Department of Cell and Developmental Biology, John Innes Centre, NR4 7UH Norwich, United Kingdom.
Department of Plant Physiology, Universitat Autònoma de Barcelona, Barcelona 08193, Spain.
Proc Natl Acad Sci U S A. 2018 Dec 26;115(52):E12443-E12452. doi: 10.1073/pnas.1816964115. Epub 2018 Dec 7.
Stressors such as soil salinity and dehydration are major constraints on plant growth, causing worldwide crop losses. Compounding these insults, increasing climate volatility requires adaptation to fluctuating conditions. Salinity stress responses are relatively well understood in , making this system suited for the rapid molecular dissection of evolutionary mechanisms. In a large-scale genomic analysis of Catalonian , we resequenced 77 individuals from multiple salinity gradients along the coast and integrated these data with 1,135 worldwide genomes for a detailed understanding of the demographic and evolutionary dynamics of naturally evolved salinity tolerance. This revealed that Catalonian varieties adapted to highly fluctuating soil salinity are not Iberian relicts but instead have immigrated to this region more recently. De novo genome assembly of three allelic variants of the high-affinity K transporter () locus resolved structural variation between functionally distinct alleles undergoing fluctuating selection in response to seasonal changes in soil salinity. Plants harboring alleles responsible for low root expression of and consequently high leaf sodium ( ) were migrants that have moved specifically into areas where soil sodium levels fluctuate widely due to geography and rainfall variation. We demonstrate that the proportion of plants harboring alleles correlates with soil sodium level over time, -harboring plants are better adapted to intermediate levels of salinity, and the allele clusters with high-sodium accumulator accessions worldwide. Together, our evidence suggests that is under fluctuating selection in response to climate volatility and is a worldwide determinant in adaptation to saline conditions.
胁迫因素，如土壤盐度和干旱，是植物生长的主要限制因素，导致全球作物歉收。除了这些因素外，气候波动的加剧要求适应不断变化的条件。在 中，盐胁迫反应相对较好理解，因此该系统适合快速进行分子剖析进化机制。在对加泰罗尼亚 进行的大规模基因组分析中，我们对来自沿海多个盐度梯度的 77 个个体进行了重测序，并将这些数据与 1135 个全球 基因组整合在一起，以详细了解自然进化出的耐盐性的人口和进化动态。这表明，适应高度波动的土壤盐度的加泰罗尼亚品种不是伊比利亚的遗物，而是最近才移民到这个地区的。高亲和力 K 转运体（）基因座的三个等位变体的从头基因组组装，解析了在响应土壤盐度季节性变化的波动选择中功能不同的等位变体之间的结构变异。携带导致 根表达低和叶片钠（）高的等位基因的植物是移民，它们专门迁移到由于地理和降雨变化导致土壤钠水平广泛波动的地区。我们证明，携带 等位基因的植物比例与土壤钠水平随时间的变化相关，- 携带植物更适应中等盐度水平，而 等位基因与全球高钠积累系聚在一起。总之，我们的证据表明，是在响应气候波动的波动选择下，是适应盐渍条件的全球决定因素。
