Trans-generational adaptation to maternal climate through hormone transport in plants [scRNA-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: single nucleus RNA-seq was performed on whole developing siliques including seeds at the bend cotyledon stage of embryo development. Plants were grown in controlled long day conditions at 16°C D/14°C N. with a single day transfer to 22°C for the relevant samples to match developmental stage. Plants are WT Col-0 or homozygous lhp1-6 in the Col-0 background.