Donors Of Resistance Research Articles

Studying a collection of common-wheat varieties for leaf rust resistance, crop yield and grain quality in the environmental conditions of Novosibirsk region.

The relationship between a variety's genotype, environmental conditions and phytopathogenic load are the key factors contributing to high yields that should be taken into account in selecting donors for resistance and high manifestation of valuable traits. The study of leaf rust resistance in 49 common wheat varieties was carried out in the field against the natural pathogen background and under laboratory conditions using single-pustule isolates with virulence to Lr9 and Lr24. It has been shown that the varieties carrying alien genes Lr6Agi2 (Tulaikovskaya 10) and Lr6Agi1 (Voevoda) were resistant to leaf rust infection both in the field and in the laboratory. Varieties KWS Buran, KWS Akvilon, KW 240-3-13, and Etyud producing crop yields from 417 to 514 g/m2 comparable to the best standard variety Sibirskaya 17 can be reasonably used as Lr24 resistance gene donors under West Siberian conditions. Omskaya 44 variety showing crop yield of 440g/m2 can be used as a donor for Lr19 and partially effective Lr26. Varieties Tuleevskaya and Altayskaya 110 with Lr9 in their genomes are recommended for the development of resistance gene-pyramided genotypes. The highest protein and gluten contents were observed in the CS2A/2M sample, while KWS Buran, Altayskaya 110, Volgouralskaya, and KWS Akvilon showed the lowest values. Varieties CS2A/2M, Tulaikovskaya 10, Pavon, and Tuleevskaya were ranked the highest in micro- (Cu, Mn, Zn, Fe) and macronutrient (Ca, Mg, K) contents among the common wheat samples from the collection, while the lowest values for most elements were observed in KWS Buran, Novosibirskaya 15, and Volgouralskaya. Winter varieties demonstrating leaf rust resistance against the infectious background typically carry adult plant resistance genes (Lr34, Lr12, and Lr13), particularly combined with the juvenile Lr26 gene. The presence of Lr41 in a winter type line (KS 93 U 62) allowed it to maintain resistance against a leaf rust pathogen clone kLr24, despite the presence of Lr24 in the genotype. Varieties Doka and Cheshskaya 17 may act as donors of resistance genes Lr26 + Lr34 and Lr9 + Lr12 + Lr13 + Lr34, as well as sources of dwarfing without losses in winter hardiness and yield under West Siberian conditions.

Identificación de fuentes de resistencia a <i>Fusarium oxysporum</i> en genotipos de <i>Physalis </i>sp.

The resistance of Cape gooseberry to Fusarium oxysporum was evaluated in 70 accessions of Physalis peruviana and related taxa (P. philadelphica, P. ixocarpa, P. floridana, P. pubescens, P. angulata, P. pruinosa, P. viscosa, P. mexicana, Nicandra physalodes, and Solanum auriculatum). These accessions were obtained from different national and international collections, including accessions from the Colombian productive sector. These represented wild materials, commercial cultivars, native and foreign weeds, and commercial ecotypes from the main producing countries: Colombia, South Africa, Kenya, and Peru. The evaluation of resistance to F. oxysporum was carried out under greenhouse conditions using the most aggressive strain supplied by the Fusarium collection maintained by the molecular microbiology laboratory of the Center for Biotechnology and Bioindustry (CBB), currently in charge of the Working Collection of Microorganisms of Agrosavia, which was isolated from infected fields. The symptoms were monitored using a severity scale, containing 10 degrees and five categories. Data information obtained from daily evaluations was analyzed through a severity evaluation and different statistical analyses. The results identified one accession belonging to Physalis peruviana and two related taxa (Physalis floridana and Solanum auriculatum) as resistant to this pathogen. These accessions could be directly used in breeding programs, either as improved cultivars or as race-specific resistance donors for other Physalis peruviana genotypes.

Evaluation of soybean genotypes against collar rot disease caused by Sclerotium rolfsii Sacc.

