Plant Developmental Biology and Plant Physiology, University of Kiel, Kiel, Germany.
Plant Biol (Stuttg). 2019 Jan;21 Suppl 1(Suppl Suppl 1):103-108. doi: 10.1111/plb.12873. Epub 2018 Aug 30.
Soil water-logging and flooding are common environmental stress conditions that can impair plant fitness. Roots are the first organs to be confronted with reduced oxygen tension as a result of flooding. While anatomical and morphological adaptations of roots are extensively studied, the root system architecture is only now becoming a focus of flooding research. Adventitious root (AR) formation shifts the root system higher up the plant, thereby facilitating supply with oxygen, and thus improving root and plant survival. We used Arabidopsis knockout mutants and overexpressors of ERFVII transcription factors to study their role in AR formation under hypoxic conditions and in response to ethylene. Results show that ethylene inhibits AR formation. Hypoxia mainly promotes AR elongation rather than formation mediated by ERFVII transcription factors, as indicated by reduced AR elongation in erfVII seedlings. Overexpression of HRE2 induces AR elongation to the same degree as hypoxia, while ethylene overrides HRE2-induced AR elongation. The ERFVII transcription factors promote establishment of an AR system that is under negative control by ethylene. Inhibition of growth of the main root system and promotion of AR elongation under hypoxia strengthens the root system in upper soil layers where oxygen shortage may last for shorter time periods.
土壤积水和洪涝是常见的环境胁迫条件，会损害植物的适应性。根部是最先受到水淹导致氧气张力降低影响的器官。尽管对根的解剖结构和形态适应性进行了广泛研究，但根系结构才刚刚成为洪涝研究的焦点。不定根（AR）的形成将根系向上延伸，从而更有利于供氧，从而提高根和植物的存活率。我们使用拟南芥基因敲除突变体和 ERFVII 转录因子过表达体来研究它们在缺氧条件下和响应乙烯时在 AR 形成中的作用。结果表明，乙烯抑制 AR 的形成。缺氧主要促进 AR 的伸长，而不是由 ERFVII 转录因子介导的形成，这表明 erfVII 幼苗中的 AR 伸长减少。HRE2 的过表达诱导 AR 伸长的程度与缺氧相同，而乙烯则会抑制 HRE2 诱导的 AR 伸长。ERFVII 转录因子促进了一个受乙烯负调控的 AR 系统的建立。缺氧下主根系统生长的抑制和不定根伸长的促进，增强了上层土壤中根系的强度，因为在这些土壤中，缺氧可能持续的时间更短。
