Identification of zygotic and nucelar seed embryos and agronomic and molecular characterization of Ubá mango tree accesses / Identificação de embriões zigóticos e nucelares de sementes e caracterização agronômica e molecular de acessos de mangueira Ubá

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The objectives of this work were to identify using ISSR molecular markers, the genetic origin, whether zygotic or nucelar, of seedlings relating to their vigor; to characterize the fruit physically and chemically and to evaluate the genetic diversity of Ubá mango tree accesses sampled in Visconde do Rio Branco, Viçosa and Ubá, based on phenotypic and genotypic characters. During the 2005/2006 crop 102 Ubá mango tree accesses were sampled with accesses 1 and 101 originating from Viçosa and the others from Visconde do Rio Branco (2 to 100 and 102), and during the 2006/2007 crop, 98 accesses were sampled in the municipality of Ubá (103 to 200). Seeds from 19 Ubá mango tree accesses from the 2005/2006 crop and 20 from the 2006/2007 crop were placed to germinate in plastic trays filled with washed sand. After fifty days, the seedlings were counted and measured for height (cm), fresh mass (g) and stem circumference (mm). In addition, the leaves were collected for later DNA extraction and analysis. For the physical and chemical characterization, 50 fruit were collected from each access, of which 30 were selected for characterization and 10 were analyzed for rotting. For ISSR-based characterization, mature leaves were harvested, using material from 102 plants out of the 200 selected. The Ubá mango tree is polyembryonic, i.e., the same seed can germinate 1 to 14 seedlings, with or without zygotic seedlings in the seed. The zygotic seedlings was found in 60% of the seeds analyzed and in 20% of them it was the most vigorous, indicating the possibility of selecting superior materials using massal selection. The use of the seed as a means of propagation generates variability among the materials cultivated because usually the most vigorous seedling of each seed selected. Genetic variability occurred among the 200 Ubá mango tree accesses, based on the physical and chemical characteristics of the fruit. The accesses numbered 15, 17, 20, 42, 85 and 102, sampled in Visconde do Rio Branco, and the accesses numbered 110, 149 and 151, sampled in Ubá, presented superior characteristics among the physical and chemical characteristics evaluated. Pulp mass is the characteristic that most influences fruit mass. Genetic variability was found among the 102 accesses characterized with ISSR molecular markers and with no duplicates, even with Ubá mango tree being polyembryonic and the accesses being originated from seeds. Besides, no difference between the localities sampled was observed, showing that the existing variability occurs among the accesses evaluated. It was concluded that it is possible to select superior materials using massal selection and that the variability found is not only phenotypic.

ASSUNTO(S)

molecular markers marcadores moleculares poliembrionia mangifera indica fitotecnia polyembryony mangifera indica

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