Mitogen-activated protein kinase kinase(MAPKK or MKK)plays an important role in plant growth,development and stress responses.In order to identify MAPKK genes related to rust resistance in foxtail mil-let and provide candidate genes for the study of rust resistance mechanism and disease-resistant molecular breeding of foxtail millet,the members of MAPKK gene family(SiMKKs)in foxtail millet were identified and analyzed at the whole genome level by bioinformatics methods.Real-time PCR was used to detect the expression level of SiMKKs gene in differ-ent tissues,under the stress of rust fungus and exogenous hormone treatment.Excel,MEGA and DnaSP were used to ana-lyze the variation sites and haplotypes of the SiMKKs gene related to rust resistance in 70 re-sequenced foxtail millet va-rieties,and the excellent rust-resistant haplotypes were identified based on phenotype analysis.The results showed that a total of 10 SiMKKs were identified in foxtail millet,which were distributed on 5 chromosomes.The number of exons ranged from 1 to 11,and the encoded protein contained 331-523 amino acids.The SiMKKs were divided into 4 groups.Groups A and B contained S/T-X5-S/T motif,while SiMKKs in groups C and D did not have this motif.Conserved Motif 1-Motif 6 existed in all SiMKK proteins.The promoter region of each SiMKK gene contained 1 to 3 biotic stress-related cis-acting elements,such as defense and stress response,methyl jasmonate(MeJA)response,salicylic acid(SA)response and elicitor activation.Except SiMKK10-1 and SiMKK10-3,the other 8 SiMKK genes were expressed with different de-grees in different tissues,and under rust infection,SA and MeJA treatments.The highest expression of SiMKK4,SiMKK5 and SiMKK1 0-2 were in roots at booting stage,and the highest expression of SiMKK6-1 and SiMKK6-2 were in stems at booting stage.The expression of SiMKK4 was up-regulated in the resistant response and down-regulated in the susceptible response within 24 h after inoculation,and its expression was related to disease resistance.The ex-pression of SiMKK4 was up-regulated within 16 h and then down-regulatedafter SA and MeJA treatments,and showed continuous changes during SA treatment.In addition,the expression patterns of the remaining 7 SiMKK genes in SA and MeJA treatments were also consistent.The coding region of SiMKK4 gene contained 7 haplotypes and Hap_1 was the dominant haplotype,and no key variation sites related to disease resistance were found.In summary,the expres-sion of SiMKK4 is identified to be associated with resistance to rust disease in foxtail millet,and SiMKK4 may participate in the early disease resistance response of foxtail millet through SA and MeJA signaling pathways.
维普
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