Genetic Analysis and Molecular Tagging a Novel Yellow Rust Resistance Gene Derived from Synthetic Hexaploid Wheat Germplasm M08

Yellow rust of wheat （caused by Puccinia striiformis Westend. f. sp. tritici Eriks.） has been periodically epidemic and severely damaged wheat production in China. The development of resistant cultivars could be an effective way to reduce yield losses of wheat caused by yellow rust. Rust reaction tests and genetic analysis indicated that M08, the synthetic hexaploid wheat derived from hybridization between Triticum durum （2n = 6X = 28; genome AABB） and Aegilops tauschii （2n = 2X = 14; genome DD）, showed resistance to current prevailing yellow rust races at seedling stage, which was controlled by a single dominant gene, designated as YrAm. Bulked segregant analysis was used to identify microsatellite markers linked to gene YrAm in an F2 population derived from cross M08 （resistant） × Jinan 17 （susceptible）. Three microsatellite marker loci Xgwm77, Xgwm285, and Xgwml31 located on chromosome 3B were mapped to the YrAm locus. Xgwml31 was the closest marker locus and showed a linkage distance of 7.8 cM to the resistance locus. Thus, it is assumed that YrAm for resistance to yellow rust may be derived from Triticum durum and is located on the long arm of chromosome 3B.

Postulation of Seedlings Resistance Genes to Yellow Rust in Commercial Wheat Cultivars from Yunnan Province in China

The objective of this study was to characterize yellow （stripe） rust resistance gene（s） in 52 commercial wheat cultivars from Yunnan Province in China, and to provide information for their rational deployment in field. Seedlings of wheat cultivars were inoculated with 25 differential isolates ofPuccinia striiformis from foreign and home to postulate resistance genes to yellow rust, and then validated by pedigree. There were 10 probable resistance genes characterized in these cultivars, in which, Yr9 was most commonly postulated to be present in thirteen cultivars. Yr21, the second, was present in four cultivars. Yr8, the third, were present in three cultivars. Yr6, Yrl 7 and Yr26, the fourth, was present in two cultivars respectively. The other gene（s） such as, Yr2＋YrA, Yr7 and Yr27, were only present in single cultivar（s）; unknown gene（s） or gene（s） combination（s） were present in 22 cultivars. One cultivar （Yunmai 42） had no resistance gene tested in this study. Cultivars such as Yunmai 52, Mian 1971-98, Kunmai 4, and Yunmai 56 carried effective genes and can be popularized mainly; Yr9 should be planted with other Yr genes. In the meantime other effective genes should be introduced to realize gene diversity for controlling wheat yellow rust. Yunmai 42 should be reduced to avoid rust breakout. Unknown gene cultivars should be utilized and be researched deeply.

Grain yield losses in yellow-rusted durum wheat estimated using digital and conventional parameters under field conditions

The biotrophic fungus Puccinia striiformis f. sp. tritici is the causal agent of the yellow rust in wheat. Between the years 2010–2013 a new strain of this pathogen(Warrior/Ambition),against which the present cultivated wheat varieties have no resistance, appeared and spread rapidly. It threatens cereal production in most of Europe. The search for sources of resistance to this strain is proposed as the most efficient and safe solution to ensure high grain production. This will be helped by the development of high performance and low cost techniques for field phenotyping. In this study we analyzed vegetation indices in the Red,Green, Blue(RGB) images of crop canopies under field conditions. We evaluated their accuracy in predicting grain yield and assessing disease severity in comparison to other field measurements including the Normalized Difference Vegetation Index(NDVI), leaf chlorophyll content, stomatal conductance, and canopy temperature. We also discuss yield components and agronomic parameters in relation to grain yield and disease severity.RGB-based indices proved to be accurate predictors of grain yield and grain yield losses associated with yellow rust(R2= 0.581 and R2= 0.536, respectively), far surpassing the predictive ability of NDVI(R2= 0.118 and R2= 0.128, respectively). In comparison to potential yield, we found the presence of disease to be correlated with reductions in the number of grains per spike, grains per square meter, kernel weight and harvest index. Grain yield losses in the presence of yellow rust were also greater in later heading varieties. The combination of RGB-based indices and days to heading together explained 70.9% of the variability in grain yield and 62.7% of the yield losses.