Collar rot caused by S. rolfsii is one of the economical diseases of soybean that can cause up to 30-40% yield loss in India. A total of 18 soybean genotypes were screened artificially during 2021 at ICAR-IISR, Indore, to study the virulence among the fungal isolates as well as to identify the resistance sources. Based on pathogenicity, Indore isolate (SRI) was found to be more virulent than Assam isolate (SRA). On the basis of percent emergence (PE) and the disease indices - root weight of inoculation (RWI) and ratio of root weight (RRW), genotypes JS 335, JS 20-34 and MACS 1620 were resistant against SRI whereas RSC 10-52 and JS 335 were found to be potential donors for resistance against SRA.

Quantitative Trait Locus Mapping for Fire Blight Resistance in an F2 Population of Malus fusca MAL0045 Uncovers Novel Resistance Loci.

Several fire blight resistance loci in Malus genotypes map on different linkage groups (LGs) representing chromosomes of the domesticated apple. Prior genetics studies primarily focused on F1 populations. A strong resistance quantitative trait locus (QTL) explained up to 66% of phenotypic variance in an F1 progeny derived from crossing the highly resistant wild apple genotype Malus fusca MAL0045 and the highly susceptible apple cultivar 'Idared', which was previously mapped on LG10 (Mfu10) of MAL0045. Strains of the causative bacterial pathogen Erwinia amylovora, notably those that show a single nucleotide polymorphism in the avrRpt2EA effector protein sequence at position 156 (e.g., Ea3049), are more virulent and overcome some known fire blight resistance donors and their QTLs. However, MAL0045 is resistant to Ea3049 and Mfu10 is not overcome, but most of the F1 progeny were highly susceptible to this strain. This phenomenon led to the assumption that other putative resistance factors not segregating in the F1 progeny might be present in the genome of MAL0045. Here, we crossed F1 progeny together to obtain 135 F2 individuals. Facilitated by genotyping-by-sequencing and phenotypic assessments, we identified and mapped two novel resistance QTLs in these F2 individuals on LGs 4 and 15, which were not identified in the F1. To our knowledge, these are the first resistance QTLs mapped in F2 progeny in Malus. In addition, we report that neither MAL0045 nor Mfu10 is broken down by a highly aggressive U.S. strain, LA635, after analyses in the original F1 individuals. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Estimation of Variability, Correlation Coefficient and Path Analysis in Improved Restorer Lines of Rice (Oryza sativa L.)

The present investigation was conducted to estimate genetic variability parameters such as genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), heritability (h2) and genetic advance (GA) along with correlations and path coefficients from data collected on 40 F4-F5 population derived from a cross between aerobic restorer AR 9-18 and blast resistant donor MSM 1212 possessing Pi54. Analysis of variance indicated significant differences among the genotypes for all the characters studied. Moderate GCV and PCV was observed for number of productive tillers per plant, number of grains per panicle, per day productivity and single plant yield. High heritability coupled with high genetic advance as percent of mean were observed for number of productive tillers per plant, number of grains per panicle, per day productivity and single plant yield, whereas high heritability coupled with moderate genetic advance as percent of mean were observed for panicle length, spikelet fertility, thousand grain weight and plant height. Grain yield per plant showed positive correlation with per day productivity, days to 50% flowering, panicle length, number of productive tillers per plant, thousand grain weight and spikelet fertility, while, negative association with number of grains per panicle and plant height. The trait per day productivity had highest direct effect on single plant yield followed by days to 50% flowering, panicle length, number of productive tillers per plant, thousand grain weight, spikelet fertility (%). Hence, per day productivity and number of productive tillers per plant are identified as key traits for developing high yielding genotypes of rice for future breeding programme.

Genetic Diversity of Barley Accessions from East Asia for Greenbug Resistance.

