Location: Crop Genetics and Breeding Research
2019 Annual Report
Objectives
1. Identify, develop, and release Southeast-adapted maize germplasm with reduced aflatoxin accumulation and resistance to key insect pests.
1A. Evaluate exotic maize germplasm from the Germplasm Enhancement of Maize (GEM) program, International Center for the Improvement of Maize and Wheat (CIMMYT), and the U.S. maize germplasm collection for reduced aflatoxin contamination.
1B. Screen for resistance to ear- and kernel-feeding insects in maize germplasm from the GEM, the CIMMYT, and the U.S. maize germplasm collection.
1C. Develop maize germplasm with reduced aflatoxin accumulation, increased resistance to insects, and enhanced agronomic performance in the southeastern Coastal Plain region.
2. Identify, develop, and release new sorghum germplasm with Southeast-adapted maturity genes and greater resistance to the sugarcane aphid, other key insects, and diseases.
2A. Evaluate sorghum lines from the U.S. germplasm collection for anthracnose resistance.
2B. Screen for foliar-feeding sugarcane aphid and fall armyworm and kernel-feeding sorghum midge resistance in sorghum lines from the U.S. germplasm collection.
2C. Develop sorghum germplasm with improved disease and insect resistance and high yield potential.
3. Develop molecular markers for reduced aflatoxin accumulation, and resistance to insects in maize and resistance to insects and foliar diseases in sorghum, and utilize molecular markers for gene identification and cultivar development.
3A. Develop molecular markers for reduced aflatoxin accumulation, and resistance to insects in maize, and utilize molecular markers for gene identification and cultivar development.
3B. Develop molecular markers for resistance to key insects and foliar diseases in sorghum, and utilize molecular markers for gene identification and cultivar improvement.
Approach
Objective 1: Exotic maize germplasm from the Germplasm Enhancement of Maize (GEM) Program, the International Maize and Wheat Improvement Center (CIMMYT), Mexico, and the U.S. maize germplasm collection will be screened for resistance to multiple insects and diseases, and reduced aflatoxin contamination under the southern climate. Equal priority will be given to the GEM and exotic germplasm, since the GEM germplasm will likely have better agronomic traits while the exotic germplasm may offer better resistance/tolerance to biotic and abiotic stress factors. Such a combination would allow us to develop new germplasm with good yield potential and resistant to multiple insects, diseases, and reduced mycotoxin contaminations. To effectively serve the seed industries, the screenings of maize insect pests will focus on key foliar-, ear- and kernel-feeding insects, in particular, fall armyworm, corn earworm and maize weevil. The genetic and biochemical bases for the biotic stress resistance in these newly identified germplasm lines will be further examined. New maize breeding crosses will be made by recombining germplasm with superior agronomic traits with the newly identified germplasm that confers multiple pest resistance and with reduced mycotoxin contamination. New maize germplasm will be developed by continuously screening and continuous self-pollination of the segregating populations. At the same time, maize recombinant inbred lines (RILs) will also be developed to identify DNA markers for multiple pest resistance.
Objective 2: A similar approach is utilized for the screening of sorghum germplasm for resistance to multiple biotic stress factors. Previously identified disease resistant and with agronomically-elite germplasm (with Ex-PVP program) in the U.S. germplasm collection will be screened for resistance to sugarcane aphid, fall armyworm, foliar anthracnose disease, and sorghum midge. The genetic and biochemical bases for insect and disease resistance will be examined. The roles of the secondary metabolites to biotic stress resistance in sorghum will also be examined. New sorghum breeding crosses will also be made using the newly identified sorghum germplasm lines that are resistant to multiple biotic stresses and with good yield potential. The breeding crosses will be continuously screened and selected, and self-pollinated to develop and release new sorghum germplasm lines (B lines, or maintainer lines). The best B lines will also be converted into A lines (or cytoplasmic-nuclear male sterile lines) to serve the seed industries. At the same time, sorghum RIL populations will be developed to identify DNA markers for multiple biotic stress resistance at vegetative and reproductive growth stages, respectively.
Objective 3: Development of molecular markers for reduced aflatoxin accumulation, and resistance to multiple pests in maize and sorghum will utilize the newly developed genetic resources (i.e., breeding crosses, RIL populations, and new germplasm lines) described in Objective 1 and Objective 2, respectively. The marker development will be performed by working closely with our collaborators and confirmed in multiple locations.
