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The potato is one of the world's most important staple crops, and China is one of the main producers of potatoes, but the industry faces soil-borne diseases such as verticillium wilt, which is also highly susceptible to verticillium wilt in most of China's potato-growing regions.
It is important to compare the biology and pathogenicity of different mating types of Skullcap isolated from potatoes and sunflowers in major growing areas of the continent to help understand the diversity of Vibrio Dahlia populations and to save those infected fields.
Diseased samples collected were cultured on PDAs and growing colonies of pathogens were isolated; Identification of the Mating Type of Vibrio dalia pathogen and its isolates obtained from diseased sunflower and potato plants using specific primers and their planting material showed that the dominant mating type population of Sunflower was MAT1-1, while the dominant mating type population of potato was MAT1-2, but race 2 was the only identified race type in all samples.
The presence of a large number of MAT1-1 isolates in potatoes is a new trend; Traditional crop rotation using sunflowers is leading to an increasing prevalence of mating type shifts of MAT1-1 and isolates in potatoes in these regions.
A quarter of the world's potatoes are produced in China, making it the world's largest potato producer, and recently the potato has been ranked as China's fourth staple crop, after rice, wheat and maize.
Verticillium wilt caused by Verticillium wilt is becoming a serious problem in the main potato producing regions on the mainland, and it can cause up to 50% yield loss.
Skullcap dahlia is one of the important species in the genus Skullcap, which not only causes a large loss of potato yield, but also threatens many other dicots such as cotton, lettuce, tomato, strawberry, pepper and sunflower.
Sunflower is one of the top oilseed crops grown for edible oil, sunflower seeds contain over 40% cooking oil and 23% protein, are a good source of fiber, vitamin E, copper, zinc and B complex vitamins, sunflower wilt caused by Vibrio dahlia is a devastating disease that threatens global sunflower production.
Vibrio dahlia, a soil-borne and seed-dispersed plant pathogenic fungus that causes wilt through the vascular system in many plant species, can form quiescent structures called sclerotia, which can survive in soil for more than 20 years, making disease control quite difficult.
Methyl bromide fumigation had been used as an effective method to control Blight caused by Vibrio d'oeia, but had been banned due to its harmful environmental effects, which made Verticillium wilt control challenging for different hosts.
Routine control of Vibrio dahlia through cultivation methods such as crop rotation has proven limited due to the existence of cross-pathogenic isolates capable of infecting and surviving in several different plant species, including weeds; However, there are some exceptions, such as the use of broccoli as a crop rotation, which has been shown to be effective in reducing soil-borne propagules and disease incidence in several cultivation systems.
Dahlia Verticillium wilt is a type of heterodomiobacter, in which sex compatibility is determined by a number of genes, one of which is a trait of the MAT site, the MAT1-1 trait contains a gene encoding a α domain, and MAT1-2 contains a gene encoding a high mobility group (HMG) DNA-binding domain for mating proteins.
In Vibrio dahlia, only one trait can be found in any isolate, as it is now. The presence of both mating types can lead to sexual reproduction, resulting in new inoculated sources in the form of ascospores during the life cycle of Vibrio d'A. d'Or, however, until now, Vibrio Dahlia has been shown to reproduce asexually on different hosts.
In terms of race types, two different types, race 1 and race 2, have been identified in different isolates of Vibrio d'Ehlia. In the 1950s, the Ve gene was introduced to tomatoes, providing farmers with new varieties that were resistant to the Race 1 strain. In lettuce and cotton, it has been identified as race 1 and race 2.
Vibrio Dahlia species 1 was identified in potato isolates in Lebanon, while potato isolates in China were largely identified as ethnicity2.
In our laboratory, over the years, we have separated all the V. from sunflowers. The Dahliae strain was identified as race only2; In some cases, in addition to sunflowers, two different ethnic types of Vibrio dahlia have been found on different hosts.
In this study, we aim to find out whether the monotonous rotation between potatoes and sunflowers has any effect on Vibrio d'Or isolated populations and their pathogenic characteristics in these host crops on the mainland.
We isolated and identified Vibrio dahlia from diseased potato and sunflower plants through the Koch hypothesis and determined their ethnicity and mating type using molecular techniques using PCR and specific primers, and the correlation between mating type, pathogenicity, and virulence was also determined in this study.
Among the 89 sunflower seed plants, 68.54% were MAT1-1 and 31.46% were MAT1-2, while among the 1 test isolate recovered from 1 sunflower seed, the proportions of MAT1-2 and MAT86-44 were 13.56% and 118.55%, respectively, and 1 isolate recovered from potato tubers, all isolates were classified as MAT2-112.
However, 1 isolate was recovered from a diseased potato plant, and the percentages of MAT1-1 and MAT2-16 compared to the results of Sunflower isolate were 96.83% and 04.3%, respectively, using one-way ANOVA (p ≤05.3), the p-value calculated from the data collected in the table was 9328, demonstrating that there was no significant difference between the mating types of Vibrio dahlia recorded in potato and sunflower samples.
Of the isolates tested above, 20 of them were randomly selected, 10 from potatoes and 10 from sunflowers, and molecular reconfirmation was performed using specific primers for Vibrio dahlia from both mating types, and the results obtained supported the results of initial identification by PCR.
MAT1-1 isolates from both hosts had amplicon lengths of 600 bp in both host samples, while MAT1-2 had amplicon lengths of 300 bp each. In the test sample, 10 MAT1-1 isolates, 10 potato and sunflower isolates, and 1 MAT2-1 isolate were randomly selected and reconfirmed as MAT1-1 or MAT2-2 mating types by PCR, respectively.
