Survey,identification And Biological Characteristics Determination Of Major Licorice Diseases In Northwest China

Northwest China is a major liquorice(Glycyrrhiza uralensis)production region,in order to identify the types and occurrence of diseases that affect the growth of liquorices.In this research investigated and identified the occurrence and damage of licorice diseases in 31 licorice producing areas in 4 provinces(autonomous regions)in Xinjiang,Gansu,Ningxia,and Inner Mongolia from 2019 to 2020.The main findings are as follows:1.Root rot disease incidence in survey plots range from 0% to 16%.A total of 136 strains were isolated from 40 samples.Three representative strains with pathogenicity were obtained in the pathogenicity test.In combination with morphological and polygene sequence analysis.The pathogens of licorice root rot were identified as F.oxysporum,F.solani and F.verticillioides.It’s found that soluble starch was the best carbon source for F.solani,the lactose was the best carbon source for F.verticillioides and Xylitol was the best carbon source for F.oxysporum;Peptone was the best nitrogen source for the three strains.All three strains are suitable for growth in PDA medium,at 25-28℃ and 12 h of alternating light and dark.p H 7 is the optimum p H for Fusarium solani and Fusarium oxysporum;p H 11 is the optimum for Fusarium verticillioides.2.In survey the disease incidence of leaf spot was ranging from 2% to 20%.Four genera and six isolates were obtained from diseased spots.Three pathogenic isolates were obtained by virulence testing Morphological identification was carried out according to the relevant literature.At the same time,combined with the Alt gene sequence and Histone gene sequences,the r DNA-ITS gene sequence was analyzed,and the pathogen of leaf spot of licorice was identified as A.alternata,A.tenuissima and A.rosae.3.Rust disease field occurrence incidence ranges from 0% to 14%.The morphological characteristics,multi-gene sequence analysis and the host genus of the specialized parasitic bacteria.The pathogen of Glycyrrhiza rust was identified as Uromyces glycyrrhizae,and the pathogen of powdery mildew was identified as Erysiphe polygoni.Through the measurement of high throughput sequence and sequence analysis,the pathogen of licorice virus disease was initially identified as geminiviridae.The initial detection of the distribution of licorice geminivirus was performed by using the designed detection primers.The results showed that licorice geminiviruses were distributed in main production areas such as Xinjiang,Ningxia and Gansu.