The greenbug, Schizaphis graminum, is a dangerous pest of barley and other grain crops in the south of Russia. An effective and environmentally friendly way to control this insect is to cultivate resistant varieties. The differential interaction between the phytophage and host plants necessitates the search for new donors of resistance. Seven hundred and seventy-eight accessions of barley from East Asian countries (313 from China, 450 from Japan, and 15 from Nepal) were evaluated for greenbug resistance. The Krasnodar population of the insect and clones isolated from it were used in the experiments. Forty heterogeneous accessions were identified, in which plants with a high level of resistance to the aphid were found. As a result of damage assessment by the 108 S. graminum clones of 11 lines selected from heterogeneous accessions, 52 insect virulence phenotypes were identified. Experiments with aphid test clones showed that all 11 lines possess diverse greenbug resistance alleles, which differ from the previously identified Rsg1, but their efficiency is low. The frequency of clones virulent to ten lines and the cultivar Post (a carrier of the Rsg1 gene) varies from 60.4% to 98.0%. The exception is line 15903, which is resistant to the aphid population and protected by one dominant gene. The high resistance of other lines against a part of the natural population of S. graminum is also under oligogenic control. Lines 15600 and 16190 each have one dominant resistance gene, and line 28129 is protected by two genes, the dominant and recessive ones. A recessive resistance gene is presumably present in line 15600. Lines 16237/1 and 16237/2, isolated from the same collection accession, each have one dominant gene effective against individual aphid clones. The loss of effectiveness of distinctly manifested resistance genes causes the expression of previously masked genes with a weak phenotypic manifestation, which differentially interact with insect genotypes.

Powdery mildew resistance of apple clonal rootstocks from the collection of the Michurinsk State Agrarian University.

Apple clonal rootstocks are the basis of modern intensive horticulture, providing a rapid increase in yield and convenience of fruit trees cultivation. Production of clonal rootstocks under high humidity often causes powdery mildew infection caused by the pathogenic fungus Podosphaera leucotricha Salm., which significantly reduces the productivity of stoolbed. Growing powdery mildew resistant genotypes is the most appropriate way to combat this disease and allows reducing the use of fungicides. To accelerate the search for resistant forms, molecular markers associated with resistance genes have been developed. However, these markers have not been used to study clonal rootstocks. The aims of the work were the field assessment of powdery mildew resistance of apple clonal rootstocks from the collection of the Michurinsk State Agrarian University and the screening of the collection for Pl-1, Pl-2, Pl-w and Pl-d resistance genes. The results of a three-year field evaluation of powdery mildew resistance of 80 rootstocks allowed us to distinguish five main groups ranging from very low to highly resistant. A group of 57 accessions was classified as powdery mildew resistant. The search for resistance genes was performed using the AT20 SCAR (Pl-1 gene), OPU02 SCAR (Pl- 2 gene), EM DM01 (Pl-d gene), and EM M02 (Pl-w gene) markers. The Pl-d and Pl-1 genes identified in 33 (41.25 %) and 31 (38.75 %) accessions, respectively, were the most common in the collection. The Pl-w gene was detected only in two accessions. Identification of the Pl-2 gene with the OPU02 SCAR marker did not reveal a fragment of the expected size. Thirty accessions with different powdery mildew resistance scores had two genes, Pl-1 and Pl-d, and highly resistant forms G16 and 14-1 had a combination of the Pl-d and Pl-w genes. These accessions can be used as donors of powdery mildew resistance for breeding new apple clonal rootstocks.

Utilization of crop wild relatives for biotic and abiotic stress management in Indian mustard [Brassica juncea (L.) Czern. & Coss.

Brassica juncea (L.) Czern. & Coss. (Indian mustard) is an economically important edible oil crop. Over the years, plant breeders have developed many elite varieties of B. juncea with better yield traits, but research work on the introgression of stress resilience traits has largely been lagging due to scarcity of resistant donors. Crop wild relatives (CWRs) are the weedy relatives of domesticated plant species which are left unutilized in their natural habitat due to the presence of certain undesirable alleles which hamper their yield potential, and thus, their further domestication. CWRs of B. juncea namely include Sinapis alba L. (White mustard), B. tournefortii Gouan. (African mustard), B. fruticulosa Cirillo (Twiggy turnip), Camelina sativa L. (Gold-of-pleasure), Diplotaxis tenuisiliqua Delile (Wall rocket), D. erucoides L. (White wall rocket), D. muralis L. (Annual wall rocket), Crambe abyssinica R.E.Fr. (Abyssinian mustard), Erucastrum gallicum Willd. (Common dogmustard), E. cardaminoides Webb ex Christ (Dogmustard), Capsella bursa-pastoris L. (Shepherds purse), Lepidium sativum L. (Garden Cress) etc. These CWRs have withstood several regimes of biotic and abiotic stresses over the past thousands of years which led them to accumulate many useful alleles contributing in resistance against various environmental stresses. Thus, CWRs could serve as resourceful gene pools for introgression of stress resilience traits into Indian mustard. This review summarizes research work on the introgression of resistance against Sclerotinia stem rot (caused by Sclerotinia sclerotiorum), Alternaria blight (caused by Alternaria brassicae), white rust (caused by Albugo candida), aphid attack, drought and high temperature from CWRs into B. juncea. However, various pre- and post-fertilization barriers due to different ploidy levels are major stumbling blocks in the success of such programmes, therefore, we also insightfully discuss how the advances made in -omics technology could be helpful in assisting various breeding programmes aiming at improvisation of stress resilience traits in B. juncea.

