粗山羊草在小麦遗传育种中的应用研究进展

小麦是世界上第二大粮食作物,对我国粮食供给起到举足轻重的作用。但目前高产、抗病及抗逆性强的小麦品种较少,使小麦的生产受到一定制约。挖掘优异遗传资源,培育高产、优质、抗逆性强的小麦品种是小麦育种的重要任务。粗山羊草是小麦D基因组的供体,蕴含着大量抗病、抗虫、抗逆和改良小麦品质的基因。为挖掘其优异基因用于小麦育种,丰富小麦的遗传资源,对小麦育种工作起到推动或借鉴作用,对粗山羊草在分子水平和抗病、抗虫、抗逆方面的研究进展进行综述,介绍了在储藏蛋白方面的研究情况,以及粗山羊草在小麦育种上的应用。     

Genome-wide identification and analysis of the regulation wheat DnaJ family genes following wheat yellow mosaic virus infection

The co-chaperone DnaJ plays an important role in protein folding and regulation of various physiological activities, and participates in several pathological processes. DnaJ has been extensively studied in many species including humans, drosophila, mushrooms, tomatoes, and Arabidopsis. However, few studies have examined the role of DnaJ in wheat (Triticum aestivum), and the interaction mechanism between TaDnaJs and plant viruses. Here, we identified 236 TaDnaJs and performed a comprehensive genome-wide analysis of conserved domains, gene structure and protein motifs, chromosomal positions and duplication relationships, and cis-acting elements. We grouped these TaDnaJs according to their domains, and randomly selected six genes from the groups for tissue-specific analysis, and expression profiles analysis under hormone stress, and 17 genes for plant virus infection stress. In qRT-PCR, we found that among the 17 TaDnaJ genes tested, 16 genes were up-regulated after wheat yellow mosaic virus (WYMV) infection, indicating that the TaDnaJ family is involved in plant defense response. Subsequent yeast two-hybrid assays verified the WYMV NIa, NIb and 7KD proteins interacted with TaDJC (TraesCS7A02G506000), which had the most significant changes in gene expression levels after WYMV infection. Insights into the molecular mechanisms of TaDnaJ-mediated stress tolerance and sensitivity could inform different strategies designed to improve crop resistance to abiotic and biotic stress. This study provides a basis for future investigation of the TaDnaJ family and plant defense mechanisms.     

TaIAA15 genes regulate plant architecture in wheat

Bread wheat (Triticum aestivum L.) is one of the most important staple crops worldwide. The phytohormone auxin plays critical roles in the regulation of plant growth and development. However, only a few auxin-related genes have been genetically demonstrated to be involved in the control of plant architecture in wheat thus far. In this study, we characterized an auxin-related gene in wheat, TaIAA15, and found that its ectopic expression in rice decreased the plant height and increased the leaf angle. Correlation analysis indicated that TaIAA15-3B was associated with plant height (Ph), spike length (SL) and 1 000-grain weight (TGW) in wheat, and Hap-II of TaIAA15-3B was the most favored allele and selected by modern breeding in China. This study sheds light on the role of auxin signaling on wheat plant architecture as well as yield related traits.     

Virome identification in wheat in the Czech Republic using small RNA deep sequencing

High-throughput deep-sequencing technology and bioinformatics analysis of the small RNA(sRNA) population isolated from plants allows universal virus detection and complete virome reconstruction for a given sample. In the present sRNA deep-sequencing analysis of virus-infected wheat samples in the Czech Republic, samples were firstly tested for barley yellow dwarf viruses(BYDVs), wheat streak mosaic virus(WSMV) and wheat dwarf virus(WDV) using ELISA, RT-PCR and PCR. Subsequent sRNA sequencing of these samples yielded more than ～60 million single-end 50-bp reads with high confidence for nine field samples of wheat. Overall, 16.5% of reads were virus-specific and 83.5% were mapped to the host. More 21-nt reads(～7.7 E+06 reads) were found than 24-nt(～6.20 E+06 reads) or 22-nt(～4.30 E+06 reads) reads. De novo assembly of the high-quality contigs revealed the presence of three earlier reported viruses in the Czech Republic: BYDVs(31.48%), WSMV(24.23%) and WDV(26.66%). We also showed the presence of cereal yellow dwarf virus(14.33%; two species CYDV-RPS and CYDV-RPV(family Luteoviridae/Polerovirus) and wheat yellow dwarf virus(WYDV, 3.30%; Luteoviridae). Phylogenetic analysis showed CYDV and WYDV grouped separately from BYDVs. Furthermore, several recombination breakpoints were found among the groups of yellow dwarf viruses(BYDVs, CYDV, and WYDV). Using RNA deep sequencing, we confirmed the presence of the three known viruses(BYDVs, WSMV, and WDV) and the first record of two species of CYDV and WYDV in wheat in the Czech Republic.     

