State Key Laboratory of Plant Physiology and Biochemistry/National Maize Improvement Center/College of Agronomy and Biotechnology/Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, 2 West Yuanmingyuan Road, Beijing 100193, P. R. China.
State Key Laboratory of Plant Physiology and Biochemistry/National Maize Improvement Center/College of Agronomy and Biotechnology/Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, 2 West Yuanmingyuan Road, Beijing 100193, P. R. China.
Mol Plant. 2019 Mar 4;12(3):360-373. doi: 10.1016/j.molp.2018.10.005. Epub 2018 Oct 25.
To optimize fitness, plants must efficiently allocate their resources between growth and defense. Although phytohormone crosstalk has emerged as a major player in balancing growth and defense, the genetic basis by which plants manage this balance remains elusive. We previously identified a quantitative disease-resistance locus, qRfg2, in maize (Zea mays) that protects against the fungal disease Gibberella stalk rot. Here, through map-based cloning, we demonstrate that the causal gene at qRfg2 is ZmAuxRP1, which encodes a plastid stroma-localized auxin-regulated protein. ZmAuxRP1 responded quickly to pathogen challenge with a rapid yet transient reduction in expression that led to arrested root growth but enhanced resistance to Gibberella stalk rot and Fusarium ear rot. ZmAuxRP1 was shown to promote the biosynthesis of indole-3-acetic acid (IAA), while suppressing the formation of benzoxazinoid defense compounds. ZmAuxRP1 presumably acts as a resource regulator modulating indole-3-glycerol phosphate and/or indole flux at the branch point between the IAA and benzoxazinoid biosynthetic pathways. The concerted interplay between IAA and benzoxazinoids can regulate the growth-defense balance in a timely and efficient manner to optimize plant fitness.
为了优化适应性，植物必须在生长和防御之间有效地分配资源。尽管植物激素串扰已成为平衡生长和防御的主要参与者，但植物管理这种平衡的遗传基础仍难以捉摸。我们之前在玉米（Zea mays）中鉴定了一个数量性状抗病基因座 qRfg2，该基因座可抵抗真菌病害赤霉茎腐病。在这里，通过图谱克隆，我们证明 qRfg2 上的致病基因是 ZmAuxRP1，它编码一个质体基质定位的生长素调节蛋白。ZmAuxRP1 对病原体的快速响应导致表达迅速而短暂地降低，从而导致根生长受阻，但增强了对赤霉茎腐病和镰刀菌穗腐病的抗性。ZmAuxRP1 被证明可以促进吲哚-3-乙酸（IAA）的生物合成，同时抑制苯并恶嗪防御化合物的形成。ZmAuxRP1 可能作为一种资源调节剂，在 IAA 和苯并恶嗪生物合成途径的分支点调节吲哚-3-甘油磷酸和/或吲哚通量。IAA 和苯并恶嗪类化合物之间的协同作用可以以一种及时和有效的方式调节生长-防御平衡，从而优化植物适应性。
