Proteomic Analysis Of Suceptible Cotton Leaves After Infection Of Verticillium Dahliae

As an important economic crop, cottton plays an important role in our national economy. Theoccrence of cotton Verticillim wilt restricts the improvement of cotton yield of our cuntry. However theVerticillim wilt is a chronic disease of cotton, conventional and integrated control measures could notcompletely eliminate the occurance of the disease. Most of the resistant cotton varieties are not highlyresisitant. Lack of resistance source and rapid genetic variation of Verticillim dahlia， increase thedifficulty of cotton Verticillim wilt resisitance breeding. Therefore, further studies on the intractionmechanism between cotton and Verticillim dahlia is particularly important.The main symptoms of Verticillium wilt of cotton are wilting and withering of leaf. Leaf is themain organ of photosynthesis and the decisive factor of cotton yield. Wilting and withering causeserious loss of cotton yield. Previous reports were often based on cotton roots to study the interactionmechnism between cotton and Verticillium dahliae. Few research focus on cotton leaves especillyproteomic changes of cotton leaves after innoculation. Therefore, studies on proteomic changes ofcotton leaves after Verticillium innoculation come to be particularly important. This research attempts toanalyze the proteomic changes of cotton leaf after innoculation of Verticillium, using succeptible Jimian11as the material. And then try to dig out proteins interacting with Verticillium dahliae, which lays thetheoretical foundation for further study of pathogenic mechanism of the pathogen.Analysis of mass spectrometry showed that proteins differentially expressed three days afterinnoculation of Verticillium dahliae are ribulose bisphosphate carboxylase large chain, ribulosebisphophate carboxylase small chain, ribulose bisphosphate carboxylase small chain and chlorophyllAB binding protein which were down-regulated, and ATP synthase beta subunit, rubisco activatingenzyme1, rubisco activating enzyme alpha2, fructose-1,6-two phosphate aldolase which wereup-regulated. Photosynthetic energy metabolism was seriously affected after infection. Expression ofRuBisCO and chlorophyll AB binding protein reduced. In order to reduce the damage, expression ofRuBisCO activating enzyme, ATP synthase beta subunit which is the key factor of ATP sysnthesis, andfrutose-1,6-two phosphate aldolase controlling photosynthetic rate increased. We hypothesized that thepathogen may interact with proteins participating in the photosynthetic energy metabolism, and affactsphotosynthetical system of cotton, leading to leaves wilting and withering eventually.In order to verify the consistency of changes in protein level and mRNA level, we conductedquantitative real-time PCR experiments. Genes chosed were RCA-1, RBCS and cab. RT-PCR can vertifythe consisitance of the changes in protein level and mRNA level, meanwhile we can see the change ateach time point after inoculation, making up for the deficiency of the single time point intwo-dimensional gel electrophoresis experiments. After inoculation of Verticillium dahliae, mRNA levelof RBCS showed a downward trend; although the expression of RCA-1increased at the beginning and then decreased, the expression quantities of each time period were higher than that of the control; theexpression level of cab also descreased. In general, changes of the three genes at the transcriptionallevel were consistent to the protein level. This result further confirmed the reliability of the analysis oftwo-dimensional electrophoresis.The conclusion is meaningful to further research on interantion between cotton and Verticilliumdahliae.