Detecção molecular de espécies de Yam mosaic virus e Badnavirus que infectam inhame (Dioscorea rotundata) cultivado no recôncavo da Bahia

Abstract

Yam (Dioscorea spp.) is a tuberous crop rich in vitamins A, B and C (ascorbic acid) and carbohydrates. It has great social and economic importance to North Eastern region of Brazil, concentrating its production in the states of Paraíba, Pernambuco, Alagoas, Bahia and Maranhão. In the Recôncavo of Bahia, the municipalities of Maragogipe, São Felipe, Cruz das Almas and São Felix are major producers. Diseases can become a threat to yam production, and the ones caused by viruses are most frequent. This work had the objective of molecular detection of Yam mosaic virus and Badnavirus species that infect yam (Dioscorea rotundata) in Bahia. Yam tubers were collected in cropping areas, left to sprout, planted in plastic bags and grown in green house, at Embrapa Cassava and Fruit Crops. Detection of Badnavirus used total DNA, extracted, adapting the method by Kamal Sharma (2009), based on centrifuging and yellow ringing. Then, Rolling Circle Amplification (RCA) was used to increase the quantity of viral circular DNA, followed by Polymerase Chain Reaction (PCR) using specific primers to Badnavirus. A band of 579 base pairs (bp) was obtained. In the extraction of RNA from yam mosaic virus, (YMV) and yam mild mosaic virus (YMMV) three methodologies were tested: Kit Axygen, Easyzol and Gambino (2008) with modifications. In all cases, RT-PCR with specific primers for these viruses was conducted. Modified Gambino (2008) yielded higher quality RNA, allowing a 586bp amplified fragment for YMV, while for YMMV there was no amplification in the samples. The obtained genomic fragments were sequenced and compared with respective sequences from a GenBank database, showing high identity with species of Badnavirus (92% similarity with isolate DBV_GH03_Dr (AM072664.1) and YMV (97% similarity with protein cap isolate DrGha4).Therefore, the presence of one species of Badnavirus and YMV was found in yam crop of the Recôncavo in Bahia.