Trans-generational adaptation to maternal climate through hormone transport in plants [bulk RNA-seq]

Whether and how organisms can inherit environmental information from their parents is a major question in evolutionary theory. Plants have evolved to link reproductive development to seasonal environmental cues and seed dormancy is highly contingent on the environmental temperature during seed set, although the mechanism by which seeds acquire seasonal timing information is unclear. Here we show that loss of maternal like heterochromatin protein 1 (LHP1) causes an inability of progeny seeds to sense temperature and that this is linked mechanistically to reduced ABA levels in seeds and hyperaccumulation of free nitrate. Remarkably, single cell transcriptomics reveals that in both maternal fruit and seed tissues, the effect of small changes in temperature closely phenocopies the lhp1 mutant phenotype and ABA biosensor imaging reveal large fluxes of maternal ABA into seeds is modulated by temperature cues. We show that temperature activates ABA production in leaves and that maternal ABA is necessary and sufficient for progeny seeds to acquire seed dormancy. Thus, we reveal that the climate experience of mother plants causes adaptation of progeny behaviour via hormone transport during seed set. Overall design: siliques were dissected to separate fruit tissue and seed tissue which were sequenced seperately. Lhp1-6 and WT Col-0 were grown at 16°CD/14°CN.

生物能否以及如何从亲代处继承环境信息，是进化理论领域的核心议题之一。植物演化出将生殖发育与季节性环境信号相偶联的机制；种子休眠高度依赖结籽期的环境温度，尽管种子获取季节性时序信息的分子机制尚未明确。

本研究发现，缺失类母源异染色质蛋白1（LHP1）会导致子代种子丧失温度感知能力，且该现象在分子机制上与种子内脱落酸（Abscisic Acid, ABA）水平降低以及游离硝酸盐过度积累相关。值得注意的是，单细胞转录组学（single cell transcriptomics）分析显示，在母本果实与种子组织中，微小的温度变化所产生的效应与lhp1突变体的表型高度相似；同时ABA生物传感器成像结果表明，母源ABA向种子的大量转运受温度信号调控。我们还证实，温度可激活叶片中ABA的合成，且母源ABA对子代种子获得休眠能力既是必需的，也是充分的。综上，本研究揭示了母本植株所经历的气候环境，可通过结籽期的激素转运过程，调控子代的适应性行为。

实验整体设计：将角果解剖以分离果实组织与种子组织，分别进行测序；实验所用材料为lhp1-6突变体与野生型哥伦比亚生态型（Col-0, WT），培养条件为16℃昼间/14℃夜间。