Impact of spectral interval on wavelet features for detecting wheat yellow rust with hyperspectral data

Detection of yellow rust using hyperspectral data is of practical importance for disease control and prevention.As an emerging spectral analysis method,continuous wavelet analysis(CWA)has shown great potential for the detection of plant diseases and insects.Given the spectral interval of airborne or spaceborne hyperspectral sensor data differ greatly,it is important to understand the impact of spectral interval on the performance of CWA in detecting yellow rust in winter wheat.A field experiment was conducted which obtained spectral measurements of both healthy and disease-infected plants.The impacts of the mother wavelet type and spectral interval on disease detection were analyzed.The results showed that spectral features derived from all four mother wavelet types exhibited sufficient sensitivity to the occurrence of yellow rust.The Mexh wavelet slightly outperformed the others in estimating disease severity.Although the detecting accuracy generally declined with decreasing of spectral interval,relatively high accuracy levels were maintained(R^(2)>0.7)until a spectral interval of 16 nm.Therefore,it is recommended that the spectral interval of hyperspectral data should be no larger than 16 nm for the detection of yellow rust.The relatively loose spectral interval requirement permits extensive applications for disease detection with hyperspectral imagery.

A new spectral index for the quantitative identification of yellow rust using fungal spore information

Yellow rust(Puccinia striiformis f.sp.Tritici)is a frequently occurring fungal disease of winter wheat(Triticum aestivum L.).During yellow rust infestation,fungal spores appear on the surface of the leaves as yellow and narrow stripes parallel to the leaf veins.We analyzed the effect of the fungal spores on the spectra of the diseased leaves to find a band sensitive to yellow rust and established a new vegetation index called the yellow rust spore index(YRSI).The estimation accuracy and stability were evaluated using two years of leaf spectral data,and the results were compared with eight indices commonly used for yellow rust detection.The results showed that the use of the YRSI ranked first for estimating the disease ratio for the 2017 spectral data(R^(2)=0.710,RMSE=0.097)and outperformed the published indices(R^(2)=0.587,RMSE=0.120)for the validation using the 2002 spectral data.The random forest(RF),k-nearest neighbor(KNN),and support vector machine(SVM)algorithms were used to test the discrimination ability of the YRSI and the eight commonly used indices using a mixed dataset of yellow-rust-infested,healthy,and aphid–infested wheat spectral data.The YRSI provided the best performance.

Molecular mapping of a novel yellow rust resistance gene of wheat using microsatellite markers

Identification and genetic analysis of yellow rust resistance have suggested that wheat line R55 carries single dominant gene conferring yellow rust resistance. The bulked segregant analysis (BSA) for an F2 population using microsatellite marker technique has indicated that the yellow rust resistance gene is located on the short arm of chromosome 1B, tightly linked to

RAPD analysis of a new yellow rust resistant wheat-ryetranslocation line

Random amplified polymorphic DNAs (RAPD) analysis is a recently developed tech-nique based on the polymerase chain reaction (PCR). Usually, arbitrary decameroligonucleotides are used in the PCR procedure at a low annealing temperature(e. g.37℃),

Chromosomal location of yellow rust resistance gene(s) in Triticum aestivum-Lophopyrum elongatum substitution lines

A set of T. aestivum-L. elongatum substitution lines were studied on yellow rust resistance at seedling stage, inheritance of the resistance and esterase-5 (Est-5) analysis. The results demonstrated that L. elongatum carried a new yellow rust resistance gene(s), which was dominant and located on chromosome 3E of L. elongatum. The biochemical locus encoding Est-5 was also located on chromosome 3E, and was tentatively named Est-E5, which was co-segregant with the Yr gene(s) in wheat background. In addition, the transmission frequencies of chromosome 3E in 3A/3E and 3D/3E hybrids selfing were significantly higher than that of chromosome 3E in 3B/3E hybrid, which was probably due to the difference on genetic relationships among A, B, D and E genomes.