Development of a method using multispectral imagery and spatial pattern metrics to quantify stress to wheat fields caused by Diuraphis noxia

The Russian wheat aphid, Diuraphis noxia, is an important pest of winter wheat, Triticum aestivum, and barley, Hordeum vulgare that has caused an annual economic loss estimated at over 1 billion dollars since it first appeared in the United States. The objective of this study was to determine the potential of combining multispectral imagery with spatial pattern recognition to identify and spatially differentiate D. noxia infestations in wheat fields. Multispectral images were acquired using an MS3100-CIR multispectral camera. D. noxia, drought, and agronomic conditions were identified as major causes for stresses found in wheat fields. Seven spatial metrics were computed for each stress factor. The analysis of spatial metrics quantitatively differentiated the three types of stress found within wheat fields. Detection and differentiation of wheat field stress may help in mapping stress and may have implications for site-specific monitoring systems to identify D. noxia infestations and help to target pesticide applications.     

Regionalization of wheat powdery mildew oversummering in China based on digital elevation

Blumeria graminis f. sp. tritici, the pathogen that causes wheat powdery mildew, is one of the most important diseases affecting wheat production in China, and the oversummering is the key stage of wheat powdery mildew epidemic. The more oversummering regionalization of wheat powdery mildew has played an important role in disease prediction, prevention and control. In this study, we analyzed the correlation between oversummering data of wheat powdery mildew and the meteorological factors over the past years, and determined that temperature was the key meteorological factor influencing oversummering of wheat powdery mildew. The average temperature at which wheat powdery mildew growth was terminated(26.2°C) was used as the threshold temperature to regionalize the oversummering range of wheat powdery mildew. This regionalization was done using the GIS ordinary kriging method combined with the Digital Elevation model(DEM) of China. The results showed that annual probability of oversummering region based on Model 26.2 were consistent with the actual survey of the more summer wheat powdery mildew. Wheat powdery mildew oversummering regions in China mainly cover mountainous or high-altitude areas, and these regions form a narrow north-south oversummering zone. Oversummering regions of wheat powdery mildew is mainly concentrated in the high-altitude wheat growing areas, including northern and southern Yunnan, northwestern Guizhou, northern and southern Sichuan, northern and southern Chongqing, eastern and southern Gansu, southeastern Ningxia, northern and southern Shaanxi, central Shanxi, western Hubei, western Henan, northern and western Hebei, western Liaoning, eastern Tibet, eastern Qinghai, western Xinjiang and other regions of China.     

Sources of resistance to wheat spot blotch

Specimens of various wheat and goatgrass species are evaluated for resistance to spot blotch caused by Cochliobolus sativus. It is shown that the frequency of resistant wheat specimens depends on the place of geographic provenance and that of goatgrass mainly on genomic composition.     

The damage risk evaluation of Aphis gossypii on wheat by host shift and fitness comparison in wheat and cotton

Aphids are considered as one of the key pests for wheat production worldwide. Major aphid species that infest wheat in China include Sitobion avenae, Rhopalosiphum padi, Schizaphis graminum and Metopolophium dirhodum. However, during our wheat field survey in Wenshang County of Shangdong Province, China, we observed that Aphis gossypii can feed on wheat. The damage risk of A. gossypii on wheat was assessed using host shift method. A population of A. gossypii collected from a wheat field in 2015 and another population reared on cotton under laboratory conditions for a decade without exposure to insecticides were used in the study. The results of host shift demonstrated that the A. gossypii colony from wheat has not yet developed wheat specialization. Moreover, the assessment of A. gossypii fitness on wheat and cotton showed that fecundity and net reproductive rate of A. gossypii population fed on wheat was significantly higher comparing to the population fed on cotton, whether the initial host of A. gossypii population was wheat or cotton. This study raises a warning that the cotton aphid has potential to establish well on wheat and it may cause significant effects under specific circumstances. Therefore, future studies are required to evaluate the effects of A. gossypii on wheat production.     

