Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura, Facultad de Agronomía, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires 1417, Argentina.
Fundaciόn Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires 1405, Argentina.
Proc Natl Acad Sci U S A. 2023 Sep 26;120(39):e2304513120. doi: 10.1073/pnas.2304513120. Epub 2023 Sep 19.
Nitrate supply is fundamental to support shoot growth and crop performance, but the associated increase in stem height exacerbates the risks of lodging and yield losses. Despite their significance for agriculture, the mechanisms involved in the promotion of stem growth by nitrate remain poorly understood. Here, we show that the elongation of the hypocotyl of , used as a model, responds rapidly and persistently to upshifts in nitrate concentration, rather than to the nitrate level itself. The response occurred even in shoots dissected from their roots and required NITRATE TRANSPORTER 1.1 (NRT1.1) in the phosphorylated state (but not NRT1.1 nitrate transport capacity) and NIN-LIKE PROTEIN 7 (NLP7). Nitrate increased PHYTOCHROME INTERACTING FACTOR 4 (PIF4) nuclear abundance by posttranscriptional mechanisms that depended on NRT1.1 and phytochrome B. In response to nitrate, PIF4 enhanced the expression of numerous genes in the hypocotyl. The growth response to nitrate required PIF4, positive and negative regulators of its activity, including AUXIN RESPONSE FACTORs, and SAURs. PIF4 integrates cues from the soil (nitrate) and aerial (shade) environments adjusting plant stature to facilitate access to light.
硝酸盐供应是支持茎生长和作物表现的基础，但与之相关的茎高增加加剧了倒伏和产量损失的风险。尽管硝酸盐对农业具有重要意义，但硝酸盐促进茎生长的机制仍知之甚少。在这里，我们表明，拟南芥下胚轴的伸长对硝酸盐浓度的快速和持续反应，而不是对硝酸盐水平本身的反应。即使在将茎从根部分离后，该反应仍然会发生，并且需要处于磷酸化状态的硝酸盐转运蛋白 1.1（NRT1.1）（而不是 NRT1.1 硝酸盐转运能力）和类 NIN 蛋白 7（NLP7）。硝酸盐通过依赖于 NRT1.1 和光敏色素 B 的转录后机制增加了 PHYTOCHROME INTERACTING FACTOR 4（PIF4）的核丰度。响应硝酸盐，PIF4 增强了下胚轴中许多基因的表达。硝酸盐的生长反应需要 PIF4，以及其活性的正、负调节剂，包括 AUXIN RESPONSE FACTORs 和 SAURs。PIF4 整合了来自土壤（硝酸盐）和空气（遮荫）环境的线索，调整植物的高度以方便获得光照。
