Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2021
Publication Date: 10/30/2021
Citation: Boerman, N.A., Moran Lauter, A., Edwards, J.W., Scott, M.P. 2021. Variation in degree of pollen exclusion for ga1-s unilateral cross incompatibility in temperate maize breeding populations. Agrosystems, Geosciences & Environment. 4(4). https://doi.org/10.1002/agg2.20220.
Interpretive Summary: Variation in degree of pollen exclusion for Ga1-s unilateral cross incompatibility in temperate maize breeding populations: Farmers growing organic corn must maintain genetic purity of their crop by preventing cross-pollination with genetically modified corn to receive the organic premium price at market. One method to maintain genetic purity of corn hybrids is to utilize Ga1-s unilateral cross incompatibility, which prevents pollination by plants that do not have Ga1-s. Commercial genetically modified corn hybrids do not have Ga1-s. Pollen exclusion varied among hybrids carrying Ga1-s with no hybrids having complete pollen exclusion capability. The specific parent lines used in a hybrid are more important than which genetic pool they were derived from for pollen exclusion capability. This indicates some parents are better suited for use with Ga1-s than others. Additionally, plant breeders developing hybrids for organic corn producers who wish to use Ga1-s to maintain genetic purity of their hybrid crop will need to ensure both parents of the hybrid have Ga1-s.
Technical Abstract: Fertilization and kernel development are crucial for breeding and agronomic production of maize which is prone to outcrossing. Because of this tendency, a major issue for organic corn farmers is to maintain genetic purity of their crop. One way to maintain this purity is to use a unilateral cross incompatibility system such as Ga1-s. However, lack of complete pollen exclusion has been reported in Ga1-s heterozygotes, complicating introgression of this trait into breeding germplasm. A systematic, quantitative evaluation of pollen exclusion rates in breeding lines would greatly facilitate use of this system. The purpose of this study is to quantitatively evaluate exogenous ga1 pollen exclusion of a diverse set of Ga1-s/ga1 F1 hybrids representing the stiff stalk and non-stiff stalk heterotic groups, and the Iowa Synthetic Corn Borer population. Differences between genotypes, but not heterotic groups, were observed when applying exogenous ga1 pollen onto heterozygotes possessing the same Ga1-s allele, indicating there are epistatic interactions between Ga1-s and modifier loci in the ga1 parents tested.