Seedling and adult plant resistance to leaf rust in 46 Chinese bread wheat landraces and 39 wheat lines with known Lr genes

Wheat leaf rust,caused by Puccinia triticina(Pt),is an important foliar disease that has an important influence on wheat yield.The most economic,safe and effective way to control the disease is growing resistant cultivars.In the present study,a total of 46 wheat landraces and 34 wheat lines with known Lr(leaf rust resistance)genes were inoculated with 16Pt pathotypes for postulating seedling resistance gene(s)in the greenhouse.These cultivars and five wheat differential lines with adult plant resistance(APR)genes(Lr12,Lr22b,Lr34,Lr35 and Lr37)were also evaluated for identification of slow rusting resistance in the field trials in Baoding,Hebei Province of China in the 2014–2015 and 2015–2016 cropping seasons.Furthermore,10 functional molecular markers closely linked to 10 known Lr genes were used to detect all the wheat genotypes.Results showed that most of the landraces were susceptible to most of the Pt pathotypes at seedling stage.Nonetheless,Lr1 was detected only in Hongtangliangmai.The field experimental test of the two environments showed that 38 landraces showed slow rusting resistance.Seven cultivars possessed Lr34 but none of the landraces contained Lr37 and Lr46.Lr genes namely,Lr9,Lr19,Lr24,Lr28,Lr29,Lr47,Lr51 and Lr53 were effective at the whole plant stage.Lr18,Lr36 and Lr45 had lost resistance to part of pathotypes at the seedling stage but showed high resistance at the adult plant stage.Lr34 as a slowing rusting gene showed good resistance in the field.Four race-specific APR genes Lr12,Lr13,Lr35 and Lr37 conferred good resistance in the field experiments.Seven race-specific genes,Lr2b,Lr2c,Lr11,Lr16,Lr26,Lr33 and LrB had lost resistance.The 38 landraces showed slow rusting resistance to wheat leaf rust can be used as resistance resources for wheat resistance breeding in China.     

Integrated pest management programme for cereal blast fungus Magnaporthe oryzae

Magnaporthe oryzae, the causal agent of blast diseases, is a destructive filamentous fungus that infects many plants including most economically important food crops, rice, wheat, pearl millet and finger millet. Magnaporthe oryzae has numerous pathotypes because of its high host-specificity in the field. The Oryza pathotype (MoO) of M. oryzae is the most devastating pathogen of rice, causing 10–30% yield loss in the world. On the other hand, the Triticum pathotype (MoT) causes blast disease in wheat, which is now a serious threat to wheat production in some South American countries, Bangladesh and Zambia. Because of low fungicide efficacy against the blast diseases and lack of availability of resistant varieties, control of rice and wheat blast diseases is difficult. Therefore, an integrated management programme should be adopted to control these two diseases in the field. Here, we introduced and summarized the classification, geographical distribution, host range, disease symptoms, biology and ecology, economic impact, and integrated pest management (IPM) programme of both rice and wheat blast diseases.     

Identification of yellow rust in wheat using in-situ spectral reflectance measurements and airborne hyperspectral imaging

The aim of this study was to evaluate the accuracy of the spectro-optical, photochemical reflectance index (PRI) for quantifying the disease index (DI) of yellow rust (Biotroph Puccinia striiformis) in wheat (Triticum aestivum L.), and its applicability in the detection of the disease using hyperspectral imagery. Over two successive seasons, canopy reflectance spectra and disease index (DI) were measured five times during the growth of wheat plants (3 varieties) infected with varying amounts of yellow rust. Airborne hyperspectral images of the field site were also acquired in the second season. The PRI exhibited a significant, negative, linear, relationship with DI in the first season (r ² = 0.91, n = 64), which was insensitive to both variety and stage of crop development from Zadoks stage 3–9. Application of the PRI regression equation to measured spectral data in the second season yielded a coefficient of determination of r ² = 0.97 (n = 80). Application of the same PRI regression equation to airborne hyperspectral imagery in the second season also yielded a coefficient of determination of DI of r ² = 0.91 (n = 120). The results show clearly the potential of PRI for quantifying yellow rust levels in winter wheat, and as the basis for developing a proximal, or airborne/spaceborne imaging sensor of yellow rust in fields of winter wheat.     

小麦抗叶锈病基因LrAlt的比较基因组学分析

斯卑尔脱小麦材料Altgold含有小麦抗叶锈病基因LrAlt。该基因被定位于小麦2A染色体短臂末端。本研究基于小麦与短柄草和水稻基因组良好的共线性关系,对小麦抗叶锈病基因LrAlt进行比较基因组学分析,发现该基因所在基因组区域对应于短柄草第5染色体和水稻第4染色体的直系同源基因组区域,据此开发出与LrAlt连锁的EST-STS标记BE498683、BE471132.1、BG605273和CD454629,并构建了LrAlt的遗传连锁图谱,这4个EST-STS标记与Xbarc212共分离,位于LrAlt近着丝粒侧,距离LrAlt 1.9cM。同时,通过筛选Graingenes 2.0公布的位于LrAlt附近的SSR标记,发现Xbarc124、Xgwm614与LrAlt紧密连锁,均与Xbarc212共分离。本研究通过比较基因组学的策略和筛选Graingenes 2.0公布的SSR标记,共得到与LrAlt紧密连锁的9个新的分子标记,为构建LrAlt的高密度精细遗传连锁图谱、分子标记辅助选择和基因聚合奠定了基础。     

Spectral vegetation indices selected for quantifying Russian wheat aphid (Diuraphis noxia) feeding damage in wheat (Triticum aestivum L.)

