Resumo: O envelhecimento da semente durante o armazenamento ou transporte pode afetar o rendimento e o custo da produção agrícola. O milho doce é um mutante natural com fraca vitalidade da semente durante o armazenamento. Neste estudo, mostramos que a dinâmica do nível de hormônio endógeno de sementes de milho doce recém-colhidas e envelhecidas foi diferente durante o processo de geminação precoce. A análise transcriptômica revelou vários novos transcritos durante o estágio inicial da germinação do milho doce nas vias de transdução de sinal e processamento de RNA. O perfil transcriptômico comparativo revelou que a expressão de muitos genes foi ativada mais cedo nas sementes envelhecidas do que nas recém-colhidas. As análises funcionais mostraram que, como duas redes principais, a sinalização de hormônios vegetais e as vias de defesa eram diferentes entre sementes de milho doce recém-colhidas e envelhecidas. As vias de sinalização de auxina, citocinina, giberelina, ácido salicílico e ácido jasmônico foram ativadas mais cedo nas sementes envelhecidas do que nas recém-colhidas no primeiro dia após a embebição. Esses resultados forneceram conhecimento para a compreensão do processo de envelhecimento de sementes de milho doce e vários genes candidatos ao estudo genético do mecanismo de envelhecimento de sementes. Resumo agrícola recémcolhidas recém colhidas precoce RNA recémcolhidas. colhidas. principais auxina citocinina giberelina embebição

Abstract: Seed ageing during storage or shipping can affect the yield and cost of agricultural production. Sweet corn is a naturally mutated corn cultivar with weak seed vitality during storage. In this study, we have shown that endogenous hormone level dynamics of fresh and aged sweet corn seeds were different during early geminating process. Transcriptomic assembling uncovered several novel transcripts during early stage of sweet corn germination in signal transduction and RNA processing pathways. Comparative transcriptomic profiling revealed that expression of many genes was activated earlier in aged seeds than fresh ones. Functional analyses showed that, as two major networks, plant hormone signaling and defense pathways were different between fresh and aged sweet corn seeds. Auxin, cytokinin, gibberellin, salicylic acid and jasmonic acid signaling pathways were activated earlier in aged seeds than fresh ones on the first day after imbibition. These results provided knowledge for understanding the ageing process of sweet corn seeds and several candidate genes for genetic study of seed ageing mechanism. Abstract production networks Auxin cytokinin gibberellin imbibition mechanism

Abstract Background: Maize (Zea mays L.) is a widely cultivated cereal and has been used as an optimum heavy metal phytoremediation crop. Metallothionein (MT) proteins are small, cysteine-rich, proteins that play important roles in plant growth and development, and the regulation of stress response to heavy metals. However, the MT genes for maize have not been fully analyzed so far. Methods: The putative ZmMT genes were identified by HMMER. The heat map of ZmMT genes spatial expression analysis was generated by using R with the log2 (FPKM + 1). The expression profiles of ZmMT genes under three kinds of heavy metal stresses were quantified by using qRT-PCR. The metallothionein proteins was aligned using MAFFT and phylogenetic analysis were constructed by ClustalX 2.1. The protein theoretical molecular weight and pI, subcellular localization, TFs binding sites, were predicted using ProtParam, PSORT, PlantTFDB, respectively. Results: A total of 9 ZmMT genes were identified in the whole genome of maize. The results showed that eight of the nine ZmMT proteins contained one highly conserved metallothio_2 domain, while ZmMT4 contained a Metallothio_PEC domain. All the ZmMT proteins could be classified into three major groups and located on five chromosomes. The ZmMT promoters contain a large number of hormone regulatory elements and hormone-related transcription factor binding sites. The ZmMT genes exhibited spatiotemporal specific expression patterns in 23 tissues of maize development stages and showed the different expression patterns in response to Cu, Cd, and Pb heavy metal stresses. Conclusions: We identified the 9 ZmMT genes, and explored their conserved motif, tissue expression patterns, evolutionary relationship. The expression profiles of ZmMT genes under three kinds of heavy metal stresses (Cu, Cd, Pb) were analyzed. In summary, the expression of ZmMTs have poteintial to be regulated by hormones. The specific expression of ZmMTs in different tissues of maize and the response to different heavy metal stresses are revealed that the role of MT in plant growth and development, and stress resistance to heavy metals.