Location: Crop Genetics Research
2022 Annual Report
Objectives
Objective 1. Characterize new sources of reniform nematode resistance in Gossypium (G.) arboreum and G. herbaceum germplasm accessions and identify DNA markers associated with resistance.
Objective 2. Introgress reniform nematode resistance from G. arboreum and G.
herbaceum accessions into G. hirsutum and develop breeding lines with resistance.
Objective 3. Determine effectiveness of unique sources of reniform resistance fromdiploid Gossypium germplasm accessions on nematode growth, reproduction, and
infection.
Objective 4. Characterize plant growth and development and yield responses to reniform nematode in susceptible and resistant cotton lines and define the relationships between soil fertility and reniform nematode severity with respect to plant damage and yield loss.
Subobjective 4a. Characterize plant growth and development and yield responses to reniform nematode in susceptible and resistant cotton lines.
Subobjective 4b. Define the relationships between soil fertility and reniform nematode severity with respect to plant damage and yield loss in susceptible and resistant cotton lines.
Objective 5. Evaluate impacts of integrated reniform nematode management practices on cotton yield, quality and reniform nematode population densities.
Subobjective 5a. Investigate the efficacy of new commercially-available nematicides on the management of the reniform nematode, cotton yield and cotton fiber quality.
Subobjective 5b. Investigate the effect of rotation with non-host/poor-host crops on management of the reniform nematode and crop yield.
Approach
Develop populations by crossing resistant accessions with one or more Gossypium (G.) arboreum accessions classified as susceptible or highly susceptible. Ovule culture will be used for the introgression of resistance from G. arboreum and G. herbaceum accessions to G. hirsutum varieties. Gossypium accessions with high levels of resistance to reniform nematode will be evaluated in growth chamber experiments to measure the effects of the resistance on number of infections, rate of development of females after infection, and production of eggs. Classical growth and agronomic analysis will be conducted over two years under field conditions at Mississippi State University’s Delta Research and Extension Center in Stoneville, Mississippi. A nutrient response experiment will be conducted under controlled environmental conditions. The relative efficacy of new seed-applied and in-furrow nematicides against the reniform nematode will be evaluated on one susceptible and two resistant cotton lines in a field trial to be established in two naturally-infested sites in Stoneville, Mississippi. A field trial will be established in a reniform nematode infested site in Stoneville, Mississippi.
Progress Report
This is the final report for project 6066-22000-075-000D, which terminated in February 2022 and was replaced with project 6066-22000-094-000D, Characterization and Introgression of Nematode Resistance into Upland Cotton. Research was conducted in Stoneville, Mississippi, by ARS researchers and university collaborators.
The research focused reducing crop losses caused by reniform nematode, a root parasitic worm that causes yield losses in upland cotton in the southeastern United States. There is no natural resistance to this nematode in upland cotton, so we have looked to related species to find useful levels of resistance that we can transfer to upland cotton. Plant growth and development in susceptible and resistant lines was characterized under nematode pressure, and links between soil fertility and nematode-induced plant damage were examined. Ultimately, integration of host plant resistance with proven methods to mitigate nematode damage such as crop rotation and the use of nematicides should reduce losses to the nematode.
Under Objective 1, we characterized new sources of reniform nematode resistance from the related Asiatic species Gossypium arboreum (A2). We identified 26 highly-resistant varieties from this collection and crossed them with highly susceptible varieties to produce populations that can be used to evaluate the genetics of resistance.
A cross between A2-113 (resistant) and A2-101 (susceptible) was used to determine how the resistance trait was inherited. Results from F2 and F2:3 generations showed that at least two recessive genes control resistance in A2-113, which means that if this source of resistance is used, large breeding populations will be necessary to identify progeny that have both required genes.
A second F2 population from the cross A2-711 (resistant) x A2-101 was evaluated for nematode resistance and the data showed that resistance was controlled by a single recessive gene. A set of 20 F3 lines from this population was challenged with reniform nematode under controlled conditions in a growth chamber to confirm inheritance of the resistance from A2-711. Collection of nematode data is complete.
A set of F2 seeds from the cross A2-354 (resistant) x A2-101, the parents, the F1 generation, and known susceptible and resistant checks were evaluated for reniform nematode resistance. Genetic analysis of the phenotypic data is pending while we are recruiting a geneticist to fill the vacancy created by the retirement of the project’s geneticist in 2021. The results will determine whether the resistance from A2-354 is a dominant or recessive trait and will give us information about the number of genes controlling the resistance.
