Identification of sweetpotato germplasm resistant to pathotypically distinct isolates of meloidogyne enterolobii from the Carolinas

Authors: Rutter, William; Wadl, Phillip; MUELLER, JOHN - Edisto Agriculture Research & Extension Center; AGUDELO, PAULA - Clemson University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2021
Publication Date: 2/18/2021
Citation: Rutter, W., Wadl, P.A., Mueller, J.D., Agudelo, P. 2021. Identification of sweetpotato germplasm resistant to pathotypically distinct isolates of Meloidogyne enterolobii from the Carolinas. Plant Disease. https://doi.org/10.1094/PDIS-02-20-0379-RE
DOI: https://doi.org/10.1094/PDIS-02-20-0379-RE

Interpretive Summary: Meloidogyne enterolobii is an invasive and hyper-virulent species of root knot nematode that has become a serious threat to sweetpotato (Ipomoea batatas) production in the Southeastern United States. The most popular sweetpotato cultivars grown in this region are highly susceptible to M. enterolobii. As a result, this pest has spread across most of the sweetpotato growing counties in the Carolinas, threatening the industry as well as other crops in the region. The development and release of new sweetpotato cultivars with resistance to M. enterolobii would help to manage and slow the spread of this pest. To support the development of new sweetpotato cultivares that are resistant to this nematode, we screened 93 sweetpotato lines selected from the USDA-GRIN germplasm collections as well as breeding programs in the United States. We identified 19 sweetpotato lines with strong resistance against an M. enterolobii isolate collected from a sweetpotato field in South Carolina. Because root-knot nematodes are known to break resistance under field conditions, we tested these 19 resistant sweetpotato lines using a second isolate of M. enterolobii collected from a sweetpotato production field in North Carolina. We found that all 19 lines are durably resistant against both nematode isolates. While characterizing these two isolates, also found that they do in fact have different host preferences, most notably on the cotton cultivar 'Deltapine61'. The resistant sweetpotato lines identified here will provide valuable breeding material to help develop new M. enterolobii resistant cultivars. The Isolate specific host preferences we have characterized will provide valuable information that could be used by both breeders and pathologists looking to phenotype resistant plant material and manage this pest in the field.

Technical Abstract: Meloidogyne enterolobii (syn. syn. mayaguensis) is an emergent species of root knot nematode that has become a serious threat to sweetpotato (Ipomoea batatas) production in the Southeastern United States. The most popular sweetpotato cultivars grown in this region are highly susceptible to M. enterolobii. As a result, this pest has spread across most of the sweetpotato growing counties in the Carolinas, threatening the industry as well as other crops in the region. The development and release of new sweetpotato cultivars with resistance to M. enterolobii would help to manage and slow the spread of this pest. To support sweetpotato resistance breeding efforts, 93 accessions selected from the USDA germplasm collection and breeding programs in the United States were screened to identify 19 lines with strong resistance to M. enterolobii. The resistance in these accessions was tested against two M. enterolobii isolates that were collected from sweetpotato production fields in the Carolinas. These isolates were found to have distinct pathotypes, with infection differences observed on cotton as well as sweetpotato. This study is the first report of intraspecific pathotypic variation in M. enterolobii, and identifies sweetpotato germplasm with resistance against both pathogenic variants of this nematode.