Host range, mating type and population structure of Magnaporthe sp. of a single barley field in São Paulo state, Brazil

Abstract

Brazil is blast disease hot spot because severe epidemics have occurred among wheat, triticale, rye, barley and oat crops. Although the first outbreak of barley blast appeared in 1998, little information is available. Therefore, this study aimed to examine host range, mating type composition and population structure of Magnaporthe sp. from a single barley field in São Paulo, Brazil. To examine pathogenicity, 25 Magnaporthe isolates were inoculated on five, three, two and two cultivars of barley, wheat, oat and rice, respectively, and one cultivar each of rye, corn, sorghum, triticale and certain weeds (Cenchrus echinatus, Setaria geniculata, Brachiaria plantaginea and Eleusine indica). Mating type distribution of 33 isolates was investigated by molecular tools. The genotypic divergence of 41 barley and five wheat isolates was investigated by 15 random amplified polymorphic DNA primers and unweighted pair group method with arithmetic mean. The host range of the barley blast pathogen included wheat, oat, rye and triticale but not rice and weeds. Sexual reproduction appeared to not be involved in the high genotypic diversity because only a single isolate, MAT1‐2, was identified. The majority of barley isolates clustered together with wheat blast, except for four, suggesting a different origin.

Unraveling the genetic structure of Brazilian commercial sugarcane cultivars through microsatellite markers

“…The median (not the mean) of the coefficient of variation estimates were used to evaluate the accuracy of the dissimilarity values [ 60 ]. All these procedures were performed in RStudio software [ 61 ] as in Urashima et al (2017) [ 62 ].…”

Wheat Blast: A Disease Spreading by Intercontinental Jumps and Its Management Strategies

“…Compared with M. oryzae pathotype Oryza, sexual reproduction is more frequent in MoT, as reflected in its high diversity found in fields (Urashima et al, 1999). However, the predominance of only one mating type suggests asexual reproduction as the predominant mode of reproduction (Urashima et al, 2017). Maciel et al (2014) reported a mixed reproductive system occurring for MoT where a best-fit strain produced by sexual reproduction is maintained generation after generation by asexual reproduction.…”

“…Fungicides become ineffective under high-disease pressure or congenial environmental conditions against the disease (Kohli et al, 2020). It is reported that sometimes even four sprays were not able to completely control WB infection in some areas of Brazil (Urashima et al, 2017), thereby affirming the fact that genetic resistance in combination with fungicides is much needed (Ceresini et al, 2018). Although fungicides are mostly used at the heading stage, their application at the seedling stage is also important in reducing inoculum load on basal or older leaves .…”

Pyricularia graminis‐tritici is not the correct species name for the wheat blast fungus: response to Ceresini et al. (MPP 20:2)

“…, ) to produce strains that are aggressive pathogens of both rice and wheat. Although there are currently no P. oryzae lineages adapted to barley or oats, these could evolve if epidemics become common in these crops (Urashima et al ., ). The potential for the evolution of new threats from P. oryzae should not be underestimated.…”