Archivio Journal of Plant Pathology

Abstract:

In November 2014, commercial soybean (Glycine max) plants grown in Mayabeque, (Cuba) showed mosaic symptoms. These plants also sustained populations of the whitefly Bemisia tabaci, the vector of begomoviruses (genus Begomovirus, family Geminiviridae). Symptomatic leaves were collected from 13 plants, total DNA was extracted and PCR was carried out with primers AV494 and AC1048 (Wyatt and Brown, 1996). A sample with a bright yellow mosaic in contrast with the milder symptoms shown by the others, yielded the expected ca. 550 bp DNA fragment. DNA from all samples was used as a template in rolling- circle amplification (RCA) using Phi29 DNA polymerase and digested with a set of restriction enzymes. Only the PCR-positive sample was amplified. EcoRV and HindIII fragments of ca. 2.6 kbp were cloned in pBluescript II SK(+) and sequenced. BLAST analysis showed that the clones corresponded to begomoviral DNA-A (2581 nt) and DNA-B (2554 nt), respectively. Pairwise identity scores with isolates selected after BLAST analysis were calculated with Sequence Demarcation Tool. DNA-A (KT381193) showed 93% nucleotide identity with Rhynchosia golden mosaic Yucatan virus (RhGMYuV) (EU021216), a begomovirus infecting Rhynchosia minima and Desmonium sp. in Mexico. DNA-B (KT381194) showed 91% nucleotide identity with RhGMYuV (FJ792608) and Rhynchosia rugose golden mosaic virus (HM236371), a begomovirus infecting R. minima in Cuba. DNA- A and DNA-B had a common region of 159 nt with an identity of 89.6% and identical iterons, indicating that they constitute a cognate pair. According to begomovirus species demarcation criteria (Brown et al., 2015), the begomovirus identified is an isolate of RhGMYuV. This is the first record of RhGMYuV infecting soybean and of the occurrence of this viral species in Cuba.