Ethnic type identification of Vibrio dahlia isolated from sunflowers and potatoes was identified as ethnicity using race-specific primers for molecular identification2.
Comparison of pathogenicity of two mating type isolates
The pathogenicity test of 20 randomly selected isolates of different mating types (MAT1-1 and MAT1-2) mentioned earlier on their respective hosts for 25 dpi was different, and the disease indices of the different mating type isolates obtained from the same host were different).
The mean disease index of MAT1-1 potato isolates was 17.29 and that of sunflower was 57.71, and for MAT1-2 isolates, the average disease indices of the two mating isolates on their respective recovery hosts were 26.79 for potato and 52.59 for sunflower, respectively.
Comparison of biological characterization of two isolates of different mating types
Morphological comparison between 1 isolate from potato (P48 and P50) and sunflower (S11 and S12) and identified as different mating types MAT1-48 (P11 and S1) and MAT2-50 (P12 and S7).
Different mating type isolates grew white hyphae after 1 day of culture, however, MAT1-48 strains, potato P11, and sunflower S1, all produced more white hyphae than MAT2-50 strains P12 and S50.
Potato strain P48 produces more melanin than strain P11; Sunflower strain S12 produces a small amount of melanin around the inoculated emboli, while more melanin is deposited in the medium by strain S4, also isolated from sunflower, but identified as a different mating type; There was no significant difference in the average growth rate or morphology of conidia and conidia.
The samples collected in this experiment were inspired by the fact that most farmers in northern China grow sunflowers and potatoes in continuous crop rotations. This contributed to an increase in the Verticillium Wilt index in sunflower and potato fields; After determining the mating type of Vibrio dahlia recovered from diseased samples, by using mating type-specific primers.
PCR results showed the presence of two specific mating types of Vibrio dahlia. MAT1-2 specific type predominates in the total test isolates, consistent with previous studies conducted in other countries around the world on V. dahlia mating type populations.
Compared to sunflower, the most MAT1-2 isolates were recovered from potatoes, which may be due to a variety of factors, and this is the first time a large number of MAT1-2 isolates have been recovered from potato samples compared to previous potato verticillium wilt studies conducted in China29.
To our surprise, MAT1-1 isolates were not recovered from potato tubers, but 55 MAT1-2 isolates were identified, indicating some resistance of potato tubers to Vibrio dahlia MAT1-1 during the fruiting period.
In addition, the limited sample size of potato tuber isolates is another reason for this result; The impact of Verticillium wilt on potatoes has attracted much attention until recent reports of infected fields in major potato producing areas in China; The continuous cultivation of crops in infected fields and the use of planting material contaminated with pathogens have led to increasing disease in Sunflower and potato producing areas.
It is not clear why there are more MAT1-2 populations in potato Vibrio d'ilia isolates, as regular MAT1-1 populations dominate in many crops, such as cotton and sunflower; The disease sample collection site where the mating type of most isolates was identified as MAT1-2 is located behind the Yin Mountain, where temperatures are mostly lower throughout the year due to its topography, and we hypothesize that the lower summer average temperature in this area may be Dahlia V in these potato fields.
The reasons for the increase in Mat1-2 populations are, on average, that most of the sites behind Yin Mutan have temperatures around 18-20 °C during the planting season, with an average precipitation of 36 mm; These environmental factors are much lower than in the Yin Shan Qian area; This may be due to selective pressure for dahlia development, and environmental factors favor the deposition of small sclerotia in soil and plant material, resulting in an elevated disease index during the planting season.
The two different types of Joryo mateing found in these fields may be the result of sexual interactions between idiotypes; Although the devastating effects of MAT1-1 populations have been widely reported in sunflowers, the average disease index recorded for MAT1-2 isolates is almost equal to MAT1-1, and the recovered disease index within sunflower populations tests different populations of dahlia pigs with different mating types.
The disease index of one mating type in Vibrio dahlia population in sunflower was higher than that of potato population. Although the disease symptoms of MAT1-1 and MAT2-4 Vibrio dahlia are similar, we observed a higher virulence of Sunflower isolate compared to potato isolate.
The large number of MAT2 isolates recovered from Verticillium wilt-infected potatoes in China happens to be the first of its kind, and some studies have reported an increasing trend of race 2 relative to race 1, possibly because it successfully colonizes a greater variety of plants during crop rotation.
In this study, we also found that the MAT1-1 and MAT1-2 strains isolated from potatoes and sunflowers were both race 2. This result is consistent with previous identification of sunflower verticillium wilt, but other research data show the presence of ethnicity in potatoes.
Verticillium wilt has recently been recognized as an important disease in potato and sunflower cultivation in most agricultural areas of China. The results of this study will provide insight into the mating type composition of V. dahlia-induced verticillium wilt in potatoes and sunflowers, and MAT1-1 has long been reported as the mating isolate for Verticillium wilt in most potato fields.
In China, the large number of MAT1-2 isolates recovered from Verticillium wilt-infected potatoes happened to be the first of these isolates to attract widespread attention.
There are indications that the increasing trend of race 2 relative to race 1 in host crops, the increasing prevalence of MAT1-1 in potatoes and the shift in mating patterns of isolates may be the result of traditional rotational farming in these areas. Mainly using sunflower, the increasing spread of Verticillium wilt among different crops in China is a concern and must be effectively managed and controlled.
The results obtained from this study will alert researchers to the diversity occurring in Vibrio Dahlia populations, and these data also provide important information for breeders and fungicide production companies to understand the dynamics of Verticillium wilt in China and the world, and we recommend that farmers introduce new resistant cash crops into crop rotation systems in these areas to reduce the amount of Vibrio Dahlia inoculated in the soil.
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