Identification of Leaf Rust Resistance Genes in Wheat Cultivars Produced in Kazakhstan

Leaf rust, caused by Puccinia recondita f. sp. tritici, is one of the major diseases of wheat in Kazakhstan. To effectively use leaf rust resistance genes (Lr), it is important for breeders to know the resistance genotype in current cultivars. In this study, 30 winter wheat entries grown and/or produced in Kazakhstan were investigated using molecular markers to determine the presence and absence of eight important Lr genes. Molecular screening of these genotypes showed contrasting differences in the frequencies of these genes. Among the 30 entries, 17 carried leaf rust resistance gene Lr1, six had Lr26 and Lr34, and Lr10 and Lr37 were found in three cultivars. Two single cultivars separately carried Lr19 and Lr68, while Lr9 was not detected in any genotypes in this study. Field evaluation demonstrated that two of the most frequent two genes (Lr1 and Lr26) to be ineffective. While Lr34 provided some protection, the remaining effective Lr genes were found only in few genotypes: Lr37 occurred in Kazakh genotypes L-1090 and Krasnovodapadskaya 210 and in the US cultivar Madsen; Lr19 and Lr68 were likely present only in Russian and Kazakh cultivars, Pallada and Yegemen, respectively. The highest resistance over three years of leaf rust testing was found in Kazakh cultivars, Karasay, Krasnovodapadskaya 210, L-1090, Arap and Yegmen, foreign cultivars Madsen, Pallada and the control Parula (Lr68). Data may assist breeders to incorporate effective Lr genes into new cultivars

Identifcation of genotypescarriers of resistance to tan spot Ptr ToxA and Ptr ToxB of Pyrenophora tritici-repentis in common wheat collection

Pyrenophora tritici-repentis (Ptr) is the causative agent of tan spot, one of the yield limiting diseases of wheat, rapidly increasing in wheat growing countries including Kazakhstan. The aim of this study was the identifcation of wheat genotypes with resistance to Ptr race 1 and race 5 and their host­selective effectors (toxins) Ptr ToxA and Ptr ToxB. A common wheat collection of 41 accessions (38 experimental and 3 controls) was characterized using the molecular markers Xfcp623 and XBE444541, diagnostic for the Tsn1 and Tsc2 genes conferring sensitivity to fungal toxins. The coincidence of the marker XBE444541 with resistance to race 5 was 92.11 %, and with Ptr ToxB, 97.37 %. Genotyping results using the marker Xfcp623 confrmed the expected response to Ptr ToxA; the presence/absence of the marker Xfcp623 completely (100 %) coincided with sensitivity/resistance to race 1 and Ptr ToxA. This demonstrates the reliability of the diagnostic marker Xfcp623 for identifying wheat genotypes with resistance to the fungus and insensitivity to Ptr ToxA. The study of the reaction of wheat germplasm to the fungal inoculation and toxin infltration showed that out of 38 genotypes analyzed 30 (78 %) exhibited resistance to both race 1 and race 5, and insensitivity to toxins Ptr ToxA and ToxB. Of most signifcant interest are eight wheat genotypes that showed resistance/insensitivity both to the two races and two toxins. The results of phenotyping were reconfrmed by the molecular markers used in this study. Sensitivity to Ptr ToxB is not always correlated with susceptibility to race 5 and is dependent on the host’s genetic background of the wheat genotype, i. e. on a specifc wheat genotype. The results of the study are of interest for increasing the efciency of breeding based on the elimination of the genotypes with the dominant alleles Tsn1 and Tsc2 sensitive to the toxins Ptr ToxA and ToxB. The genotypes identifed will be used in wheat breeding for resistance to tan spot

Pyrenophora tritici-repentis population structure in the Republic of Kazakhstan and identification of wheat germplasm resistant to tan spot

Pyrenophora tritici-repentis is a causative agent of tan spot in wheat. In recent years, there has been an increasing spread and harmfulness of wheat tan spot. The aim of the research was to study the racial composition of the P. tritici-repentis population in the Republic of Kazakhstan. A collection of 30 common wheat accessions, including promising lines and cultivars from Kazakhstan and CIMMYT–ICARDA, was assessed for resistance to P. triticirepentis in a greenhouse and characterized using the Xfcp623 molecular marker, diagnostic for the Tsn1 gene. Monosporic isolates of P. tritici-repentis isolated from the southeastern region were assigned to certain races based on the manifestation of symptoms of necrosis/chlorosis on standard differentials (Glenlea, 6B662, 6B365). Five races of P. tritici-repentis have been identified, including races 1, 2, 3, 7 and 8. It has been shown that races 1 and 8 of P. tritici-repentis are dominant. As a result of the analysis of the frequency of occurrence of the P. tritici-repentis races, it was found that race 1 (50 %) producing Ptr ToxA and Ptr ToxB and race 8 (35 %) producing Ptr ToxA, Ptr ToxB and Ptr ToxC turned out to be dominant. From a practical point of view, of greatest interest are 16 wheat samples, which demonstrated resistance to race 1 and confirmed insensitivity to Ptr ToxA in a molecular screening. These include eight Kazakhstani (4_PSI, 10204_2_KSI, 10204_3_KSI, 10205_2_KSI, 10205_3_KSI, 605_SP2, 632_SP2, Dana) and seven foreign lines (KR11-20, KR11-03, KR11-9014, 11KR-13, KR12-9025, KR12-07, GN-68/2003). The results of this study are of interest in wheat breeding programs for tan spot resistance

