Integrative genetic and molecular delineation of indeterminate gametophyte1 (ig1) gene governing paternal haploid induction in maize

Le résumé fourni par la source

The doubled haploid (DH) technology aids in accelerated crop breeding. The indeterminate gametophyte1 ( ig1 )-based paternal haploid inducer (HI) line in maize results in haploids carrying nuclear and cytoplasmic genome from source- and inducer- parent, respectively. Here, we sequenced the entire Ig1 gene (5431 bp) among eight wild-type ( Ig1: two exons) and two mutant ( ig1: one exon) inbreds. It revealed eight haplotypes of Ig1 among these inbreds with a haplotype diversity score of 0.956 and nucleotide diversity (P i ) value of 0.013. The insertion of Hopscotch retrotransposon in ig1 resulted in a truncated protein with 138 amino acids, in contrast to 260 amino acids in wild-type IG1 protein. The study also revealed that the disruption of leucine zipper in mutant IG1 protein was responsible for its non-functionality. We developed a functional marker (MGU-IG1-Hopscotch) specific to Hopscotch insertion and validated it in five F 2 populations. Moreover, 15 InDel markers were used to study Ig1 gene diversity among 48 diverse maize inbreds which, based on these markers, were grouped in six clusters with 17 haplotypes. Of these, five markers differentiated the wild-type and mutant allele of Ig1 . The study identified 10 paralogues having >30 % sequence identity to Ig1 . In F 2 populations, an average haploid induction rate (HIR) was higher in mutant homozygotes ( ig1/ig1 ; 2.36 %) than that of the heterozygotes ( Ig1/ig1 , 1.49 %). The ig1- positive plants also produced seeds with twin embryos at the rate of 0–1.6 %. The functional marker ‘MGU-IG1-Hopscotch’ assumes great significance in the development of ig1 -based paternal HI lines for conversion of maize inbreds into cytoplasmic male sterile (CMS) versions. This is the first report of development of functional marker and haplotype analysis for Ig1 gene in maize.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.