Under normal growth conditions, Phytochrome-Interacting Fact...

created [InstanceEdit:9924415]
dbId 9924446
displayName Under normal growth conditions, Phytochrome-Interacting Fact...
literatureReference
modified [InstanceEdit:9928314] Naithani, Sushma, 2024-11-13
schemaClass Summation
text Under normal growth conditions, Phytochrome-Interacting Factor-like 15 (OsPIL15) promotes transcription of the RMD1 in the light-exposed tissue (stem, leaves, flowers). RMD1 protein is localized on the surface of chloroplasts/statoliths, and it interacts with cytoskeleton components (actin and bundle microtubules) to direct the movement and proper spatial organization of the statoliths in the opposite direction of gravity. Accordingly, RMD1 and OsPIL15 promote shoot-negative gravitropism/counter the effect of gravity (Song et al., 2019) that leads to compact/erect plants with narrow tiller angles. However, OsPIL15 is negatively regulated by the OsPHYB/pfrB. Thus, OsPIL15 integrates light and gravity signals to regulate the tiller angle in rice. Reduction in OsPIL15 or RMD1 expression causes large tiller angles, whereas OsPIL15-overexpression leads to narrow tiller angles (Xie et al. 2019). RMD1 expression does not occur in roots under normal growth conditions. In roots (in the dark), Phytochrome-Interacting Factor 16 (OsPIL16) represses transcription of the RMD1 gene (Song et al., 2019). OsPIL15 is expressed in roots; however, OsPIL16 has a stronger effect on RMD expression in roots than OsPIL15 (Song et al., 2019). Thus, the absence of RMD1 promotes growth in the direction of gravity/gravitropism. In light, OsPIL16 is degraded, and RMD1 gene expression occurs, leading to negative shoot gravitropism. The rmd mutants show a bending growth pattern in seedlings, stunting phenotype in mature plants, aberrant inflorescence (panicle), and seed shape. At the microscopic level, the rmd mutants show severe defects in cell elongation and microfilament organization.

However, RMD1 expression in columella cells of root cap is upregulated under phosphate deficiency, resulting in a reduction in root angle and the formation of shallower roots? to improve phosphate acquisition from the topsoil (Huang et al., 2018).