Progress Report
Research activities have been focused on the genetic improvement of maize and sorghum for yield related traits, resistance to Aspergillus flavus infection and aflatoxin accumulation, and damage caused by disease and insect pests. For maize breeding efforts, inbreds and hybrids from Germplasm Enhancement of Maize (GEM) program from North Carolina and international and national germplasm center were evaluated for resistance to whorl and ear feeding insects, and reduced aflatoxin accumulation. In addition, older commercial hybrids and other maize germplasm lines (such as from the GEM program and collaborators) are being evaluated for foliar and ear-feeding insect resistance. New breeding crosses have been made and advanced for new maize germplasm development by screening for insect and disease resistance, low aflatoxin accumulation, heat and drought tolerance, and good agronomic traits (e.g., no lodging and good yield potential). In 2018, a total of nine sets of breeding crosses and inbred populations were advanced for new germplasm development with insect resistance and reduced aflatoxin accumulation. Ninety-four new hybrid testcrosses were evaluated in a four-replication test for both yield and aflatoxin in 2018.
We also participated in the Georgia state variety trial for corn, and evaluated 54 commercial corn hybrids for ear-feeding insect resistance in five years, and provided the information for growers to use for hybrid selection. We also assessed efficacy of new transgenic technology and monitored Bacillus thuringiensis (Bt) resistance in natural insect pest populations with existing technology.
We participate in the South Eastern Regional Aflatoxin Trial (SERAT) with two separate trials for yield and aflatoxin accumulation, respectively. Five hybrids from our team were entered for the trial in 2018 and our location again served as a test location for the trial with 36 entries. We also worked with other scientists from the Aflatoxin Mitigation Center of Excellence (AMCOE) project by advancing breeding populations derived from 4-way and 8-way crosses with high level of aflatoxin resistance from Texas A&M at Tifton, Georgia. In 2018 we generated 461 selections from these populations in the breeding nursery by selecting for superior agronomic traits.
A minimum path set of 41 B73-teosinte introgression lines (ILs) was acquired from the Maize Genetics Stock Center. Seed production on these lines was low in our environment, but enough seed for experiments was recovered for all but one IL. The remaining 40 ILs and B73 have been screened for aflatoxin in inoculated experiments over two seasons. No significant differences between any of the ILs and B73 were observed. Seed is being increased for future experiments to screen for resistance to insects or other diseases.
We are participating in the Genomes to Fields (G2F) project. This is a multi-location study involving scientists from ARS and universities from across the U.S. and Canada. Each year we have planted approximately 500 hybrid plots at our location, and recorded yield and other phenotypic data, which are shared with the G2F collaborators. A WatchDog mini weather station is used to log in-field weather conditions, and these data are also shared with the G2F team. The first three years (2014-2016) of genotypic, phenotypic, and weather data from this project are now available to the public through weblinks, as well as inbred ear images from the first two years.
Sugarcane aphid causes severe yield and economic losses to sorghum which requires us to focus on providing growers with short- and long-term solutions for managing this invasive pest. We have been participating in an area-wide project for sugarcane aphid management since 2016, in addition to participating in the State Variety Test. In 2018, 37 grain, 23 silage, and 24 forage sorghum hybrids were evaluated and published in the State Variety Annual Report, which provided growers with short-term solutions on aphid management by identifying the best sorghum hybrids in our region. For long-term solution, we are working on new germplasm screening and development. A total of 296 grain sorghum germplasm lines were screened for sugarcane aphid and anthracnose resistance in 2018. A total of 11 breeding crosses were made using sorghum inbreds with aphid and fall armyworm resistant parents, and a total of 665 segregating accessions, derived from these crosses were evaluated and advanced in 2018. In 2018, 38 sweet sorghum selections were evaluated for sugarcane aphid resistance, lodging, juice brix (sugar content) and other traits. Seven were selected for further evaluation and seed increase in 2019.
In order to map genetic regions for sugarcane aphid resistance, we planted 104 inbred lines from the cross of a highly resistant parent with a highly susceptible parent in a replicated study in a naturally infested field in Tifton, Georgia. In cooperation with an ARS scientist at Mayaguez, Puerto Rico, a major genetic region for aphid resistance was found on Chromosome 6. An additional field experiment is being conducted in 2019 to confirm and refine the genetic position. Markers linked to this genetic region will be useful for breeding sugarcane aphid resistance into elite sorghum lines.
Accomplishments
Review Publications
Chu, X., Wang, W., Ni, X., Zheng, H., Zhao, X., Zhuang, H., Lawrence, K.C., Li, C., Li, Y., Lu, C. 2019. Evaluation of growth characteristics of Aspergillus parasiticus inoculated in different culture media by shortwave infrared (SWIR) hyperspectral imaging. Journal of Innovative Optical Health Sciences. 11(5):Article 1850031 (15 pages).
