Brassinosteroids Positively Modulate Growth: Physiological, Biochemical and Anatomical Evidence Using Two Tomato Genotypes Contrasting to Dwarfism
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Growth and development are vital processes in the life cycles of plants. Brassinosteroids (BRs) are steroids that when exogenously applied can regulate several biological responses. The aim of this research was to investigate the possible interferences caused by the exogenous application of BR on growth and metabolism using two genotypes of the DWARF gene, MT-d and MT-D, that are BR-deficient and BR-efficient, respectively. The experiment had four treatments with two genotypes (BR-efficient and BR-deficient) and two levels of brassinosteroids (0 and 100 nM BR, described as − BR and + BR, respectively). This study revealed that the exogenous application of BR promoted improvement in growth, inducing increases in all variables of both genotypes evaluated. In general, BR-deficient plants sprayed with BR had effects more intense, confirming the benefits of this steroid on photosynthetic apparatus and gas exchange. The changes in the anatomical characteristics of the leaf are related to the contribution of BR on the influx and consequent fixation of CO2. In addition, modifications related to root anatomy occurred as a result of the BR action with the purpose of increasing the root protection and absorption of water and nutrients. Increases in photosynthetic pigments suggest that the role of BR is linked with chlorophyll biosynthesis and the maintenance of chloroplast integrity, resulting from associations with the increases found in the activities of antioxidant enzymes that modulate the accumulation of reactive oxygen species.
KeywordsChlorophyll fluorescence DWARF gene Gas exchange Leaf anatomy Solanum lycopersicum 24-Epibrassinolide
This research had financial supports from Fundação Amazônia de Amparo a Estudos e Pesquisas (FAPESPA/Brazil), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq/Brazil) and Universidade Federal Rural da Amazônia (UFRA/Brazil) to AKS Lobato. In other hand, CF Maia was supported with scholarship from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq/Brazil).
AKSL was advisor of this project, planning all phases of this research. CFM conducted the experiment in the greenhouse and performed physiological, biochemical and morphological determinations, while BRSS measured anatomical parameters.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no competing interests.
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