| Categories genes  | Tags growth  resistance  lodging  lodging resistance  height  lignin  lignin biosynthesis  plant growth  development  fertility  pollen  sterility  seed  pollen development  root  root development  reproductive  root growth  ga  ga  cell elongation  GA  GA biosynthesis 
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  • Key message
    • Rice leucine-rich repeat extensin-like protein OsPEX1 mediates the intersection of lignin deposition and plant growth
    • When OsPEX1 was ectopically expressed in rice cultivars with tall stature that lacks the allele of semi-dwarf 1, well-known green revolution gene, the resulting transgenic plants displayed reduced height and enhanced lodging resistance
    • Lastly, we demonstrated that modulating OsPEX1 expression could provide a tool for improving rice lodging resistance
    • Conversely, OsPEX1-suppresssed transgenics displayed low lignin content and reduced transcriptional abundance of genes associated with lignin biosynthesis, indicating that the OsPEX1 mediates lignin biosynthesis and/or deposition in rice
    • Our study uncovers a causative effect between the expression of OsPEX1 and lignin deposition
    • The OsPEX1 gene is preferentially expressed in rice anther, suggesting that it may be involved in the regulation of pollen development
    • Effect of extensin-like OsPEX1 on pollen fertility in rice
    • The OsPEX1 RNAi transgenic lines showed a significant decrease in seed setting rate (10%~30%) due to pollen sterility
    • However, whether and how OsPEX1 affects root growth is unclear
    • Here, we found that overexpression of OsPEX1 retarded root growth by reducing cell elongation likely caused by an increase of lignin deposition, whereas knockdown of OsPEX1 had an opposite effect on root growth, indicating that OsPEX1 negatively regulated root growth in rice
    • Further investigation uncovered the existence of a feedback loop between OsPEX1 expression level and GA biosynthesis for proper root growth
    • This was supported by the facts that exogenous GA(3) application downregulated transcript levels of OsPEX1 and lignin-related genes and rescued the root developmental defects of the OsPEX1 overexpression mutant, whereas OsPEX1 overexpression reduced GA level and the expression of GA biosynthesis genes
    • Moreover, OsPEX1 and GA showed antagonistic action on the lignin biosynthesis in root
    • Taken together, this study reveals a possible molecular pathway of OsPEX1mediated regulation of root growth through coordinate modulation of lignin deposition via a negative feedback regulation between OsPEX1 expression and GA biosynthesis
    • In contrast to the tissue specificity of Arabidopsis PEX genes in reproductive organs, rice OsPEX1 is also highly expressed in roots in addition to reproductive tissue
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