Articles

Genomic localization of the maize cross-incompatibility gene, Gametophyte factor 1 (ga1)


Abstract


Gametophyte factors in maize (Zea mays L) mediate pollen-pistil interactions that confer preferential fertilization of some pistil genotypes by pollen carrying compatible alleles. Non-Mendelian segregation ratios caused by game¬tophyte factors have been observed in maize since the early 1920’s. In this study, we mapped the ga1 locus by analyzing segregation distortion and QTL for seed set in recombinant inbred lines from the cross B73 × Hp301. The dent corn parent of this cross, B73, carries ga1, whereas the popcorn parent Hp301 carries the Ga1-s al¬lele conferring preferential fertilization and cross-sterility. High density genotyping-by-sequencing markers were used to delineate the position of ga1 to a 2.6 Mbp region of the B73 reference sequence (AGP version 2). We also mapped ga1 based on its inheritance in backcross between W22 (ga1) and a near-isogenic line carrying Ga1-s on a chromosome segment introgressed from a popcorn variety. The chromosome blocks introgressed from popcorn into W22 were identified with a high-density SNP assay. We created simple sequence repeat markers targeting sequences linked to ga1 to track its inheritance in the W22 backcross populations. Recently, other researchers independently mapped ga1 in crosses of Chinese dent and popcorn lines, and we compared our results to theirs with reference to the B73 reference sequence. All lines of evidence were consistent, with the intervals containing ga1 among all studies overlapping in a 2.2 Mbp interval on chromosome 4 containing 13 predicted genes in the B73 reference sequence.

Keywords

gametophyte factor, pollination, compatibility

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Maydica - A journal devoted to maize and allied species

ISSN: 2279-8013