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PATHOGENIC, MORPHOLOGICAL AND MOLECULAR ASPECTS OF FUSARIUM SPP. FROM PASSION FRUIT PLANTS WITH SYMPTOMS OF PREMATURE DEATH DISEASE
MS CARVALHO-DIAS1, NAR PERES1, NL SOUZA2 and EE KURAMAE-IZIOKA2 1Departamento de Horticultura; 2Departamento de Defesa Fitossanitaria-FCA/UNESP-CP 237-Botucatu/SP-18603-970, Brazil Background and objectives
The disease of premature death (morte prematura) affects the culture of yellow passion fruit (Passiflora edulis f. flavicarpa) in several Brazilian states and the causal agent is unknown at all. The principal symptom of the disease is the sudden wilt of the plant which is very similar to Fusarium wilt disease symptom [1]. There is an hypothesis that both diseases are caused by the same pathogen from the genera Fusarium. The aim of this research was to verify the Fusarium spp. isolates obtained from passion fruit plants with symptom of premature death for: pathogenicity in young passion fruit plants and to try to reproduce the disease symptom in different reproductiye growth stages of the plants; morphological aspects as colony colour, macro and microconidia size; and, molecular characterisation by RAPD (Random Amplified Polymorphic DNA) markers [2]. Materials and methods
Three isolates of Fusarium spp. used in pathogenicity tests were also studied for morphological and molecular aspects. Plants cultivated in greenhouse were inoculated with isolates of Fusarium spp. for screening the more aggressive one. Then, the selected isolate was inoculated in three different reproductive growth stages of passion fruit plants. Results and conclusions
It was observed that isolate of the fungi reproduced symptom of premature death disease in young plants after eight weeks and also in the reproductive stages. Two isolates morphologically similar were also genetically similar (75%) by RAPD analysis, but when both of them were compared to an isolate similar to Fusarium solani, low similarity was found (23%). So it is possible to conclude that Fusarium spp. causing premature death disease in passion fruit plants is not Fusarium solani. On the other hand the causal agent of this disease could be Fusarium oxysporum f. sp. passiflorae. References
1. Gardner DE, 1989. Plant Disease 73, 476-78. 2. Grajal-Martin MJ, Simon CJ, Muehlbauer FJ, 1993. Phytopathology 83, 612-14.