Phytopathological screening and molecular marker analysis of wheat germplasm from Kazakhstan and CIMMYT for resistance to tan spot

Tan spot caused by the fungus Pyrenophora tritici-repentis is an important leaf spot disease in wheat growing areas throughout the world. The study aims to identify wheat germplasm resistant to tan spot based on phytopathological screening and molecular marker analysis. A collection of 64 common wheat germplasms, including cultivars and breeding lines from Kazakhstan and CIMMYT, was assessed for tan spot resistance in greenhouse conditions and characterized using the Xfcp623 molecular marker, diagnostic for the Tsn1 gene. All wheat cultivars/lines varied in their reaction to tan spot isolate race 1, ranging from susceptible to resistant. Most accessions studied (53 %) were susceptible to Ptr race 1. Spring wheat cultivars were more susceptible to race 1 than winter wheat cultivars. As a result of genotyping, an insensitive reaction to Ptr ToxA was predicted in 41 wheat cultivars (64 %). The tsn1 gene carriers identified included 27 Kazakhstani and 14 CIMMYT cultivars/lines, demonstrating insensitivity to Ptr ToxA. The majority of the Tsn1 genotype were sensitive to race 1 and showed susceptibility to the pathogen in the field. Disease scores from seedling stage positively correlated with field disease ratings. Of particular interest are 27 wheat accessions that demonstrated resistance to spore inoculation by Ptr race 1, were characterized by insensitivity to ToxA and showed field resistance to the pathogen. The results of this study will contribute to wheat breeding programs for tan spot resistance with Marker Assisted Selection using the closely flanking markers

Effect of Current Density on Electrodeposition of Nickel-Organic Microcapsules Composite Coatings

A formation of protective composite coatings based on nickel and organic substance of inert nature, containing a corrosion inhibitor, encapsulated in a polymer shell, was studied. The microcapsules were synthesized in an aqueous-organic emulsion using the method of formation of shell of the modified gelatine on the surface of microdroplets. Composite coatings were obtained by electrochemical codeposition of nickel matrix and microcapsules, suspended in the electrolyte. Changes of surface morphology, microhardness and corrosive properties of coatings with respect to changes of deposition parameters of coatings were investigated. The distribution of particle sizes in coatings depending on the current density was studied. It was shown that an increase in the mass fraction of the microcapsules in the coating leads to an increase in its corrosion resistance

Yield stability and drought resistance in wheat

There is little information on interaction between productivity, stability and drought resistance of crop. This problem is very important in Kazakhstan, where the most of the agricultural area is located in arid and semiarid regions. In this context the genotype × environment interaction (GEI) is of major importance to the plant breeders in developing improved drought resistant cultivars. In this study GEI and stability parameters of recombinant inbred lines (RILs) has been determined by field testing at three contrasting environments. The comparison of the performance and stability of the lines L3, L10, L5, L1 indicated that this breeding material tended to display better performance for main of productivity traits and stability for plant grain yield as compared with other RILs and parental forms. There was positive association between high leaf Relative Water Content (RWC), low leaf Relative Water Loss (RWL) and yield stability. Both physiological parameters (RWC and RWL) are good indicators of drought adaptation by wheat genotypes. A comparison of glume pubescent and unpubescent lines has shown close negative correlation for spike RWL and spike RWC of all pubescent RILs (R2= -0.845). So the glume pubescence can be used as a morphological marker and indirect criterion for selection of drought resistant genotypes. As a result several promising lines combining high yield stability and drought resistance has been selected and used in breeding program

IDENTIFICATION OF STEM RUST RESISTANCE SOURCES IN WHEAT BY USING MOLECULAR MARKERS

Puccinia graminis f. sp. tritici induces stem rust, which is the cause of a considerable crop loss. Race Ug99 of P. graminis f. sp. tritici (pathotype TTKS) is virulent to the majority of wheat varieties. According to FAO reports, major wheat-producing countries to the east of Iran (Afghanistan, India, Pakistan, Turkmenistan, Uzbekistan and Kazakhstan) are greatly endangered. It is necessary to seek resistance sources to stem rust with identified Sr genes. Screening with PCR SSR and STS markers associated with effective Sr genes (Sr2, Sr22, Sr24 and Sr46) was undertaken to identify Sr gene sources. Twelve accessions with the Sr2-gene were identified. Seven resistant lines were found to possess Sr24/Lr24 genes. Sr46 was identified in one line. PCR analysis revealed the presence of Sr22 in six promising lines. The results are used in wheat breeding programs for stem rust resistance with marker-assisted selection