| Alternaria alternata infection is one of the key factors for causing of cotton premature leaf senescence which is a serious hazard to cotton production.Therefore,exploration and utilization of cotton resistance to Alternaria alternata is an effective way to control cotton premature leaf senescence.Mitogen-activated protein kinases(MAPK)cascades is an important signal transduction system,which plays an important role in plant resistance to various biological and abiotic stresses.In order to reveal the signal transduction mechanism of cotton resistance to Alternaria alternata,all the GhMAPK and GhMAPKK genes have been screened out from the Gossypium hirsutum genome.Then multiple sequence alignment and phylogenetic analysis were performed on these genes and their roles in cotton resistance to Alternaria alternata were tested by virus-induced gene silencing technology(VIGS).The main research results are as follows:1.Based on the gene annotation information of Gossypium hirsutum genome-wide and the multiple sequence alignment results,53 GhMAPK and 24 GhMAPKK genes were screened out,and they were named based on its homologous AtMAPK and AtMAPKK gene.The protein sequence alignment results showed that most of GhMAPK contain the T-X-Y sequence which is typical of plant MAPK,but in Gh_A07G1299(GhMAPK4-3),Gh_D07G1410(GhMAPK4-8)and Gh_A10G2117(GhMAPK17-1),the T-X-Y was transformed into T-X-C.The majority of GhMAPKK contain the conserved motif D(I/L/V)K and phosphorylation site S/ T-XXXXX-S/T which were specific to plant MAPKK,but in Gh_D07G0094(GhMAPKK6-2)and Gh_A07G0085(GhMAPKK6-4)the DIK was transformed into HIK,in Gh_A01G1308(GhMAPKK7-1)and Gh_D01G1562(GhMAPKK7-2)the S-XXXXX-S/T was transformed into S-XXXXX-N.Phylogenetic tree analyses showed that the GhMAPK and GhMAPKK families could be classified into four groups corresponding to the group A,B,C and D in Arabidopsis.2.Constructing GhMAPK and GhMAPKK silence vectors and using VIGS technology to study whether GhMAPK and GhMAPKK were involved in cotton resistance to Alternaria alternata.The results showed that the disease resistance of GhMAPK3,GhMAPK7,GhMAPK9,GhMAPK19,GhMAPKK2,GhMAPKK3 and GhMAPKK9 gene silenced cotton was significantly reduced and their disease index was significantly higher than that of wild type control and empty vector control,which indicated that these genes positively regulate cotton resistance to Alternaria alternata.3.For the selected 4 GhMAPK and 3 GhMAPKK,the cotton resistance regulation roles for the different homologous genes of them were further tested by target silencing strategy.The results indicated that homologous genes GhMAPK3b(GhMAPK3-2,GhMAPK3-4)of GhMAPK3;GhMAPK7b(GhMAPK7-2,GhMAPK7-5)and GhMAPK7c(GhMAPK7-3,GhMAPK7-6)of GhMAPK7;GhMAPK9a(GhMAPK9-1,GhMAPK9-3)and GhMAPK9b(GhMAPK9-2,GhMAPK9-4)of GhMAPK9;GhMAPK19b(GhMAPK19-2,GhMAPK19-5)and GhMAPK19c(GhMAPK19-3,GhMAPK19-6)of GhMAPK19;GhMAPKK2a(GhMAPKK2-1,GhMAPKK2-4)and GhMAPKK2b(GhMAPKK2-2,GhMAPK2-5)of GhMAPKK2 and GhMAPKK9a(GhMAPKK9-1,GhMAPKK9-2)of GhMAPKK9 positive regulate cotton resistance to Alternaria alternata.While other five homologous genes GhMAPK3a(GhMAPK3-1,GhMAPK3-3);GhMAPK7a(GhMAPK7-1,GhMAPK7-4),GhMAPK7d(GhMAPK7-7);GhMAPK19a(GhMAPK19-1,GhMAPK19-4);GhMAPKK2c(GhMAPKK2-3,GhMAPKK2-6)and GhMAPKK9b(GhMAPKK9-3)had no function in regulation of cotton resistance to Alternaria alternata. |
PDF Full Text Request