R Genes Research Articles

Shiga Toxin (Stx) Phage-Encoded Lytic Genes Are Not Required for the Mouse Virulence of O157:H7 Escherichia coli Stx2-Producing Clinical Isolates.

Shiga toxin (Stx)-producing Escherichia coli (STEC) is a major cause of foodborne diarrheal illness in the United States and globally, and serotype O157:H7 is frequently associated with STEC outbreaks and sporadic cases in the United States. Severe systemic diseases associated with STEC are mediated by Stx types, particularly subtype Stx2a, encoded on inducible bacteriophages. We previously identified two STEC O157:H7 clinical isolates, JH2010 and JH2012, that exhibit a large difference in virulence in a streptomycin (Str)-treated mouse model. In this study, we aimed to identify a genetic basis for the difference in virulence between those strains. Comparison of the stx2a phage sequences showed that JH2012 lacks the lytic genes S and R on the phage genome. We also demonstrated that compared to JH2012 cultures, cultures of JH2010 released more Stx2 into the supernatant and were more sensitive to bacterial lysis during growth with ciprofloxacin (Cip), an inducer of stx phages. We therefore generated an stx2a phage SR deletion mutant strain of JH2010 to determine if those genes were responsible for the high virulence of that strain. We found that deletion of the SR genes from the stx2a phage in JH2010, and another O157:H7 strain, JH2016, resulted in increased cellular retention of Stx2, but there was no difference in virulence compared to the wild-type strains. Our results indicate that the stx2a phage SR genes are involved in Stx2 localization and phage-mediated cell lysis in vitro but that they are not required in wild-type STEC strains for virulence in a mouse model. IMPORTANCE The release of Stx from STEC has been thought to be tied to phage-mediated lysis of the host bacterial cell. In this study, we found that the stx2a phage lytic genes are not required for the virulence of pathogenic O157:H7 clinical isolates in a murine model of STEC infection or for release of Stx2a into the supernatant of bacterial cultures. These results point to an alternate mechanism for Stx2a release from STEC strains.

Identification of wheat stem rust resistance genes in wheat cultivars from Hebei province, China.

Wheat stem rust is caused by Puccinia graminis f. sp. tritici. This major disease has been effectively controlled via resistance genes since the 1970s. The appearance and spread of new races of P. graminis f. sp. tritici (eg., Ug99, TKTTF, and TTRTF) have renewed the interest in identifying the resistance gene and breeding cultivars resistant to wheat stem rust. In this study, gene postulation, pedigree analysis, and molecular detection were used to determine the presence of stem rust resistance genes in 65 commercial wheat cultivars from Hebei Province. In addition, two predominant races 21C3CTHTM and 34MRGQM were used to evaluate the resistance of these cultivars at the adult-plant stage in 2021-2022. The results revealed that 6 Sr genes (namely, Sr5, Sr17, Sr24, Sr31, Sr32, Sr38, and SrTmp), either singly or in combination, were identified in 46 wheat cultivars. Overall, 37 wheat cultivars contained Sr31. Sr5 and Sr17 were present in 3 and 3 cultivars, respectively. Gao 5218 strong gluten, Jie 13-Ji 7369, and Kenong 1006 contained Sr24, Sr32, and Sr38, respectively. No wheat cultivar contained Sr25 and Sr26. In total, 50 (76.9%) wheat cultivars were resistant to all tested races of P. graminis f. sp. tritici in field test in 2021-2022. This study is important for breeding wheat cultivars with resistance to stem rust.

Genetic architecture of rust resistance in a wheat (Triticum turgidum) diversity panel.

Wheat rust diseases are widespread and affect all wheat growing areas around the globe. Breeding strategies focus on incorporating genetic disease resistance. However, pathogens can quickly evolve and overcome the resistance genes deployed in commercial cultivars, creating a constant need for identifying new sources of resistance. We have assembled a diverse tetraploid wheat panel comprised of 447 accessions of three Triticum turgidum subspecies and performed a genome-wide association study (GWAS) for resistance to wheat stem, stripe, and leaf rusts. The panel was genotyped with the 90K Wheat iSelect single nucleotide polymorphism (SNP) array and subsequent filtering resulted in a set of 6,410 non-redundant SNP markers with known physical positions. Population structure and phylogenetic analyses revealed that the diversity panel could be divided into three subpopulations based on phylogenetic/geographic relatedness. Marker-trait associations (MTAs) were detected for two stem rust, two stripe rust and one leaf rust resistance loci. Of them, three MTAs coincide with the known rust resistance genes Sr13, Yr15 and Yr67, while the other two may harbor undescribed resistance genes. The tetraploid wheat diversity panel, developed and characterized herein, captures wide geographic origins, genetic diversity, and evolutionary history since domestication making it a useful community resource for mapping of other agronomically important traits and for conducting evolutionary studies.