Crosses with other resistant accessions (A2-690, A2-737, and A2-849) were made for population development to evaluate the genetics of resistance. The F1 seeds were planted in the field during the 2021 growing season to develop segregating F2 populations for future screening. The populations are in storage until the new geneticist is hired.
The goal of Objective 2 was to use ovule culture to introgress the resistance from Asiatic cotton into upland cotton. Because Asiatic and upland cotton have different numbers of chromosomes, they do not readily cross. Instead, there is a difficult embryo rescue process that must be used to move resistance from the Asiatic species into upland cotton. The process requires special techniques for extracting a developing hybrid cotton embryo, growing it on artificial media, and regenerating a plant. Approximately 2,300 embryos were obtained from 176 crosses during this project cycle, although growth of the embryos in culture was often poor and one set of embryos was lost entirely due to the government shutdown in 2018-19. Ultimately, 30 seedlings and seven hybrid plants were successfully recovered for seven Asiatic cotton accessions. The next step is to restore fertility to these hybrids.
Work on Objective 3 sought to determine the impact of unique sources of resistance from Asiatic cotton species on nematode infection, growth, and reproduction. Plants that are resistant to reniform nematode will reduce the population of the nematode over time, but not all resistant cotton varieties will achieve this reduction in the same manner. Experiments to determine what mechanisms our most resistant plants use to suppress nematode populations, which might include limiting the number of nematodes that can infect the roots, stopping growth and development of the nematodes after they infect the roots, or limiting reproduction by the nematodes were conducted. During this project cycle, we investigated these mechanisms in multiple experiments for six accessions (A2-100, A2-190, A2-354, A2-690, A2-737, and A2-995) that we identified as being very resistant to reniform nematode. Work on this objective fell behind schedule due to the shift to maximized telework and worksite occupancy limitations associated with the COVID-19 pandemic. Data for accessions A2-100, A2-190, A2-354, A2-690, and the first run of A2-737 and A2-995 have been collected and are ready for analysis. Data collection for the second run of the experiments involving A2-737 and A2-995 is in progress.
Objective 4 was to characterize plant growth and development and yield responses to reniform nematode in susceptible and resistant cotton lines and define the relationships between soil fertility and reniform nematode severity with respect to plant damage and yield loss.
A field trial designed to characterize plant growth and development and yield responses to reniform nematode in susceptible and resistant cotton varieties was successfully completed during the 2017 and 2018 field seasons. The plants were tested in a field that was infested with reniform nematode. Briefly, differences between susceptible upland cotton varieties (Deltapine 16 and PHY 490 W3FE) and resistant lines (08SS110-NE06 and 08SS100) were evident as soon as one month after planting with respect to physiological effects on the cotton plants, with resistant varieties having greater transpiration, photosynthesis, stomatal conductance, and carbon dioxide assimilation efficiency than the susceptible varieties. These differences in physiological functions of the plants translated to differences in the rate of plant growth and development, with resistant varieties reaching specific vegetative and reproductive stages of development more quickly and exhibiting greater vigor. Resistant varieties had higher yields than susceptible ones and resulted in less reniform nematode reproduction.
Three repeated greenhouse studies evaluated the effects of nitrogen, potassium, and phosphorus application on plant growth and reproduction and pathogenicity of reniform nematode on the same varieties used in the field trial described above. Reniform nematode reproduction was not affected by the increased application of nitrogen, potassium, or phosphorus, with resistant lines reducing nematode reproduction compared to susceptible ones. Increasing soil fertility improved plant growth; however, no interactions with plant resistance were observed. These results indicate yield losses will still occur in susceptible cultivars even though fertility management improved plant growth.
Finally, under Objective 5 we evaluated the impacts of nematicides and crop rotation on cotton yield and quality, and on reniform nematode population densities.
