Resistance Of Wheat Genotypes Research Articles

Evaluation of stripe rust resistance and analysis of resistance genes in wheat genotypes from Pakistan and Southwest China

IntroductionStripe rust, caused by Puccinia striiformis f. sp. tritici, poses a significant threat to wheat quality and production worldwide. The rapid evolution of Pst races caused several resistance genes to be ineffective.MethodsThis study evaluated stripe rust resistance genes in 349 Pakistan and Southwest China genotypes. We utilized previously published functional and linked molecular markers to detect 13 major stripe rust resistance genes: Yr5, Yr9, Yr10, Yr15, Yr17, Yr18, Yr26, Yr29, Yr30, Yr36, Yr48, Yr65, and YrSp. Field evaluations assessed IT and resistance levels, while the impact of gene combinations on resistance was also analyzed.ResultsField evaluations showed that over 60% of Chuanyu wheat, 50% of recent Pakistani cultivars, and 20% of historic Pakistani lines were resistant to current stripe rust races. In Chuanyu wheat, the dominant genes were Yr17, YrSp, and Yr48; however, Yr17, Yr26, and YrSp were overused, while Yr36 was absent, and Yr18 was rare. In historic lines, Yr5, Yr17, Yr18, and Yr26 were prevalent, with Yr15, Yr26, and YrSp demonstrating effective resistance against current stripe rust races. Furthermore, the study identified specific combinations of Yr genes (Yr26+Yr48, Yr29+Yr5, Yr26+Yr30, and Yr30+Yr17) that enhanced resistance to Pst.DiscussionThis research highlights effective resistance genes and gene combinations for stripe rust in wheat and emphasizes the deployment of durable resistance. The findings guide the strategic use of these genes in breeding programs aimed at developing durable resistance in wheat genotypes in Pakistan and Southwest China.

Comparative physiological and transcriptomic analyses reveal ascorbate and glutathione coregulation of cadmium toxicity resistance in wheat genotypes

BackgroundCadmium (Cd) is a heavy metal with high toxicity that severely inhibits wheat growth and development. Cd easily accumulates in wheat kernels and enters the human food chain. Genetic variation in the resistance to Cd toxicity found in wheat genotypes emphasizes the complex response architecture. Understanding the Cd resistance mechanisms is crucial for combating Cd phytotoxicity and meeting the increasing daily food demand.ResultsUsing two wheat genotypes (Cd resistant and sensitive genotypes T207 and S276, respectively) with differing root growth responses to Cd, we conducted comparative physiological and transcriptomic analyses and exogenous application tests to evaluate Cd detoxification mechanisms. S276 accumulated more H2O2, O2−, and MDA than T207 under Cd toxicity. Catalase activity and levels of ascorbic acid (AsA) and glutathione (GSH) were greater, whereas superoxide dismutase (SOD) and peroxidase (POD) activities were lower in T207 than in S276. Transcriptomic analysis showed that the expression of RBOHA, RBOHC, and RBOHE was significantly increased under Cd toxicity, and two-thirds (22 genes) of the differentially expressed RBOH genes had higher expression levels in S276 than inT207. Cd toxicity reshaped the transcriptional profiling of the genes involving the AsA-GSH cycle, and a larger proportion (74.25%) of the corresponding differentially expressed genes showed higher expression in T207 than S276. The combined exogenous application of AsA and GSH alleviated Cd toxicity by scavenging excess ROS and coordinately promoting root length and branching, especially in S276.ConclusionsThe results indicated that the ROS homeostasis plays a key role in differential Cd resistance in wheat genotypes, and the AsA-GSH cycle fundamentally and vigorously influences wheat defense against Cd toxicity, providing insight into the physiological and transcriptional mechanisms underlying Cd detoxification.

Molecular breeding for rust resistance in wheat genotypes.

Rusts are a group of major diseases that have an adverse effect on crop production. Those targeting wheat are found in three principal forms: leaf, stripe, and stem rust. Leaf rust causes foliar disease in wheat; in Egypt, this causes a significant annual yield loss. The deployment of resistant genotypes has proved to be a relatively economical and environmentally sustainable method of controlling the disease. Gene pyramiding can be performed using traditional breeding techniques. Additionally, pathotypes can be introduced to examine specific leaf rust genes, or the breeder may conduct more complex breeding methods. Indirect selection via DNA markers linked to resistance genes may facilitate the transfer of targeted genes, either individually or in combination, even in a disease-free environment. The use of selective crosses to counter virulent races of leaf, stripe, and stem rust has resulted in the transfer of several resistance genes into new wheat germplasm from cultivated or wild species. Quantitative trait locus (QTL) technology has been adopted in a wide variety of novel approaches and is becoming increasingly recognized in wheat breeding. Moreover, several researchers have reported the transference of leaf and stripe rust resistance genes into susceptible wheat cultivars.