Identification of eight Berberis species from the Yunnan-Guizhou plateau as aecial hosts for Puccinia striiformis f.sp.tritici,the wheat stripe rust pathogen

Puccinia striiformis Westend.f.sp.tritici Erikss.(Pst)infects wheat and causes stripe rust.The rust is heteroecious with wheat as the primary uredinial and telial host and barberry(Berberis spp.)as the alternate pycnial and aecial host.More than 40 Berberis species have been identified as alternate hosts for Pst,and most of these are Chinese Berberis species.However,little is known about Berberis species or their geographic distributions in the Yunnan-Guizhou plateau in southwestern China.The Yunnan-Guizhou plateau is considered to be an important and relatively independent region for the evolution of the wheat stripe rust pathogen in China because the entire disease cycle can be completed within the region.In this study,we conducted a survey of barberry plants in the Yunnan-Guizhou plateau and identified the eight Pst-susceptible Berberis species under controlled conditions,including B.julianae,B.tsienii,B.veitchii,B.wilsonae,B.wilsonae var.guhtzunica,B.franchetiana,B.lepidifolia and B.pruinosa.These species are reported here for the first time to serve as alternate hosts for the wheat stripe rust pathogen under controlled conditions.

Mapping of wheat stripe rust resistance gene Yr041133 by BSR-Seq analysis

Puccinia striiformis Westend. f. sp. tritici(Pst) pathotype CYR34 is widely virulent and prevalent in China.Here, we report identification of a strpie rust resistance(Yr) gene, designated Yr041133, in winter wheat line 041133. This line produced a hypersensitive reaction to CYR34 and conferred resistance to 13 other pathotypes. Resistance to CYR34 in line 041133 was controlled by a single dominant gene. Bulked segregant RNA sequencing(BSR-Seq) was performed on a pair of RNA bulks generated by pooling resistant and susceptible recombinant inbred lines. Yr041133 was mapped to a 1.7 c M genetic interval on the chromosome arm 7 BL that corresponded to a 0.8 Mb physical interval(608.9–609.7 Mb) in the Chinese Spring reference genome. Based on its unique physical location Yr041133 differred from the other Yr genes on this chromosome arm.

Molecular mapping of a stripe rust resistance gene in Chinese wheat cultivar Mianmai 41

Stripe rust, caused by Puccinia striiformis f. sp. tritici（Pst）, is one of the most damaging diseases of wheat. Chinese wheat cultivar Mianmai 41 showed high resistance against most of the prevailing Pst races in China. Genetic analysis of the F1, F2 and F2：3 populations from a cross between Mianmai 41 and a susceptible line Mingxian 169 indicated that resistance to Pst race CYR32 was conferred by a single dominant gene, temporarily designated as Yr MY41. Molecular marker analysis placed the gene on chromosome 1B near the centromere. Six co-dominant genomic SSR markers Xwmc329, Xwmc406, Xgwm18, Xgwm131, Xgwm413, and Xbarc312, and one STS marker Xwe173 linked with the resistance gene. The two closest flanking SSR markers were Xgwm18 and Xwmc406, with genetic distances of 2.0 and 4.9 c M, respectively. A seedling test with 29 Pst isolates indicated the reaction patterns of Mianmai 41 were different from those of lines carrying Yr3, Yr9, Yr10, Yr15, Yr26, and Yr CH42 on chromosome 1B. Allelic tests indicated that Yr MY41 is likely a new allele at Yr26 locus.

QTL Mapping for Adult-Plant Resistance to Stripe Rust in a Common Wheat RIL Population Derived from Chuanmai 32/Chuanyu 12

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a devastating wheat disease worldwide. The Chinese wheat cultivar Chuanmai 32 has shown stable resistance to stripe rust for 10 yr in Sichuan Province, a hotspot for stripe rust epidemics. The objective of the present study was to map quantitative trait loci （QTL） for adult-plant resistance （APR） to stripe rust in a population of 140 recombinant inbred lines （RILs） derived from Chuanmai 32/Chuanyu 12. Field trials were conducted in Chengdu and Yaan, Sichuan, from 2005 to 2008, providing stripe rust reaction data for 6 environments. 797 simple sequence repeat （SSR） markers were screened for association with stripe rust reaction, initially through bulked segregant analysis （BSA）. Based on the mean disease values averaged across environments, the broad-sense heritability of maximum disease severity （MDS） was 0.75. Two QTLs for stripe rust resistance were detected by composite interval mapping （CIM）. They were designated QYr.caas-3BL and QYr.caas-3BS and explained from 6.6 to 20.1%, respectively, of the phenotypic variance across environments. QYr.caas-3BL came from Chuanmai 32; QYr.caas-3BS with lower effect was from the susceptible parent Chuanyu 12. Both QTLs appear to be new.

