Variabilidade genética de acessos de maracujazeiro-doce caracterizada por marcadores RAPD e avaliação da resistência à bacteriose e à virose do endurecimento dos frutos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Sweet passion fruit (Passiflora alata Curtis) is gaining importance in the in natura fruit market due to differential pricing. Genetic breeding is crucial to improve crop quality and productivity, and identification of sources resistance a relevant stage for any breeding program. The objective the present work was to analyze the genetic variability of accesses of P. alata obtained from cultivated population and of wild accesses and to evaluate resistance sweet passion fruit accesses the to bacterial blight caused by (Xanthomonas axonopodis pv. passiflorae) and to passion fruit woodiness viruses. (caused by PWV or CABMV) under greenhouse and field conditions. Unthe present work, genetic variability of 17 sweet passion fruit accesses was analyzed, nine of them from a cultivated population and eight wildones, was analyzed by using RAPD (Random Amplified Polymorphic DNA) molecular markers. The genomic DNA of each access was extracted and decamers primers were used to obtain RAPD molecular markers. The markers have been converted into a matrix of binary data, used as base to estimate genetic distances between accesses and to produce grouping analysis. Among the studied accesses, genetic variability was observed between accesses from cultivated and wild population of P. alata, the wild accesses contribuing the most to the range of the genetic basis of the studied materials. Moreover, resistance to bacterial blight of nine sweet passion fruit accesses (seven obtained from cultivated population and two wild accesses) under greenhouse and field conditions was assessed. Under field conditions, five leaves randomly selected from each plant, were analyzed. The average number of lesions per leaf, the average diameter of lesions, the average lesioned area per leaf and the percentage of healthy and sick leaves were evalucted. Under greenhouse conditions, inoculation with the isolate 767 (UnB) of Xanthomonas axonopodis pv. Passiflorae was performed and the average longitudinal diameter, the average transverse diameter, the average diameter of the lesion and the average lesioned area were evaluated 5, 10 and 15 days after inoculation. Results were significant only for the greenhouse experiment, where the access with higher resistance level was the J-type, followed by the D-type. Furthermore, the resistance to passion fruit woodiness viruses. of such accesses was studied, under greenhouse and field conditions, likewise. Under field conditions, incidence and severity were evaluated. For evaluation of the severity it was used a scale for plant and leaf. Under controlled greenhouse conditions, the inoculation was produced mechanically in each access. The incidence of plants presenting viral infection symptoms (incidence) was measured. The highest resistance level to fruit was observed on wild accesses N1 and N2. Under field conditions, the incidence and severity of passion fruit woodiness viruses increased over time, possibly due to the dissemination of virus by the vector aphid. It was verified differences is possible to verify resistance levels in between plants of the same family, stressing the importance of evaluation and selection of individual plants. Thus, the presence of high genetic variability among the studied accesses, also reflected in the resistance to passion fruit woodiness viruses and bacterial blight, generate promising perspectives for the breeding of this species, enabling the future release of varieties with desirable characteristics.

ASSUNTO(S)

ciencias agrarias passiflora alata pre-breeding genetic basis base genética biotecnologia biotechonology passiflora alata pré-melhoramento

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