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Proc Natl Acad Sci U S A. 2014 Jul 15. pii: 201411859. [Epub ahead of print]

Strigolactones regulate rice tiller angle by attenuating shoot gravitropism through inhibiting auxin biosynthesis.

Author information

  • 1State Key Laboratory of Plant Genomics andNational Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; and.
  • 2National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; and.
  • 3State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China.
  • 4State Key Laboratory of Plant Genomics andNational Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; and yhwang@genetics.ac.cn jyli@genetics.ac.cn.

Abstract

Tiller angle, a key agronomic trait for achieving ideal plant architecture and increasing grain yield, is regulated mainly by shoot gravitropism. Strigolactones (SLs) are a group of newly identified plant hormones that are essential for shoot branching/rice tillering and have further biological functions as yet undetermined. Through screening for suppressors of lazy1 (sols), a classic rice mutant exhibiting large tiller angle and defective shoot gravitropism, we identified multiple SOLS that are involved in the SL biosynthetic or signaling pathway. We show that SL biosynthetic or signaling mutants can rescue the spreading phenotype of lazy1 (la1) and that SLs can inhibit auxin biosynthesis and attenuate rice shoot gravitropism, mainly by decreasing the local indoleacetic acid content. Although both SLs and LA1 are negative regulators of polar auxin transport, SLs do not alter the lateral auxin transport of shoot base, unlike LA1, which is a positive regulator of lateral auxin transport in rice. Genetic evidence demonstrates that SLs and LA1 participate in regulating shoot gravitropism and tiller angle in distinct genetic pathways. In addition, the SL-mediated shoot gravitropism is conserved in Arabidopsis. Our results disclose a new role of SLs and shed light on a previously unidentified mechanism underlying shoot gravitropism. Our study indicates that SLs could be considered as an important tool to achieve ideal plant architecture in the future.

PMID:
25028496
[PubMed - as supplied by publisher]
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