Abstract:
Isoxaben is a pre-emergent herbicide used to control broadleaf weeds. While the phytotoxic mechanism is not completely understood, isoxaben interferes with cellulose synthesis. Certain mutations in cellulose synthase complex proteins can confer isoxaben tolerance; however, these mutations can cause compromised cellulose synthesis and perturbed plant growth, rendering them unsuitable as herbicide tolerance traits. We conducted a genetic screen to identify new genes associated with isoxaben tolerance by screening a selection of Arabidopsis thaliana T-DNA mutants. We found that mutations in a FERREDOXIN-NADP(+) OXIDOREDUCTASE-LIKE (FNRL) gene enhanced tolerance to isoxaben, exhibited as a reduction in primary root stunting, reactive oxygen species accumulation and ectopic lignification. The fnrl mutant did not exhibit a reduction in cellulose levels following exposure to isoxaben, indicating that FNRL operates upstream of isoxaben-induced cellulose inhibition. In line with these results, transcriptomic analysis revealed a highly reduced response to isoxaben treatment in fnrl mutant roots. The fnrl mutants displayed constitutively induced mitochondrial retrograde signalling, and the observed isoxaben tolerance is partially dependent on the transcription factor ANAC017, a key regulator of mitochondrial retrograde signalling. Moreover, FNRL is highly conserved across all plant lineages, implying conservation of its function. Notably, fnrl mutants did not show a growth penalty in shoots, making FNRL a promising target for biotechnological applications in breeding isoxaben tolerance in crops.
摘要:
isoxaben是一种发芽前除草剂,用于控制阔叶杂草。虽然植物毒性机制尚未完全了解,异羟苯干扰纤维素合成。纤维素合酶复合物蛋白中的某些突变可以赋予异羟苯耐受性;然而,这些突变会导致纤维素合成受损和植物生长紊乱,使它们不适合作为除草剂耐受性性状。通过筛选拟南芥T-DNA突变体,我们进行了遗传筛选,以鉴定与异草酚耐受性相关的新基因。我们发现FERREDOXIN-NADP(+)氧化还原酶样(FNRL)基因的突变增强了对异恶沙芬的耐受性,表现为主根发育迟缓的减少,活性氧积累和异位木质化。fnrl突变体在暴露于isoxaben后没有表现出纤维素水平的降低,表明FNRL在异氧苯诱导的纤维素抑制的上游起作用。根据这些结果,转录组学分析显示,fnrl突变体根中对异氧苯处理的反应大大降低。fnrl突变体显示组成型诱导的线粒体逆行信号,和观察到的异洛沙芬耐受性部分依赖于转录因子ANAC017,线粒体逆行信号传导的关键调节因子。此外,FNRL在所有植物谱系中都高度保守,暗示其功能的守恒。值得注意的是,fnrl突变体在芽中没有表现出生长损失,使FNRL成为生物技术应用于作物耐异恶沙芬育种的有希望的目标。