Detection and quantification of Ralstonia solanacearum through conventional and molecular techniques and spoilage in stored potato at different temperatures during storage

Abstract

Bacterial wilt (Ralstonia solanacearum) infected potato samples collected from Odisha (cv. Kufri Pukhraj) and Uttarakhand (cv. Kufri Jalandhar), to study decay of potato tubers, other pathogens associated with potato tubers and survivability of R. solanacearum during storage at different temperatures (5, 15, 25 and 35 oC) up to 60 days. Minimum decay of stored potato of Kufri Jalandhar (5.82%) and Kufri Pukhraj (7.53%) was found at 5oC followed by 15oC after 60 days of storage. R. solanacearum, Erwinia spp. and Bacillus spp. were found to be common in rotted potato of both the potato cultivars Kufri Pukhraj and Kufri Jalandhar. In case of fungi, Fusarium oxysporum, Mucor genevensis and Penicillium sp. were common in both potato cultivars while Macrophomina phaseolina was recorded only on Kufri Pukhraj cultivar. Study on survivability of R. solanacearum in stored potato tubers cvs. Kufri Pukhraj and Kufri Jalandhar at 5, 15, 25 and 35oC temperatures up to 60 days by dilution plate technique, conventional-PCR and RT- PCR methods. The population of R. solanacearum was found maximum at 5 oC (6.27 cfu log/g tissue and 6.20 cfu log/g tissue) followed by 15 oC and minimum at 25 and 35 oC stored potato samples in both the potato cultivars Kufri Pukhraj and Kufri Jalandhar by serial dilution plating techniques respectively. Conventional PCR results also confirmed the detection of R. solanacearum at 5 and 15oC stored potato which was gradually increased up to 60 days of storage in both the cultivars, whereas the samples stored at 25 and 35oC the detection of R. solanacearum was gradually declined after 20 days of storage. The detection and quantification R. solanacearum population by RT –PCR, maximum population of R. solanacearum was recorded in 5oC stored potato followed by 15 oC. The CT value of R. solanacearum was 26.90 at 5oC and 34.67 at 35oC in Kufri Pukhraj whereas 25.70 at 5 oC and 31.70 at 35oC in Kufri Jalandhar after 60 days of storage.