Disease Survey And Important Diseases' Pathogen Molecular Identification Of Hylocereus Polyrhizus(Cactaceae) In Hainan

Dragon fruit Hylocereus polyrhizus Webb.Britton&Rose(Cactaceae)commonly known as pitaya or strawberry pear,is widely cultured in tropical and subtropical regions of China and has become increasingly important fruit in recent years.native to the tropicalforest regions of Mexico and Central and South America Pacific Ocean coast.Prevalent form of cultivation until little more than Several decades was in small-scale family production.However,since ifs cultivation in commercial plantations and further domestication started in earnest,some symptoms of rotting and spots in stems and fruits were being observed.in some cases,but commercial production plots had to be abandoned due to the diseases.There were more and more reachies about dragon fruit diseases had been reported in the word.Aiming in such a situation,a more comprehensive and detailed study on the fungal and viral disease of dragon fruit all over the Hainan province was accomplishen in this program.The main conclusion of this thesis as follows:1 The inverstigation showed that there were 10 kinds of disease been found on dragon fruit,in whitch the canker disease caused by Neoscytalidium dimidiatum.(Penz.)Crous&Slippers,stem rot caused by Fusarium solani(Mart.)Sacc.anthracnose caused by Colletotrichum gloeosporioides Penz,stem spot caused by Phomosis sp.?sooty mould caused by Fusarium equiseti(Corda)Sacc?fruit rot caused by Bipolaris sp.?foot rot?viral disease caused by Cactus virus X?Zygocactus virus X and Pitaya virus X,chilling injury and fruit cracking.2.The study on biological characteristics of N.dimidiatum.showed the optimal conditions for mycelial and sporulation:the temperation was 30??35?,pH was 7,the carbon sources was starch,the nitrogen sources were yeast extract powder,the medium was PSA medium formycelial growth;and the temperation 30??35?,pH was 7,the carbon sources was starch,the nitrogen sources were yeast extract powder,the medium was PSA medium for mycelial growth,for mycelial growth was CA medium.Experiments on Phomosis sp.figured out the optimum conditions for mycelial growth:the temperature was 25 ??28?;the pH was 8;the carbon sources were starch or xlose;the nitogen sourse was yeast extract powder and the fungal could not use the urea as the nitrogen.The related research on F.equiseti showed the optimum condintion for mycelial growth and sporulation:the temperature was 25??28?and 28?;the pH was 8?9and 6,the medium was PDA and LB,the carbon sources were lactose(for both),starch,glucose,sucrose(for growth only)and xlose(for porulation);the nitrogen sourses were diseaseyeast extract powder and beef extract.3.The PCR results of fungus rDNA-ITS amplificatiom using universal primer pair ITS1/ITS4 suggested that:the sequences of the suspected strains of 1409HSCA1?1410BSZL1?1410SMPF1,which were proved to be lacated in the rDNA-ITS of N.dimidiatum,Phomosis sp.,and F.equiseti after blast and homology analysis.We confirmed that,as a result,the rDNA-ITS analysis should be a dependable method for fungal pathogens of dragon fruit canker disease;stem spot and sooty mould desease.4.Indoor toxicity of six fungicides to N.dimidiatum,Phomosis sp.,and F.equiseti was tested by messuring mycelial growth rate.The result showed that all of the fungicides were able to inhibit the growth of fungal pathogens in our expriments.Duojunling was highliest toxic to N.dimidiatum,Lvfei after it,but Amixida showed very low toxity to the fungal pathogens.Duojunling was highliest toxic to Phomosis sp.,Rovral and Topsin-M after it,but Lvfei showed very low toxity to this fungal pathogens.Howere Lvfei was highliest toxic to F.equiseti,Bilv after it,but Daktarin showed very low toxity to the fungal pathogens.5.The RT-PCR detection showed that:These sequencese and its length were CVX-003 isolate Hainan(354 bp)?SVX-301 isolate Hainan(122 bp)?ZVX-501 isolate Hainan(233 bp)?PVX-701 isolate Hainan(322bp)?CVX004 isolate Hainan(923)?PVX702 isolate Hainan(876).And we known that CVX-003 isolate Hainan and CVX004 isolate Hainan classified as the partial sequences of Cacts virus X,ZVX-501 isolate Hainan classified as the partial sequences of Zygocactus virus X,PVX702 isolate Hainan classified as the partial sequences of Pitaya virus X,after blast and respectively homology analysis.Therefore,we considered that there're at least 3 kind of virus inhabiting in virus-like symptomatic samples on dragon fruit stems.