关键词: 谷子, 重组自交系群体, 株高, 株型, QTL, 候选基因

Abstract:

【Objective】 Plant height is a trait that plays an important role in the increase of foxtail millet yield. The dynamic changes of foxtail millet plant height at different growth stages were studied, and the QTL loci and effects controlling plant height were identified to provide a theoretical basis for plant type breeding of foxtail millet. 【Method】 In this study, a recombinant inbred line population YRRIL containing 215 lines were used as the research object, and the YRRIL population was planted in two environments, Yulin, Shaanxi and Mizhi, Shaanxi, in May 2023, respectively. The phenotypic values of plant height trait of each family were measured at five stages: seedling, elongation, booting, tasseling, and ripening period, respectively. Combined with the genetic linkage map of the YRRIL population, genetic analysis and dynamic QTL mapping of plant height trait at different growth stages of millet were carried out, and the unconditional QTL and conditional QTL controlling plant height of millet were identified. On this basis, candidate gene prediction for important QTL was carried out using Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis methods. 【Result】 In the entire growth period of the millet plant height growth trend was the “S” type curve, from the elongation stage to the booting stage, the growth rate of plant height was faster, which was the key stage of plant height development. In the two environments, plant height of each family line of the population showed continuous distribution at different periods. A total of 86 QTL related to plant height were detected at five periods in the two environments, which were distributed on all 9 chromosomes of the foxtail millet genome. It contained 48 unconditional QTL and 38 conditional QTL, and the phenotypic contribution rate of unconditional QTL was 1.13%-17.49%, of which 6 could be detected repeatedly at two growth periods, and the rest were detected only at one growth period. The phenotypic contribution rate of conditional QTL was 1.97%-14.69%, of which one could be detected repeatedly at two growth stages, and the rest were detected only at one growth stage. No QTL that can be detected in three or more periods were present in either unconditional QTL analysis or conditional QTL analysis. A total of 12 major QTL were detected by unconditional QTL and conditional QTL analysis in two environments, of which 6 QTL were newly identified as primary loci in this study. Based on the prediction and analysis of genes within the main effect QTL interval combined with functional annotation of homologous genes screened out 14 candidate genes that might be related to foxtail millet plant height, among which Seita.1G242300.1, Seita.6G110200.1, and Seita.7G143300.1 were all able to directly regulate plant height development. 【Conclusion】 In the two environments, a large number of QTL were detected to be involved in the phenotypic regulation of plant height trait during the whole growth and development of foxtail millet, with 79 (91.86%) played a role in one period and 7 (8.14%) played a role in two periods and there were no QTL detected in three or more periods, including 12 major QTL. The QTL detected by unconditional and conditional analysis methods accounted for 55.81% and 44.19%, respectively, and 16 (18.60%) were both unconditional and conditional QTL. The QTL effects controlling plant height development at different stages varied, with smaller effect in the seedling stage and generally larger effects from the elongation to the tasseling stage.

Key words: foxtail millet, RIL, plant height, plant architecture, QTL, candidate genes