The conserved splicing factor PRP21 regulates abscisic acid response and seed germination in Arabidopsis [RNA-Seq]

Seed germination is a critical developmental stage in the life cycle of plants, and its regulation is essential for ensuring crop productivity, particularly under adverse environmental conditions. Here, we find that the Arabidopsis thaliana PRE-MRNA-PROCESSING (PRP21) is crucial for the regulation of abscisic acid (ABA) response of seed germination. Our RNA deep sequencing and poly(A) tag sequencing analyses reveal that PRP21 is involved in pre-mRNA splicing, genome-wide gene transcription, and mRNA 3' end processing, highlighting its multifunctional role in gene regulation. Furthermore, we find that PRP21 interacts with various splicing factors and small nuclear ribonucleoproteins, suggesting its involvement in spliceosome assembly. Additionally, we demonstrate that PRP21 negatively regulates the expression of ABA-responsive genes, such as ABSCISIC ACID-INSENSITIVE 3 (ABI3), ABSCISIC ACID-INSENSITIVE 5 (ABI5), EARLY METHIONINE-LABELED 1 (EM1), and EARLY METHIONINE-LABELED 6 (EM6), thereby modulating ABA response and seed germination. Our findings underscore the importance of PRP21 in coordinating transcriptional and post-transcriptional processes, and provide insights into the molecular mechanisms underlying seed germination, potentially guiding crop improvement for stress tolerance. Examination of the mRNA expression of wild type and prp21 mutant in Arabidopsis at 2, 7, and 14 days old.