Population Dynamics of Phytophthora infestans in Egypt Reveals Clonal Dominance of 23_A1 and Displacement of 13_A2 Clonal Lineage.

Potato (Solanum tuberosum L.) and tomato (S. lycopersicum L.) are the most economically important vegetable crops in Egypt and worldwide. The winter crop in Egypt is particularly prone to late blight caused by Phytophthora infestans. A total of 152 P. infestans isolates were isolated from the 2013, 2014, 2016 and 2018 winter crops with 82 isolates from potato, 69 from tomato and one isolate from eggplant (S. melongena L.). All isolates belonged to the A1 mating type with no evidence of A2 or self-fertile strains. The majority of isolates (53%) were sensitive to metalaxyl, 32% were intermediate and 15% were resistant. Variation in aggressiveness between three P. infestans isolates EG-005 (13_A2) and EG-276 (23_A1) from potato, and EG-237 (23_A1) from eggplant was determined on tuber slices and leaflets of 10 potato cultivars. The eggplant isolate EG-237 showed higher sporulation capacity compared with the other tested isolates and was able to infect potato (Lady Rosetta cv) and tomato (Super Strain B cv). The simple sequence repeat (SSR) genotyping data showed that in contrast to our previous work (3-year period 2010-12) in which the proportion of 13_A2 lineage was 35%, all isolates belonged to the 23_A1 lineage. There was no evidence for the existence of the A2 mating type or 13_A2 lineage even in the destroyed field crops of some cultivars (Cara, Bellini and Valor) that had been reported as resistant to 23_A1. The data have been submitted into the Euroblight database to allow temporal and spatial genetic diversity to be examined in comparison with other regional P. infestans populations. The AVR2 and AVR2-like RXLR effector genes were amplified and sequenced. In the avirulent AVR2 gene, only one heterozygous SNP was detected at position 31 in the N terminus in six isolates out of eleven, whereas two heterozygous SNPs were detected at position 29 in the N-terminus and ninety-two in the C- terminus of the AVR2-like gene. This suggests that changes in the previously reported virulence profile of 23_A1 are not related to commercial cultivars carrying the R2 gene. In addition, this is the first report of P. infestans on eggplant in Egypt.

Evaluation of Resistance to Stem Rust and Identification of Sr Genes in Russian Spring and Winter Wheat Cultivars in the Volga Region

The Volga region is one of the main grain-producing regions of Russia. Wheat stem rust caused by Puccinia graminis f. sp. tritici is among the most destructive fungal diseases of wheat. Recently, its harmfulness has increased in the Volga region. In this regard, an analysis of the resistance and diversity of the Sr genes in the Russian wheat cultivars is necessary. In this work, 126 wheat cultivars (including 23 durum wheat cultivars and 103 bread wheat cultivars) approved for use in the Volga region were evaluated for their resistance to two samples of P. graminis f. sp. tritici populations from different Volga region areas at the seedling stage. Specific DNA primers were used to identify resistance genes (Sr2, Sr24, Sr25, Sr26, Sr28, Sr31, Sr32, Sr36, Sr38, Sr39, and Sr57). Highly resistant cultivars (30 from 126) were identified. In bread wheat cultivars, the genes Sr31 (in 19 cultivars), Sr24 (in one cultivar), Sr25 (in 15 spring wheat cultivars), Sr28 (in six cultivars), Sr38 (in two cultivars), and Sr57 (in 15 cultivars) and their combinations—Sr31 + Sr25, Sr31 + Sr38, Sr31 + Sr28, Sr31 + Sr57, Sr31 + Sr28 + Sr57, and Sr31 + Sr24—were identified. The obtained results may be used to develop strategies for breeding rust-resistant cultivars.

