β-carotene content in maize grain and the allelic state of the lycopene-ε-cyclase and β-carotene hydroxylase 1 genes in maize genotypes of Ukrainian breeding

Abstract

Aim. To identify potential donors of increased β-carotene content in grain and favorable alleles of the lycopene-ε-cyclase (lycε) and β-carotene hydroxylase 1 (crtRB1) genes among maize genotypes of Ukrainian breeding by assessing the β-carotene content in grain and analyzing the associations between the β-carotene content and the allelic state of carotenogenesis genes. Methods. Spectrophotometric analysis, polymerase chain reaction, statistical methods. The content of total carotenoids by β-carotene in corn kernels was analyzed twice: at the time of harvest (September 2024) and after nine months of storage (June 2025). Results. Significant variability in β-carotene content among the studied genotypes was established. At the time of grain harvesting, this indicator was on average 4.67 mg/kg (2.70–7.14 mg/kg), and after nine months of storage, it decreased on average by 46.68% and amounted to 2.49 mg/kg (1.98–3.71 mg/kg). The degree of loss varied considerably depending on the genotype (12.59–62.18%). The two-way ANOVA analysis showed that the greatest contribution to the variation of the «β-carotene content» trait in grain was the duration of storage (51.7%), while the contribution of the genotype was 30.7%, and their interaction — 15.2%. According to the lycε-SNP216 marker of the lycopene-ε-cyclase gene, the genotypes with the G allele (61.1%), the T allele (33.3%) and one heterozygous G/T genotype (5.6%) were identified, while according to the crtRB1-3′TE marker of the β-carotene hydroxylase 1 gene, unfavorable (296 and 296+875 bp) alleles (94.4%) prevailed. A tendency towards an increase in the β-carotene content was found in genotypes with the favorable G allele of the lcyε gene (4.79±0.43 mg/kg) compared to genotypes with the T allele (4.13±0.55 mg/kg). The genotype Kros256S with the heterozygous state of crtRB1 (296+543 bp) was characterized by an increased post-storage content of β-carotene (3.71 mg/kg). At the same time, the detection of albeit limited number of genotypes with a favorable (543 bp) allele provides an opportunity to conduct a full-fledged statistical analysis of the influence of favorable alleles of this gene on the post-storage content of β-carotene in future. It was found that the most promising potential donors for maize breeding for an increased content of provitamin A are the genotypes Kros268S and DK3172 ZM, which combined a high content of β-carotene with the presence of a favorable allele G of the lycε gene, as well as Kros256S, which was characterized by a high content of β-carotene both at the time of grain harvest and after nine months of storage and contained the favorable allele G of the lycε gene and the allele 543 bp of crtRB1 gene. Conclusions. For corn genotypes of Ukrainian selection, the content of β-carotene in the grain at the time of harvesting and after nine months of storage was comprehensively assessed in combination with the determination of the allelic status of the lcyε and crtRB1 genes. The features of the manifestation of the allelic state of the lcyε and crtRB1 genes regarding the variability of the β-carotene content in the grain and its preservation were established. Potential donors of increased β-carotene content in grain and favorable alleles of carotenogenesis genes lycε and crtRB1 were identified among the maize genotypes of Ukrainian breeding. The genotypic variability of β-carotene content in grain was assessed at the time of grain harvest and after nine months of storage. Genotypes carrying the favorable allele G of the lycε gene were characterized by a tendency to increased β-carotene content in grain, while the assessment of the influence of the favorable allele 543 bp of the crtRB1 gene requires an expansion of the sampling of studied genotypes. Genotypes Kros268S, DK3172 ZM and Kros256S may be considered to be the most promising potential donors for maize breeding for increased β-carotene content in grain. The results obtained can be used for selection of starting material and marker-assisted selection of maize for increased β-carotene content in grain.