Analysis And Evaluation For The Pathogenicity Of Colletotrichum Gloeosporioides And Resistance Of Fig Cultivars To Anthracnose

Fig anthracnose is one of the important diseases during the growing and storage periods of figs(Ficus carica).Because the disease harms leaves and fruits,it often rots a large number of fruits,seriously affecting the yield and quality of figs.In this study,the fig varieties(lines)with different susceptibility levels were used as materials to evaluate the resistance of fig varieties to anthracnose,identify the differences in susceptibility and disease resistance of cultivars,screen for anthracnose resistance of figs,and explore physiological and biochemical resistance factors.SSR analysis of genetic diversity among varieties was conducted to analyze the mechanism of fig resistance to anthracnose.At the same time,we collected the fig anthracnose strains to determine the pathogenicity of the anthracnose strains,clarify the differences in pathogenicity differentiation,and analyze the pathogenic mechanism between the anthracnose strains.With a view to further exploring the interaction mechanism between figs and anthracnose,providing theoretical basis for preventing and controlling fig anthracnose in the field.The main findings are as follows:1 Pathogenicity analysis of anthracnoseIn vitro inoculation of leaves and fruits of 11 anthracnose strains in the susceptible variety 108B was determined.The results showed that the pathogenicity on the leaves was divided into three types:strong,medium and weak.5 strains such as A2,Y2,C2,I,and H are moderately pathogenic types,and 4 strains such as A5,Y10,M5,and M1are weakly pathogenic types;the pathogenicity of the fruit is divided into 4 types:strong,medium,weak and non-pathogenic,of which H4 strain is a strong pathogenic type,3 strains such as A2,Y2 and Y9 are medium pathogenic types,3 strains such as C,I and M1 are weak pathogenic types,The four strains A5,M5,Y and K7 are non-pathogenic.Among them,Y2,Y,and Y10 were isolated from the fruit,K7,M1,M5,I,and C were obtained from the leaves,and H4,A2,and A5 were obtained from the petioles.The pathogenicity is more consistent with the fig-like parts of pathogens.2 Comparison of biological characteristics of strong and weak pathogenic strains The mycelial growth rate of K7 and A5 strains of Colletotrichum gloeosporioides,the germination rate of conidia under different conditions and the rate of attachment cells were measured.The results showed that the growth rate,spore production,conidia germination rate and attachment cell formation rate of the highly pathogenic strain K7 were significantly higher than those of the weakly pathogenic strain A5.The growth rate of K7 mycelium was 1.11 mm/d at 28°C;K7 spore production was 2×10~6CFU/ml under solid PDA medium and 2.3×10~6CFU/ml under liquid PDA medium;The optimal p H for K7 conidia germination was 6 at 24h,and the germination rate was 93.89%;the optimal p H for K7 appressorium generation is 3,and the generation rate is 57.07%;the optimal germination temperature of K7 is 30?,and the germination rate can reach 93.48%;the optimum temperature for the generation of K7appressorium is 30?,and the generation rate is 58.12%;the germination rate of K7conidia was higher under 24h light condition,reaching 98.43%;the productivity of K7 appressorium reached 46.77%under 24h light;the optimal germination rate of K7bacteria at a relative humidity of 97%is 97.46%;When the relative humidity is 92%,the rate of attached cell generation is 83.75%.The average growth rate of A5 anthrax at 28?is 0.94 mm/d;spore production under liquid PDA medium is 1.1×10~6CFU/ml;the optimal p H for A5 conidia germination is 3,with a germination rate of 89.13%;the optimal p H for A5appressorium generation is 5,and the generation rate is up to 11%;the optimal germination temperature of A5 is 30?,and the germination rate is 77.53%;the optimum temperature for A5 appressorium formation is 30?,and the generation rate is 20.66%;the generation rate of A5 appressorium reached 13.64%under 12h alternating light and dark;the optimum germination rate of A5 bacteria under the condition of 100%relative humidity is 77.32%;the production rate of A5 reaches12.47%under the condition of relative humidity of 100%.3 Comparative analysis of CWDEs activity of different pathogenic strainsCompare the difference of CWDEs enzyme activity between K7 and A5 in pure culture and inoculated on different varieties.The results showed that K7 could produce PG,PMG and CX enzymes under the induction of enzyme production under pure culture,while A5 only produced PG and PMG.The enzyme activity was significantly different after inoculation in different varieties,the activity of CX in K7in the same variety was much higher than that in A5;after A5 infects different varieties,the activities of PG and CX in susceptible varieties are higher than those of resistant varieties;after K7 infects different varieties,the PMG and CX activities of susceptible varieties are higher than those of resistant varieties,from the side,it showed a positive correlation with the pathogenicity of anthrax.4 Analysis of disease resistance of varieties According to the anthracnose field disease grading standards,the field resistance analysis and indoor inoculation identification were used to analyze the disease resistance of the varieties.Field resistance survey results indicate that Jinaofen and108B are susceptible to anthrax;Qingpi showed middle sense;Masitam,121E,Bojihong and 110C showed disease resistance.Seven fig varieties were inoculated with strong pathogenic strain K7 for identification.The results showed that 108B was a highly susceptible variety;Qingpi was a moderately susceptible variety;Masitam,Jinaofen,121E,Bojihong and 110C are disease-resistant varieties,and the two identification results are basically the same.5 Comparative Analyses of Defense Enzyme Activities of VarietiesBy inoculating different varieties,the activity of 4 plant basic defense enzymes such as POD,PPO,SOD and PAL were measured,the results showed that the difference in enzyme activity between the early inoculated varieties and the obvious difference between inoculated and uninoculated between the same varieties,the peak time of PAL and PPO activity in the leaves of disease-resistant varieties of figs was earlier than that of susceptible varieties,and the susceptible varieties responded slowly to pathogen infection;the increase of SOD activity in resistant varieties was significantly higher than that of susceptible varieties;after inoculation,the POD activity in leaves of Bojihong and 108B showed an upward trend,and the peak POD activity of the susceptible varieties was earlier than that of the resistant.6 SSR analyses of fig varieties and its relationship with anthracnose resistanceEight pairs of SSR primers from the fig genome reported by Khadar et al.Were used to analyze the genetic diversity of seven different fig varieties and their relationship with disease resistance using SSR molecular marker technology.The results show that there are differences in the genetic relationship between breeds.Jinaofen and 110C are grouped into one class;Qingpi and 108B are grouped into one class,it shows that the relationship between the two is strong.Combining the above field investigation and indoor inoculation to identify the relationship between varieties resistance,Qingpi and 108B are middle susceptible varieties;Masitam,121E,Bojihong,Jinaofen,and 110C are disease-resistant varieties.The Masitam,Jinaofen,121E and Bojihong varieties all have a 550bp DNA fragment,while the Qingpi,110C and 108B varieties do not have this band.Possible variety resistance is related to550bp DNA fragment.