Investigation of urediospore morphology, histopathology and epidemiological components on wheat plants infected with UV‐B‐induced mutant strains of Puccinia striiformis f. sp. tritici

Abstract

Planting resistant cultivars is the most economical and effective measure to control wheat stripe rust caused by Puccinia striiformis f. sp. tritici (Pst), but the cultivars often lose their resistance due to the emergence of new physiological races. The UV‐B‐irradiated urediospores of the Pst physiological race CYR32 in China were inoculated on wheat cultivar Guinong 22 for screening virulence‐mutant strains. CYR32 and mutant strains (CYR32‐5 and CYR32‐61) before and after UV‐B radiation were used to conduct urediospore morphological and histopathological observations and an investigation of epidemiological components. The results showed that UV‐B radiation affected the urediospore morphology of each strain. UV‐B radiation inhibited urediospore invasion and hyphal elongation, which mainly manifested as decreases in germination rate, quantities of hyphal branches, haustorial mother cells and haustoria and hyphal length. After wheat cultivar Mingxian 169 was inoculated with the UV‐B‐irradiated urediospores, the incubation period was prolonged, and the infection efficiency, lesion expansion rate, total sporulation quantity and area under the disease progress curve were reduced. The results demonstrated that CYR32‐5 and CYR32‐61 may have more tolerance to UV‐B radiation than CYR32. The results are significant for understanding mechanisms of Pst virulence variations and implementing sustainable management of wheat stripe rust.

Proteomic Analysis of UV-B-Induced Virulence-Mutant Strains of Puccinia striiformis f. sp. tritici Based on iTRAQ Technology

“…In the previous study (Zhao et al, 2019), the urediospores of the Pst physiological race CYR32 were irradiated with UV-B radiation under a radiation dose (the radiation intensity was 250 µw/cm 2 , and the radiation time was 95 min) for which the relative lethal rate of urediospores was approximately 90% (i.e., the relative germination rate of urediospores was approximately 10%); then the irradiated urediospores were inoculated on the seedlings of Guinong 22 to screen virulence-mutant strains. Finally, two virulence-mutant strains named CYR32-5 and CYR32-61, with stable infection types on Guinong 22 throughout four successive generations, were obtained.…”

“…It has been reported that UV-B radiation can induce virulence variation in Pst ( Shang et al, 1994 ; Huang et al, 2005 ; Wang et al, 2009 ; Zhao et al, 2019 ). Similarly, in studies on two other important pathogens— Puccinia triticina ( Neugebauer et al, 2018 ) and P .…”

“…Reported studies on the effects of UV-B radiation on Pst have focused on changes in the epidemiological components of Pst after UV-B radiation ( Jing et al, 1993 ; Cheng et al, 2014 ), screening of virulence-mutant strains of Pst by UV-B radiation ( Shang et al, 1994 ; Huang et al, 2005 ; Wang et al, 2009 ; Zhao et al, 2019 ), and random amplified polymorphic DNA (RAPD) analysis of the UV-B-induced virulence-mutant strains of Pst ( Huang et al, 2005 ; Wang et al, 2009 ). An important study on Pst ( Zheng et al, 2013 ) revealed the whole genome information of CYR32, a dominant physiological race of Pst in China, using high-throughput sequencing technology, which provided an important basis for the identification and functional verification of Pst proteins.…”

“…In our previous study ( Zhao et al, 2019 ), two UV-B-induced virulence-mutant strains, CYR32-5 and CYR32-61, were screened from the UV-B-irradiated urediospores of CYR32 on the seedlings of the wheat cultivar Guinong 22. In this study, after germination of the urediospores of the original strain (CYR32) and the two UV-B-induced virulence-mutant strains (CYR32-5 and CYR32-61), proteins were extracted from the germinated urediospores and germ tubes, the DEPs among the proteomes of the three Pst strains were screened by using the proteomics method based on iTRAQ technology, and then the acquired DEPs were subjected to COG (Cluster of Orthologous Groups) annotations, KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses, and quantitative reverse transcription PCR (qRT-PCR) assays.…”

Early Interactions of Rust Pathogen Puccinia arachidis (Speg.) with Groundnut Genotypes Varying in Resistance

“…Among the rust fungi, the early infection processes were well studied in hostpathogen combinations of wheat-P. striiformis f.sp. tritici (Ma and Shang, 2009, Wang et al, 2010, Zhang et al, 2012, Esmail et al, 2018, Zhao et al, 2019, wheat -P. triticina (Wang et al, 2012, Wesp-Guterres et al, 2013, wheat-P. graminis (Maree et al, 2020), barley -P. graminis (Maree et al, 2020), Coffee -Hemileia vastatrix (Ramiro et al, 2009), soybean -Phakopsora pachyrhizi (Vittal et al, 2014) and grapevine-Neophysopella tropicalis and N. meliosmae-myrianthae (Santos et al, 2020). However, such studies characterizing rust resistance in groundnut at cellular and tissue levels are limited.…”