A four-year rotational study was completed during this project cycle to determine the impact on reniform nematode populations. Peanut, corn, soybean, and resistant cotton were the rotational crops planted, with a block of continuous cotton for the purpose of comparison over time. In 2017, both peanut and corn reduced nematode numbers during the cropping season, whereas nematode populations increased on cotton. Corn, continuous cotton, and plots of cotton cultivars susceptible or resistant to reniform nematode were the main rotational crops for the 2018 field season. Corn reduced nematode numbers by 46% during the cropping season, while nematode populations increased by as much as 52% on susceptible cotton. Corn, continuous cotton, peanut, and reniform nematode resistant soybean were the main rotational crops for the 2019 field season. Reniform nematode numbers in soil were reduced by 42% in corn plots, by 30% in reniform nematode resistant soybean plots, and by 13% in peanut plots during the cropping season, while nematode populations increased by as much as 24% on continuous cotton. In 2020, the rotational crops included corn, peanut, and reniform nematode resistant soybean, which were compared to continuous cotton as the control. Soil reniform nematode population densities were significantly reduced at the end of the growing season for the non-host crops with corn and soybean having lower nematode populations than peanut, whereas nematode population densities increased during the growing season for continuous cotton.
Reniform nematode resistant upland cotton breeding lines M123-1337, 08SS100, 08SS110-NE06 OP and the susceptible cultivar DP 1646 were included in multi-year field trails to evaluate the effect of nematicides on cotton productivity. Nematicide formulations were applied in-furrow, as seed treatments, or in combination. Seed-applied nematicides included BioST (heat-killed Burkholderia rinojenses), Nemastrike (tioxazafen), and COPeO Prime (fluopyram). The nematicides applied in-furrow were Velum Total (imidacloprid and fluopyram) and Temik 15G (aldicarb). Greater yields were recorded for the nematicide applications. Yields also improved for the nematode resistant upland cotton lines following the application of nematicides. Additionally, nematicides reduced soil nematode populations with greater reductions observed when nematicides were used in combination with resistant lines.
Accomplishments
1. Impact of reniform nematode on plant growth and development characterized in resistant cotton. Cotton lines resistant to reniform nematode have been recently developed to reduce yield losses from reniform nematode, yet little is known of their agronomic and physiological responses under field conditions. This research was conducted by ARS researchers and university collaborators in Stoneville, Mississippi, to determine if reniform nematode populations, cotton development, and cotton productivity vary among reniform nematode resistant (08SS110-NE06.OP and 08SS100) and susceptible (Deltapine 16 and PHY 490 W3FE) cotton lines in a field infested with the nematode. In both years of the study, reniform nematode populations in plots with resistant lines were significantly smaller than in plots with susceptible lines at harvest. However, no differences were observed for maximum plant growth rates among any of the lines tested. Resistant line 08SS110-NE06.OP had the highest late season vigor. Despite growing under higher reniform nematode pressure, the susceptible line PHY 490 W3FE showed comparable yields to 08SS110-NE06.OP. The study was unable to definitively quantify the relative contribution of resistance, innate vigor, and varietal response to management practices with respect to final crop yield. Nonetheless, this study is the first detailed report describing the development of these resistant cotton lines under reniform nematode pressure and provides a foundation for other researchers to use in future investigations.
Review Publications
Erpelding, J.E. 2021. Genetic characterization of the brown lint phenotype for desi cotton (Gossypium arboreum) accession PI 408765 (cv."Sanguineum-1"). Plant Breeding. 140(6):1115-1122. https://doi.org/10.1111/pbr.12977.
Erpelding, J.E. 2021. Genetic analysis of the Asiatic cotton (Gossypium arboreum) petal spot phenotypes. Plant Breeding. 141(1):71-76. https://doi.org/10.1111/pbr.12984.
Bellaloui, N., Turley, R.B., Stetina, S.R. 2021. Cottonseed protein, oil, and minerals in cotton (Gossypium hirsutum L.) lines differing in curly leaf morphology. Plants. 10(3):525. https://doi.org/10.3390/plants10030525.
Bellaloui, N., Turley, R.B., Stetina, S.R. 2021. Influence of curly leaf trait on cottonseed micro-nutrient status in cotton (Gossypium hirsutum L.) lines. Plants. 10(8):1-16. https://doi.org/10.3390/plants10081701.
Singh, B., Chastain, D.R., Reddy, K., Snider, J.L., Krutz, L.J., Stetina, S.R., Sehgal, A. 2021. Agronomic characterization of cotton genotypes susceptible and resistant to reniform nematode in the United States Midsouth. Agronomy Journal. 113(5):4280-4291. https://doi.org/10.1002/agj2.20755.
