Rice tillering is an important agronomic trait affecting grain yield. Here, we identified a high-tillering mutant tillering20 (t20), which could be restored to the wild type by treatment with the strigolactone (SL) analog rac-GR24. T20 encodes a chloroplast ζ-carotene isomerase (Z-ISO), which is involved in the biosynthesis of carotenoids and their metabolites, SL and abscisic acid (ABA). The t20 mutant has reduced SL and ABA, raising the question of how SL and ABA biosynthesis is coordinated, and whether they have overlapping functions in tillering. We discovered that rac-GR24 stimulated T20 expression and enhanced all-trans-β-carotene biosynthesis. Importantly, rac-GR24 also stimulated expression of Oryza sativa 9-CIS-EPOXYCAROTENOID DIOXYGENASE 1 (OsNCED1) through induction of Oryza sativa HOMEOBOX12 (OsHOX12), promoting ABA biosynthesis in shoot base. On the other hand, ABA treatment significantly repressed SL biosynthesis and the ABA biosynthetic mutants displayed elevated SL biosynthesis. ABA treatment reduced the number of basal tillers in both t20 and wild-type plants. Furthermore, while ABA-deficient mutants aba1 and aba2 had the same number of basal tillers as wild type, they had more unproductive upper tillers at maturity. This work demonstrates complex interactions in the biosynthesis of carotenoid, SLs and ABA, and reveals a role for ABA in the regulation of rice tillering.

水稻分ing是影响谷物产量的重要农艺性状。在这里，我们确定了一个高分mutant突变体therling20（t20），可以通过用strigolactone（SL）类似物rac -GR24处理将其恢复为野生型。T20编码叶绿体ζ-胡萝卜素异构酶（Z-ISO），参与类胡萝卜素及其代谢产物SL和脱落酸（ABA）的生物合成。在T20突变体已经减少SL和ABA，提高的SL和ABA生物合成是如何协调的问题，以及他们是否已在分蘖功能重叠。我们发现rac -GR24刺激T20表达并增强全反式-β-胡萝卜素的生物合成。重要的是，rac -GR24还通过诱导水稻HOMEOBOX12（OsHOX12）来刺激水稻9-CIS-环氧类胡萝卜素二氧化合酶1（OsNCED1）的表达，促进芽基中ABA的生物合成。另一方面，ABA处理显着抑制SL生物合成，而ABA生物合成突变体显示SL生物合成升高。ABA处理可减少t20和野生型植物中基础分till的数量。此外，而缺乏ABA的突变体aba1和aba2基部分as的数量与野生型相同，成熟时上部分un的生产率更高。这项工作证明了类胡萝卜素，SLs和ABA生物合成中的复杂相互作用，并揭示了ABA在调节水稻分ing中的作用。