Haploid identification using tropicalized haploid inducer progenies in maize

Camila Bastos Ribeiro,Guilherme Tomaz Braz,Lamartine Da Nóbrega Filho,Vânia Helena Techio,João Cândido De Souza,Murilo Candido Ruy,Gisele Cenzi,Maria Beatriz Silva,Francielly De Cássia Pereira,Kaio Olímpio Das Graças Dias,Breno Alvarenga Rezende

doi:10.1590/1984-70332018v18n1a3

Camila Bastos Ribeiro, Guilherme Tomaz Braz + Show 9 more

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https://doi.org/10.1590/1984-70332018v18n1a3

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Abstract

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.

Highlights

Doubled haploid (DH) technology is widely used in maize (Zea mays) breeding for line development
We established a protocol for chromosome duplication in maize haploid plants
The experiments were conducted in the greenhouse of the Department of Biology at the Federal University of Lavras (UFLA), Minas Gerais (MG), Brazil, in 2012/2013 and 2014/2015

Summary

Introduction

Doubled haploid (DH) technology is widely used in maize (Zea mays) breeding for line development. Many steps are required to obtain a DH line: crosses between the haploid inducer and the donor genotype, identification of the haploid seeds, chromosome duplication of the haploid plants, planting the doubled haploid seeds for self-pollination, and, harvesting seeds of the DH line. Each of these steps can be inefficient, especially because there is not enough information about this process under tropical conditions. The morphological R1-nj (Navajo) marker usually used in inducing haploid seeds exhibits purple color in the endosperm and in the embryo, and it has been the trait most used for haploid discrimination (Chase and Nanda 1965). Other screening traits can be used, such as radicle color (Chaikam et al 2016) and radicle length (Rotarenco et al 2010), plant vigor (Battistelli et al 2013), and pollen viability

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