Genetic Differentiation and Mixed Reproductive Strategies in the Northern Corn Leaf Blight Pathogen Setosphaeria turcica From Sweet Corn in Fujian Province, China

Abstract

The northern corn leaf blight (NCLB) pathogen Setosphaeria turcica (Luttrell) Leonard and Suggs is one of the main biotic constraints on sweet corn (Zea mays L.) yield and quality in Fujian Province, China. Currently, however, there is comparatively little information available regarding the distribution of mating types, population genetics, and reproductive strategies of this pathogen in Fujian. In this study, we investigated the distribution of mating types and population genetics of 117 isolates of S. turcica collected from seven of the main sweet corn-growing regions in Fujian Province, based on multiple polymerase chain reaction analyses using two mating type-specific primer pairs and 11 inter-simple sequence repeat markers. Furthermore, we examined the mode of reproduction of Fujian S. turcica populations. Both MAT1-1 and MAT1-2 mating types were detected throughout all seven sampling locations. The majority of MAT1-2 isolates were detected from Dongyou, Jian’ou, Pingnan, Songxi, and Longyan, whereas a large proportion of the detected MAT1-1 isolates were among those collected from Dongfeng and Nanjing. Furthermore, we detected five shared multi-locus haplotypes among S. turcica isolates from Dongyou, Jian’ou, Pingnan, Nanjing, and Songxi, whereas no shared haplotypes were observed between the Dongfeng (or Longyan) population and these five populations. Pairwise comparisons of the indices ΦPT and Nm, and population structure and principal coordinate analyses indicated genetic differentiation between both the regional and the mating type populations of S. turcica in Fujian. The skewed mating type ratio associated with low a haplotypic diversity and evident linkage disequilibrium reveals a mixed reproductive strategy for S. turcica populations in Fujian Province. The findings of this study advance our current understanding of the genetic diversity, population structure, and reproductive strategies of S. turcica populations infecting sweet corn in Fujian Province, and will potentially contribute to further resistance breeding efforts.

Genetic Diversity and Population Genetic Structure of Setosphaeria turcica From Sorghum in Three Provinces of China Using Single Nucleotide Polymorphism Markers

“…In this study, we identified a relatively high level of gene flow (6.2385) of S. turcica isolates between Henan and Shanxi, indicating frequent gene exchange between these two populations. The value of Fst between Henan/Shaanxi (0.1573) and Shanxi/Shaanxi (0.1202) was greater than Henan/Shanxi (0.0385), demonstrating relatively moderate genetic divergence between these populations, which was lower than that previously reported by Dai et al (2021) . In addition, the result of the AMOVA analysis demonstrated the genetic variation within populations, rather than those between populations, was the major source of genetic variation, which was consistent with previous reports by Li et al (2019) and Ma et al (2020a) .…”

“…Moderate level of genetic diversity in these three population was found as indicated by Shannon’s information index (0.51–0.57), which is somewhat incongruent with previous studies on the genetic diversity of S. turcica isolates. Ma et al (2020a) and Dai et al (2021) , respectively, attained low Shannon’s information index of 0.20 to 0.37 and 0.07 to 0.33, indicating low genetic diversity among different populations. Whereas Human et al (2016) and Nieuwoudt et al (2018) both achieved high level of genetic diversity with Shannon’s information index of 0.87 to 0.90 and 0.66 to 0.94.…”

“…By using type-specific PCR primers, we were able to identify two mating types, including MAT1-1 and MAT1-2, which are present in all the three different geographic populations. Although the distribution of the two mating types in three populations was not exactly equal, especially the Shanxi population had an obviously skewed distribution toward MAT1-2, but on the whole, the total ratio of the MAT1-1 and MAT1-2 was close to 1:1, indicating a positive association between the possibility of sexual reproduction among populations and genetic diversity ( Dai et al, 2021 ). Such a premise seems to be contradictory with the moderate genetic diversity in three S. turcica populations as revealed in this study.…”

“…NLB is very prevalent, spreading more widely, especially in the environment, such as warm and humid conditions, that is conductive to the development of the disease ( Ferguson and Carson, 2004 ), which causes considerable economic destruction. The disease mainly infects sorghum leaves, whose typical symptoms are long fusiform, light brown to brown in the center, purple at the edge, and irregular ring patterns can be seen in the early stage ( Dai et al, 2021 ). Upon NLB infection, the yield of sorghum could be severely compromised as the result of reduction in photosynthetic potential of the plant.…”

Molecular and Morphological Characterization of Exserohilum turcicum (Passerini) Leonard and Suggs Causing Northern Corn Leaf Blight of Maize in Bihar

“…Conical flasks with 2% potato dextrose broth were used to culture E. turcicum isolates for 10 days at 26 ± 2 °C. A few changes to the modified CTAB procedure [ 21 , 22 ] were made in order to extract DNA from the growing mycelial mats. Using liquid nitrogen, the collected fungus mats were ground into a fine powder.…”