Identification of new sources of wheat stem rust resistance genes

Stem rust disease is widespread in the wheat-growing regions of Kazakhstan. Despite a large number of studies, the protection of wheat from the pathogen Puccinia graminis f. sp. tritici is considered one of the crucial problems. Chemical control has almost no impact on this disease and no exact result. The only effective way to control this disease is to cultivate resistant varieties and lines. Currently, 60 Sr resistance genes are known. Among them, Sr2, Sr22, Sr25/Lr19, Sr28, Sr36, and Sr39 gene sources are efficient at stem rust disease in different conditions of Kazakhstan. The molecular markers Xgwm533, CFA2019, PSY-E1, wPt-7004, Xgwm319 and Sr39#50 linked to Sr2, Sr22, Sr25/Lr19, Sr28, Sr36 and Sr39 were used, respectively. As a result of PCR analysis, the Sr2 gene was identified in six lines out of 16 lines, namely, GA951395-10-7/WX98D011-U38, Select, GA961565-27-6/KS99U673, GA961662-1-7/TAM107, VA01W-283/WX030513 and Sonalika. Five wheat lines were found as carriers of the Sr22 gene: Line c-19SB, Lutescens 7-04-4, Lutescens 220-03-45, GA961662-1-7/TAM107 and Line D 25 77. There are three lines that are carriers of Sr25/Lr19 gene sources, namely, Lutescens 220-03-45, Advance, and Line D 25 77. The Sr28 gene was identified in four wheat genotypes (GA951395-10-7/WX98D011-U38, Select, Advance and VA01W-283/WX03ASHTS0513) and the positive control W2691Sr2Bkt. An expected fragment (170 bp) for Xgwm319 properly for Sr36 gene was identified in four lines (GA951395-10-7/WX98D011-U38, Advance, VA01W-283/WX03ASHTS0513, GA961662-1-7/TAM107). The 10 wheat varieties were identified using primers Sr39 # 50R/F (Line C-19SB, Omskaya 37, Lutescens 7-04-4, Lutescens 220-03-45, Select, GA951395-10-7 / WX98D011-U38, Advance, GA961662-1-7 / TAM107’, VA01W-283/WX03ASHTS0513 and Line D 25 77). The studied sources of resistance can be used in breeding programs to create varieties of common wheat with durable resistance to stem rust.

The Orphan GPR50 Receptor Regulates the Aggressiveness of Breast Cancer Stem-like Cells via Targeting the NF-kB Signaling Pathway.

The expression of GPR50 in CSLC and several breast cancer cell lines was assessed by RT-PCR and online platform (UALCAN, GEPIA, and R2 gene analysis). The role of GPR50 in driving CSLC, sphere formation, cell proliferation, and migration was performed using shGPR50 gene knockdown, and the role of GPR50-regulated signaling pathways was examined by Western blotting and Luciferase Assay. Herein, we confirmed that the expression of G protein-coupled receptor 50 (GPR50) in cancer stem-like cells (CSLC) is higher than that in other cancer cells. We examined that the knockdown of GPR50 in CSLC led to decreased cancer properties, such as sphere formation, cell proliferation, migration, and stemness. GPR50 silencing downregulates NF-kB signaling, which is involved in sphere formation and aggressiveness of CSLC. In addition, we demonstrated that GPR50 also regulates ADAM-17 activity by activating NOTCH signaling pathways through the AKT/SP1 axis in CSLC. Overall, we demonstrated a novel GPR50-mediated regulation of the NF-κB-Notch signaling pathway, which can provide insights into CSLC progression and prognosis, and NF-κB-NOTCH-based CSLC treatment strategies.

