Fisiologia Vegetal
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/185
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Resultados da Pesquisa
Item Desmonostoc salinum CCM-UFV059, a novel cyanobacteria from a saline- alkaline lake: molecular and physiological responses to light, desiccation and salt stress(Universidade Federal de Viçosa, 2019-02-22) Alvarenga, Luna Viggiano de; Araújo, Wagner Luiz; http://lattes.cnpq.br/5025552116262277Cyanobacteria are widespread photosynthetic prokaryotes and are among the oldest organisms on Earth. During their long evolution, cyanobacteria developed an enormous diversity in terms of morphology, metabolic plasticity and molecular properties, which seems to be important factors to cope with limiting environmental conditions and allowed their ecological success in almost all known photic ecosystems. The first part of this work consisted of the taxonomic characterization, using the polyphasic approach, of the strain Desmonostoc salinum CCM-UFV059, a filamentous heterocytous cyanobacterium isolated from a hypersaline lake. Taken together, our data allowed the description of a new species and the first strain of the Desmonostoc genus from a saline environment. The second part of this work aimed to decipher the main salt acclimation mechanisms present in Desmonostoc salinum CCM-UFV059, because most studies on cyanobacterial salt acclimation have been carried out on unicellular strains, which cannot fix N 2 . We performed a comparative study using the model strain Nostoc PCC7120, and we could observe a remarkable high salt tolerance displayed by Desmonostoc salinum CCM-UFV059. In cells of Desmonostoc salinum CCM-UFV059 the intracellular sodium content was significantly lower than in Nostoc PCC7120 and these cells were able to sustain photosynthetic activity up to 0.5 M NaCl while Nostoc PCC7120 cells were not. Moreover, Desmonostoc salinum CCM- UFV059 induced sucrose over-accumulation under desiccation stress conditions, which allowed this strain to survive harsh desiccation stress. Together with the presence of highly unsaturated lipids in the membrane, the high sucrose production and the intense export of sodium could explain, at least partially, how Desmonostoc salinum CCM-UFV059 is capable of acclimate to high salinities and to resist longer desiccation periods. Collectively, our results provide the first insights into the physiological adaptations explaining the remarkable high salt and desiccation tolerance presented by this strain. Furthermore, given that cyanobacteria have several biotechnological applications, such as the production of biomass for human and animal consumption, and metabolites of industrial interest, the third part of this work was performed to analyze the physiological and metabolic responses of Desmonostoc salinum CCM-UFV059 submitted to different light availabilities, aiming at finding the light regime suitable for maximal biomass production as well as to better understand how distinct growth conditions may interfere within the basal metabolism. Collectively our results indicate that Desmonostoc salinum CCM-UFV059 display a highly plastic metabolism and the ability to grow in a large range of light regimes, that open the possibility to outdoor cultivation and commercial use of this species that has a great biotechnological potential. Notwithstanding, further research is clearly required in order to enable a large scale cultivation of Desmonostoc salinum CCM-UFV059.Item Natural variation in physiological traits in a large panel of brazilian Capsicum chinense acessions(Universidade Federal de Viçosa, 2013-02-27) Souza, Laíse Rosado de; Nesi, Adriano Nunes; http://lattes.cnpq.br/5863685236810324Diversity of accessions within the same specie has been reported as an alternative way to search for physiological and metabolic traits that may have large effects on both growth regulation and biomass production. This work aimed to investigate physiological and metabolic traits as well as its interactions with plant growth and fruit production using 49 genetically diverse brazilian pepper accessions of Capsicum chinense. These different accessions were grown together and genetic variation was observed for many traits. Although the analysis of each variable individually allowed the formation of up to seven distinct groups, as observed for plant height, working with the whole data set by multivariate analyzes allowed the separation of the 49 accessions in only three clusters. Interestingly, the groups formed by this analysis did not follow the geographical origin of the genotypes. The first cluster contains two accessions with lower plant height and relative growth rate (RGR). On the other hand, the same accessions had the highest specific leaf area (SLA), high photosynthesis rates and have the highest nitrate (NO 3 ) content. Genotypes in the second cluster demonstrate opposite behavior for growth parameters and NO 3, however they had an undefined pattern for gas exchange parameters and water use efficiency (WUE), despite having low values of SLA. The third cluster comprised the other accessions with the most diverse results for the investigated characteristics. Altogether, these results reinforce the idea that, although the accessions belong to the same species, they have diverse adaptation mechanisms being a highly interesting source of information for plant breeders. In addition, it was demonstrated that fruit set is positively correlated with photosynthesis. However, photosynthesis does not explain alone the differences in accession susceptibility to fruit abortion. Metabolite analysis revealed that malate and fumarate had different responses in Capsicum. Although fumarate did not individually contribute to the accession group separation, a large number of significant correlations was observed. In summary the results obtained suggest fumarate as an important metabolite that might be involved in the regulation of both shoot and fruit growth and development of C. chinense. Apart from extending our knowledge of biological mechanism and pathways within the Capsicum genus the work presented here highlights the importance of studying genetic variation as a mean to understand how a specie adapts to different local environments.