| Citrus Huanglongbing is a devastating disease in the production of citrus in the world.Once the plant is infected,there is no effective chemical control,and it can only be excavated and destroyed.Eleven of China’s 19 citrus-producing provinces(municipalities and autonomous regions)have been affected by the disease,severely restricting the healthy development of the citrus industry.In present research,catharanthus roseus was used as a test material to study the regulation and mechanism of arbuscular mycorrhizal(AM)fungi on catharanthus roseus infection of citrus Huanglongbing through pot experiment.The internal connection of Candidatus Liberibacter asiaticus(CLas)in the catharanthus roseus provides a theoretical basis for the prevention and treatment of citrus Huanglongbing and explores new ways of controlling.The main findings were as follows:(1)This article investigates the situation of the citrus industry and the occurrence of citrus Huanglongbing in Liuzhou in recent years by reviewing relevant information,summarizes and analyzes the measures and existing problems that Liuzhou has taken to prevent and control citrus Huanglongbing in recent years,and puts forward corresponding countermeasures and suggestions.Mainly to increase the publicity of the hazards of Huanglongbing,establish and improve the prevention and control system,improve the citrus disease-free seedling breeding system,census and record of citrus Huanglongbing,strictly dig out disease trees to cut off the source of infection,prevente citrus psyllid and increase financial support.(2)The stem diameter,stem length and leaf number of catharanthus roseus decreased by 20.56%,31.80% and 35.68%,respectively,after catharanthus roseus was infected.There was a large amount of deciduous leaves in the plants,and the deciduous rate reached54.35%.The dry weight of the underground part and the aboveground part also decreased by 80.17% and 64.37%,respectively.(3)Catharanthus roseus inoculated with AS and Mix2 can reduce the occurrence of citrus Huanglongbing and alleviate the harm of citrus Huanglongbing to catharanthus roseus.The incidence rate is reduced by20% and the disease index is reduced by 25.51%.(4)Inoculation of AM fungi can promote the growth of catharanthus roseus.Inoculation with GS2 could significantly increase the stem diameter,stem length,number of leaves,fresh weight and dry weight of catharanthus roseus,and the fresh weight and dry weight increased by 22.54% and 29.63% compared with the control.Inoculation of AS and Mix2 significantly promoted the absorption of N and P by catharanthus roseus.The above-ground P content of catharanthus roseus inoculated with AS increased by 56%,and the above-ground and underground P content of catharanthus roseus inoculated with Mix2 increased by 52.33% and 41.67%,respectively.(5)After infection with citrus Huanglongbing,AM fungi can significantly increase the activity of POD and SOD.Among them,the POD activity in the leaves of catharanthus roseus inoculated with AS,the SOD activity in the roots and leaves increased by 44.95%,16.13% and13.13%,respectively,and the catharanthus roseus inoculated with Mix2 the activity of SOD in the leaves increased by 19.52%.However,most of the inoculation with AM fungi failed to increase the activity of PAL,AOS and LOX.(6)The content of CLas in the veins of catharanthus roseus susceptible treatments was detected by real-time fluorescent quantitative PCR,and it was found that the content of CLas in the veins of catharanthus roseus inoculated with AM fungi was not significantly different from that of non-mycorrhizal catharanthus roseus. |
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