Joint International Research Laboratory of Metabolic & Developmental Sciences, State Key Laboratory of Hybrid Rice, SJTU-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
Future Food Beacon and School of Biosciences, University of Nottingham, LE12 5RD, United Kingdom.
Proc Natl Acad Sci U S A. 2022 Jul 26;119(30):e2201072119. doi: 10.1073/pnas.2201072119. Epub 2022 Jul 18.
Soil compaction represents a major agronomic challenge, inhibiting root elongation and impacting crop yields. Roots use ethylene to sense soil compaction as the restricted air space causes this gaseous signal to accumulate around root tips. Ethylene inhibits root elongation and promotes radial expansion in compacted soil, but its mechanistic basis remains unclear. Here, we report that ethylene promotes abscisic acid (ABA) biosynthesis and cortical cell radial expansion. Rice mutants of ABA biosynthetic genes had attenuated cortical cell radial expansion in compacted soil, leading to better penetration. Soil compaction-induced ethylene also up-regulates the auxin biosynthesis gene . Mutants lacking OsYUC8 are better able to penetrate compacted soil. The auxin influx transporter OsAUX1 is also required to mobilize auxin from the root tip to the elongation zone during a root compaction response. Moreover, mutants penetrate compacted soil better than the wild-type roots and do not exhibit cortical cell radial expansion. We conclude that ethylene uses auxin and ABA as downstream signals to modify rice root cell elongation and radial expansion, causing root tips to swell and reducing their ability to penetrate compacted soil.
土壤板结是一个主要的农业挑战，它抑制了根系的伸长，从而影响了作物的产量。根系利用乙烯来感知土壤板结，因为受限的空气空间会导致这种气态信号在根尖周围积累。乙烯抑制了根系的伸长，并促进了在紧实土壤中的径向扩张，但它的机械基础仍不清楚。在这里，我们报告说，乙烯促进脱落酸（ABA）的生物合成和皮层细胞的径向扩张。ABA 生物合成基因缺失的水稻突变体在紧实土壤中的皮层细胞径向扩张减弱，从而使根系更容易穿透土壤。土壤紧实诱导的乙烯也上调了生长素生物合成基因 。生长素流入载体 OsAUX1 也需要在根系紧实反应中从根尖向伸长区运输生长素。此外， 突变体比野生型根系更容易穿透紧实土壤，并且不会表现出皮层细胞的径向扩张。我们的结论是，乙烯利用生长素和 ABA 作为下游信号来修饰水稻根细胞的伸长和径向扩张，导致根尖膨胀，并降低其穿透紧实土壤的能力。
