National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
Mol Plant. 2010 Sep;3(5):794-806. doi: 10.1093/mp/ssq042. Epub 2010 Sep 16.
MicroRNAs (miRNAs) are ∼21-nucleotide noncoding RNAs that play critical roles in regulating plant growth and development through directing the degradation of target mRNAs. Axillary meristem activity, and hence shoot branching, is influenced by a complicated network that involves phytohormones such as auxin, cytokinin, and strigolactone. GAI, RGA, and SCR (GRAS) family members take part in a variety of developmental processes, including axillary bud growth. Here, we show that the Arabidopsis thaliana microRNA171c (miR171c) acts to negatively regulate shoot branching through targeting GRAS gene family members SCARECROW-LIKE6-II (SCL6-II), SCL6-III, and SCL6-IV for cleavage. Transgenic plants overexpressing MIR171c (35Spro-MIR171c) and scl6-II scl6-III scl6-IV triple mutant plants exhibit a similar reduced shoot branching phenotype. Expression of any one of the miR171c-resistant versions of SCL6-II, SCL6-III, and SCL6-IV in 35Spro-MIR171c plants rescues the reduced shoot branching phenotype. Scl6-II scl6-III scl6-IV mutant plants exhibit pleiotropic phenotypes such as increased chlorophyll accumulation, decreased primary root elongation, and abnormal leaf and flower patterning. SCL6-II, SCL6-III, and SCL6-IV are located to the nucleus, and show transcriptional activation activity. Our results suggest that miR171c-targeted SCL6-II, SCL6-III, and SCL6-IV play an important role in the regulation of shoot branch production.
微 RNA（miRNA）是约 21 个核苷酸的非编码 RNA，通过指导靶 mRNA 的降解，在调控植物生长和发育中发挥关键作用。腋芽分生组织的活性，进而影响枝梢分支，受到涉及植物激素如生长素、细胞分裂素和独脚金内酯的复杂网络的影响。GAI、RGA 和 SCR（GRAS）家族成员参与多种发育过程，包括腋芽生长。在这里，我们表明拟南芥 microRNA171c（miR171c）通过靶向 GRAS 基因家族成员 SCARECROW-LIKE6-II（SCL6-II）、SCL6-III 和 SCL6-IV 进行切割，负调控枝梢分支。过表达 MIR171c（35Spro-MIR171c）的转基因植物和 scl6-II scl6-III scl6-IV 三重突变体植物表现出类似的减少枝梢分支表型。在 35Spro-MIR171c 植物中表达任何一种 miR171c 抗性版本的 SCL6-II、SCL6-III 和 SCL6-IV 均可挽救减少的枝梢分支表型。Scl6-II scl6-III scl6-IV 突变体植物表现出多种表型，如叶绿素积累增加、主根伸长减少以及叶片和花的异常模式。SCL6-II、SCL6-III 和 SCL6-IV 定位于细胞核，并显示转录激活活性。我们的结果表明，miR171c 靶向的 SCL6-II、SCL6-III 和 SCL6-IV 在调控枝梢产生中发挥重要作用。
