Maria A. Kolesova

Background. Cherry plum ( Prunus cerasifera Ehrh.) is a unique stone fruit crop. Development of fungal diseases, including brown rot, shot hole, red leaf spot, and rust, leads to a significant decrease in the yield and marketable quality of P. cerasifera fruits. Planting cherry plum orchards with resistant cultivars is a highly effective method of disease control. Breeding for disease resistance requires availability of the trait’s genetic diversity. P. cerasifera accessions from the unique collection maintained at Maikop Experiment Station of VIR can be utilized as sources of such diversity. The objective of the project was to identify cherry plum cultivars resistant to fungal diseases among those bred at Maikop Experiment Station. Materials and methods. The tested material included 14 accessions of P. cerasifera . Resistance to fungal diseases was assessed in the collection orchard of Maikop Experiment Station according to a generally accepted scale in 2011–2022. Results and conclusions. It was established that weather conditions during the flowering, growing and fruit-ripening periods of P. cerasifera plants affected the degree of damage by fungal diseases. Long-term research showed that cherry plum cultivars developed at Maikop Experiment Station of VIR were resistant to brown rot and shot hole. Most P. cerasifera cultivars were observed to possess resistance to rust and red leaf spot. Twelve cherry plum cultivars with combined resistance to four diseases were also identified. They can be recommended to breeders for the development of P. cerasifera cultivars with combined resistance to fungal diseases.

Leaf rust (caused by Puccinia triticina Erikss., Pt) is a severe foliar disease of cultivated wheat worldwide. Severe development of the disease results in significant losses in seed yield and quality. Growing immune varieties is the most rational method for Pt control in terms of effectiveness and ecological safety. However, the gene pool of cultivated wheat is very narrow for seedling Pt effective resistance genes, which hampers breeding for this trait. One of the well-known methods to broaden genetic diversity for resistance is the introgression of highly effective genes from wild relatives into the genomes of cultivated wheat. The Aegilops L. species have been proven to be perfectly suited for this purpose. No gene for Pt resistance has been transferred to wheat from Aegilops biuncialis Vis. (Lorent’s goatgrass) up to now. Previously, we selected eight accessions of the species from the VIR (N.I. Vavilov All-Russian Institute of Plant Genetic Resources) genebank that showed a perfect level of resistance to leaf rust. In this research, we studied the genetic control of resistance using hybridological, phytopathological, and molecular analyses. According to the F₁–F₃ hybrid evaluation results, each accession possesses one dominant gene for Pt resistance, and genes in different accessions are allelic or very tightly linked. Phytopathological test clone analysis showed that this gene is not identical to Lr9, Lr19, Lr24, Lr39, and Lr47, which are effective against Pt populations in some areas of Russia. This conclusion was partially supported by the results of the identification of DNA markers specific to these genes in bread wheat. Thus, we identified one dominant gene (temporarily symbolized as LrBi1) for effective seedling Pt resistance; it is recommended for introgression to cultivated wheat via interspecific hybridization.

   Background. European plum (Prunus domestica L.) is a widespread stone fruit crop in Krasnodar Territory and Adygea. Development of fungal diseases, including brown rot, shot hole, red leaf spot, and rust, leads to a significant decrease in the harvest and marketable quality of P. domestica fruits. Therefore, breeding for resistance to these diseases is very important for planting highly productive European plum orchards. The objective of this study was to identify P. domestica cultivars resistant to four fungal diseases under the conditions of the foothill zone of Adygea.   Materials and methods. The research material included 25 P. domestica cultivars from the collection orchard of Maikop Experiment Station of VIR. Resistance to fungal diseases was assessed in 2011–2022 using a conventional scale.   Results and conclusions. Weather and climate conditions during the flowering, fruit growth and ripening periods of European plum affected the degree of damage inflicted by fungal diseases. Many years of testing resulted in identifying P. domestica cultivars with different scores of resistance to brown rot, shot hole, and rust. Ten P. domestica cultivars were characterized by group resistance to the abovementioned diseases: ‘Anna Shpet’ (k-3325), ‘Vengerka Rannyaya’ (k-3459), ‘Vengerka Italyanskaya’ (k-3444), ‘Musa Dzhaliev’ (k-26994), ‘Vengerka Vkusnaya’ (k-43323), ‘Persikovaya Michurina’ (k-30706), ‘Chernosliv Adygeyskiy’ (k-23743), ‘Chernosliv Shuntukskiy’ (k-23707), ‘Yekaterina’ (yellow) (k-3520), and ‘Vasсova’ (k-27639). They can be recommended to plum breeders for the development of P. domestica cultivars with group resistance to fungal diseases in the foothill zone of Adygea.