Assessment of Leaf Rust Resistance in Wheat Genotypes in Natural Environmental Conditions of Tandojam

Assessment of Leaf Rust Resistance in Wheat Genotypes in Natural Environmental Conditions of Tandojam

Resistance to Wheat Curl Mite in Arthropod-Resistant Rye-Wheat Translocation Lines

The wheat curl mite, Aceria toschiella (Keifer), and a complex of viruses vectored by A. toschiella substantially reduce wheat yields in every wheat-producing continent in the world. The development of A. toschiella-resistant wheat cultivars is a proven economically and ecologically viable method of controlling this pest. This study assessed A. toschiella resistance in wheat genotypes containing the H13, H21, H25, H26, H18 and Hdic genes for resistance to the Hessian fly, Mayetiola destructor (Say) and in 94M370 wheat, which contains the Dn7 gene for resistance to the Russian wheat aphid, Diuraphis noxia (Kurdjumov). A. toschiella populations produced on plants containing Dn7 and H21 were significantly lower than those on plants of the susceptible control and no different than those on the resistant control. Dn7 resistance to D. noxia and H21 resistance to M. destructor resulted from translocations of chromatin from rye into wheat (H21—2BS/2RL, Dn7—1BL/1RS). These results provide new wheat pest management information, indicating that Dn7 and H21 constitute resources that can be used to reduce yield losses caused by A. toschiella, M. destructor, D. noxia, and wheat streak mosaic virus infection by transferring multi-pest resistance to single sources of germplasm.

Cell Wall Biomolecular Composition Plays a Potential Role in the Host Type II Resistance to Fusarium Head Blight in Wheat.

Fusarium head blight (FHB) is a serious disease of wheat worldwide. Cultivar resistance to FHB depends on biochemical factors that confine the pathogen spread in spikes. Breeding for cultivar resistance is considered the most practical way to manage this disease. In this study, different spectroscopy and microscopy techniques were applied to discriminate resistance in wheat genotypes against FHB. Synchrotron-based spectroscopy and imaging techniques, including focal plane array infrared and X-ray fluorescence (XRF) spectroscopy were used to understand changes in biochemical and nutrients in rachis following FHB infection. Sumai3 and Muchmore were used to represent resistant and susceptible cultivars to FHB, respectively, in this study. The histological comparison of rachis showed substantial differences in the cell wall thickness between the cultivars after infection. Synchrotron-based infrared imaging emphasized substantial difference in biochemical composition of rachis samples between the two cultivars prior to visible symptoms; in the resistant Sumai3, infrared bands representing lignin and hemicellulose were stronger and more persistent compared to the susceptible cultivar. These bands may be the candidates of biochemical markers for FHB resistance. Focal plane array infrared imaging (FPA) spectra from the rachis epidermis and vascular bundles revealed a new band (1710 cm−1) related to the oxidative stress on the susceptible cultivar only. XRF spectroscopy data revealed differences in nutrients composition between cultivars, and between controls and inoculated samples, with substantial increases observed for Ca, K, Mn, Fe, Zn, and Si in the resistant cultivar. These nutrients are related to cell wall stability, metabolic process, and plant defense mechanisms such as lignification pathway and callose deposition. The combination of cell wall composition and lignification plays a role in the mechanism of type II host resistance to FHB. Biochemical profiling using the synchrotron-based spectroscopy holds potential for screening wheat genotypes for FHB resistance.

Development of a real-time PCR method for the identification of wheat genotypes carrying different eyespot resistance genes

With 2 figures and 7 tables Abstract Eyespot, caused by Oculimacula acuformis and O. yallundae, is an important disease of wheat (Triticum aestivum). The two pathogens generate similar symptoms and cannot be distinguished visually. In order to distinguish O. acuformis and O. yallundae infections and to identify reliable quantitative differences in the level of resistance of wheat genotypes, two SYBR Green based real-time PCR assays were developed. The influence of time after inoculation until sample collection, the effect of species (O. acuformis, O. yallundae), and the relevance of wheat cultivars carrying Pch1, Pch2, or none of the resistance genes on the pathogen-DNA content were analysed. The most clear-cut difference of pathogen content between resistant and susceptible wheat genotypes was obtained 12 weeks after inoculation with O. yallundae. Growth chamber tests using artificial inoculation with O. yallundae and sampling 12 weeks after inoculation for real-time PCR is shown to be a reliable procedure to determine the resistance level of wheat against eyespot. Likewise, this is the basis for the development of efficient molecular markers.

