Location: Soybean/maize Germplasm, Pathology, and Genetics Research
Project Number: 5012-21000-031-000-D
Project Type: In-House Appropriated
Start Date: Jan 3, 2023
End Date: Jan 2, 2028
Objective:
Objective 1: Conduct research to develop genetic resource maintenance, evaluation, or characterization methods and, in alignment with the overall NPGS Plan, then apply them to avoid backlogs in maize genetic stock and information management.
Objective 2: Acquire, distribute, and maintain the safety, genetic integrity, health, and viability of maize genetic stocks and associated descriptive information.
Approach:
We will phenotype maize genetic stocks to ensure their identity and trueness-to-type. For newly acquired stocks for which molecular data are available, we will work with submitters to confirm the presence of molecular phenotypes within increased materials. Kernel and ear traits will be evaluated on the cob and after the seeds have been shelled. Seedling traits will be evaluated in sand benches and shortly after germination in the field. Adult plant traits will be evaluated in an observation field. If homozygous viable, mutant plants will be marked for increase and these can be self- or sib-pollinated to generate seeds homozygous for the mutant. Unique quality control processes will be developed for novel stock types and traits. These processes will be customized to address the challenges that emerge, including procedures to avoid backlogs. Lethal recessive traits must be maintained as heterozygotes and screened each generation to determine which F2 ears carry the mutant trait. We will use appropriate conservation tools to maintain our genetic stock collection. We also will maintain a database of information about our stocks with tools that ensure information is provided to the public. We will develop database tools, in conjunction with the MaizeGDB team, to help users submit requests and help us determine which seed sources to use to fulfill these requests. Each spring, we will use our database tools to determine which stocks in our core collection need to be regenerated and propagated due to supply or age of seed. In all cases, seeds are hand planted to assure purity and all pollinations are done by hand using traditional methods of maize. To propagate stocks, we use appropriate genetic controlled crossing techniques (e.g., self or sib pollinations, outcrosses; seedling, adult or pollen observations) depending on the nature of the stock (e.g., dominant vs. recessive mutants; lethal vs. homozygous viable mutants; male-sterile vs. barren stalk vs. fully fertile, etc). To prepare for harvest, we take crossing notes to prepare labels that will be attached to harvested ears. We hand-harvest the crop as individual ears to ensure the integrity of the individual stocks. The seeds are then dried on the ear. After drying, we score for kernel and ear traits, after which we shell seeds from each cob and place each ear’s seeds into individual coin-type envelopes with the ear’s pedigree and phenotype noted on the envelope. We conduct sand-bench seedling tests to determine the presence of seedling mutant traits. For adult traits, we hold seeds for observation in the next growing season. Once the quality of an ear carrying the trait of interest is assessed, the seeds from that ear are entered into our inventory database and the seeds are stored in their envelope under low humidity cold storage conditions. Samples of genetic stocks that haven’t previously been backed up into long-term storage will be sent to the NLGRP in Fort Collins, CO to ensure that all maize mutants in our collection are preserved.
