Identification of resistance genes is important for developing leaf rust resistant wheat (Triticum aestivum) cultivars. A total of 102 Chinese winter wheat cultivars and advanced lines were inoculated with 24 pathotypes of Puccinia triticina for postulation of leaf rust resistance genes effective at the seedling stage. These genotypes were also planted in the field for characterization of slow rusting responses to leaf rust in the 2006–07 and 2007–08 cropping seasons. Fourteen leaf rust resistance genes—Lr1, Lr2a, Lr3bg, Lr3ka, Lr14a, Lr16, Lr17a, Lr18, Lr20, Lr23, Lr24, Lr26, Lr34, and LrZH84—either singly or in combinations, were postulated in 65 genotypes, whereas known resistance genes were not identified in the other 37 accessions. Resistance gene Lr26 was present in 44 accessions. Genes Lr14a and Lr34 were each detected in seven entries. Lr1 and Lr3ka were each found in six cultivars, and five lines possessed Lr16. Lr17a and Lr18 were each identified in four lines. Three cultivars were postulated to possess Lr3bg. Genes Lr20, Lr24, and LrZH84 were each present in two cultivars. Each of the genes Lr2a and Lr23 may exist in one line. Fourteen genotypes showed slow leaf rusting resistance in two cropping seasons.
Wheat leaf rust, caused by Puccinia triticina, is an important fungal disease of wheat in China. To study races of the pathogen in China, leaf rust samples were collected from 14 provinces in 2014 and 15 provinces in 2015. From the samples, 494 single-uredinial isolates were derived from the 2014 collection and 649 from the 2015 collection. These isolates were tested on 40 near-isogenic lines of Thatcher carrying single leaf rust resistance genes. From the isolates, 84 races were identified in 2014 and 65 races in 2015. Races THTT (22.1%), THTS (19.6%), THJT (8.7%), PHTT (4.9%), and PHJT (3.6%) were the most common races in 2014, and THTT (28.4%), THTS (12.8%), THJT (11.6%), THJS (9.9%), and PHTT (9.7%) were the most frequent in 2015. All of these races were avirulent to resistance genes Lr9 and Lr24. THTT and THTS, the most frequent races in both years, were widely distributed throughout the country. The frequencies of isolates with virulence to Lr1, Lr2a, Lr2c, Lr3, Lr16, Lr26, Lr11, Lr17, LrB, Lr10, Lr14a, Lr2b, Lr3bg, Lr14b, Lr32, Lr33, and Lr50 were over 80%, whereas the frequencies of virulence to Lr9, Lr19, Lr25, Lr28, Lr29, and Lr47 were less than 3.5%. In the present study, all isolates were avirulent to Lr24 and Lr38. The race analysis and individual virulence frequencies provide guidance to breeders in choosing leaf rust resistance genes for use in breeding programs.
Wheat leaf rust, caused by Puccinia triticina, is a common fungal disease of wheat in China. In order to identify races and determine the individual virulence of isolates in different wheat-growing regions in China, leaf rust samples collected from 18 provinces in 2011 to 2013 were tested on 37 Thatcher near-isogenic lines each carrying a different single leaf rust resistance gene. A total of 158 races were identified. Races THTT (19.5%), THTS (16.9%), PHTT (7.7%), THJS (5.0%), THJT (4.2%), and PHTS (4.0%) were the most predominant races in 2011 to 2013. All of these races were avirulent to resistance genes Lr9 and Lr24. The two most frequent races, THTT and THTS, were widely distributed. The frequencies of the isolates with virulence to Lr1, Lr2c, Lr3, Lr16, Lr26, Lr17, LrB, Lr10, Lr14a, Lr3bg, Lr14b, Lr33, Lr37, and Lr50 exceeded 90%. Frequencies of virulence to Lr2a, Lr3ka, Lr11, Lr30, Lr2b, and Lr32 exceeded 70% but were less than 90%. Frequencies of virulence to Lr18, Lr21, Lr15, Lr23, Lr33+34, Lr36, Lr39, and Lr44 were below 70%, whereas the frequency of virulence to Lr25 was less than 1%. All isolates were avirulent to Lr9, Lr19, Lr24, Lr28, Lr42, Lr29, Lr38, and Lr47. The identified races and individual virulence frequencies provide a basis for selection of effective leaf rust resistance genes for use in breeding programs and can also provide information for the study of race evolution of P. triticina.
A group of polyene macrolides mainly composed of two constituents was isolated from the fermentation broth of Streptomyces roseoflavus Men-myco-93-63, which was isolated from soil where potato scabs were repressed naturally. One of this macrolides was roflamycoin, which was first reported in 1968, and the other was a novel compound named Men-myco-A, which had one methylene unit more than roflamycoin. Together, they were designated RM. This group of antibiotics exhibited broad-spectrum antifungal activities in vitro against 17 plant pathogenic fungi with 50% effective concentration (EC50) values of 2.05-7.09 μg/mL and 90% effective concentration (EC90) values of 4.32-54.45 μg/mL, which indicates their potential use in plant disease control. Furthermore, their biosynthetic gene cluster was identified, and the associated biosynthetic assembly line was proposed based on a module and domain analysis of polyketide synthases (PKSs) and supported by findings from gene inactivation experiments. Importance Streptomyces roseoflavus Men-myco-93-63 is a biocontrol strain that has been studied in our laboratory for many years and exhibits a good inhibitory effect in many crop diseases. Therefore, the identification of antimicrobial metabolites is necessary and our main objective. In this work, chemical, bioinformatic and molecular biological methods were combined to identify the structures and biosynthesis of the active metabolites. This work provides a new alternative agent for the biological control of plant diseases and is helpful for improving both the properties and yield of the antibiotics via genetic engineering.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.