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Background: Soybean (Glycine max) is an important oil provider and ecosystem participant. The protein phosphatase 2C (PP2C) plays important roles in key biological processes. Molecular evolution and functional analysis of the PP2C family in soybean are yet to be reported. Results: The present study identified 134 GmPP2Cs with 10 subfamilies in soybean. Duplication events were prominent in the GmPP2C family, and all duplicated gene pairs were involved in the segmental duplication events. The legume-common duplication event and soybean-specific tetraploid have primarily led to expanding GmPP2C members in soybean. Sub-functionalization was the main evolutionary fate of duplicated GmPP2C members. Meanwhile, massive genes were lost in the GmPP2C family, especially from the F subfamily. Compared with other genes, the evolutionary rates were slower in the GmPP2C family. The PP2C members from the H subfamily resembled their ancestral genes. In addition, some GmPP2Cs were identified as the putative key regulator that could control plant growth and development. Conclusions: A total of 134 GmPP2Cs were identified in soybean, and their expansion, molecular evolution and putative functions were comprehensively analyzed. Our findings provided the detailed information on the evolutionary history of the GmPP2C family, and the candidate genes can be used in soybean breeding.

The effect of crop domestication on photosynthetic productivity has been well‐studied, but at present, none examines its impacts on leaf anatomy and, consequently, light use efficiency in cotton. We investigated leaf and vein anatomy traits, light use efficiency (LUE) and gas exchange in 26 wild and 30 domesticated genotypes of cotton grown under field conditions. The results showed that domestication resulted in a higher photosynthetic rate, higher stomatal conductance, and lower lamina mass per area. Higher LUE was underpinned by the thicker leaves, greater vein volume, elongated palisade and higher chlorophyll content, although there was no difference in the apparent quantum yield. The lower vein mass per area in domesticated genotypes contributed to the reduction of lamina mass per area, but there was no decrease in vein length per area. Our study suggests that domestication has triggered a considerable shift in physiological and anatomical traits to support the increase in LUE.