Genome-wide association studies in a barley (Hordeum vulgare) diversity set reveal a limited number of loci for resistance to spot blotch (Bipolaris sorokiniana)

Abstract Spot blotch caused by Bipolaris sorokiniana is an important disease in barley worldwide, causing considerable yield losses and reduced grain quality. In order to identify QTL conferring resistance to spot blotch, a highly diverse worldwide barley set comprising 449 accessions was phenotyped for seedling resistance with three isolates (No 31, SH 15 and SB 61) and for adult plant resistance at two locations (Russia and Australia) in two years. Genotyping with the 50 k iSelect barley SNP genotyping chip yielded 33,818 informative markers. Genome-wide association studies (GWAS) using a compressed mixed linear model, including population structure and kinship, revealed 38 significant marker-trait associations (MTA) for spot blotch resistance. The MTA corresponded to two major QTL on chromosomes 1H and 7H and a putative new minor QTL on chromosome 7H explaining between 2.79% and 13.67% of the phenotypic variance. A total of 10 and 14 high-confidence genes were identified in the respective major QTL regions, seven of which have a predicted involvement in pathogen recognition or defence

Validation of Molecular Markers of Barley Net Blotch Resistance Loci on Chromosome 3H for Marker-Assisted Selection

The most widespread and harmful disease of barley is net form of net blotch caused by the ascomycete Pyrenophora teres f. teres Drechsler (Ptt). A cost effective and environmentally sustainable strategy for barley protection against Ptt is to develop barley cultivars possessing genetic resistance. In previous GWA analysis, we identified SNP-markers associated with a resistance locus on chromosome 3H in the interval of 45.82-54.53 cM. These SNPs have been described previously in the literature to be located within the same region of chromosome 3H. The aim of the study was to validate QTL markers controlling resistance to Ptt on chromosome 3H in this region by KASP genotyping in four F-2 populations of crosses between the resistant cultivars, Morex, Fox, and Zolo, and the accession, Local k-21578, with the susceptible barley cv. Gesine and in a doubled haploid (DH) population of Canadian Lake Shore (CLS)/Harrington. Eleven of fifteen studied markers showed high efficacy (97.5-100%) for co-segregation with resistance to Ptt in the DH population, CLS/Harrington. Three of these markers located at 54.53 cM and one at 51.27 cM were effective in two F-2 populations of crosses of Morex and Fox with susceptible cv. Gesine. These markers are also located close to each other on the physical map (442,203,921-443,119,491 bp). Apparently, in cultivars, CLS, Morex, and Fox, resistance to Ptt is determined by the same locus. Markers JHI-Hv50k2016-166392 (47.1 cM, 112,536,071 bp), Clone ID 3255462_1 (51.63 cM, 363,531,898 bp), and Clone ID 3255462_2 (51.63 cM, 363,531,871 bp) showed high efficacy in the DH population and in the F-2 population, Local k-21578/Gesine. Apparently, at least two loci controlling Ptt resistance exist in the chromosome region of 47.0-54.3 cM: one at 46.0-48.44 cM and another at 51.27-54.8 cM. These regions were found to harbor several genes involved in important plant functions, including disease response and signaling pathways. Allele-specific PCR markers were developed based on the KASP assay data and tested on six resistant, two moderately resistant, and two susceptible barley genotypes. Four markers were found to be effective to differentiate susceptible and resistant barley genotypes. The KASP and allele-specific PCR markers associated with Ptt resistance on chromosome 3H will be useful for pyramiding resistance QTLs in barley marker-assisted selection

Expression of the transcription factor encoding gene <i>StTCP23</i> in potato plants infected with the tuber spindle viroid

Background The potato spindle tuber viroid (PSTVd) is the smallest of all known potato pathogens. PSTVd is a circular, single-stranded RNA molecule that does not code for proteins. Symptoms caused by PSTVd lead to a significant reduction in tuber yield or death of the plant. PSTVd infection triggers the silencing of host-plant genes and induces disease symptoms in the plant via vd-sRNA. The StTCP23 potato gene which encodes a transcription factor is one of the targets of PSTVd. The aim of the study was to assess the effect of inoculation of potato plants of cv. ‘Colomba’ with the PSTVd viroid NicTr-3 strain on the StTCP23 expression in infected plants.Materials and methods. Potato plants of cv. ‘Colomba’ were inoculated with leaf sap of the tomato cv. ‘Rutgers’ in which the PSTVd viroid NicTr-3 strain was propagated. RT-PCR with specific primers was used to confirm the infection of potato plants with the viroid. Diversity of RNA molecules in the PSTVd population was revealed using RT, cloning, and sequencing of the viroid. The expression of the StTCP23 gene in infected potato plants was assessed by quantitative PCR with the ef1α gene as a reference.Results. Symptoms of infecting ‘Colomba’ plants with the PSTVd viroid strain NicTr-3 were not detected, while the presence of the viroid in potato leaves was confirmed by molecular methods. Ten mutations were found in individual variants of the PSTVd strain NicTr-3, responsible for reducing the viroid’s aggressiveness. An increase in the expression of StTCP23 was shown at 3 time points in ‘Colomba’ plants inoculated with the NicTr-3 strain compared to the control.Conclusion. The mechanism of interaction between PSTVd and the StTCP23 gene in an infected potato plant is not universal and depends both on the potato genotype and viroid strain. Additional studies are required to prove the existence of specific interaction mechanisms between the host-plant and viroid strain genotypes

