| Pyrus is China’s staple fruit.In resent years,early defoliation disease has becoming a main problem in south regions of Pyrus pyrifolia production regions.There are Many reasons threat caused the early deciduous,Such as rain,extreme especially temperature and humidity,lacking of nutrient elements,phytotoxicity,and plant diseases and insect pests.and so on.Previous researches studies have shown that pear black spot and anthracnose are considered to be the main cause reason of early defoliation disease.Pyrus pyrifolia Sandy pear sandy is one of the four main types of pear cultivated,mainly distributed in rainy and moderate climate’s southern region.Endogenous hormone ethylene(ET)is one of the important components of plant hormone,Participating in in plant mature and aging of leaves,flowers and s,fruit.mature and aging,It which induces of flower bud differentiation and breaking dormancy and so on.At the same time,A large number of researches results have overviewd that ethylene plays an important role in pathogen induced disease resistance reaction caused by pathogens,which combines as well as jasmonic(JA)acid and salicylic acid(SA).Abscisic acid(ABA)takes effect in water stress and heat stress.Therefore,endogenous hormones ET and ABA are likely to be an important hormones that which can regulate early defoliation disease.Pyrus pyrifolia leaves whereas treated leaves with(ETH treated、ACC treated、SA treated、ABA treated、AOA treated、MGBG treated and 1-MCP then treated)of sandy pear‘P.pyrifolia’ were used as materials to we analysis of ethylene the role of ethylene in Colletotrichum fructicola induced early defoliation in this study.The contents of disease index,endogenous hormones,peroxidase,superoxide dismutase,catalase and hydrogen peroxide were tested in the both treated and contrasted control leaves.The Real-time PCR technology was used to analyze the relative expressions of different related genes.The results were as follows:(1)We find the anthrax bacteria belonged to the anthrax bacteria(Colletotrichum)by analysising the morphological structure of mycelium,hyphae and conidia,and the phyloge-netic tree,as well as the clone sequencing of ITS gene.(2)We find that all the treatments with ETH、ACC、MGBG、AOA、SA、ABA、1-MCP on 5d,25 d and 50 d,leaves disease index were higher than control,leaves disease index were the lowest after treating with ACC,then the ETH and SA treatment,the treatme nt by AOA is the highest,which is twice as much as processed by ACC.(3)Through analysising of endogenous H2O2 content,POD,SOD and CAT enzyme activity in the leaves after pathogen infection treated with ETH,ACC,MGBG,AOA,SA,ABA,1-MCP and control.we reveal that the content of H2O2,POD and SOD enzyme activity in the leaves was first increasing,and then decreasing,whereas CAT activities was decreasing.The H2O2 content,POD and SOD enzyme activities were the highest at the25 d after anthrax inoculation,and the enzyme activity of CAT reached the lowest level at50 d after anthrax inoculation.(4)The results of the determination of five endogenous hormones in pear leaves showed that the ET content in leaves was same in different treatments,and the trend was gradually increasing.The treatment of ETH,MGBG and ACC The content of ET in leaves was significantly higher than that in other treated leaves;The change of ABA content in control leaves and 1-MCP treated leaves were first increasing,and then decreasing,while for the other 6 treatment leaves,the ABA content was increasing.The content of GA in the leaves after pathogen infection treated with MGBG,ABA and control were increasing,whereas other treated leaves were first increasing,and then decreasing.The content of SA in the leaves after pathogen infection treated with AOA,SA and 1-MCP were increasing,and the change law of the content of SA in the leaves treated with MGBG was “N”,whereas other treated leaves were first increasing,and then decreasing.The content of GA in the leaves after pathogen infection treated with different treatment were increasing.(5)Through analysising of different associated genes relative expressions.we reveal that the expressions of PR1 and NPR1 in leaves were higher than other treated leaves,especially the expression of PR1 gene.At the same time,the expressions of PR1、NPR1、TGA1 and BG were higher than other treated leaves.The expression levels of EIN3,ERF1 and ACS genes in the leaves which treated with ACC were also significantly increased.And the rate of growth is much higher than that of the control and other treatments. |
