Diversidade genética acessada por RAPD e indução de variabilidade fenotípica em pimenteira ornamental mediada por giberelina

Abstract

Peppers (Capsicum anuum) originate in the American continent and belongs to the family Solanaceae. This species presents diversity for characteristics of size, flower and fruit, which gives it different potentialities of use, aimed at the consumption in natura, industrialization and for ornamental use. The characterization of genotypes has great importance in the identification and selection of genotypes according to characters of interest. The identification of higher parents has been performed through the evaluation of morphological, agronomic and more recently, molecular markers, that allow to characterize and determine the genetic divergence within and among plant species. The phenotypic expression of any character results from genetic and environmental effects. Among the environmental effects, the hormones play an extremely important role. The gibberellins (GA3) are plant hormones essential to the development of the plant, such as internodes elongation and development of flowers and fruits, so the objective of this work was to evaluate the genetic diversity of ornamental pepper genotypes by means of RAPD markers, and Phenotypic variability induced by the application of GA3 in different ornamental pepper genotypes (Capsicum annuum L.). The experiments were carried out at the Plant Biotechnology Laboratory of the Agricultural Sciences Center of the Federal University of Paraíba (CCA-UFPB). The genomic DNA was extracted from young shoots of 18 accessions of C. annuun and using the CTBA method. In the RAPD amplification reactions, 15 primers were used for Capsicum, (MEP-01 to MEP-15). The obtained marks were converted into a binary matrix, from which the genetic dissimilarity matrix was constructed using the Sokal binary distance, Tocher grouping method and also the main components method was used to construct the dendrogram, if Ward's method and All loci were polymorphic. The most similar pair of accesses was 355 x 348 (0.220), while the most dissimilar pair of accessions was 4 x 17 (0.855). The population evaluated in this study presented high genetic diversity and Phenotypic variability in capsicum induced by GA3. Five accessions of Capsicum belonging to the Germplasm Bank (CCA / UFPB) were used, with concentrations of GA3 (0, 25, 50, 75 and 100 mg / L) administered in spray applications at three day intervals, from the 27th day after transplanting. The plants were evaluated for 21 morphoagronomic characteristics of plant, flower and fruits. The experimental design was completely randomized, 5x5. The data were submitted to analysis of variance, with averages grouping by the Scott-Knott test (p = 0.05) and for the significant variables regression analysis was performed. With the Scott-knott test, it can be observed that the interactions of the factors studied (Access x Doses) for the characteristics of flower diameter, petal length, pedicel length, larger fruit diameter, pericarp thickness and number of seeds per fruit were those that presented significance, and may indicate the use of gibberellin to induce phenotypic variability for these characteristics in the 5 accessions studied, the indicated doses are between 50mg / L-1 and 100mg / L-1 for the characteristics studied.