Next Generation Sequencing analysis of the effects of seed HSF (HaHSFA9 or HSFA4a) overexpression in transgenic tobacco

Background: Heat Stress Factor A9 (A9), a seed-specific transcription factor contributing to seed longevity, also enhances phytochrome-dependent seedling greeningResults: The RNA-seq analyses of imbibed-seed transcripts here reported indicated, potential, additional effects of A9 on cryptochrome-mediated blue-light responses. These analyses also suggested that in contrast to the A9 effects on longevity, which require coactivation by additional factors as A4a, A9 alone might suffice for the enhancement of photomorphogenesis at the seedling stage. We find that upon its seed-specific over-expression, A9 indeed enhanced the expected blue-light responses. Comparative loss-of-function analyses of longevity and greening, performed by similar expression of dominant-negative and inactive forms of A9, not only confirmed the additional greening effects of A9, but also were consistent with A9 not requiring A4a (or additional factors) for the greening effectsConclusion: Our results strongly indicate that A9 would differentially regulate seed longevity and photomorphogenesis at the seedling stage, A9 alone sufficing for both the phytochrome- and cryptochrome-dependent greening enhancement effects

背景：热胁迫因子A9（Heat Stress Factor A9，简称A9）是一类种子特异性转录因子，既参与调控种子寿命，还可增强依赖光敏色素（phytochrome）的幼苗绿化过程。
结果：本研究针对吸胀种子转录本开展的RNA测序（RNA-seq）分析显示，A9还可能参与隐花色素（cryptochrome）介导的蓝光响应通路。该分析同时表明，与A9调控种子寿命的作用模式不同——后者需要A4a等额外因子的共激活，A9单独即可介导幼苗阶段的光形态建成（photomorphogenesis）增强。我们通过种子特异性过表达A9，证实其确实能增强预期的蓝光响应。通过以相似表达模式构建A9的显性负突变体与失活变体，开展寿命与绿化的功能丧失对比分析，不仅验证了A9额外的绿化调控功能，同时也证实A9介导绿化效应时无需A4a（或其他额外因子）的辅助。
结论：本研究结果充分表明，A9可差异化调控种子寿命与幼苗阶段的光形态建成；其单独即可介导依赖光敏色素与隐花色素的绿化增强效应。