The effects of insect infestation in agricultural crops are of major economic interest because of increased cost of pest control and reduced final yield. The Russian wheat aphid (RWA: Diuraphis noxia) feeding damage (RWAFD), referred to as ??hot spots??, can be traced, indentified, and isolated from uninfested areas for site specific RWA control using remote sensing techniques. Our objectives were to (1) examine the use of spectral reflectance characteristics and changes in selected spectral vegetation indices to discern infested and uninfested wheat (Triticum aestivum L.) by RWA and (2) quantify the relationship between spectral vegetation indices and RWAFD. The RWA infestations were investigated in irrigated, dryland, and greenhouse growing wheat and spectral reflectance was measured using a field radiometer with nine discrete spectral channels. Paired t test comparisons of percent reflectance made for RWA-infested and uninfested wheat yielded significant differences in the visible and near infrared parts of the spectrum. Values of selected indices were significantly reduced due to RWAFD compared to uninfested wheat. Simple linear regression analyses showed that there were robust relationships between RWAFD and spectral vegetation indices with coefficients of determination (r ²) ranging from 0.62 to 0.90 for irrigated wheat, from 0.50 to 0.87 for dryland wheat, and from 0.84 to 0.87 for the greenhouse experiment. These results indicate that remotely sensed data have high potential to identify and separate ??hot spots?? from uninfested areas for site specific RWA control.     

基于深度学习的小麦条锈病病害等级识别

目的 为提高小麦条锈病危害程度分级精度,开展小麦条锈病病害等级自动化、准确、快速识别方法研究。方法 在复杂田间条件下,使用手机拍摄图像,构建含有不同等级条锈病的小麦叶片数据集,利用GrabCut与YOLOv5s相结合的方法进行小麦叶片与复杂背景自动化分割。为了增强ResNet50对表型特征的提取能力,增加Inception模块,依据划分的小麦条锈病病害等级标准,对小麦条锈病病害等级进行识别。采用准确率、查全率、查准率等评价指标分析改进的ResNet50模型(B-ResNet50)在数据集上的表现。结果 GrabCut与YOLOv5s相结合对大田复杂背景下的小麦叶片图像实现了自动、准确、快速地分割。B-ResNet50识别小麦条锈病叶片的平均准确率为97.3%,与InceptionV3(87.8%)、DenseNet121(87.6%)、ResNet50(88.3%)相比,准确率大幅提升,比原始模型(ResNet50)高出9个百分点。结论 利用深度学习对小麦条锈病病害等级进行识别,对防治小麦条锈病的精准施药具有重要意义,可为田间复杂条件下小麦条锈病的防治提供技术支持。     

Effects of sodium benzoate on growth and physiological characteristics of wheat seedlings under compound heavy metal stress

In this study, we investigated the effect of exogenous sodium benzoate on wheat seedlings(Yangmai 16) grown under heavy metal stress. The results showed that 2.4 mmol kg~(–1) of heavy metals significantly inhibited growth and delayed emergence of wheat seedlings. Under compound heavy metal stress, application of 2–4 g L~(–1) sodium benzoate significantly increased(P0.01) chlorophyll content and chlorophyll fluorescence parameters F_v/F_m and F_v/F_o of wheat, compared to the control(water treatment). Further analysis showed that application of 2–4 g L~(–1) sodium benzoate alleviated osmotic stress by promoting the accumulation of osmolytes such as soluble proteins and free proline, increased the activity of superoxide dismutase(SOD) and reduced malondialdehyde content(MDA). In contrast, higher concentrations of sodium benzoate solution(6 g L~(–1)) inhibited the growth of wheat seedlings and even caused damage to seedlings. Correlation analysis showed that when the sodium benzoate concentration was in the range of 1.97–3.12 g L~(–1)(2016) and 1.58–3.27 g L~(–1)(2017), values of chlorophyll and its components, root activity, SOD activity, soluble protein, and free proline content were the highest. When the sodium benzoate concentration was raised to 2.59 g L~(–1)(2016) or 3.02 g L~(–1)(2017), MDA content was the lowest. Ultimately, exogenous sodium benzoate(2–4 g L~(–1)) facilitates root development and improves the root activity of wheat seedlings grown under compound heavy metals stress, thereby effectively alleviating the damage of compound heavy metal stress in wheat seedlings.     

