Fine Mapping and Functional Research of Key Genes for Photoperiod Sensitivity in Maize

Abstract

Maize is native to the tropics and is very sensitive to photoperiod. Planting in temperate regions with increased hours of daylight always leads to late flowering, sterility, leggy plants, and increased numbers of maize leaves. This phenomenon severely affects the utilization of tropical maize germplasm resources. The sensitivity to photoperiod is mainly reflected in differences in plant height (PH), ear height (EH), total leaf number (LN), leaf number under ear (LE), silking stage (SS), and anthesis stage (AT) in the same variety under different photoperiod conditions. These differences are more pronounced for varieties that are more sensitive to photoperiod. In the current study, a high-density genetic map was constructed from a recombinant inbred line (RIL) population containing 209 lines to map the quantitative trait loci (QTL) for photoperiod sensitivity of PH, EH, LN, LE, SS, and AT. A total of 39 QTL were identified, including three consistent major QTL. We identified candidate genes in the consensus major QTL region by combined analysis of transcriptome data, and after enrichment by GO and KEGG, we identified a total of four genes (Zm00001d006212, Zm00001d017241, Zm00001d047761, and Zm00001d047632) enriched in the plant circadian rhythm pathway (KEGG:04712). We analyzed the expression levels of these four genes, and the analysis results showed that there were significant differences in response under different photoperiod conditions for three of them (Zm00001d047761, Zm00001d006212 and Zm00001d017241). The results of functional verification showed that the expression patterns of genes rhythmically oscillated, which can affect the length of the hypocotyl and the development of the shoot apical meristem. We also found that the phenotypes of the positive plants were significantly different from the control plants when they overexpressed the objective gene or when it was knocked out, and the expression period, phase, and amplitude of the target gene also shifted. The objective gene changed its own rhythmic oscillation period, phase, and amplitude with the change in the photoperiod, thereby regulating the photoperiod sensitivity of maize. These results deepen our understanding of the genetic structure of photoperiod sensitivity and lay a foundation for further exploration of the regulatory mechanism of photoperiod sensitivity.

Genetic diversity of North American popcorn germplasm and the effect of population structure on nicosulfuron response

“…Besides the number of lines, a major difference between previous studies and the results presented here is that morphological traits were not included when determining phylogenetic relationships and population structure. All traits are composed of genotypic and environmental effects, and many of the vegetative and phenological traits included in previous analyses of popcorn are known to be affected by photoperiod sensitivity, including plant height, ear height, leaf number, and days to flowering (Fei et al 2022). As few as four genomic regions have been identified that control photoperiod responses in these traits (Coles et al 2010).…”

Genetic diversity of North American popcorn germplasm and the effect of population structure on nicosulfuron response

“…Besides the number of accessions, a major difference between previous studies of North American Popcorn germplasm and the results presented here is that morphological traits were not included when determining phylogenetic relationships and population structure. All traits are composed of genotypic and environmental effects, and many of the vegetative and phenological traits included in previous analyses of popcorn are known to be affected by photoperiod sensitivity, including plant height, ear height, leaf number, and days to flowering (Fei et al., 2022). As few as four genomic regions have been identified that control photoperiod responses in these traits (Coles et al., 2010).…”

Integrated IBD Analysis, GWAS Analysis and Transcriptome Analysis to Identify the Candidate Genes for White Spot Disease in Maize

“…For instance, Zm00001d005347 encodes monodehydroascorbate reductase homolog 1 (https://www.uniprot.org/ (accessed on 1 May 2023)). Many related reports have stated that this region is associated with several QTNs of essential traits, e.g., PH, EH, anthesis stage and seed desiccation [37,38]. The pedigrees of QB512 and QR273 include tropical materials, which have good resistance to MWS, but frustratingly, have long growth periods and poor seed desiccation.…”