolia. The selected wild rice accessions with high leaf photosynthesis per unit area had anatomical features such as larger mesophyll cells with more chloroplasts, fewer mesophyll cells between two adjacent veins, and higher mesophyll cell and chloroplast surface area exposed to intercellular space. Our results show the existence of desirable variations in Rubisco activity, electron transport rate, and leaf anatomical features that could be targeted for increasing the photosynthetic efficiency of cultivated rice varieties.
提高光合效率对于增加作物可持续产量以养活不断增长的世界人口的重要性已得到广泛认可。作物叶片光合作用的自然遗传变异在很大程度上未被用于提高产量潜力。稻属，包括栽培稻及其野生近缘种，提供了巨大的遗传变异性，可用于探索光合差异以及潜在的生化、光化学和发育特性。我们对六种栽培稻基因型和三种野生稻基因型的叶片光合作用及相关生理参数进行了量化，并鉴定出光合效率高的野生稻种质。拟合A/Ci曲线和生化分析表明，与光合效率高的野生稻种质澳洲野生稻和阔叶野生稻相比，栽培稻品种IR 64和日本晴的叶片光合作用受到叶片氮含量、核酮糖-1,5-二磷酸羧化酶（Rubisco）活性和电子传递速率的限制。所选的单位面积叶片光合效率高的野生稻种质具有一些解剖学特征，如叶肉细胞较大且叶绿体较多、相邻两条叶脉之间的叶肉细胞较少，以及暴露于细胞间隙的叶肉细胞和叶绿体表面积较大。我们的结果表明，在Rubisco活性、电子传递速率和叶片解剖学特征方面存在理想的变异，可将其作为提高栽培稻品种光合效率的目标。
