Annual Report
3606 seed samples, representing 3436 different stocks, were supplied in response to 210 requests in 2024. Interest in reverse genetics tools, such as the UniformMu sequence indexed stocks, remained high. Requests that included UniformMu stocks represented approximately 39% of our total requests. Other popular stock requests in 2023 included the Nested Association Mapping (NAM) RILs, haploid-inducing lines, male sterile cytoplasm’s, Fast-flowering mini-maize, kernel starch quality traits, and plant architecture traits.
Approximately 4.1 acres of nursery were grown this summer at the Crop Sciences Research & Education Center located at the University of Illinois. Early season field conditions were excellent. Our first planting started in mid-May and germination for our crossing nurseries was good. We reorganized our planting layout for a portion of our observation nursery to test machine planting. The strategy worked well, and we anticipate machine planting all of our observation nursery this year, which is nearly half our total acreage. We will continue to hand plant our crossing nursery. Near ideal conditions persisted through the summer and we did not need to irrigate. There were sufficient stands for a good increase in almost all instances. Disease pressure was typical with corn ear smut the most common cause of ear and kernel loss. Oddly, root worm beetles were nearly absent this year and Japanese beetle populations were lower than normal. Aphids were unusually thick in tassels, but did not affect pollination, only the pollinators.
Special Plantings were made for the following stocks:
- Plantings were made of recently donated stocks from the collections of Jim Birchler (3 B-chromosome stocks), Erik Vollbrecht (a Bz2 kn1 linkage stock), Carolyn Rasmussen (1 clumped tassel stock and 4 YFP marker stocks), and Chong Teng (temperature sensitive male sterile line). These stocks will be made available for request once a sufficient inventory was produced.
- Three stock collections have reached our timeline for repropagation. 1) the original Intermated B73xMo17 (IBM) population consisting of 293 Recombinant Inbred Lines (RILs); 2) the rare isozyme collection from Major Goodman, consisting of 106 stocks; 3) the collection of 129 UniformMu kernel mutants with rough map positions donated by Mark Settles. Over the past three seasons we have successfully propagated 92% of the IBM RILs, 93% of the Goodman collection, and all of the available Settles’ mapped kernel mutants. The remaining stocks will be challenging to increase due to poor germination or difficult propagation. We are working with Matt Krakowski to increase the remaining Goodman stocks and we will request alternative sources of the remaining IBM lines from collaborators.
Allele tests
In addition to our normal stock propagation activities, we conducted 87 allele tests with short plant mutants [dwarf (d*), brachytic (br*), nana (na*)] and kernel mutants [rough endosperm (rgh*), and opaque (op*)]. The goal was to identify new alleles of genetically characterized mutants and to identify new plant stature and kernel development mutants. The following table shows the tabulated results.
Phenotype-Only Stocks
| Stock | No. stocks planted | No. stocks allele tested | No. allelic to reference alleles | No. not allelic to reference alleles | Reference alleles |
|---|---|---|---|---|---|
| d* | 11 | 8 | 7 | 1 | an1, d1, d3, d5 |
| br* | 26 | 17 | 14 | 3 | br1, br2, br3 |
| o* | 1 | 1 | 1 | 0 | pro1 |
As expected, most phenotype only mutants were allelic to the reference mutants. However, we found several that were not allelic, which suggests they may be mutations in uncharacterized genes. Allele information will be uploaded to the stock pages and the stock names will be changed to reflect their allele status.
Gustin JL, Zimmerman SA, Sachs MM. 2025. Allelism of Uncharacterized Dwarf Mutants in Maize. microPublication Biology. 10.17912/micropub.biology.001504
Sequencing Phenotype-Only Mutants
The phenotype-only collection is requested at far lower frequency than the core collection. To increase its value to the research community, we have developed a pipeline to assign rough map positions using Bulk Segregant Analysis sequencing (BSAseq). The pipeline was developed using dwarf5 (d5) as a positive control. The chromosomal location of d5 could be identified with as little as 5x genome coverage (Figure 1) and 10 mutant plants.
Based on current sequencing technology, we can map mutants for as little as $200 per mutant using the University of Illinois sequencing center. We are in the process of sequencing the first 50 dwarf and small plant mutants using this pipeline.
Imaging Mutants
We have developed standardized image collection and annotation methods for 4 developmental time points at which most stock phenotypes can be distinguished: 10-day old seedlings, V5, flowering, mature ear (Figure 3). Scans and images are linked to the stock pages so that Stock Center staff have easy access to pictures of each stock as well as the genetic information. The library will be particularly useful for the large number of unmapped ‘phenotype only’ mutants in the collection for which no representative image is available. Ethy Cannon at MaizeGDB added a bulk image upload tool to our new curation tools (Figure 2). Once uploaded, the image file names are parsed to identify the correct stock, and the images are then automatically displayed on the stock page. We added 498 stock images to our mutant image library this past year. We can conveniently mark the image as public (for public view) or private (for curator viewing only).
Marty Sachs
Director
Jeff Gustin
Curator
Shane Zimmerman
Agric Sci Res Tech (Plants)
Josh Tolbert
Information Tech Specialist