Identification of QTL for adult plant resistance to stripe rust in bread wheat line C33

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a serious disease in bread wheat(Triticum aestivum L.). Identification and use of adult plant resistance(APR) resources are important for stripe rust resistance breeding. Bread wheat line C33 is an exotic germplasm that has shown stable APR to stripe rust for more than 10 years in Sichuan Province of China. Here, 183 recombinant inbred lines(RILs) derived from the cross between C33 and a susceptible line X440 were genotyped with diversity arrays technology(DArT) markers to identify resistance quantitative trait locus(QTL). Field trials were conducted in five years at Chengdu and Xindu of Sichuan Province, using maximum disease severity(MDS) as stripe rust reaction phenotypes. A total of four quantitative trait loci(QTLs) were detected, respectively designed as QYr.saas-3 AS, QYr.saas-5 AL, QYr.saas-5 BL, and QYr.saas-7 DS, explaining 4.14–15.21% of the phenotypic variances. QYr.saas-5 BL and QYr.saas-7 DS were contributed by C33. However, the level for stripe rust resistance contributed by them was not strong as C33, suggesting the presence of other unidentified QTLs in C33. QYr.saas-7 DS corresponded to Yr18 and QYr.saas-5 BL remains to be formally named. The RIL lines carrying combinations QYr.saas-5 AL, QYr.saas-5 BL, and QYr.saas-7 DS showed comparability resistance with C33. The present study provides resources to pyramid diverse genes into locally adapted elite germplasm to improve the stripe rust resistance of bread wheat.     

Identification of the resistance gene to powdery mildew in Chinese wheat landrace Baiyouyantiao

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most damaging diseases to wheat in the world. The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic. Wheat landraces are important resources of resistance to many diseases. Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance. The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew. To identify the resistance gene in this landrace, Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F₁, BC₁, F₂, and F_2:3 were tested with Bgt isolate E09. The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene, tentatively designated PmBYYT. An Illumina wheat 90K single-nucleotide polymorphism (SNP) array was applied to screen polymorphisms between F₂-resistant and F₂-susceptible DNA bulks for identifying the chromosomal location of PmBYYT. A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chromosome 7B, indicating that PmBYYT may be located on this chromosome. A genetic linkage map of PmBYYT consisting of two simple sequence repeat markers and eight SNP markers was developed. The two flanking markers were SNP markers W7BL-8 and W7BL-15, with genetic distances of 3 and 2.9 cM, respectively. The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay. The flanking markers of gene PmBYYT will benefit marker-assisted selection (MAS) and map-based cloning in breeding wheat cultivars with powdery mildew resistance.     

Evaluation of a new method for quantification of heat tolerance in different wheat cultivars

Heat stress seriously affects wheat production in many regions of the world. At present, heat tolerance research remains one of the least understood fields in wheat genetics and breeding and there is a lack of effective methods to quantify heat stress and heat tolerance in different wheat cultivars. The objective of this study was to use various wheat cultivars to evaluate stress intensity(δ) and a new method for quantification of heat tolerance and compare this technique with three other currently utilized methods. This new parameter for heat tolerance quantification is referred to as the heat tolerance index(HTI) and is an indicator of both yield potential and yield stability. Heat treatments were applied in a controlled setting when anthesis had been reached for 80% of the wheat. The stress intensity evaluation indicated heat shock was the main factor associated with kernel weight reduction while grain yield reduction was mainly associated with chronic high temperature. The methods evaluation showed that a temperature difference of 5°C from natural temperatures was a suitable heat treatment to compare to the untreated controls. HTI was positively correlated with yield under heat stress(r=0.8657, δ_(2010)=0.15, in 2009–2010; r=0.8418, δ_(2011)=0.20, in 2010–2011; P0.01), and negatively correlated with yield reduction rate(r=–0.8344, in 2009–2010; r=–0.7158, in 2010–2011; P0.01). The results of this study validated the use of HTI and temperature difference control for quantifying wheat heat tolerance that included the yield potential and the stability of different wheat cultivars under heat stress. Additionally, 10 wheat cultivars showed high HTI and should be further tested for their heat confirming characteristics for use in wheat heat tolerance breeding.