P-Coumaric Acid And Other Phenolic Compounds Response To The Infection Of Pseudomonas Syringae Pv. Actinidiae In Kiwifruit Leaves

The kiwifruit bacterial canker is the most devastating disease of kiwifruit caused by Pseudomonas syringae pv.actinidiae（Psa）,which cause a serious threat to the development of kiwifruit industry.Psa was listed in the list of forest phytosanitary objects in China in 1996 and listed as a prohibited organisms in 2009.Because of the Anti-Pseudomonas activity of p-Coumaric acid and other phenolic compounds,we speculate that they may play an important role in kiwifruit during the infection of Pseudomonas syringae pv.actinidiae.In the world,Psa is divided into 5 different kinds of biovar according to the genetic diversity and toxin productivity（biovar 1-biovar5）,and different strains have different virulence.The HPLC conditions of kiwifruit were optimized.In this study,different genotype strains（biovar1、biovar2、biovar3 and biovar4）were treated with p-Coumaric and different cultivars（Actinidia deliciosa‘Jinkui’and Actinidia chinensis‘Hongyang’）were treated with biovar3（JF8）which has the most virulence.We try to explore the function of p-Coumaric acid and other phenolic compounds on the basis of Metabolome and Transcriptome and find the key regulatory gene.The purpose is to provide a basis for the evaluation of germplasm resources of kiwifruit about resistance of Psa.The results showed that:1.Low concentrations of p-Coumaric promote the growth of Psa and high concentration inhibits the growth of Psa;Different Psa have different sensitivities to p-Coumaric.18004（biovar4）and K3（biovar2）are most sensitive to p-Coumaric,inhibiting the growth of Psa at the concentration of about 120μg/ml.When the concentration of p-Coumaric reached 160μg/ml,the growth of KW30（biovar1）was inhibited.JF8（biovar3）have the most virucence and it was inhibit at the concentration of p-Coumaric was about 300μg/ml;For JF8,it presents two quadratic function about concentration and△OD₆₀₀ in both low concentration and high concentration,one is y=-1E-06x2+0.0003x+0.0011（x≤320μg/ml）and the other is y=-1E-09x2-8E-05x+0.0224（320μg/ml≤x≤2560μg/ml）.The growth of JF8 was gradually increased with the increase of the concentration of p-Coumaric when the concentration no higher than 160μg/ml,promote effect was maximum when the concentration is about 160μg/ml,and while the promoting effect was gradually reduced before the concentration of p-Coumaric reached 300μg/ml.Finally,JF8 growth gradually reduced with the increase of the concentration of p-Coumaric until it is no longer to grow.2.The contents of p-Coumaric acid,arbutin,gallic acid,chlorogenic acid,epicatechi n,vanillin and trans-Cinnamic acid of‘Hongyang’leaves were higher than‘Jin kui’leave s without treatment.The content of epicatechin of‘Hongyang’were 5.5 times higher tha n‘Jinkui.11 kinds of total phenol content of‘Hongyang’were 2.9 times higher than‘Jin kui’.The contents of caffeic acid,ferulic acid,phlorizin,trans-Cinnamic acid,1,2-Dihydr oxybenzene and gallic acid were significantly lower than control.The contents of p-Cou maric acid,caffeic acid,ferulic acid,vanillin,phlorizin and ctrans-Cinnamic acid in leave s of‘Hongyang’reached the maximum value on the 4th day after treatment.3.The average content of lignin of‘Hongyang’leaves was 5.720 mg/100mg FW,and the content of lignin was 6.212 mg/100mg FW after inoculation one day.The average content of lignin of‘Jinkui’leaves was 8.334 mg/100mg FW,and then becomes8.623mg/100mg FW after inoculation one day.The activity of POD of‘Hongyang’and‘Jinkui’were increased after inoculation one day.Therefore,we infer that the initial content of lignin and the activity of POD may play an important role in the risistant of Psa.The content of phenolic compounds was decreased in the phenylalanine pathway in the early stage of inoculating Psa,One part of the phenolic compounds were decomposed and utilization by Psa,and the other part were transformed into lignin to resist pathogen invasion.4.Transcriptome test indicates that the sequencing integrity of‘Jinkui’is credible,Because of the comparison of Total Reads,Total Base Pairs and reference genome,reference gene 100.00%.Compared with Psa treatment,there were 823 differential expression genes.553 genes were up-regulated,and 270 genes were down-regulated.Ten transgenic genes were selected to validate the transcriptome and the results of q RT-PCR were consistent with those of transcriptome sequencing,which indicated that the results of the transcriptase sequencing were reliable.