MicroRNAs expression dynamics reveal post-transcriptional mechanisms regulating seed development in Phaseolus vulgaris L.

The knowledge on post-transcriptional regulation mechanisms implicated in seed development(SD)is still limited,particularly in one of the most consumed grain legumes,Phaseolus vulgaris L.We explore for the first time the miRNA expression dynamics in P.vulgaris developing seeds.Seventy-two known and 39 new miRNAs were found expressed in P.vulgaris developing seeds.Most of the miRNAs identified were more abundant at 10 and 40 days after anthesis,suggesting that late embryogenesis/early filling and desiccation were SD stages in which miRNA action is more pronounced.Degradome analysis and target prediction identified targets for 77 expressed miRNAs.While several known miRNAs were predicted to target HD-ZIP,ARF,SPL,and NF-Y transcription factors families,most of the predicted targets for new miRNAs encode for functional proteins.MiRNAs-targets expression profiles evidenced that these miRNAs could tune distinct seed developmental stages.MiRNAs more accumulated at early SD stages were implicated in regulating the end of embryogenesis,postponing the seed maturation program,storage compound synthesis and allocation.MiRNAs more accumulated at late SD stages could be implicated in seed quiescence,desiccation tolerance,and longevity with still uncovered roles in germination.The miRNAs herein described represent novel P.vulgaris resources with potential application in future biotechnological approaches to modulate the expression of genes implicated in legume seed traits with impact in horticultural production systems.

Molecular dynamics of pre-germinative metabolism in primed eggplant(Solanum melongena L.)seeds

Seed priming,a pre-sowing technique that enhances the antioxidant/DNA repair activities during the pre-germinative metabolism,still retains empirical features.We explore for the first time the molecular dynamics of pre-germinative metabolism in primed eggplant(Solanum melongena L.)seeds in order to identify hallmarks(expression patterns of antioxidant/DNA repair genes combined with free radical profiles)useful to discriminate between high-and lowquality lots.The hydropriming protocol hereby developed anticipated(or even rescued)germination,when applied to lots with variable quality.ROS(reactive oxygen species)raised during hydropriming and dropped after dry-back.Upregulation of antioxidant/DNA repair genes was observed during hydropriming and the subsequent imbibition.Upregulation of SmOGG1(8-oxoguanine glycosylase/lyase)gene detected in primed seeds at 2 h of imbibition appeared as a promising hallmark.On the basis of these results,the investigation was restricted within the first 2 h of imbibition,to verify whether the molecular landscape was reproducible in different lots.A complex pattern of antioxidant/DNA repair gene expression emerged,reflecting the preponderance of seed lot-specific profiles.Only the low-quality eggplant seeds subjected to hydropriming showed enhanced ROS levels,both in the dry and imbibed state,and this might be a useful signature to discriminate among lots.The plasticity of eggplant pre-germinative metabolism stimulated by priming imposes a plethora of heterogeneous molecular responses that might delay the search for quality hallmarks.However,the information hereby gained could be translated to eggplant wild relatives to speed-up their use in breeding programs or other agronomical applications.

Depletion of tyrosyl-DNA phosphodiesterase 1a(MtTdp1a)affects transposon expression in Medicago truncatula

The role of plant tyrosyl-DNA phosphodiesteritdase 1a in genome stability is studied using a Medicago Etruncatula Mt Tdp1a-depleted line. Lack of Mt Tdp1 a results e in a 39% reduction of methylated cytosines as compared thto control. RNA-Seq analyses revealed that 11 DNA transto posons and 22 retrotransposons were differentially exrpressed in the Tdp1a-2a line. Among them all, DNA etttransposons（Mu DR, h AT, DNA3-11_Mad） and seven retroetransposons（LTR（Long Terminal Repeat）/Gipsy, LTR/Copia,LLTR and Non LTR/L1） were down-regulated, while the15 retrotransposons were up regulated. Results suggest that the occurrence of stress-responsive cis-elements as well as changes in the methylation pattern at the LTR promoters might be responsible for the enhanced retrotransposon transcription.