The Status of Wheat Stem Rust in Syria During the Period 2018-2021

Kassem, M. 2023. The Status of Wheat Stem Rust in Syria During the Period 2018-2021. Arab Journal of Plant Protection, 41(4): 339-347. https://doi.org/10.22268/AJPP-41.4.339347 Wheat stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is an important disease of wheat in the world. This disease is also observed in Syria and repeatedly increased from one year to another during the last decade. This study aimed to investigate the status of the distribution of the disease in the Syrian wheat fields, in addition to its virulence by evaluating the reaction type of differential lines and local varieties. The results of the field survey showed that the spread of wheat stem rust disease in all studied regions in Syria (northern, central and coastal regions) during the period 2018-2021. The prevalence of infected fields reached 59, 75, 67, 59%, respectively, with some variability among regions based on the moisture level (rainfall/irrigation) and average temperature. In general, the infection with Pgt appeared in wheat fields earlier than usual in Syria (mid-May), with costal wheat field infection observed at the beginning of April, whereas from mid to late April in the central and northern regions. The dominant bulk of Pgt characterized by increased virulence, year after year in Syria. The percentage of susceptible genes reached 77% in 2021, whereas it was 47.7% in 2018. One major gene Sr13 was still effective against Pgt population. Reaction type of resistance genes varied, some of them maintained the reaction type during the study period, but most of them was susceptible and moderately susceptible, and the others lost its resistant. For example, genes 9e, 24 and 31 that were resistant in 2018 began to lose resistance in 2019. The reaction type of Syrian local cultivars was affected by the virulence of the Pgt bulk. The percentage of susceptible cultivars was 66.6%, the moderately susceptible was 20.8%, and the moderately resistant was 12.5% and restricted to three varieties (Doma 6, cham 9 and Bohouth9), whereas resistant varieties were absent. Keywords: Differential lines, Cham 9, Bohouth 9, wheat stem rust, Sr2, Sr13, Syria

Identification of carriers of the wheat genotypes stem rust (Puccinia graminis f.sp. tritici) resistance genes

Stem rust in recent years has acquired an epiphytotic character, causing significant economic damage for wheat production in some parts of Kazakhstan. On the basis of a race composition study of the stem rust populations collected in 2016-2017 in South-Eastern and northern regions of Kazakhstan were identified. The race differentiation of stem rust using a tester set of 6 Sr genes differentiator lines was carried out. In different conditions of Kazakhstan, the Sr22 and Sr25/Lr19 gene sources are effective. As a result of PCR analysis, the Sr22 gene was found in 5 lines of 6 samples taken for the study: Line C-19SB, Lutescens 7-04-4, Lutescens 220-03-45, GA961662-1-7/TAM107, Line D 25 77. Sr25/Lr19 is a carrier of sources: Lutescens 220-03-45, Advance, Line D 25 77. The Sr22 and Sr25/Lr19 gene was Lutescens 220-03-45 and Line D 25 77. These sources are recommended for inclusion in the breeding process for developing stem rust resistant varieties in the region.

HI 1634 (PusaAhilya), high yielding bread wheat variety tolerant to terminal heat stress conditions of Central Zone

HI 1634 (Pusa Ahilya), a high yielding bread wheat variety with an average yield of 51.6 q/ha was released by Central Sub-Committee on Crop Standards, Notification and Release of Varieties for Agricultural Crops, Government of India vide notification No. S.O. 500 E dated 29.01.2021 for commercial cultivation under late sown irrigated conditions of central wheat growing zone of India. HI 1634 performed superior when grown under various sowing conditions with seedling and adult plant resistance to all pathotypes of stem and leaf rusts which are virulent in India and postulated to have stem rust gene Sr31. HI 1634 had an excellent chapati quality and bread making quality along with good levels of essential micronutrients like iron and zinc content. HI 1634 will be a high yielding and terminal heat tolerant bread wheat variety ensuring better market price for farmers and will be a new option for the millers and baking industries.Â

Identification of the Resistance Gene Sr2 in some Egyptian Wheat Hybrids

Identification of the Resistance Gene Sr2 in some Egyptian Wheat Hybrids

Puccinia graminis f. sp. tritici Population Causing Recent Wheat Stem Rust Epidemics in Kazakhstan Is Highly Diverse and Includes Novel Virulence Pathotypes

Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a reemerging disease that caused severe epidemics in northern Kazakhstan and western Siberia in the period of 2015 to 2019. We analyzed 51 stem rust samples collected between 2015 and 2017 in five provinces in Kazakhstan. A total of 112 Pgt races were identified from 208 single-pustule isolates. These races are phenotypically and genotypically diverse, and most of them are likely of sexual origin. No differentiation of phenotypes and single-nucleotide polymorphism genotypes was observed between isolates from Akmola and North Kazakhstan provinces, supporting the idea of a wide dispersal of inoculum in the northern regions of the country. Similarities in virulence profiles with Pgt races previously reported in Siberia, Russia, suggest that northern Kazakhstan and western Siberia constitute a single stem rust epidemiological region. In addition to the races of sexual origin, six races reported in Europe, the Caucasus, and East Africa were detected in Kazakhstan, indicating that this epidemiological region is not isolated, and spore inflow from the west occurs. Virulence alone or in combination to several genes effective against the Ug99 race group was detected, including novel virulence on Sr32 + Sr40 and Sr47. The occurrence of a highly diverse Pgt population with virulence to an important group of Sr genes demonstrated the importance of the pathogen's sexual cycle in generating new and potentially damaging virulence combinations.

Wheat Genes Associated with Different Types of Resistance against Stem Rust (Puccinia graminis Pers.).

Stem rust is one wheat’s most dangerous fungal diseases. Yield losses caused by stem rust have been significant enough to cause famine in the past. Some races of stem rust are considered to be a threat to food security even nowadays. Resistance genes are considered to be the most rational environment-friendly and widely used way to control the spread of stem rust and prevent yield losses. More than 60 genes conferring resistance against stem rust have been discovered so far (so-called Sr genes). The majority of the Sr genes discovered have lost their effectiveness due to the emergence of new races of stem rust. There are some known resistance genes that have been used for over 50 years and are still effective against most known races of stem rust. The goal of this article is to outline the different types of resistance against stem rust as well as the effective and noneffective genes, conferring each type of resistance with a brief overview of their origin and usage.

Insights into established and emerging roles of SR protein family in plants and animals.

Splicing of pre-mRNA is an essential part of eukaryotic gene expression. Serine-/arginine-rich (SR) proteins are highly conserved RNA-binding proteins present in all metazoans and plants. SR proteins are involved in constitutive and alternative splicing, thereby regulating the transcriptome and proteome diversity in the organism. In addition to their role in splicing, SR proteins are also involved in mRNA export, nonsense-mediated mRNA decay, mRNA stability, and translation. Due to their pivotal roles in mRNA metabolism, SR proteins play essential roles in normal growth and development. Hence, any misregulation of this set of proteins causes developmental defects in both plants and animals. SR proteins from the animal kingdom are extensively studied for their canonical and noncanonical functions. Compared with the animal kingdom, plant genomes harbor more SR protein-encoding genes and greater diversity of SR proteins, which are probably evolved for plant-specific functions. Evidence from both plants and animals confirms the essential role of SR proteins as regulators of gene expression influencing cellular processes, developmental stages, and disease conditions. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.

Characterization of wheat monogenic lines with known Sr genes and wheat cultivars for resistance to three new races of Puccinia graminis f. sp. tritici in China

Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a potentially devastating fungal disease of wheat worldwide. The present study was to evaluate the resistance of 42 wheat monogenic lines with known stem rust resistance (Sr) genes and 69 wheat cultivars to three new Pgt races (34C0MRGQM, 34C3MKGQM, and 34C6MTGSM) identified from aeciospores at the seedling and adult-plant stages. The phenotyping results revealed that monogenic lines harboring resistance genes Sr9e, Sr17, Sr21, Sr22, Sr26, Sr30, Sr31, Sr33, Sr35, Sr36, Sr37, Sr38, Sr47, SrTmp, and SrTt3 were effectively resistant to all three Pgt races at the seedling and adult-plant stages. In contrast, monogenic lines containing Sr5, Sr6, Sr7b, Sr9a, Sr9d, Sr9f, Sr9g, Sr9b, Sr16, Sr24, Sr28, and Sr39 were highly susceptible to these races at both seedling and adult-plant stages. The other lines with Sr8a, Sr10, Sr11, Sr13, Sr14, Sr15, Sr18, Sr20, Sr19, Sr23, Sr25, Sr27, Sr29, Sr32, and Sr34, displayed variable levels of resistance to one or two of the tested races. Seedling infection types (ITs) and adult-plant infection responses (IRs) indicated that 41 (59.4%) of the wheat cultivars showed high resistance to all the three races. Molecular marker analysis showed that four wheat culitvars likely carried Sr2, 20 wheat culitvars likely carried Sr31, 9 wheat culitvars likely carried Sr38, and none of the cultivars carried Sr24, Sr25, and Sr26. Our results provide a scientific basis for rational utilization of the tested Sr genes and wheat cultivars against these novel Pgt races.