Resistance to Tan Spot and Stagonospora nodorum Blotch in Wheat-Alien Species Derivatives

Tan spot (caused by Pyrenophora tritici-repentis) and Stagonospora nodorum blotch (SNB) (caused by Stagonospora nodorum) are destructive fungal diseases of wheat (Triticum aestivum) throughout the world. Host plant resistance is thought to be an efficient and economical method of control. The objective of the present study was to identify novel sources of tan spot and SNB resistance in wheat genotypes derived from the crosses between wheat and alien species. Evaluations were conducted at the seedling stage in a growth chamber with 100% relative humidity. For each genotype, three replications were used for each disease. Among the 199 wheat-alien species derivatives evaluated, 65 exhibited resistance to tan spot and 30 showed resistance to SNB similar to BR34, a Brazilian wheat line used as the resistant control. Eleven derivatives were resistant to both diseases. Reactions of the derivatives and their respective wheat parents to tan spot and SNB suggest that resistance genes in the derivatives are derived from alien species. These derivatives can serve as desirable bridges for introgression of resistance genes from alien species to cultivated wheat, and could contribute novel and effective tan spot and SNB resistance to wheat breeding.

Introduction of new indices to identify relative drought tolerance and resistance in wheat genotypes

Three new indices namely: abiotic-stress tolerance index (ATI) (Abiotic-stress Tolerance Index), stress susceptibility percentage index (SSPI) (Stress Susceptibility Percentage Index) and stress non-stress production index (SNPI) were introduced to identify relatively tolerant (through ATI and SSPI) and resistant (through SNPI) genotypes under nonirrigated and irrigated conditions. Sixteen bread wheat genotypes (in 2004, under a moderate stress with SI = 0.31) and twenty durum wheat genotypes (2004 and 2005 under a severe stress with SI = 0.57) were studied in field experiments under non-irrigated and irrigated conditions. Yield changes in non-irrigated and irrigated conditions for different genotypes, the primary selection of genotypes for relative drought tolerance or resistance and a comparison between new indices and previous ones were studied. In this paper, “relative tolerance and resistance” phrases are used instead of “tolerance and resistance” because we believe that, generally, there are no complete tolerance and resistance to abioticstress. ATI and SSPI exhibited a positive significant simple correlation with TOL, Yp and SSI, but their correlations with RDI were significantly negative. ATI and SSPI differentiated between relative tolerant and intolerant genotypes better than TOL and SSI in some cases and were considered as a favorite index for the selection of relatively tolerant genotypes. ATI and SSPI are powerful to select extreme tolerant genotypes with yield stability and may be can use of them as parents in conformation to a QTL population for yield stability in two irrigated and non-irrigated conditions, because, both of them are related to relatively yield stability and may be state that a genotype with suitable yield stability carries drought tolerance or other related trait genes. SNPI had a positive correlation with yield changes in both non-irrigated and irrigated conditions and negative correlation with SSI and TOL, therefore, to select a genotype with appropriate, high and stable yield in both stress and non-stress conditions for commercial aims, it is suggested to use SNPI as a desirable index because this index supports stable and high yield in both conditions (especially in non-irrigated condition) simultaneously.

Assessment of macroscopic components of leaf rust resistance in wheat genotypes containing Lr12 and Lr13

Monogenic resistance in wheat (Triticum aestivum L.) to leaf rust, caused by Puccinia recondita Rob. ex. Desm. f. sp. tritici, has generally not been durable. Durable resistance, as well as an improved expression of resistance, have been associated with Lr gene combinations. In this study, the assumption that Lr12 and Lr13 may interact to condition improved resistance to leaf rust, was investigated. Four Thatcher (Tc) x RL6011 F3 lines (13/12–3, 13/12–9, 13/12- 19 and 13/12–40), homozygous for both Lr13 and Lr12, were selected and their leaf rust resistance compared with the parents (CT263 [=TcLr13] and RL6011 [=TcLr12]), the single gene lines Tc/13–22 and TC/12–16, and Thatcher. In addition to infection type studies in seedlings and adult plants, lines were compared according to macroscopic components of resistance, as well as disease ratings in the field. Flag leaf infection type studies showed that Lr12 is effective against most pathotypes of P. recondita f. sp. tritici occurring in South Africa. Conversely, Lr13 is ineffective against the dominant pathotypes, implying that the gene has no value as a monogenic source of resistance. Based on the fact that several pathotypes are avirulent to these genes, they should be manipulated with relative ease in local breeding programmes directed at utilizing these sources in combination with other Lr genes. Infection types on the flag leaves of lines carrying both Lr12 and Lr13 often displayed chlorosis and necrosis. These ratings on primary and flag leayes, as well as the quantitative components latent period, uredium density and uredium size, did not indicate clear differences between the digenic lines and the most resistant parent. In the absence of a pathotype virulent to both genes, the combination lines were resistant in the field. Data obtained were not conclusive in suggesting pronounced resistance enhancement due to combining Lr12 with Lr13.