Transmission of potato spindle tuber viroid between <i>Phytophthora infestans</i> and host plants

Potato spindle tuber viroid (PSTVd) is a naked, circular, single-stranded RNA (356–363 nucleotides in length) which lacks any protein-coding sequences. It is an economically important pathogen and is classified as a high-risk plant quarantine disease. Moreover, it is known that PSTVd is mechanically transmitted by vegetative plant propagation through infected pollen, and by aphids. The aim of this study is to determine the possibility of viroid transmission by potato pathogen Phytophthora infestans (Mont.) de Bary. PSTVd-infected (strain VP87) potato cultivars Gala, Colomba, and Riviera were inoculated with P. infestans isolate PiVZR18, and in 7 days, after the appearance of symptoms, re-isolation of P. infestans on rye agar was conducted. RT-PCR diagnostics of PSTVd in a mixture of mycelia and sporangia were positive after 14 days of cultivation on rye agar. The PSTVd-infected P. infestans isolate PiVZR18v+ was used to inoculate the healthy, viroid-free plants of potato cv. Gala and tomato cv. Zagadka. After 60 days, an amplification fragment of PSTVd was detected in the tissues of one plant of tomato cv. Zagadka by RT-PCR with the primer set P3/P4, indicating successful transmission of PSTVd by P. infestans isolate PiVZR18v+. This result was confirmed by sequencing of the RT-PCR amplicon with primers P3/P4. The partial sequence of this amplicon was identical (99.5 %) to PSTVd strain VP87. RT-PCR showed the possibility of viroid stability in a pure culture of P. infestans isolate PiVZR18v+ after three consecutive passages on rye agar. PSTVd was not detected after the eighth passage on rye agar in P. infestans subculture. These results are initial evidence of potato viroid PSTVd being bidirectionally transferred between P. infestans and host plants

Operational features of the Far East forests

Forest area of the Far East reaches almost 50 % of the forest area of the Russian Federation. The share of the operational forest fund accounts for about 50 %, the rest are protective, protected, low-density, near-tundra and reserve forests. Most of the operational forests have been developed. The permissible volume of wood withdrawal is 92.0 million m3 . Moreover, it is planned to harvest only 14 % by selective logging, the rest of the wood is planned to harvest by clear cuts. Care felling and forest health improving felling in the forests of the Far East are carried out in insignificant volumes. Timber harvesting during the creation of infrastructure facilities is organized mainly in subjects with a developed mining industry. The high diversity of forests and the differences in their growing conditions determined the need to allocate 12 special forest areas here, in 10 of which timber harvesting is carried out. Both continuous and selective logging methods are used. The main volume of logging take place on the Far Eastern taiga region and amounts 8.9 million m3 , mainly by continuous logging. Selective logging of up to 3.5 million m3 of wood prevails in the Amur-Primorsky coniferous-deciduous area. In the Kamchatka taiga, Trans-Baikal forest-steppe and Altai-Sayan mountain-taiga forest areas, timber harvesting is carried out in insignificant volumes, only for the own needs of the population. Currently, due to the significant depletion of operational forests, the dynamics of timber harvesting in the Far Eastern Federal District tends to decrease

Взаимное восприятие арабов и иранцев: история и современность

The relevance of the topic of the study is due to the traditional perception of animosity between the citizens of the Islamic Republic of Iran and the Arab states due to historical and religious factors, as well as the statements of the political elites. The purpose of this study is to reveal the real mutual perception of Iranians and Arabs. In the context of the epidemiological situation in the world and the limitations of field research, the sociological surveys and forums posted on the Internet on this topic are of interest. The authors rely on a comparative approach in their study. On the basis of this research, aspects of contradictions and solidarity of the parties on a number of issues have been established. In addition, it has been confirmed that there is little or no antipathy towards one another among ordinary citizens of the Arab and Persian worlds, although the Arab side has a slightly more negative attitude.Актуальность темы исследования обусловлена традиционным представлением о неприязни между гражданами Исламской Республики Иран и арабских государств в силу исторических и религиозных факторов, а также заявлений политических элит. Цель данного исследования - выявить реальные особенности взаимного восприятия иранцев и арабов. Учитывая эпидемиологическую обстановку в мире и ограничения в проведении полевых исследований, интерес представляют размещенные в сети Интернет социологические опросы и форумы по данной тематике. Опираясь на сравнительный метод исследования, авторы выявили особенности взаимного восприятия сторон в таких аспектах, как история, политика, религия и язык. Доказано, что среди простых арабов и иранцев практически отсутствует неприязнь друг к другу, хотя арабская сторона и настроена несколько более негативно по отношению к иранскому государству