To reveal genetic diversity for effective resistance to five foliar diseases and toxic aluminum ions, the entire collection of wheat species from the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR) originating from Ethiopia and Eritrea were studied regarding their traits. The collection contains 509 samples of four wheat species (Triticum aestivum—122 samples; T. aethiopicum—340 samples; T. polonicum—6 samples; and T. dicoccum—41 samples). The majority of accessions are new entries of landraces added to the Vavilov collection as a result of the Russian–Ethiopian expedition in 2012. Wheat seedlings were inoculated with causal agents of leaf rust (Pt), powdery mildew (Bgt), Septoria nodorum blotch (SNB), and dark-brown leaf spot blotch (HLB). The types of reaction and disease development were assessed to describe the levels of resistance. All samples of T. aethiopicum were also screened for seedling and adult resistance to Pt, Bgt, and yellow rust (Pst) under field conditions after double inoculation with the corresponding pathogens. To study tolerance to abiotic stress, seedlings were grown in a solution of Al³⁺ (185 µM, pH 4,0) and in water. The index of root length was used to characterize tolerance. Seedlings belonging to only two accessions out of those studied—k-68236 of T. aethiopicum and k-67397 of T. dicoccum—were resistant to Pt at 20 °C but susceptible at 25 °C. Specific molecular markers closely linked to the five genes for Pt resistance effective against populations of the pathogen from the northwestern region of Russia were not amplified in these two entries after PCR with corresponding primers. Four entries of T. dicoccum—k-18971, k-18975, k-19577, and k-67398—were highly resistant to Bgt. All samples under study were susceptible to HLB and SNB. Under field conditions, 15% of the T. aethiopicum samples were resistant to Pst, both at the seedling and the flag leaf stages, but all were susceptible to the other diseases under study. Among the evaluated samples, 20 entries of T. aestivum, 1 of T. polonicum (k-43765), and 2 of T. dicoccum (k-18971, k-67397) were tolerant to aluminum ions. The identified entries could be valuable sources for the breeding of T. aestivum and other wheats for resistance to biotic and abiotic stresses.

Genome-wide association studies (GWAS) are among the genetic tools for the mining of genomic loci associated with useful agronomic traits. The study enabled us to find new genetic markers associated with grain yield as well as quality. The sample under study consisted of spring wheat cultivars developed in different decades of the last century. A panel of 186 accessions was evaluated at VIR’s experiment station in Pushkin across a 3-year period of field trials. In total, 24 SNPs associated with six productivity characteristics were revealed. Along with detecting significant markers for each year of the field study, meta-analyses were conducted. Loci associated with useful yield-related agronomic characteristics were detected on chromosomes 4A, 5A, 6A, 6B, and 7B. In addition to previously described regions, novel loci associated with grain yield and quality were identified during the study. We presume that the utilization of contrast cultivars which originated in different breeding periods allowed us to identify new markers associated with useful agronomic characteristics.

Climate change, growing world population and increasing food demand require higher yields and adaptability of crops, including spring bread wheat. Modern plant breeding based on achievements of genetics has a significant impact on plant resistance to diseases, climate variability and other factors. Genome wide association studies (GWAS) is one of genetics tools for mining of genome loci associated with economically important traits. In the current study, we applied GWAS to reveal QTL for spike productivity and grain quality using a panel of spring varieties of Triticum aestivum L. bred in different decades of the last century in Russia and Germany. The study has enabled to find new genetic markers associated with grain yield and quality. Studying genetic basis of grain yield and quality by comparison of wheat varieties from different breeding periods, including landraces preserved as the source of valuable genetic diversity for breeding and genetic studies, makes it possible not only to understand selection processes in the past, but also to develop strategies for future breeding work.

