Haploid identification using tropicalized haploid inducer progenies in maize
Camila Bastos Ribeiro, Francielly de Cássia Pereira, Lamartine da Nóbrega Filho, Breno Alvarenga Rezende, Kaio Olímpio das Graças Dias, Guilherme Tomaz Braz, Murilo Candido Ruy, Maria Beatriz Silva, Gisele Cenzi, Vânia Helena Techio and João Cândido de Souza
Abstract: The aim of this study was to identify maize haploid plants and compare the efficiency of identification of maize haploid plants using the R1-nj morphological marker, plant vigor, flow cytometry, chromosome counting, and microsatellite molecular markers under tropical conditions. We also established a protocol for chromosome duplication in maize haploid plants. Fourteen S0:1 and seven S2:3 haploid inducer progenies were crossed with GNZ9501 in 2012/2013 and 2014/2015, respectively. Through use of the R1-nj trait, we were able to identify 552 putative haploid seeds in 2012/2013 and 260 putative haploid seeds in 2014/2015. Only 1.84% were true positives according to flow cytometry in 2012/2013. In 2014/2015, 75% of the putative haploids were true negatives according to molecular markers. Plant vigor had a high proportion of true negatives. Molecular markers and flow cytometry are more efficient in classifying plant ploidy level. Chromosome duplication was efficient in all plants.