Mapping a stable adult-plant stripe rust resistance QTL on chromosome 6AL in Chinese wheat landrace Yibinzhuermai

Stripe rust,caused by Puccinia striiformis f.sp.tritici(Pst),is one of the most important diseases threatening the yield and stability of wheat production in China and many other countries.Identification and utilization of new genes for durable stripe rust resistance are important for ongoing control of this disease.The objectives of this study were to identify quantitative trait loci(QTL)associated with adult-plant stripe rust resistance in the Chinese wheat landrace Yibinzhuermai(YBZR)and to provide wheat breeders with new sources of potentially durable resistance.A total of 117 recombinant inbred lines(RILs)(F5:8)derived from a cross between YBZR and highly susceptible cultivar Taichung 29(TC29)were assessed for stripe rust severity in field experiments at Wenjiang in 2016 and 2017 and Chongzhou in 2016,2017,2018,and 2019 in Sichuan following inoculation with a mixture of current Pst races.The RILs were genotyped using the Wheat55K single nucleotide polymorphism(SNP)array.Three QTL were identified on chromosome arms 6AL,5BL and 7DS.QYr.YBZR-6AL and QYr.YBZR-7DS conferred major effects in all field environments,explaining 10.6%to 14.7%and 11.5%to 21.2%of phenotypic variation,respectively.The QTL on 5BL and 7DS likely correspond to previously known QTL,whereas QYr.YBZR-6AL is probably novel.Haplotype analysis revealed that the resistance allele at QYr.YBZR-6AL was present in 2.8%of 324 Chinese wheat landraces.SNP markers closely linked with QYr.YBZR-6AL were converted to kompetitive allele-specific PCR markers and validated in the RIL population and a subset of 92 wheat cultivars.QYr.YBZR-6AL and its markers should be useful in breeding programs to improve the level and durability of stripe rust resistance.

Wheat stripe rust resistance gene Yr24/Yr26：A retrospective review

The objective of this review is to describe events in China and elsewhere that are related to the discovery, genetic identification, use, and ultimate break-down of a single wheat gene for resistance to stripe rust, namely Yr24/Yr26. In our retrospective analysis there was an early assumption of at least three genes at or near the locus, which caused an erroneous presumption of genetic diversity for resistance. It is an example of another boom and bust cycle in plant breeding with races virulent to Yr26(V26 races) now being the majority race group in the Chinese Pst population. We have attempted to present our story in a historical and personal context demonstrating research inputs from different national and international groups, as well as some significant contemporary side issues. It covers the period from the late 1980 s to 2017, during which significant rapid advances in the molecular biology of host: pathogen genetics occurred. We attempt to describe both successes and drawbacks in our work.

Wheat powdery mildew resistance gene Pm64 derived from wild emmer (Triticum turgidum var.dicoccoides) is tightly linked in repulsion with stripe rust resistance gene Yr5

Stripe rust and powdery mildew are both devastating diseases for durum and common wheat.Pyramiding of genes conferring resistance to one or more diseases in a single cultivar is an important breeding approach to provide broader spectra of resistances in wheat improvement. A new powdery mildew resistance gene originating from wild emmer(Triticum turgidum var.dicoccoides) backcrossed into common wheat(T. aestivum) line WE35 was identified. It conferred an intermediate level of resistance to Blumeria graminis f. sp. tritici isolate E09 at the seedling stage and a high level of resistance at the adult plant stage. Genetic analysis showed that the powdery mildew resistance in WE35 was controlled by a dominant gene designated Pm64. Bulked segregant analysis(BSA) and molecular mapping indicated that Pm64 was located in chromosome bin 2 BL4-0.50–0.89. Polymorphic markers were developed from the corresponding genomic regions of Chinese Spring wheat and wild emmer accession Zavitan to delimit Pm64 to a 0.55 cM genetic interval between markers WGGBH1364 and WGGBH612, corresponding to a 15 Mb genomic region on Chinese Spring and Zavitan 2 BL, respectively. The genetic linkage map of Pm64 is critical for fine mapping and cloning. Pm64 was completely linked in repulsion with stripe rust resistance gene Yr5. Analysis of a larger segregating population might identify a recombinant line with both genes as a valuable resource in breeding for resistance to powdery mildew and stripe rust.

