The current incidence of viral disease in korean sweet potatoes and development of multiplex rt-PCR assays for simultaneous detection of eight sweet potato viruses

Abstract

Sweet potato is grown extensively from tropical to temperate regions and is an important food crop worldwide. In this study, we established detection methods for 17 major sweet potato viruses using single and multiplex RT-PCR assays. To investigate the current incidence of viral diseases, we collected 154 samples of various sweet potato cultivars showing virus-like symptoms from 40 fields in 10 Korean regions, and analyzed them by RT-PCR using specific primers for each of the 17 viruses. Of the 17 possible viruses, we detected eight in our samples. Sweet potato feathery mottle virus (SPFMV) and sweet potato virus C (SPVC) were most commonly detected, infecting approximately 87% and 85% of samples, respectively. Furthermore, Sweet potato symptomless virus 1 (SPSMV-1), Sweet potato virus G (SPVG), Sweet potato leaf curl virus (SPLCV), Sweet potato virus 2 ( SPV2), Sweet potato chlorotic fleck virus (SPCFV), and Sweet potato latent virus (SPLV) were detected in 67%, 58%, 47%, 41%, 31%, and 20% of samples, respectively. This study presents the first documented occurrence of four viruses (SPVC, SPV2, SPCFV, and SPSMV-1) in Korea. Based on the results of our survey, we developed multiplex RT-PCR assays for simple and simultaneous detection of the eight sweet potato viruses we recorded.

Keywords: disease incidence; multiplex RT-PCR; sweet potato viruses.

Fig. 1

Geographic location of the sweet potato fields surveyed in 2012. A total of 154 sweet potato specimens were collected from 40 cultivated fields in 10 regions of 5 Korean provinces, as indicated.

Fig. 2

Representative virus symptoms observed in sweet potato: (A) vein banding and purpling; (B) chlorotic local lesions and purpling; (C) vein clearing and mottle; (D) vein clearing and leaf malformation; (E) leaf curling; (F) leaf curling in a cultivated field.

Fig. 3

Simultaneous detection of all possible combinations among SPLCV, SPFMV, SPVG, and SPLV by multiplex RT-PCR. Lane M: 100 bp ladder; Lane 1: SPLV; Lane 2: SPVG; Lane 3: SPFMV; Lane 4: SPLCV; Lane 5: SPLV and SPVG; Lane 6: SPLV and SPFMV; Lane 7: SPLV and SPLCV; Lane 8: SPVG and SPFMV; Lane 9: SPVG and SPLCV; Lane 10: SPFMV and SPLCV; Lane 11: SPLV, SPVG, and SPFMV; Lane 12: SPLV, SPVG, and SPLCV; Lane 13: SPLV, SPFMV, and SPLCV; Lane 14: SPVG, SPFMV, and SPLCV; Lane 15: SPLV, SPVG, SPFMV, and SPLCV.

Fig. 4

Simultaneous detection of all possible combinations among SPCFV, SPVC, SPV2, and SPSMV-1 by multiplex RT-PCR. Lane M: 100 bp ladder; Lane 1: SPCFV; Lane 2: SPVC; Lane 3: SPV2; Lane 4: SPSMV-1; Lane 5: SPCFV and SPVC; Lane 6: SPCFV and SPV2; Lane 7: SPCFV and SPSMV-1; Lane 8: SPVC and SPV2; Lane 9: SPVC and SPSMV-1; Lane 10: SPV2 and SPSMV-1; Lane 11: SPCFV, SPVC, and SPV2; Lane 12: SPCFV, SPVC, and SPSMV-1; Lane 13: SPCFV, SPV2, and SPSMV-1; Lane 14: SPVC, SPV2, and SPSMV-1; Lane 15: SPCFV, SPVC, SPV2, and SPSMV-1.