英文摘要

Nitrate is the preferred form of nitrogen for most plants, acting both as a nutrient and a signaling molecule. However, the components and regulatory factors governing nitrate uptake in bread wheat (Triticum aestivum), one of the world's most important crop species, have remained unclear, largely due to the complexity of its hexaploid genome.

Here, based on recently released whole-genome information for bread wheat, the high-affinity nitrate transporter 2 (NRT2) and the nitrate-assimilation-related (NAR) gene family are characterized. We show that ABA-GE deconjugation is stimulated in bread wheat roots by nitrate resupply following nitrate withdrawal, leading to enhanced root-tissue ABA accumulation, and that this enhancement, in turn, affects the expression of root-type NRT2/NAR genes. TaANR1 is shown to regulate nitrate-mediated ABA accumulation by directly activating TaBG1, while TaWabi5 is involved in ABA-mediated NO₃^- induction of NRT2/NAR genes.

Building on previous evidence establishing ABA involvement in the developmental response to high-nitrate stress, our study suggests that ABA also contributes to the optimisation of nitrate uptake by regulating the expression of NRT2/NAR genes under limited nitrate supply, offering a new target for improvement of nitrate absorption in crops.

中文摘要（谷歌机翻译）

硝酸盐是大多数植物的首选氮素形式，既可作为营养物又可作为信号分子。然而，控制面包小麦（世界上最重要的农作物之一）中硝酸盐吸收的成分和调控因素仍不清楚，这主要是由于其六倍体基因组的复杂性。

在此，根据最近发布的面包小麦全基因组信息，对高亲和力硝酸盐转运蛋白2（NRT2）和硝酸盐同化相关（NAR）基因家族进行了表征。我们表明，硝酸盐撤除后，硝酸盐再供应会刺激面包小麦根中的ABA-GE解偶联，从而导致根组织ABA积累增强，而这种增强反过来又会影响根型NRT2 / NAR基因的表达。显示TaANR1通过直接激活TaBG1来调节硝酸盐介导的ABA积累，而TaWabi5参与ABA介导的NRT2 / NAR基因的NO₃^-诱导。

基于先前的证据，证明ABA参与了对高硝酸盐胁迫的发育反应，我们的研究表明ABA还通过调节有限的硝酸盐供应下的NRT2 / NAR基因的表达来促进硝酸盐吸收的优化，为改良提供了新的目标作物中硝酸盐的吸收。