四川省育成小麦品种和高代品系对条锈病的抗病性评价

四川省不仅是条锈菌冬繁区,也是我国东部麦区重要的春季初侵染菌源地和毒性变异地。准确评价四川小麦新育成品种和高代品系对条锈病的抗性水平,能为合理培育和使用抗病品种提供重要依据。利用当前条锈菌优势小种和4个地点的成株期鉴定圃对来自四川省的115份小麦育成品种和299份高代品系进行苗期和成株期抗病性鉴定。结果表明,新育成品种苗期对优势小种的高抗CYR32、CYR33和CYR34的比例发生不同程度的变化,对CYR32的高抗比例为40.9%、对CYR34的高抗比例为17.4%,而供试高代品系高抗比例从52.3%降至46.2%;中抗类型育成品种从20.0%增加到40.9%,高代品系从19.6%增加至33.2%。表明条锈菌优势小种更替后一些材料仍保留了部分抗性,后期选育的高代品系兼顾对新小种的抗病性。育成品种在四川成都和甘肃清水成株期鉴定,高抗品种所占比例较低,分别为13.9%和3.5%,但高代品系高抗类型比例较高,分别为42.2%和8.5%,表明甘肃和四川条锈菌的致病类型和发病环境条件存在较大差异,近年来四川小麦成株抗条锈病育种取得显著进展。

汽车涂装车间两种板材混线前处理磷化膜外观缺陷问题的解决

介绍了轿车涂装车间前处理在调试过程中对热镀锌板材车身及冷轧板材车身磷化膜外观缺陷问题的分析过程和解决方案。分析不同板材磷化膜产生发黄、颜色不均匀、黑点、锈点和斜条纹的主要原因,并通过设备与槽液工艺参数的逐项调整及验证,探究解决磷化膜外观缺陷的思路及方法,保证了两种板材车身混线生产时磷化膜外观品质符合要求。

中国小麦条锈病综合治理理论与实践

小麦条锈病是影响小麦安全生产的重要生物灾害。文中介绍了全国小麦锈病工作者通过60多年通力协作,对小麦条锈病综合治理理论和技术研究取得的显著成绩,系统揭示了中国小麦条锈病的越冬、越夏规律、菌源传播规律、病菌致病性变异途径以及品种抗病性"丧失"的规律与原因,发现中国小麦条锈病存在秋季菌源和春季菌源2大菌源基地。提出了"综合治理越夏异变区、持续控制冬季繁殖区和全面预防春季流行区"的病害源头治理策略,研发出小麦条锈病分子诊断、异地测报以及抗锈良种、药剂拌种、退麦改种、适期晚种和带药侦查、打点保面等一系列病害监测预警和关键防治技术,构建了以生物多样性利用为核心的中国小麦条锈病菌源基地综合治理技术体系,在生产上大规模推广应用,防病保产效果极其显著。文中并对病菌致病性变异机制、早期预警和越夏易变区生态治理等问题进行了讨论。

Sentinel-2影像和BP神经网络结合的小麦条锈病监测方法

选用包含红边等多种不同波段信息的多光谱卫星数据,为区域尺度上展开作物病害监测研究提供更加丰富有效的信息,相比于常规的宽波段卫星遥感影像,搭载红边波段的Sentinel-2影像对作物病害胁迫更加敏感,能显著提高模型精度。该文以陕西省宁强县小麦条锈病为研究对象,基于Sentinel-2影像共提取了26个初选特征因子:3个可见光波段反射率(红、绿、蓝)、1个近红外波段反射率、3个红边波段反射率、14个对病害敏感的宽波段植被指数和5个红边植被指数。结合K-Means和ReliefF算法筛选病害敏感特征,最终筛选出3个宽波段植被指数,包括:增强型植被指数(enhanced vegetation index,EVI)、结构加强色素指数(structure intensive pigment index,SIPI)、简单比值植被指数(simpleratio index,SR),2个红边波段植被指数:归一化红边2植被指数(normalized red-edge2 index,NREDI2)、归一化红边3植被指数(normalized red-edge3 index,NREDI3)。利用BP神经网络方法(back propagation neural network,BPNN),分别以宽波段植被指数和宽波段植被指数结合红边波段指数作为输入变量构建小麦条锈病严重度监测模型,对比2种模型的监测精度。结果显示,基于宽波段植被指数结合红边波段植被指数的监测模型的总体精度达到83.3%,Kappa系数0.73,优于仅基于宽波段植被指数特征所建监测模型的精度73.3%,Kappa系数0.58。说明红边波段能够为病害监测提供有效信息,采用宽波段植被指数和红边波段植被指数相结合的方法能够有效提高作物病虫害监测模型精度。