Gametophytic incompatibility in Mexican maize breeds

Abstract

Sporophytic and gametophytic incompatibility avoids self-fecundation or cross-fertilization, and it is a form of reproductive isolation. The cross-incompatibility genes in maize from loci ga1 and tcb1, cause recognition or reject between stigma and pollen, and from them depends presence or absence of grain in maize ear. The aim of this study was to detect alleles of cross-incompatibility of ga1 and tcb1 in collections representing maize breeds groups from Mexico. The work was made at Centro Universitario de Ciencias Biológicas y Agropecuarias from Universidad de Guadalajara, located in Zapopan, Jalisco, Mexico during agricultural spring-summer 2007 to 2009 cycles. Under rainfall conditions 184 accessions of Mexican maize breeds were assessed based in percentage of grain filling in ear in their crosses with recessive male testers (without incompatibility factors) and dominant female testers (with incompatibility factors). The analysis of variance suggested highly significant differences as well between breeds as between accessions within breeds for locus ga1. With regards locus tcb1 there were found only highly significant differences between breeds. Allele Ga1-S, responsible of non-reciprocal incompatibility, was detected in 53.8% of accessions, while neutral allele Ga1-m and recessive allele ga1 was identified in 55.43 and 15.76%, respectively. Allele Tcb1-S was detected at very low rates, mainly found in breeds Elotes-Occidentales and Maíz- Dulce.