FIGURE 2.

Exonucleolytic mRNA degradation pathways in plants. mRNA deadenylation can be performed through three different pathways mediated by the PAN2/3 complex, the CCR4/CAF1/NOT complex, or the PARN enzyme. After deadenylation, mRNAs may be degraded in 3′-5′ direction (3′-5′ mRNA decay) or in 5′-3′ direction (5′-3′mRNA decay). In the 3′-5′ route, transcripts are degraded by the exosome or by SOV. In the case of the 5′-3′ route, it is imperative to remove the 5′ CAP structure of the transcripts by the decapping complex before their degradation by XRN4. Proteins in color represent proteins that participate in regulating plant tolerance to abiotic stress. DCP5 and VCS are positive regulators of plant tolerance to drought. SPI positively regulates Arabidopsis tolerance to high salt. The LSM1-7 complex attenuates tolerance to drought and the cold acclimation process, while promoting salt stress tolerance. Solid and dotted arrows represent established and theoretical pathways, respectively.