Ancient relaxation of an obligate short-day requirement in common bean through loss of CONSTANS-like gene function

第一作者：Ana M. González

第一单位：西班牙CSIC-MBG

通讯作者：Marta Santalla

 Abstract 

背景回顾：Common bean (Phaseolus vulgaris L.) is a major global food staple and source of dietary protein that was domesticated independently in Mexico and Andean South America. 

提出问题：Its subsequent development as a crop of importance worldwide has been enabled by genetic relaxation of the strict short-day requirement typical of wild forms, but the genetic basis for this change is not well understood. 

研究基础：Recently, a loss of photoperiod sensitivity was shown to result from mutations in the phytochrome photoreceptor gene Ppd/PHYA3 that arose independently within the two major domesticated lineages.

主要研究：Here, we define a second major photoperiod sensitivity locus, at which recessive alleles associate with deleterious mutations affecting the CONSTANS-like gene COL2. 

结果1-col2单倍型：A wider survey of sequence variation in over 800 diverse lines, including wild, landrace, and domesticated accessions, show that distinct col2 haplotypes are associated with early flowering in Andean and Mesoamerican germplasm. 

结果2-两步适应：The relative frequencies and distributions of COL2 and PHYA3 haplotypes imply that photoperiod adaptation developed in two phases within each gene pool: an initial reduction in sensitivity through impairment of COL2 function and subsequent complete loss through PHYA3. 

结果3-作用机制：Gene expression analyses indicate that COL2 functions downstream of PHYA3 to repress expression of FT genes and may function in parallel with PvE1, the bean ortholog of a key legume-specific flowering repressor. 

结论：Collectively, these results define the molecular basis for a key phenological adaptation, reveal a striking convergence in the naturally replicated evolution of this major crop, and further emphasize the wider evolutionary lability of CONSTANS effects on flowering time control.

 摘 要 

菜豆是全球主要的食物和膳食蛋白来源，在墨西哥和安第斯南美被独立驯化。菜豆后来能够作为一种重要的作物在全球范围内被广泛种植，主要是由于其不再像野生品种一样，需要十分严格的短日照条件，但这种变化的遗传基础还不清楚。最近的研究显示，在两个主要驯化品系中，独立出现了光敏色素光受体基因Ppd/PHYA3的突变，导致其丧失了光周期敏感性。本文中，作者鉴定了另外一个主要的光周期敏感性位点，该位点上隐性等位基因与影响类CO基因COL2的有害突变相关。通过对超过800个包括野生种、地方品种以及驯化种不同品系的序列变异分析显示，不同的col2单倍型与安第斯和中美洲种资的早花相关。COL2和PHYA3单倍型的相对频率和分布暗示，在每个基因库中，光周期适应分为两个阶段：最初通过COL2功能受损而降低敏感性，随后通过PHYA3完全丧失敏感性。基因表达分析显示COL2作用于PHYA3的下游，抑制FT基因的表达，可能与豆科植物特异性开花抑制因子PvE1基因平行发挥作用。综上，本文的研究鉴定了一个物候适应的分子基础，揭示了菜豆在自然重复演化过程中的趋同效应，同时进一步阐明了CO作用于开花时间控制的更加广泛的演化不稳定性。

 通讯作者 

**Marta Santalla**

doi: https://doi.org/10.1016/j.cub.2021.01.075

Journal: Current Biology

Published date: Feb 19, 2021