Jiang, H., Wang, W., Ni, X., Zhuang, H., Yoon, S.C., Lawrence, K.C. 2018. Recent advancement in near infrared spectroscopy and hyperspectral imaging techniques for quality and safety assessment of agricultural and food products in the China Agricultural University. NIR news (Near Infrared Reflectance News). 29(8):19-23.
Zhang, S., Gu, S., Ni, X., Li, X. 2019. Genome size reversely correlates with host plant range in Helicoverpa species. Frontiers in Physiology. 10:Article 29.
Chu, X., Wang, W., Ni, X., Zheng, H., Zhao, X., Zhang, R., Li, Y. 2018. Growth identification of Aspergillus flavus and Aspergillus parasiticus by visible/near infrared hyperspectral imaging. Applied Sciences. 8:Article 513.
Zhao, X., Wang, W., Ni, X., Chu, X., Li, Y., Sun, C. 2018. Evaluation of near-infrared hyperspectral imaging for detection of peanut and walnut powders in whole wheat flour. Applied Sciences. 8:Article 1076.
Yang, L., Fountain, J.C., Ji, P., Ni, X., Chen, S., Lee, R.D., Kemerait, R.C., Guo, B. 2018. Deciphering drought-induced metabolic responses and regulation in developing maize kernels. Plant Biotechnology Journal. 16:1616-1628. https://doi.org/10.1111/pbi.12899.
Harris-Shultz, K.R., Brewer, M., Wadl, P.A., Ni, X., Wang, H. 2018. A sugarcane aphid 'Super-Clone' predominates on sorghum and johnsongrass from four US states. Crop Science. 58:2533-2541. https://doi.org/10.2135/cropsci2018.03.0151.
Armstrong, J.S., Harris-Shultz, K.R., Ni, X., Wang, H., Knoll, J.E., Anderson, W.F. 2019. Utilizing biodemographic indices to identify perennial bioenergy grasses as sugarcane aphid (Hemiptera: Aphididae) host plants. Trends in Entomology. 15:1-14.
Wei, J., Liang, G., Wu, K., Gu, S., Guo, Y., Ni, X., Li, X. 2018. Cytotoxicity and binding profiles of activated Cry1Ac and Cry2Ab to three insect cell lines. Insect Science. 25:655-666.
Ni, X., Cottrell, T.E., Buntin, G., Li, X., Wang, W., Zhuang, H. 2019. Monitoring of brown stink bug (Hemiptera: Pentatomidae) population dynamics in corn to predict its abundance using weather data. Insect Science. 26:536-544.
Zhang, M., Wei, J., Ni, X., Zhang, J., Jurat-Fuentes, J.L., Fabrick, J.A., Carriere, Y., Tabashnik, B.E., Li, X. 2019. Decreased Cry1Ac activation by midgut proteases associated with Cry1Ac resistance in Helicoverpa zea. Pest Management Science. 75(4):1099-1106. https://doi.org/10.1002/ps.5224.
Wang, H., Ni, X., Harris-Shultz, K.R. 2019. Molecular evolution of the plant ECERIFERUM1 and ECERIFERUM3 genes involved in aliphatic hydrocarbon production. Computational Biology and Chemistry. 80:1-9.
Alkhalifah, N., Campbell, D., Falcon, C., Miller, N., Romay, M., Walls, R., Walton, R., Yeh, C., Bohn, M., Buckler IV, E.S., Ciampitti, I., Flint Garcia, S.A., Gore, M., Graham, C., Hirsch, C., Holland, J.B., Hooker, D., Kaeppler, S., Knoll, J.E., Lauter, N.C., Lee, E., Lorenz, A., Lynch, J., Moose, S., Murray, S., Nelson, R., Rocheford, T., Rodriguez, O., Schnable, J., Scully, B.T., Smith, M., Springer, N., Thomison, P., Tuinstra, M., Wisser, R., Xu, W., Ertl, D., Schnable, P., De Leon, N., Spalding, E., Edwards, J.W., Lawrence-Dill, C. 2018. Maize genomes to fields: 2014 and 2015 field season genotype, phenotype, environment, and inbred ear image datasets. Biomed Central (BMC) Plant Biology. 11:452. https://doi.org/10.1186/s13104-018-3508-1.
Harris-Shultz, K.R., Davis, R.F., Wallace, J., Knoll, J.E., Wang, H. 2019. A novel QTL for root-knot nematode resistance is identified from a South African sweet sorghum line. Phytopathology. 109(6):1011-1017. https://doi.org/10.1094/PHYTO-11-18-0433-R.
