Genome wide analysis of<i>Ga1-s</i>modifiers in maize

Hurst, Preston; Liang, Zhikai; Smith, Christin; Yerka, Melinda K.; Sigmon, Brandi; Rodrı́guez, Oscar; Jc, Schnable

doi:10.1101/543264

Cited by 4 publications

(3 citation statements)

References 43 publications

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“…Because all hybrids contained the same allele of Ga1-s, these differences cannot be due to effects of the Ga1-s allele. In light of previous studies that have identified modifier loci in homozygous lines (Hurst et al, 2019;Shrestha, 2016), the most likely explanation for these differences is modifier loci present within the genetic backgrounds included in this study. We cannot rule out that allelic effects due to the ga1 allele carried by each hybrid exist, since the different hybrids probably have different structural variants of their ga1 alleles; however, the ga1/ga1 parent lines have been observed extensively and pollen exclusion has not been reported.…”

Section: Discussionmentioning

confidence: 80%

Variation in degree of pollen exclusion for ga1‐s unilateral cross incompatibility in temperate maize breeding populations

Boerman

Lauter

Edwards

et al. 2021

Agrosystems Geosci & Env

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Fertilization and kernel development are crucial for breeding and agronomic production of maize (Zea mays L.), 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 F 1 hybrids representing the stiff stalk and nonstiff 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.

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Section: Discussionmentioning

confidence: 80%

Variation in degree of pollen exclusion for ga1‐s unilateral cross incompatibility in temperate maize breeding populations

Boerman

Lauter

Edwards

et al. 2021

Agrosystems Geosci & Env

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“…A similar study searching for the modifiers of the gametophyte factor Ga1s showed evidence of significant QTL on chromosomes 4 and 10 (Shrestha 2016). Similarly, a genome-wide association study by Hurst ( 2019) identified seven significant SNPs as possible modifiers of the Ga1-s system (Hurst et al 2019). It is currently unknown whether these modifiers and their molecular mechanisms are unique or shared between cross-incompatibility systems.…”

Section: Discussionmentioning

confidence: 99%

Genomic mapping of the modifiers of teosinte crossing barrier 1 (Tcb1)

Maharjan

Khaipho-Burch

Awale

et al. 2022

Preprint

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Pollen cross-contamination has been a major problem for maize breeders. Mechanical methods applied to avoid cross-contamination are largely ineffective and time-consuming. Cross incompatibility barriers are genetic factors involved in maize fertilization that can be used as an effective method to prevent pollen cross-contamination. Teosinte crossing barrier 1 (Tcb1) is a cross-incompatibility system in which silks possessing dominant Tcb1-s reject pollen possessing the recessive allele (tcb1). However, successful fertilization occurs when Tcb1-s pollen falls upon tcb1 silks or under self-fertilization of Tcb1-s pollen on Tcb1-s silks. Previous studies have shown that the efficacy of dominant Tcb1-s was reduced when repeatedly backcrossing with maize inbred lines suggesting the presence of modifiers to Tcb1-s. To find those modifiers, we conducted a QTL mapping experiment using the Intermated B73 x Mo17 (IBM) recombinant inbred lines (RILs) for two consecutive years. Two significant and stable QTL were identified on chromosomes 4L and 5S explained 16% and 17.6% of the total phenotypic variation (R2), and both had negative additive effects. Further investigation of these QTL regions identified twelve candidate genes that could modify Tcb1-s activity. The introgression of the Tcb1-s genetic system, and its appropriate modifying factors, could be a novel and reliable solution for cultivar isolation in maize breeding.

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“…The degree to which Ga1-s corn lines can exclude unwanted pollen is complicated by genetic background and zygosity of the Ga1-s locus 9 . In addition, QTL for genetic modifiers have been shown to effect pollen exclusion in popcorn 12 . Researchers examined representatives from Supergold, Amber Pearl, and South American popcorn heterotic groups for the presence of genetic loci that alter the ability of Ga1-s to exclude ga1/ga1 pollen.…”

Section: Introductionmentioning

confidence: 99%

The maize Ga1-s allele confers protection against ga1 pollen in popcorn and dent corn

Lauter

Edwards

Scott

2022

Sci Rep

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Because corn pollen can be carried great distances by wind, maintaining genetic purity of corn grain is challenging. The challenge is substantially reduced in popcorn, which carries the Ga1-s allele preventing pollination by ga1 plants, which include the vast majority of non-popcorn commercial maize varieties in the U.S.. Ga1-s can be transferred into dent corn but the effectiveness of the Ga1-s allele in popcorn and dent corn has never been compared, which is important because each are regulated differently regarding GMO contamination. We compared pollen exclusion of commercial popcorn hybrids, Ga1-s dent corn hybrids and normal dent corn hybrids for their ability to exclude ga1 pollen using a sensitive field-based assay. While both popcorn and Ga1-s dent corn had significantly better pollen exclusion than normal dent corn, popcorn was significantly better than Ga1-s dent corn on average. Some Ga1-s dent hybrids excluded as well or better than some popcorn lines suggesting that identification of hybrids comparable to popcorn is possible. The information in this study will support revised gene purity regulations potentially decreasing costs and increasing genetic purity of organic corn.

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Genome wide analysis ofGa1-smodifiers in maize

Cited by 4 publications

References 43 publications

Variation in degree of pollen exclusion for ga1‐s unilateral cross incompatibility in temperate maize breeding populations

Variation in degree of pollen exclusion for ga1‐s unilateral cross incompatibility in temperate maize breeding populations

Genomic mapping of the modifiers of teosinte crossing barrier 1 (Tcb1)

The maize Ga1-s allele confers protection against ga1 pollen in popcorn and dent corn

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