Responsive features of SiPRR37 to photoperiod and temperature, abiotic stress and identification of its favourable allelic variations in foxtail millet (Setaria italica L.)
ACTA AGRONOMICA SINICA
In this study, the clock gene SiPRR37 was cloned from the foxtail millet variety Yangu 11, and bioinformatics analysis, tissue specific expression analysis, diurnal expression patterns analysis under four different photo-thermal combinational conditions and responsive characteristics analysis to five abiotic stresses such as NaCl, ABA, PEG, low temperature and Fe were performed to reveal the mechanisms that SiPRR37 participated in regulating of photo-thermal interaction and coped with abiotic
... resses. Mutation sites of SiPRR37 were detected by re-sequencing of 160 millet materials, which were used for haplotype analysis to explore the effect of SiPRR37 on main agronomic traits. The results showed that the CDS length of SiPRR37 gene was 2247 bp, which encoded 748 amino acids and contained REC and CCT domains. The phylogenetic analysis based on PRR37 proteins showed that foxtail millet had the closest relationship with broomcorn millet, sorghum and maize. Promoter prediction analysis found that various responsive elements to light, temperature, auxin, GA, ABA, MeJA, drought and salt stresses were detected in promoter region of SiPRR37. The decreasing order of relative expression level of SiPRR37 was root, panicle neck, panicle, parietal leaf, secondary parietal leaf and stem. Under four photo-thermal combinational conditions, SiPRR37 gave only one expression peak during the light period, and regardless of high temperature (27℃) or low temperature (22℃), the expression peak advanced under short-day condition compared to long-day condition, regardless of long-day or short-day, the expression peak advanced at low temperature (22℃) compared to high temperature (27℃). The expression of SiPRR37 was inhibited by NaCl and low temperature (15℃) stresses, induced by PEG-simulated drought stress and Fe stress. SiPRR37 participated in ABA signaling transduction process. The 10 SNPs in CDS region of SiPRR37 divided 160 millet materials into 19 haplotypes, of which Hap_7, Hap_10 and Hap_19 were favorable haplotypes for improving panicle traits. SiPRR37 exhibited circadian expression, and was regulated by photoperiod and temperature simultaneously. SiPRR37 participated in the responses of foxtail millet to salt stress, low temperature stress, drought stress and Fe stress. At the same time, SiPRR37 was correlated with heading stage and multiple panicle traits, showing certain application potential in high-yield molecular-assisted breeding of foxtail millet.