MOLECULAR DETECTION AND CONTROLLING OF SEED-BORNE Colletotrichum spp. IN COMMON BEAN AND SOYBEAN
Zagazig Journal of Agricultural Research
Seed-borne fungi cause several diseases of common bean (Phaseolus vulgaris L.) and soybean (Glycine max L.). The survey of seed-borne fungi of common bean and soybean was carried out on three Egyptian Governorates (Behera, Dakahlia, and Ismailia) in Egypt. Nineteen fungal species comprising therteen genera were isolated from the collected common bean and soybean seed samples, using standard blotter i,e. Alternaria alternata, Alternaria spp., Aspergillus niger, Aspergillus ochraceous,
... flavus, Botryodiplodia sp., Cladosporium sp., Colletotrichum lindemuthianum, Colletotrichum dematium, Fusarium solani, Fusarium moniliforme, Fusarum oxysporum, Macrophomina phaseolina, Myrothecium sp., Penicillium spp, Rhizoctonia solani, Stemphylium spp., Trichoderma spp. and Trichothecium sp. Pathogenicity tests proved that C. lindemuthianum and C. dematium were pathogenic to common bean and soybean. Polymerase chain reaction (PCR) has many beneficial characteristics that make it highly applicable for detecting Colletotrichum spp. of seeds. PCR diagnosis method and DNA extraction considered one of the most important steps and purity of DNA template for successful PCR assay. For the PCR amplification of C. lindemuthianum and C. dematium, two primers ClF4 and ClF5, stander blotter, agar plate, and deep freezing method were used as seed healthy testing methods. Stander blotter was proved the past and quickly method to detect seed-born of C. lindemuthianum and C. dematium. Trichoderma harzianum reduced linear growth for C. lindemuthianum and C. dematium followed by Trichoderma viride and Bacillus subtilis recording (3.3 cm and 3.9 cm, respectively) followed by Pseudomonas floursence that display a high linear growth (7.4 cm). On the other hand, fungicide Aetro 30% (Iprodione + Tebuconazole) recorded the least linear growth (0.9 cm) for C. lindemuthianum and C. dematium compared with negative control recorded (9.0 cm in diameter). Thymus plant extract caused the lowest liner growth (3.7 cm). Plant extract concentrations caused a significant reduction in the growth of C. lindemuthianum and C. dematium. The highest concentration (1.5 %) gave less fungal growth while the lowest one (0.5%) showed the highest fungal growth compared with negative control. Key words: Common and soybean, Colletotrichum lindemuthianum and Colletotrichum dematium, PCR, fungicides, bio-agent and plant extract. Adegbite and Amusa (2008) reported that, members of the genus Colletotrichum have been reported to cause two major diseases in cowpea. These are anthracnose and brown blotch. These diseases are very destructive due to the susceptibility of many cowpea lines to them. Wrather et al. (2003) isolated Phythium sp., Phytophthora sojaes, Rhizoctonia solani, Fusarium sp, Macrophomina phaseolina, Sclerotium rolfsii, Diaporthe sojae and Colletotrichum truncatum from soybean seeds. (Shovan et al., 2008;Wrather and Koenning, 2009) collected a total of 33 soybean seed samples from different locations, representing three cultivars and 16 genotypes for detection of the seed borne-fungi of soybean. They detetced ten fungi including nine genera i.e. Alternaria alternata, Aspergillus flavus, Aspergillus niger, Cheatomium globosum, Colletotrichum dematium, Curvularia luanata, Fusarium oxysporum, M. phaseolina, Penicillium sp. and Rhizopus stolonifer. Farzana, (2012) recorded 124 seed-borne fungal infections on four varieties of soybean, six fungi were identified as F. oxysporum, A. flavus, A. niger, C. truncatum, Rhizopus stolonifer and Penicillium sp.