Rearrangement with the nkd2 promoter contributed to allelic diversity of the r1 gene in maize (Zea mays).

SUMMARYThe maize red1 (r1) locus regulates anthocyanin accumulation and is a classic model for allelic diversity; changes in regulatory regions are responsible for most of the variation in gene expression patterns. Here, an intrachromosomal rearrangement between the distal upstream region of r1 and the region of naked endosperm 2 (nkd2) upstream to the third exon generated a nkd2 null allele lacking the first three exons, and the R1‐st (stippled) allele with a novel r1 5′ promoter region homologous to 5′ regions from nkd2‐B73. R1‐sc:124 (an R1‐st derivative) shows increased and earlier expression than a standard R1‐g allele, as well as ectopic expression in the starchy endosperm compartment. Laser capture microdissection and RNA sequencing indicated that ectopic R1‐sc:124 expression impacted expression of genes associated with RNA modification. The expression of R1‐sc:124 resembled nkd2‐W22 expression, suggesting that nkd2 regulatory sequences may influence the expression of R1‐sc:124. The r1‐sc:m3 allele is derived from R1‐sc:124 by an insertion of a Ds6 transposon in intron 4. This insertion blocks anthocyanin regulation by causing mis‐splicing that eliminates exon 5 from the mRNA. This allele serves as an important launch site for Ac/Ds mutagenesis studies, and two Ds6 insertions believed to be associated with nkd2 mutant alleles were actually located in the r1 5′ region. Among annotated genomes of teosinte and maize varieties, the nkd2 and r1 loci showed conserved overall gene structures, similar to the B73 reference genome, suggesting that the nkd2‐r1 rearrangement may be a recent event.

Evidence for a Hepatitis B Virus Short RNA Fragment Directly Targeting the Cellular RRM2 Gene.

The hepatitis B virus (HBV) is one of the smallest but most highly infectious human pathogens. With a DNA genome of only 3.2 kb and only four genes, HBV successfully completes its life cycle by using intricate processes to hijack the host machinery. HBV infects non-dividing liver cells in which dNTPs are limited. As a DNA virus, HBV requires dNTPs for its replication. HBV induces the ATR-mediated cellular DNA damage response pathway to overcome this constraint. This pathway upregulates R2 (RRM2) expression in generating an active RNR holoenzyme catalyzing de novo dNTP synthesis. Previously we reported that ERE, a small RNA fragment within the HBx ORF, is sufficient to induce R2 upregulation. Interestingly, there is high sequence similarity between ERE and a region within the R2 5′UTR that we named R2-box. Here, we established a mutant cell line in the R2-box region of the R2 gene using CRISPR-Cas9 technology to investigate the R2 regulation by ERE. This cell line expresses a much lower R2 level than the parental cell line. Interestingly, the HBV infection and life cycle were severely impaired. These cells became permissive to HBV infection upon ectopically R2 expression. These results validate the requirement of the R2 gene expression for HBV replication. Remarkably, the R2-box mutated cells became ERE refractory, suggesting that the homology region between ERE and R2 gene is critical for ERE-mediated R2 upregulation. Thus, along with the induction of the ATR pathway of the DNA damage response, ERE might also directly target the R2 gene via the R2-box.

Estimation results of the spring bread wheat varieties on disease resistance in the Kazan Research Center

