Developmental Effects of Decapping

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Science  13 Jul 2007:
Vol. 317, Issue 5835, pp. 171
DOI: 10.1126/science.317.5835.171c

The balance between synthesis and degradation controls mRNA abundance. Goeres et al. have found that the 5′ to 3′ mRNA degradation pathway involves an mRNA decapping complex and is crucial for seedling development in Arabidopsis. The phenotypes of varicose (vcs) and trident (tdt) mutants were similar: defective leaf formation with vein defects, short roots with swollen root hairs, and swollen hypocotyls. Confocal microscopy revealed that the shoot apical meristem cells were disorganized in the vcs and tdt plants and that leaf primordia were absent in seedlings that were 3 days old, which is when the leaf primordia would normally appear. Further analysis suggested that the tdt vascular phenotype arose as a consequence of defective formation of the provascular cell specification, which is controlled by auxin signaling, in the hypocotyl-to-cotyledon transition zone. TDT encodes a protein homologous to DCP2, which in yeast and mammals is an mRNA decapping enzyme. VCS, which interacts with TDT, appears to be important for localizing TDT to cytoplasmic P bodies, which are sites of mRNA decapping and degradation. However, in vcs and tdt mutants, not all mRNAs exhibited decreased decay rates, suggesting that this particular mRNA decay pathway was specific to a subset of transcripts. — NRG

Plant Cell 19, 1549 (2007).

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