Data from: QTL mapping of temperature sensitivity reveals candidate genes for thermal adaptation and growth morphology in the plant pathogenic fungus Zymoseptoria tritici

Different thermal environments impose strong, differential selection on populations, leading to local adaptation, but the genetic basis of thermal adaptation is poorly understood. We used quantitative trait locus (QTL) mapping in the fungal wheat pathogen Zymoseptoria tritici to study the genetic architecture of thermal adaptation and identify candidate genes. Four wild-type strains originating from the same thermal environment were crossed to generate two mapping populations with 263 (cross 1) and 261 (cross 2) progeny. Restriction site-associated DNA sequencing was used to genotype 9745 (cross 1) and 7333 (cross 2) single-nucleotide polymorphism markers segregating within the mapping population. Temperature sensitivity was assessed using digital image analysis of colonies growing at two different temperatures. We identified four QTLs for temperature sensitivity, with unique QTLs found in each cross. One QTL had a logarithm of odds score >11 and contained only six candidate genes, including PBS2, encoding a mitogen-activated protein kinase kinase associated with low temperature tolerance in Saccharomyces cerevisiae. This and other QTLs showed evidence for pleiotropy among growth rate, melanization and growth morphology, suggesting that many traits can be correlated with thermal adaptation in fungi. Higher temperatures were highly correlated with a shift to filamentous growth among the progeny in both crosses. We show that thermal adaptation has a complex genetic architecture, with natural populations of Z. tritici harboring significant genetic variation for this trait. We conclude that Z. tritici populations have the potential to adapt rapidly to climate change and expand into new climatic zones.不同的热环境会对种群施加强烈且具有分化性的选择压力，进而引发局部适应，但目前学界对热适应的遗传基础仍知之甚少。本研究以小麦壳针孢菌（Zymoseptoria tritici）——一种小麦真菌病原菌——为研究对象，采用数量性状基因座（QTL）定位技术，解析热适应的遗传架构并筛选候选基因。我们选取源自相同热环境的4株野生型菌株进行杂交，构建了两个作图群体：杂交组合1包含263个子代菌株，杂交组合2包含261个子代菌株。采用限制性酶切位点相关DNA测序技术，对两个作图群体内分离的单核苷酸多态性标记进行基因分型，其中杂交组合1共获得9745个有效标记，杂交组合2共获得7333个有效标记。通过对两种不同温度下培养的菌落进行数码图像分析，评估菌株的温度敏感性。本研究共鉴定出4个与温度敏感性相关的QTL，且每个杂交组合仅存在特有的QTL。其中1个QTL的对数似然比（LOD）得分大于11，仅包含6个候选基因，包括PBS2——该基因编码一种丝裂原活化蛋白激酶激酶，在酿酒酵母（Saccharomyces cerevisiae）中已被证实与低温耐受相关。该QTL与其他多个QTL均表现出对生长速率、黑色素化及生长形态的多效性调控特征，这表明真菌的诸多性状均可与热适应存在关联。在两个杂交组合的子代中，高温环境均与菌丝状生长的转变呈现显著相关性。本研究证实，热适应的遗传架构较为复杂，小麦壳针孢菌的自然种群中存在与该性状相关的大量遗传变异。综上，小麦壳针孢菌种群具备快速适应气候变化并拓展至新气候区域的演化潜力。