Cucurbit Leaf Crumple Virus: An Important Pathogen of Cucurbit and Snap Bean Crops.

Abstract

TAXONOMY: Cucurbit leaf crumple virus (CuLCrV); Begomovirus cucurbitae; Geminiviridae; Geplafuvirales. GEOGRAPHICAL DISTRIBUTION: The presence of CuLCrV is exclusively limited to North America, mainly Mexico and the United States. PHYSICAL PROPERTIES: CuLCrV is a bipartite begomovirus comprising two circular single-stranded DNA molecules (DNA-A and DNA-B), encapsidated within geminate icosahedral particles. GENOME AND ORGANIZATION: CuLCrV possesses a bipartite genome of DNA-A (2632 nucleotides) and DNA-B (2600 nucleotides). DNA-A contains five open reading frames (ORFs): AV1 (coat protein), AC1 (replication-associated protein), AC2 (transcriptional activator protein), AC3 (replication enhancer protein) and AC4. DNA-B contains two ORFs: BV1 (nuclear shuttle protein) and BC1 (movement protein). TRANSMISSION: CuLCrV is transmitted by the sweetpotato whitefly, Bemisia tabaci, in a persistent, circulative and non-propagative manner. HOSTS: CuLCrV primarily infects crop members of the Cucurbitaceae and snap bean (Phaseolus vulgaris, Fabaceae). Multiple weed species belonging to Brassicaceae, Convolvulaceae, Cucurbitaceae and Verbenaceae act as persistent virus reservoir hosts. SYMPTOMS: Symptom expression varies with host and infection timing. In cucurbits, infection induces leaf crumpling, thickening and downward curling of leaves, with green streaks and distortion of fruits. In snap bean, symptoms include leaf distortion, chlorosis and malformed pods. CONTROL: No commercial cultivars with resistance to CuLCrV are available for cucurbit crops, although some resistance has been reported in snap bean cultivars. Therefore, management relies primarily on integrated disease management.