Estudo da expressão gênica associada à senescência foliar e remobilização de ferro para a semente no arroz

• Autor(a) principal: Vital, Camilo Elber
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4317
• topic: Arroz; Folha bandeira; Grão; Fatores de transcrição; Genes "Yellow Stripe"; Elementos cis; Rice; Flag leaf; Grain; Transcription factors; "Yellow Stripe" genes; Cis elements; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETAL

Rice is one of the most important cereals in the world in terms of consumption and supply of calories, however, is relatively poor in nutrients. It has been shown that this flag leaf just below the panicle plays an important role in supplying nutrients to the rice grain development. Thus, was analyzed the effect of panicle removal on senescence and the expression of genes related to the leaf senescence process and the nutrients translocation in the flag leaf of two rice cultivars (BR-IRGA 409 and IRGA 417). Additionally, we carried out an in silico analysis (microarray data) of the expression of iron transporters of the Yellow Stripe family (YS) and were also checked possible cis elements present in the promoter region of these genes. The protein profile of the flag leaf and no flag leaf in two stages of grain development was compared to detect differentially expressed proteins using statistical tests to reduce false positives. The results confirm that removal of the panicle retards the senescence of flag leaves of cultivars. Two of the transcription factors analyzed (OSNAP and OsNAC like GmNAC3) showed a large increase of expression during senescence of flag leaves mainly at the final stage of grain filling compared with no senescent leaves. The removal of the panicle caused a decrease in the expression of these genes in flag leaf. One of the well-characterized genes of YS family(OsYSL2) had higher expression in the milky stage of IRGA 417 genotype. This fact, coupled with higher levels of OsNAAT1 in the flag leaf and the greatest expression of OsYSL2 and OsNAS3 in the milky stage in the grain, may suggest the higher iron content in this genotype. In silico analysis of microarray data in grains showed that some genes within the YS family, OsYSL6, OsYSL13 and OsYSL5 have relatively high expression during the whole process of grain filling, while other genes (OsYSL18, OsYSL1, OsYSL15, and OsYSL4 OsYSL12) have increased only in the dough stage. OsNAS and OsNAAT genes involved in synthesis of iron chelators for the transport mediated by YS genes had higher expression in the milk stage during grain filling. The 18 putative candidate genes of YS family showed various cis ix sequences possibly related to the process of senescence including responsive elements to abscisic acid, auxin, salicylic acid, jasmonate and ethylene. Analysis of protein profiles demonstrated variation in the percentage of spot volume when comparing the milk and dough developmental stages and also flag leaf and no flag leaf. Thus, the expression of transcription factors related to senescence or response to iron deficiency in the flag leaf can be related to the remobilization of nutrients during grain filling. Likewise, the expression in the grain of iron transporter genes or involved in the synthesis of chelators during leaf senescence contribute to the process. The difference in protein profile shows that possible changes in metabolism during senescence of flag leave. The best elucidation of the regulation of transcription factors linked to leaf senescence and its relationship with genes involved in the remobilization of nutrients may be of great importance for the development of plans that aimed remedy the problems of human nutritional deficiency.