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Title: Recent Advances in the Molecular Characterization of Sweetpotato Begomoviruses

Author
item Ling, Kai-Shu
item ZHANG, SHUOCHENG - Alcorn State University

Submitted to: National Sweetpotato Collaborators Group Progress Report
Publication Type: Abstract Only
Publication Acceptance Date: 1/22/2011
Publication Date: 1/22/2011
Citation: Ling, K., Zhang, S. 2011. Recent Advances in the Molecular Characterization of Sweetpotato Begomoviruses. National Sweetpotato Collaborators Group Progress Report. pgs 11-12.

Interpretive Summary: N/A

Technical Abstract: Although sweetpotato leaf curl disease has been observed on sweetpotato in Japan and Taiwan since 1985, molecular characterization of sweetpotato begomoviruses has only been conducted in recent years. In the U.S., two begomoviruses, Sweet potato leaf curl virus (SPLCV) and Sweet potato leaf curl Georgia virus (SPLCGV) have been identified in Louisiana. Recently, several new begomoviruses were also identified on sweetpotato or morning glory (Ipomoea sp.) plants in other parts of the world, including Brazil, China, and Spain. Additionally, numerous strains or variants of SPLCV have also been identified in India, Italy, Japan, Kenya, Korea, and Peru. To determine the genetic diversity and distribution of sweetpotato begomoviruses in other sweetpotato growing regions in the U.S., we focused our efforts in molecular characterization of field collected isolates in Mississippi and South Carolina. Using rolling-circle amplification, a total of 52 clones in full-genome were obtained. Initial inspection of a sequence alignment revealed a strong genetic diversity among the U.S. isolates, tentatively grouped into 10 genotypes. Majority of the isolates (50/52) in eight genotypes were closely related to SPLCV. Among them, four genotypes from South Carolina with 91-92% sequence identity to the type member of SPLCV-US were considered a new strain; whereas four other genotypes from Mississippi with >95% sequence identity to SPLCV-US were considered variants. In addition, a novel begomovirus was identified in the sample (US:SC:646B-9) from South Carolina, with <89% of sequence identity to all known begomoviruses. Hence, a provisional name Sweet potato leaf curl South Carolina virus (SPLCSCV) is proposed. Moreover, a natural recombinant consisting of two distinct parental genomic sequences from SPLCV and SPLCGV was identified in a sample from Mississippi. The knowledge of greater genetic diversity of begomoviruses on sweetpotato will likely have a major impact on PCR-based virus detection and on disease management practice through breeding for virus resistance.