Transcriptome and translatome profiling and translational network analysis during seed maturation reveals conserved transcriptional and distinct translational regulatory patterns

Abstract

25Seed maturation is an important plant developmental process that follows embryo development. It is 26 associated with a series of physiological changes such as the establishment of desiccation tolerance, 27 seed longevity and seed dormancy. However, the translational dynamics associated with seed 28 maturation, especially its connection with seed germination remains largely elusive. Here 29 transcriptome and translatome profiling were performed during seed maturation. During seed 30 maturation we observed a gradual disappearance of polysomes and a relative increase of monosomes, 31 indicating a gradual reduction of global translation. Comparing the levels of polysomal associated 32 mRNAs with total mRNA levels showed that thousands of genes are translationally regulated at early 33 sates of maturation, as judged by dramatic changes in polysomal occupancy. By including previous 34 published data from germination and seedling establishment, a translational regulatory network: 35SeedTransNet was constructed. Network analysis identified hundreds of gene modules with distinct 36 functions and transcript sequence features indicating the existence of separate translational regulatory 37 circuits possibly acting through specific regulatory elements. The regulatory potential of one such 38 element was confirmed in vivo. The network identified several seed maturation associated genes as 39 central nodes, and we could confirm the importance of many of these hub genes with a maturation 40 associated seed phenotype by mutant analysis. One of the identified regulators an AWPM19 family 41 protein PM19-Like1 (PM19L1) was shown to regulate seed dormancy and longevity. This putative 42 RBP also affects the transitional regulation of one its, by the SeedTransNet identified, target mRNAs. 43Our data shows the usefulness of SeedTransNet in identifying regulatory pathways during seed phase 44 transitions . 45 46

Reproduction Multitasking: The Male Gametophyte

“…RBPs often bind cis-elements of the regulated mRNA sequences, namely their 5 UTRs, including uORFs. Interestingly, highly similar sequence motifs were identified in 5 UTRs of monosome-associated stored transcripts in pollen (68) and seeds (3,4). Therefore, in pollen tubes and perhaps in other tip-growing cell types, the mRNA-bound monosomes likely represent the sequestrome pool of stored mRNAs.…”