Functional variants of DOG1 control seed chilling responses and variation in seasonal life-history strategies in Arabidopsis thaliana
Functional variants of DOG1 control seed chilling responses and variation in seasonal life-history strategies in Arabidopsis thaliana
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DOI：
10.1073/pnas.1912451117
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发表时间：
2020-01
影响因子：
11.1
通讯作者：
Alejandra Martínez-Berdeja;Michelle C. Stitzer;M. Taylor;M. Okada;E. Ezcurra;D. Runcie;J. Schmitt
中科院分区：
文献类型：
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作者：
Alejandra Martínez-Berdeja;Michelle C. Stitzer;M. Taylor;M. Okada;E. Ezcurra;D. Runcie;J. Schmitt
种子萌发的季节性时间对于不同气候条件下的植物适应性至关重要。为了在一年中正确的时间发芽，种子会对季节性的环境信号做出反应，比如寒冷的温度。我们的特点是遗传变异的种子休眠反应冷在整个地理范围内广泛的一年生植物。冬季条件下种子次生休眠的诱导（将发芽限制在秋季）与开花时间正相关，构建了冬季和春季季节性生活史策略。种子低温反应的变化与一个已知的休眠基因的功能变体密切相关。这些变种显示了与更新世冰川循环有关的古代多样性的证据，并与物种地理范围内的气候梯度有关。种子萌发的季节性时间决定了植物实现的环境生态位，对于适应气候非常重要。季节性萌发的时间取决于种子休眠解除或冷诱导的模式，并与开花时间的变化相互作用，以构建不同的季节生活史。为了表征种子冷却反应和相关生活史综合征的自然变异的遗传基础和气候关联，我们从广泛的气候范围内选择了559个完全测序的模式一年生物种拟南芥，并对13个冷层积处理范围内的种子萌发以及开花和衰老的时间进行了评分。萌发策略沿着2个主轴连续变化：1）总体萌发分数和2）诱导与解除休眠的冷。种子对低温反应的自然变化与开花时间和衰老相关，从而产生一系列季节性生活史综合征。全基因组关联确定了几个基因座与种子冷冻反应的自然变异，包括已知的功能多态性的候选基因DOG1的自我结合域。DOG1单倍型的同源性揭示了与更新世气候变化时期相关的这些功能变体的古老分歧，梯度森林分析表明候选SNP的等位基因转换与气候梯度显著相关。这些结果为A.过去的气候周期以及当地对当代气候的适应形成了拟南芥的发芽生态位和相关的生活史综合征。
Significance The seasonal timing of seed germination is critical for plant fitness in different climates. To germinate at the right time of year, seeds respond to seasonal environmental cues, such as cold temperatures. We characterized genetic variation in seed dormancy responses to cold across the geographic range of a widespread annual plant. Induction of secondary seed dormancy during winter conditions (which restricts germination to autumn) was positively correlated with flowering time, constructing winter and spring seasonal life-history strategies. Variation in seed chilling responses was strongly associated with functional variants of a known dormancy gene. These variants showed evidence of ancient diversification associated with Pleistocene glacial cycles, and were associated with climate gradients across the species’ geographical range. The seasonal timing of seed germination determines a plant’s realized environmental niche, and is important for adaptation to climate. The timing of seasonal germination depends on patterns of seed dormancy release or induction by cold and interacts with flowering-time variation to construct different seasonal life histories. To characterize the genetic basis and climatic associations of natural variation in seed chilling responses and associated life-history syndromes, we selected 559 fully sequenced accessions of the model annual species Arabidopsis thaliana from across a wide climate range and scored each for seed germination across a range of 13 cold stratification treatments, as well as the timing of flowering and senescence. Germination strategies varied continuously along 2 major axes: 1) Overall germination fraction and 2) induction vs. release of dormancy by cold. Natural variation in seed responses to chilling was correlated with flowering time and senescence to create a range of seasonal life-history syndromes. Genome-wide association identified several loci associated with natural variation in seed chilling responses, including a known functional polymorphism in the self-binding domain of the candidate gene DOG1. A phylogeny of DOG1 haplotypes revealed ancient divergence of these functional variants associated with periods of Pleistocene climate change, and Gradient Forest analysis showed that allele turnover of candidate SNPs was significantly associated with climate gradients. These results provide evidence that A. thaliana’s germination niche and correlated life-history syndromes are shaped by past climate cycles, as well as local adaptation to contemporary climate.