Location: Genetics and Sustainable Agriculture Research
2018 Annual Report
Objectives
1. Discover genes from tetraploid landraces of Gossypium (G.) hirsutum and related tetraploid Gossypium species for nematode resistance, improved agronomic traits, and fiber properties, and use them to develop and release diverse cotton germplasm lines with enhanced yield and quality.
1.1. Develop and evaluate recombinant inbred lines (RILs) from random mated population of primitive accessions (RM-PAP), develop random mated population of G. barbadense, G. hirsutum, G. mustelinum, G. tomentosum (RM-BHMT), and evaluate RILs from random mated population barbadense Upland (RM-BUP).
1.2. Evaluate chromosomes 04, 17, and 18 from G. barbadense, G. hirsutum, G. mustelinum, and G. tomentosum.
1.3. Identify new genes for reniform (RN) and root-knot (RKN) nematode resistance.
1.4. Identify SNPs associated with RN resistance in the MT2468 Ren 1 germplasm line and incorporate this resistance with known RKN and RN resistance QTLs in germplasm with improved agronomic and fiber properties.
2. Develop improved foundational molecular knowledge of nematode resistance mechanisms, nematode biology, and fiber properties.
2.1. Fine-mapping of RKN resistance QTLs on chromosomes 11 and 14 and functional characterization of candidate genes within the respective mapping intervals.
2.2. Identify specific genes and signaling pathways required for GB-713 derived RN resistance.
Approach
Approach to objective 1: Random mated populations will be developed introgressing genes from three wild tetraploid species via chromosome substitution lines crossed with upland cultivars. Recombinant Inbred Lines (RIL) development will begin for this population. In the prior cris project we developed three random mated populations from Upland varieties (RMUP), Gossypium barbadense (RMBUP), and land race primitive accession (RMPAP) crossed with cultivars. RIL have also been developed from these three random mated populations. These RIL will be evaluated and used for association of markers with fiber quality traits. Chromosome Specific Recombinant Inbred Lines (CSRIL) will be developed by crossing individual chromosome specific chromosome substitution lines from three wild tetraploid species with a common parent (TM-1). Comparison of chromosome substitution lines for specific chromosomes from tetraploid species will be made. Molecular markers will be associated with resistance to root knot and reniform nematodes, as well as fiber quality traits.
Approach to objective 2: Fine-mapping of resistance QTLs on chromosomes 11 and 14 should allow the development of more efficient molecular markers for marker assisted selection. Identification of genes underlying the activity of each QTL will enhance our understanding of how the resistance works. In the previous cris project we developed 550 RIL from a random mated population that included a root knot nematode resistant parent as one of the parents. These RIL and parents have been sequenced and will be used to select lines showing recombination between known QTL mapping intervals for chromosome 11 and 14 which contain QTL for root knot nematode resistance. We will evaluate these selected recombination lines in growth chambers to discover the sequences responsible for resistance. We will then identify functional characteristics of candidate genes in these sequence regions. Knowledge of the putative function of the resistance gene should allow us to construct hypotheses of how these genes are mediating resistance. We have developed isolines for two genes responsible for resistance to reniform nematode. Transcriptome profiling of susceptible and resistant isolines in response to reniform nematode infection will be used to identify signaling pathways involved in resistance and should provide a list of candidate genes that can be functionally characterized. Gene silencing technology will be used to confirm candidate genes and their contribution of candidate gene to resistance.
Progress Report
This project replaces 6064-21000-014-00D, "Genetic Enhancement of Cotton by Marker-Assisted and Conventional Breeding, and Introgression of Genes from Exotic Gossypium Species."
For Objective 1, field plots were planted and maintained during summer of 2018, but no results are available. Research on the Objective 2 has begun, but no results are available at this time. This project is on track for all objectives.
Accomplishments