To identify new sources of effective resistance to four foliar diseases of wheat, 173 accessions of four wheat species, Triticum boeoticum, T. urartu, T. araraticum, and T. dicoccoides, from the VIR collection were tested at the juvenile and adult growth stages for resistance to leaf rust (Pt = Puccinia triticina), powdery mildew (Bgt = Blumeria graminis tritici), Septoria nodorum blotch (SNB), and dark-brown leaf spot blotch (HLB = Helminthospjrium leaf blotch). The accessions included new additions to the collection, some old samples that had never been tested before, as well as earlier tested samples noted for high levels of juvenile resistance to some fungal diseases. Natural populations of Puccinia triticina and Blumeria graminis f. sp. tritici, mixture of Parastagonospora nodorum and Bipolaris sorokiniana isolates were used to inoculate and to evaluate resistance to Pt, Bgt, SNB, and HLB, respectively. Two samples of T. boeoticum, three of T. urartu, and one of T. araraticum were resistant to leaf rust at both tested stages. Further tests (phytopathological and molecular analyses) excluded Lr9, Lr19, Lr24, Lr41, or Lr47 as single genes controlling resistance; hence, these accessions likely carry new effective leaf rust resistance genes. High level of Bgt resistance was identified in three entries of T. boeoticum, one of T. araraticum, and eleven of T. dicoccoides. All tested accessions were susceptible to HLB and SNB at both tested stages. Accessions identified as resistant are valuable plant material for introgressive hybridization in bread and durum wheat breeding. The results are discussed in the context of N.I. Vavilov’s concept of crop origin and diversity, and the laws of plant natural immunity to infectious diseases.

Background. Powdery mildew (Blumeria graminis (DC.) E.O. Speer f. sp. tritici Em. Marchal) is widespread and harmful in all regions of bread wheat cultivation. Severe development of powdery mildew leads to a decrease in the number and weight of grains. Growing resistant cultivars is the most environmentally friendly and economically profitable method to protect wheat from the disease. Development of such cultivars requires a search for new donors of effective genes controlling the resistance. To expand the genetic diversity of wheat for resistance to B. graminis, wild relatives of Triticum aestivum L., including Aegilops L. spp., are widely used. The aim of this work was to characterize seven Aegilops spp. for effective seedling and adult plant resistance to powdery mildew.Materials and methods. The material of the study consisted of 437 accessions representing 7 Aegilops spp. (Ae. speltoides Tausch, Ae. caudata L., Ae. biuncialis Vis., Ae. tauschii Coss., Ae. cylindrica Host, Ae. crassa Boiss. and Ae. ventricosa Tausch) from the collection of the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR, St. Petersburg). Juvenile resistance was studied when the seedlings were inoculated with the agent of powdery mildew under controlled laboratory conditions; the adult plant resistance, after artificial inoculation of the plants and under natural infection in the fields of Pushkin and Pavlovsk Laboratories of VIR. Complex populations of the B. graminis agent were used for inoculation. The types of response to infection were scored 10 days after inoculation according to a conventional scale.Results and conclusions. As a result of the tests, susceptibility to powdery mildew was shown in all Aegilops accessions of the D-genome group; all the studied representatives of Ae. speltoides, Ae. caudata and Ae. biuncialis were highly resistant to powdery mildew.

Background. Identification of effective genes for disease resistance in resistant plant samples is the most important step toward recommending them for breeding. There are three main methods for such identification: hybridological analysis, phytopathological test, and DNA marking. The method of PCR markers is widely used in Russia to identify resistance genes in wheat relatives, including the genus Aegi lops L. for resistance to leaf rust. From a theoretical viewpoint, the presence of a certain amplification fragment can hardly be interpreted as a definite proof of the presence of a resistance gene: during the species evolution, recombinations and mutations could occur, resulting in disturbance of the fragment’s presence and phenotypic expression of its connection with resistance. The purpose of this work was a comparison between molecular-genetic and phytopathological methods to identify leaf rust resistance genes Lr9 and Lr41 in three Aegilops species.Materials and methods. We identified leaf rust resistance genes Lr9 and Lr41 in forty Aegilops accessions using PCR with J13 and GDM35 primers, respectively. In the phytopathological test, the seedlings were infected with the pathogen population (avirulent to Lr9 and Lr41 genes) and the fungus clones virulent to the wheat line with the Lr9 gene.Results and conclusions. According to the data of molecular marking, the Lr41 gene was present in twelve Ae. tauschii Coss. accessions; Lr9 in four Ae umbellulata Zhuk. accessions and four of Ae. biuncialis Vis. All accessions of Ae. tauschii, two of Ae. umbellulata, and three of Ae. biuncialis, possessing effective resistance genes according to the molecular testing, were susceptible to the pathogen population. For three Ae. umbellulata accessions resistant to the population, where DNA marking failed to identify an Lr9 gene, the presence of this gene was shown by a phytopathological test. Thus, there were significant differences in the postulation of effective Lr9 and Lr41 leaf rust resistance genes in Aegilops accessions after a phytopatological test and the use of DNA markers.