Location: Insect Control and Cotton Disease Research
Project Number: 3091-22000-035-063-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Jan 1, 2021
End Date: Dec 31, 2021
Objective:
1) Advance the introgression of Fov4 resistance from SA-3208 into the BAR 32-30 breeding line that is homozygous for Ren2,3 and Mi1,2 and highly resistant to both root-knot and reniform nematodes. Evaluate resistant lines (BC1 and F2) in Fov1 and Fov4 infested soils and fields. Stack the insect resistant trait caryophyllene alcohol into the Fov4 and nematode resistant lines. 2) Advance the introgression of Fov4 resistance from ‘Pima S-4’, ‘Pima S-6’, and ‘Seabrook Sea Island 12B-2’, and from Gossypium arboreum accession # 190 into the BAR 32-30 line. Identify and evaluate homozygous Fov4 resistant lines (BC5S2 or BC5S3) in field tests. Identify markers associated with resistance. 3) Advance the introgression of Fov4 resistance from triple species hybrids derived from G. arboretum (4 accessions), G. herbaceum, G. armourianum, G. turneri into the BAR32-30 line. Identify and evaluate homozygous Fov4 resistant lines (BC5S1), advance to BC5S2 levels and evaluate in field tests. 4) Characterize genetic variation, virulence, and nematode interactions of Fov1 and Fov4, and elucidate virulence determinants and host resistance mechanisms through differential expression and functional genomic approaches.
Approach:
1) Highly Fov4 resistant progenies (BC1) were identified in the BAR32-30 background with Fov4 resistance introgressed from SA-3208. Fov1/nematode and Fov4 resistance will be tested in infested fields. Backcrossing will be continued until BC5 level followed by selfing to identify and generate homozygous BC5S2 progeny lines. Fov1/nematode and Fov4 resistant lines will be evaluated and released. The selected lines will be further stacked with insect resistance trait derived from G. armourianum or G. turneri possessing genes responsible for converting caryophyllene to caryophyllene alcohol which has been shown to suppress aphids, thrips, white flies, and army worms in bioassays. 2) Pima S-4, Pima S-6, Seabrook Sea Island 12B2, Gossypium arboreum accession # 190 have been backcrossed 5 generations into BAR 32-30 line to introgress Fov4 resistance genes. BC5S2 or BC5S2 will be screened for homozygous resistant lines for Fov4 resistance. Seed of BC5S3 homozygous Fov4 resistant lines from G. arboreum accession #190 will be increased and evaluated in field tests and released. 3) Six lines of BC5S1 plants with Fov4 resistance introgressed from triple species hybrids in the BAR32-30 background will be screened for homozygous resistance to Fov4 and further advanced to BC5S2 levels, evaluated in the field tests, and released. 4) SSR and SNP markers associated with Fov4 resistance will be identified and mapped using DNA from susceptible and resistant backcross lines derived from different sources of resistance. The developed markers will be utilized for marker assisted breeding. 5) Determine genetic variation among Fov1, Fov4, and their interaction with nematodes on disease development on the resistant and susceptible cotton lines. Virulence determinants and resistance mechanisms will be elucidated by RNA-seq analyses utilizing low vs. high virulent Fov4 or various genotypes of Fov1 isolates. High fusaric acid producing isolates vs. low fusaric acid producing isolates in conjunction with nematodes will also be utilized to elucidate disease responses of resistant and susceptible cotton lines at the molecular levels. The role of candidate virulence factors of the pathogen and resistance or susceptibility genes of the host in the disease development will be elucidated by functional genomic approaches.
