Laboratory of Genetics, Wageningen University & Research, Wageningen, Netherlands.
Bioinformatics Group, Wageningen University & Research, Wageningen, Netherlands.
Plant J. 2022 Dec;112(5):1298-1315. doi: 10.1111/tpj.16005. Epub 2022 Nov 7.
Photosynthesis is a key process in sustaining plant and human life. Improving the photosynthetic capacity of agricultural crops is an attractive means to increase their yields. While the core mechanisms of photosynthesis are highly conserved in C plants, these mechanisms are very flexible, allowing considerable diversity in photosynthetic properties. Among this diversity is the maintenance of high photosynthetic light-use efficiency at high irradiance as identified in a small number of exceptional C species. Hirschfeldia incana, a member of the Brassicaceae family, is such an exceptional species, and because it is easy to grow, it is an excellent model for studying the genetic and physiological basis of this trait. Here, we present a reference genome of H. incana and confirm its high photosynthetic light-use efficiency. While H. incana has the highest photosynthetic rates found so far in the Brassicaceae, the light-saturated assimilation rates of closely related Brassica rapa and Brassica nigra are also high. The H. incana genome has extensively diversified from that of B. rapa and B. nigra through large chromosomal rearrangements, species-specific transposon activity, and differential retention of duplicated genes. Duplicated genes in H. incana, B. rapa, and B. nigra that are involved in photosynthesis and/or photoprotection show a positive correlation between copy number and gene expression, providing leads into the mechanisms underlying the high photosynthetic efficiency of these species. Our work demonstrates that the H. incana genome serves as a valuable resource for studying the evolution of high photosynthetic light-use efficiency and enhancing photosynthetic rates in crop species.
光合作用是维持植物和人类生命的关键过程。提高农作物的光合作用能力是增加其产量的一种有吸引力的手段。虽然 C 植物的光合作用核心机制高度保守，但这些机制非常灵活，允许光合作用特性有很大的多样性。在这种多样性中，少数几种特殊的 C 物种能够在高光强下维持高光合作用的光能利用效率。十字花科的 Hirschfeldia incana 就是这样一种特殊的物种，由于它易于生长，因此是研究这种特性的遗传和生理基础的理想模型。在这里，我们提供了 H. incana 的参考基因组，并证实了其高光合作用的光能利用效率。虽然 H. incana 的光合速率是迄今为止在十字花科中发现的最高的，但与其密切相关的 Brassica rapa 和 Brassica nigra 的光饱和同化速率也很高。H. incana 基因组通过大的染色体重排、物种特异性转座子活性和重复基因的差异保留，从 B. rapa 和 B. nigra 中广泛多样化。参与光合作用和/或光保护的 H. incana、B. rapa 和 B. nigra 中的重复基因，其拷贝数与基因表达之间呈正相关，为这些物种高光合作用效率的机制提供了线索。我们的工作表明，H. incana 基因组是研究高光合作用光能利用效率进化和提高作物物种光合速率的宝贵资源。
