Development of resistances for host plants of watermelon from wild sources (Citrullus colocynthis) against whiteflies

Authors: Simmons, Alvin; Levi, Amnon

Submitted to: Phytoma
Publication Type: Trade Journal
Publication Acceptance Date: 7/30/2017
Publication Date: 9/1/2017
Citation: Simmons, A.M., Levi, A. 2017. Development of resistances for host plants of watermelon from wild sources (Citrullus colocynthis) against whiteflies. Phytoma. 291:54-57.

Interpretive Summary: Whiteflies are global pests on many crops, including watermelon. Damage is from their feeding and from the many damaging plant viruses that they transmit. ARS scientists in Charleston, SC, have been conducting research on resistance in watermelon against whiteflies using seeds collected in the wild as part of an overall effort to improve the protection of commercial watermelon from pests and diseases. The scientists previously found that desert watermelon species have resistance against whiteflies, and they are able to cross the wild species of Citrullus colocynthis with the cultivated watermelon (Citrullus lanatus) and produce viable seeds. The researchers are also assessing what makes these plants resistant to pests in their efforts to improve cultivated watermelon with this wild source of germplasm. Plant resistance to pests like whiteflies is a crop production strategy that growers may use to reduce the use of pesticides.

Technical Abstract: Whiteflies of the Bemisia tabaci complex are global pests. Members of this species complex, sometimes called biotypes, have the same phenotype, but are genetically distinct. This whitefly complex feeds on a wide range of plant species (over 1,000). B. tabaci Middle East-Asia Minor 1 (MEAM1, also called B biotype) causes the most global whitefly problems in agriculture. The acceptance and performance by B. tabaci varies widely on its different hosts and among cultivars within a crop species. Some hosts are highly receptive, while others are moderate or poor hosts. Whiteflies also transmits many plant viruses. Host plant resistance to pests is a crop production strategy that growers may employ to reduce the use of pesticides. We have been conducting research on resistance watermelon accessions collected in the wild against whiteflies as part of an overall effort to improve the protection of watermelon cultivars from diseases and pests. Although, commercial watermelons (Citrullus lanatus) have a narrow genetic base, there is wide genetic diversity within and among Citrullus species. Some genotypes of the desert watermelon species C. colocynthis exhibit resistance against whiteflies. We are able to cross this wild species with the cultivated watermelon and produce viable seeds. Antibiosis, antixenosis (nonpreference), and plant tolerance all have a role in whitefly resistance in the wild genotypes. Research was conducted in the field, greenhouse and laboratory, and included a Y-tube monitoring technique for rapid testing of whitefly behavior, oviposition and survival. Compared with cultivated watermelon, these plants emit an unpleasant odor from the perspective of humans, is hardy to biotic and abiotic stress, and the performance of whiteflies is impeded. We are assessing the mechanisms of resistance and the improvement of cultivated watermelon with this wild source of germplasm. The researchers are also assessing what makes these plants resistant to pests in our research to improve cultivated watermelon with this wild source of germplasm.