AnÃlise computacional de genes associados ao metabolismo de fixaÃÃo de nitrogÃnio no feijÃo-caupi (Vigna unguiculata) e cana-de-aÃÃcar (Saccharum spp.)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The biological nitrogen fixation has been one of the main targets in what refers to plantsâ mineral nutrition, being explored in agriculture as an environmentally benign nitrogen source besides the fact that it can reduces the use of chemical fertilizers, which increases the cost of the production and causes damages to the environment. In this context, the symbiotic relationship between bacteria of the Rhizobiaceae family and leguminous roots is distinguished, enabling the absorption of nitrogen by the plant supplied by the bacteria in root nodules, while this microorganism makes use of the fotoshyntates and the microaerobic environment provided by the plant. This work aimed to identify, through computational tools, gene sequences involved in the nitrogen fixation (including NORK, DMI3, NIN, NSP1, Annexin, CCS52a, ENOD40, ENOD8, NOD26, DMT1, NOD70, Glutamine synthase, Leghemoglobin, NOD35 and Sucrose synthase) in the transcriptomes of Vigna unguiculata and Saccharum officinarum. It was possible to identify 263 orthologs to the nodulins studied in the cowpea transcriptome, highlighting the Leghemoglobins that corresponded to 95% of the clusters found. Regarding the genes studied in sugarcane, 195 ortholog clusters could be observed, often presenting high similarity with monocot nodulins. In a general view, it was possible to find the presence of the nodulins in all analyzed tissues, with different expression levels. Most of the transcripts were in the libraries of infected leaves and roots under salt stress in cowpea and of flowers and roots in the case of sugarcane. When analyzed through multiple alignments, the nodulins from different organisms and those found in cowpea showed greater similarity among species that belonged to the same class. Regarding the Angiosperms in general, the Fabaceae family was separated from the others, confirming the divergence and specific function of these genes within this group. The results of the present study suggest the involvement of these nodulins in highly conserved pathways of the plant development, confirming the multifunctional role of these genes besides the beneficial interaction with microorganisms. In a general view, this work has the potential to collaborate with the development of molecular markers for the improvement of the species studied, as well as for the understanding of the abundance, diversity and evolution of these genes. The study may also provide ways to elucidate the mechanisms involving these genes in other pathways, besides nitrogen fixation, promoting not only the additional control of this process, but also a possible expansion of this beneficial relationship to economically important nonleguminous plants.

ASSUNTO(S)

cana-de-aÃÃcar genetica bioinformÃtica bioinformatic nitrogen biological fixation est feijÃo-caupi cowpea sugarcane genÃtica molecular

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