Data from: Independent and parallel evolution of new genes by gene duplication in two origins of C4 photosynthesis provides new insight into the mechanism of phloem loading in C4 species

C4 photosynthesis is considered one of the most remarkable examples of evolutionary convergence in eukaryotes. However, it is unknown whether the evolution of C4 photosynthesis required the evolution of new genes. Genome-wide gene-tree species-tree reconciliation of seven monocot species that span two origins of C4 photosynthesis revealed that there was significant parallelism in the duplication and retention of genes coincident with the evolution of C4 photosynthesis in these lineages. Specifically, 21 orthologous genes were duplicated and retained independently in parallel at both C4 origins. Analysis of this gene cohort revealed that the set of parallel duplicated and retained genes is enriched for genes that are preferentially expressed in bundle sheath cells, the cell type in which photosynthesis was activated during C4 evolution. Furthermore, functional analysis of the cohort of parallel duplicated genes identified SWEET-13 as a potential key transporter in the evolution of C4 photosynthesis in grasses, and provides new insight into the mechanism of phloem loading in these C4 species.C4光合作用（C4 photosynthesis）被视为真核生物进化趋同现象中最具代表性的实例之一。然而，目前尚不明确C4光合作用的演化是否依赖新基因的起源。针对涵盖两次C4光合作用起源事件的7种单子叶植物开展全基因组基因树-物种树调和分析后，研究发现：在这些演化谱系中，与C4光合作用演化同步的基因重复与保留事件呈现出显著的平行性特征。具体而言，共有21个直系同源基因在两次C4起源过程中均独立发生了平行的基因重复与保留。对该基因集合的分析显示，这类经平行重复并保留的基因，显著富集于优先在维管束鞘细胞（bundle sheath cells）中表达的基因类群——而在C4演化进程中，光合作用正是在该类细胞中被激活的。此外，对该平行重复基因集合的功能分析鉴定出SWEET-13可作为禾本科植物C4光合作用演化过程中的潜在关键转运蛋白，同时为这类C4植物的韧皮部装载机制提供了全新的研究视角。