Identification Of Potato Rhizosphere Cyst Nematodes And Diversity Of Colonizing Fungi In Guizho

In this research,the potato,recognized as the third most significant food crop in China,was investigated.Cyst nematodes,noteworthy pathogenic nematodes inflicting substantial economic damage globally on an annual basis,were identified in the potato rhizosphere.The study was conducted in Guizhou to ascertain the various species of cyst nematodes present.Key aspects including biological traits,life cycles,generation timelines,and efficient detection methods for these important cyst nematodes were examined.Concurrently,colonizing fungi were isolated and purified from the cysts,eggs,and females of Globodera rostochiensis.These species were classified utilizing morphological and molecular biology methodologies.Additionally,the diversity of these colonizing fungi,as well as the frequency of isolation for distinct groups,were analyzed.The study yielded the following results:1.Following the flotation procedure and separation of the collected potato rhizosphere soil and root tissue,cyst nematode samples were obtained from the potato rhizosphere.These samples were subsequently identified using morphological and molecular biological methods,leading to the identification of three species of cyst nematodes:G.rostochiensis,G.artemisiae,and Cactodera sp.Of these,G.rostochiensis was identified as the dominant species.2.Variations amongst distinct populations were evaluated by comparing the mt DNA-COI and r DNA-ITS gene sequences of G.rostochiensis derived from different sources.The study found that G.rostochiensis populations in Guizhou and Canada exhibited the highest congruity,with no base difference identified between the sequences.3.Drawing on the mt DNA-COI gene sequence of G.rostochiensis in this research,specific primers were developed and screened.This resulted in a pair of primers,termed Gr S2,deemed effective for detecting G.rostochiensis.Further,a distinctive PCR detection system for potato nematodes in Guizhou was established,using this system to identify samples from potato cyst nematode-affected areas within Guizhou.4.Through a combination of field observations and indoor pot experiments,the life cycle and generation timelines for the G.rostochiensis population in Guizhou were established.The data showed that it took 21-35 days for this population to develop from second-stage juveniles to females at room temperature(with an average range of 17-25℃).The formation of cysts by the females took around 28-42 days.The complete life cycle spanned 56-77days,and in the primary affected area,there was typically one generation.5.A total of 178 fungal strains were isolated and purified from the females,cysts,and eggs of G.rostochiensis.These strains were identified based on morphological and molecular biological characteristics,and were found to belong to 19 distinct genera.The highest number of isolates were Fusarium,with 116 strains and an isolation frequency of 65.17%.This was followed by Penicillium with 23 strains and an isolation frequency of 12.29%.Other strains belonged to Aspergillus(5.62%),Linnemannia(2.81%),Dactylonectria(2.25%),and Mortierella(1.69%).There were also2 strains each of Peniophora,Rigidoporus,Plectosphaerella,and Talaromyces,each accounting for 1.12%.One strain each was found of Colletotrichum,Fomitopsis,Schizophyllum,Verticillium,Chaetomium,Exophiala,Oidiodendron,Paraphoma,and Pyrenochaeta.Among these 19 genera,Fusarium and Penicillium are commonly known,with numerous studies both in agricultural production and other applications.Conversely,Fomitopsis,Schizophyllum,Exophiala,Oidiodendron,Paraphoma,and Pyrenochaeta are less common,and have been rarely reported in China.The results highlight a rich diversity of colonizing fungi of G.rostochiensis in Guizhou province,encompassing a broad spectrum of fungal species.