In the Republic of Tatarstan, due to favorable soil-climatic and market conditions, spring wheat production is developed, but wheat grain yields are limited by a number of unfavorable factors, one of which is a spread of fungal diseases. At the same time, the pressure of pathogenic fungi makes it possible to carry out fruitful breeding work in Tatarstan on resistance to diseases, which is on of the main activity of the Kazan Research Center of the RAS. The purpose of the current study was to estimate ten new varieties for resistance to major fungal diseases. The study on resistance to leafy diseases, such as powdery mildew, stem rust, brown leaf rust, dark brown leaf blotch was carried out at a natural infectious background, to kernel smut on an artificial infectious background inoculating seeds with spores of kernel smut. The study was carried out between the years of 2017 and 2021. The analysis for the possible presence of stem rust resistance genes was performed by a PCR analysis. As a result of the study, there was found out that the varieties ‘Sto let TASSR’, ‘Balkysh’, ‘Khazine’, ‘Chistopolskaya’, ‘Bulyak’ had a complex resistance to all studied diseases. The variety ‘Sitara’ had a strong field resistance to powdery mildew and kernel smut. The variety ‘Barakat’ had a strong field resistance to powdery mildew and leaf rust. The variety ‘Nadira’ was moderately resistant to powdery mildew and dark brown leaf spot. The varieties ‘Ekada 265’ and ‘Ekada 282’ were highly resistant to local stem rust populations. The molecular genetic estimation of the stem rust resistant varieties of spring bread wheat ‘Chistopolskaya’, ‘Sto let TASSR’, ‘Balkysh’, ‘Ekada 282’ for the identification of effective Sr-genes has shown that their resistance is apparently regulated by the Sr31 gene.

A newlycharacterized allele of ZmR1 increases anthocyanin content in whole maize plant and the regulation mechanism of different ZmR1 alleles.

The novel ZmR1CQ01 allele for maize anthocyanin synthesis was identified, and the biological function and regulatory molecular mechanisms of three ZmR1 alleles were unveiled. Anthocyanins in maize are valuable to human health. The R1 gene family is one of the important regulatory genes for the tissue-specific distribution of anthocyanins. R1 gene allelic variations are abundant and its biological function and regulatory molecular mechanisms are not fully understood. By exploiting genetic mapping and transgenic verification, we found that anthocyanin pigmentation in maize leaf midrib was controlled by ZmR1 on chromosome 10. Allelism test of maize zmr1 EMS mutants confirmed that anthocyanin pigmentation in leaf sheath was also controlled by ZmR1. ZmR1CQ01 was a novel ZmR1 allelic variation obtained from purple maize. Its overexpression caused the whole maize plant to turn purple. ZmR1B73 allele confers anthocyanin accumulation in near ground leaf sheath rather than in leaf midribs. The mRNA expression level of ZmR1B73 was low in leaf midribs, resulting in no anthocyanin accumulation. ZmR1B73 overexpression promoted anthocyanin accumulation in leaf midribs. Loss of exon 5 resulted in ZmR1ZN3 allele function destruction and no anthocyanin accumulation in leaf midrib and leaf sheath. DNA affinity purification sequencing revealed 1010 genes targeted by ZmR1CQ01, including the bz2 in anthocyanin synthesis pathway. RNA-seq analysis showed 55 genes targeted by ZmR1CQ01 changed the expression level significantly, and the expression of genes encoding key enzymes in flavonoid and phenylpropanoid biosynthesis pathways were significantly up-regulated. ZmR1 functional molecular marker was developed. These results revealed the effects of transcriptional regulation and sequence variation on ZmR1 function and identified the genes targeted by ZmR1CQ01 at the genome-wide level.

Identificación de regiones asociadas a la resistencia del tizón tardío y virus en germoplasma de papa mediante marcadores moleculares

The combination of traits of economic interest in new potato cultivars, such as resistance to late blight, viral diseases, and culinary quality are important to achieve their adoption by farmers. In the present work, molecular markers were used to identify regions associated to late blight, the viruses PVY and PLRV resistance, in 50 materials belonging to the National Institute of Agricultural Research (INIA-Venezuela): commercial cultivars, differentials of blight, advanced clones from CIP and hybrids from the Fundación PROINPA of Bolivia. DNA extraction was carried out from vitroplants and known microsatellite, SCAR and CAPS molecular markers were used. Among 96 to 26% of the accessions amplified regions of the QTL tbr of chromosome XII, associated with resistance to blight. Only the differential R9 and crc2/P8 from PROINPA amplified the R1 gene region. Between 18 and 68% of the genotypes presented the regions associated with the PVY and PLRV resistance genes (Ryadg and N genes), respectively; only 10% amplified both regions; while in 24% these genes were not detected, among them are the commercial varieties Granola, Andinita and Cartayita. This study generated valuable information to support genebank curators and breeders in potato genetic improvement programs of this country.