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Maize is the second most important staple food crop in the world after wheat. For maize hybrid seed production, a prominent step is detasseling in the female parent, which is laborious, time consuming, and increases the hybrid seed cost by 15 to 20 percent. Hence, to overcome this problem, exploitation of male sterility in maize crops gains special significance. In this direction, the research was conducted to transfer cytoplasmic male sterility (CMS-C) from a CMS donor (VL192114) into the female parents (CAL1514 and ZL153493) of heat- and drought-resilient maize hybrids (RCRMH-2 and RCRMH-3) by a marker-assisted backcross scheme. The present research used Diversity Array Technology (DArTag) and Kompetitive Allele Specific PCR (KASP)-based single-nucleotide polymorphic markers for background selection in backcross populations. Genome recovery percentage ranged from 64.25 to 72.70, 78.94 to 87.69 and 82.28 to 90.77 percent in the BC1F1, BC2F1 and BC3F1 population, respectively, in the CAL1514 population, while it was 63.47 to 73.55, 78.16 to 88.76 and 83.96 to 91.81 percent in the BC1F1, BC2F1 and BC3F1 population, respectively, in the ZL153493 population. When the near-isogenic CMS lines of both populations are compared for agro-morphological traits with their recurrent parents, the agronomic qualities of recurrent parents, as well as the attributes of distinctness, uniformity and stability, are shown. Therefore, male sterility-transferred, female lines of RCRMH-2 and RCRMH-3 maize hybrids can be used directly to produce maize hybrid seed without the need of the detasseling process. [ABSTRACT FROM AUTHOR]

Genome-wide association studies are a powerful method to dissect the genetic basis of traits, although in practice the effects of complex genetic architecture and population structure remain poorly understood. To compare mapping strategies we dissected the genetic control of flavonoid pigmentation traits in the cereal grass sorghum by using high-resolution genotyping-by-sequencing single-nucleotide polymorphism markers. Studying the grain tannin trait, we find that general linear models (GLMs) are not able to precisely map tan1-a, a known loss-of-function allele of the Tannin1 gene, with either a small panel (n = 142) or large association panel (n = 336), and that indirect associations limit the mapping of the Tannin1 locus to Mb-resolution. A GLM that accounts for population structure (Q) or standard mixed linear model that accounts for kinship (K) can identify tan1-a, whereas a compressed mixed linear model performs worse than the naive GLM. Interestingly, a simple loss-of-function genome scan, for genotype-phenotype covariation only in the putative loss-of-function allele, is able to precisely identify the Tannin1 gene without considering relatedness. We also find that the tan1-a allele can be mapped with gene resolution in a biparental recombinant inbred line family (n = 263) using genotyping-by-sequencing markers but lower precision in the mapping of vegetative pigmentation traits suggest that consistent gene-level resolution will likely require larger families or multiple recombinant inbred lines. These findings highlight that complex association signals can emerge from even the simplest traits given epistasis and structured alleles, but that gene-resolution mapping of these traits is possible with high marker density and appropriate models.