Gene duplication and polyploidization are genetic mechanisms that instantly add genetic material to an organism's genome. Subsequent modification of the duplicated material leads to the evolution of neofunctionalization (new genetic functions), subfunctionalization (differential retention of genetic functions), redundancy, or a decay of duplicated genes to pseudogenes. Phytochromes are light receptors that play a large role in plant development. They are encoded by a small gene family that in tomato is comprised of five members: PHYA, PHYB1, PHYB2, PHYE, and PHYF. The most recent gene duplication within this family was in the ancestral PHYB gene. Using transcriptome profiling, co‐expression network analysis, and physiological and molecular experimentation, we show that tomato SlPHYB1 and SlPHYB2 exhibit both common and non‐redundant functions. Specifically, PHYB1 appears to be the major integrator of light and auxin responses, such as gravitropism and phototropism, while PHYB1 and PHYB2 regulate aspects of photosynthesis antagonistically to each other, suggesting that the genes have subfunctionalized since their duplication.

中文翻译：

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植物色素B1 / B2的亚功能化会导致生长素和光合作用的差异。

基因复制和多倍体化是遗传机制，可立即将遗传物质添加到生物体的基因组中。复制材料的后续修饰导致新功能化（新的遗传功能），亚功能化（遗传功能的差异保留），冗余或复制基因向假基因的降解。植物色素是在植物发育中起重要作用的光受体。它们由番茄中的一个小基因家族编码，该家族由五个成员组成：PHYA，PHYB1，PHYB2，PHYE和PHYF。该家族中最近的基因重复发生在祖先的PHYB中基因。使用转录组分析，共表达网络分析以及生理和分子实验，我们显示了番茄SlPHYB1和SlPHYB2既显示常见功能又显示非冗余功能。具体而言，PHYB1似乎是光和生长素反应（如重力和光致趋向性）的主要整合者，而PHYB1和PHYB2相互拮抗地调节光合作用的各个方面，表明这些基因自复制以来就已亚功能化。