National Center for Animal and Plant Health, Apdo 10 CP 32700, San Jose de las Lajas, Habana, Cuba
In a survey conducted in Havana Province during January and February 2003, symptoms of curling and light yellowing of leaves were found in squash plants (Curcubita pepo). DNA from leaves of six symptomatic squash plants was extracted (1) and hybridized at high stringency with specific probes of the intergenic region of Tomato yellow leaf curl virus (TYLCV, genus begomovirus) isolated in Cuba by using a nonradioactive hybridization kit (AlkPhos Direct Labeling and Detection Systems; Amersham Pharmacia Biotech Inc., Piscataway, NJ). Three samples were positive in the nonradioactive analyses. The same samples were positive using polymerase chain reaction (PCR) when the DNA was analyzed with degenerate primers PAL1v1978/PAR1c715 for DNA-A (5), specific primers, ORITY1/ORITY2, for the intergenic region (2), and overlapping specific primers for TYLCV (3). Fragments of 1.4, 0.750, and 2.8 kb were cloned using pGem-T Easy (Promega, Madison, WI), and the six clones obtained were sequenced using the Terminator Cycle Sequencing Kit in a SEQ 4 × 4 machine (Amersham Pharmacia Biotech Inc.). Sequences of three fragments exhibited 95 to 97% homology with TYLCV (GenBank Accession Nos. AF414089 and AF260331). Additionally, we did not obtain a PCR product when DNA was amplified using degenerate primers PBV1c800/PBC1v2039 for DNA-B (4). These results suggest that TYLCV is present in squash in field plantations, and these plants may serve as a virus reservoir for other crops such a tomatoes.
References: (1) S. L. Dellaporta et al. Plant. Mol. Biol. Rep. 1(4):19, 1983. (2) Y. Martínez et al. Rev. Prot. Veg. 18(3):168, 2003. (3) M. K. Nakhla et al. Plant Dis. 78:926, 1994. (4) M. Rojas et al. Plant Dis. 77:340, 1993.