Identification of resistance to Sugarcane mosaic virus, Sugarcane streak mosaic virus, and Sugarcane bacilliform virus in new elite sugarcane accessions in India.

Sugarcane mosaic and leaf fleck diseases are significant viral diseases affecting sugarcane crops in India. The use of resistant sugarcane varieties is considered the most economical and effective approach to manage viral diseases, especially in vegetatively propagated crops such as sugarcane. Sugarcane mosaic virus (SCMV) and Sugarcane streak mosaic virus (SCSMV) are the primary pathogens responsible for mosaic disease in sugarcane-growing regions of India. Sugarcane bacilliform virus (SCBV), causing leaf fleck disease, is also often found in mixed infections with mosaic symptoms. The study aimed to identify new sources of resistance by screening sugarcane germplasm for resistance to SCMV, SCSMV, and SCBV. The screening was carried out under high inoculum using the infector row method in both plant and ratoon crops. Out of 129 genotypes tested, only 8 were found to be free of mosaic viruses, indicating a rare occurrence of resistant sources. The study revealed that mosaic disease is widespread, with nearly 95% of tested varieties/genotypes being infected with mosaic viruses. SCMV, SCSMV, and SCBV were detected in 121 out of 129 genotypes using the RT-PCR and PCR assays. Based on their response to the viruses, the tested genotypes were categorized into different resistance grades: highly resistant (grade 1), resistant (grade 2), moderately resistant (grade 3), susceptible (grade 4), and highly susceptible (grade 5). The results of the study provide valuable information about elite resistance resources that can be used for the prevention and control of mosaic disease. These resistant genotypes could also serve as potential donors for mosaic and leaf fleck disease resistance in breeding programs.

Assessment of Indian wheat germplasm for Septoria nodorum blotch and tan spot reveals new QTLs conferring resistance along with recessive alleles of Tsn1 and Snn3.

The leaf blight diseases, Septoria nodorum blotch (SNB), and tan spot (TS) are emerging due to changing climatic conditions in the northern parts of India. We screened 296 bread wheat cultivars released in India over the past 20 years for seedling resistance against SNB (three experiments) and TS (two experiments). According to a genome-wide association study, six QTLs on chromosome arms 1BL, 2AS, 5BL, and 6BL were particularly significant for SNB across all three years, of which Q.CIM.snb.1BL, Q.CIM.snb.2AS1, Q.CIM.snb.2AS.2, and Q.CIM.snb.6BL appeared novel. In contrast, those on 5BS and 5BL may correspond to Snn3 and Tsn1, respectively. The allelic combination of tsn1/snn3 conferred resistance to SNB, whereas that of Tsn1/Snn3 conferred high susceptibility. As for TS, Tsn1 was the only stably significant locus identified in this panel. Several varieties like PBW 771, DBW 277, and HD 3319, were identified as highly resistant to both diseases that can be used in future wheat improvement programs as resistant donors.

Breeding for black rot resistance in grapevine: advanced approaches for germplasm screening

Crop improvement by means of traditional or molecular breeding is a key strategy to accomplish the European Green Deal target of reducing pesticides by 50% by 2030. Regarding viticulture, this is exacerbated by the massive use of chemicals to control pathogen infections. Black rot is an emergent disease caused by the ascomycete Phyllosticta ampelicida, and its destructiveness is alarming vine growers. Implementing and improving effective phenotyping strategies are fundamental preliminary steps to breed disease resistant varieties and this work suggests good practices adopted for this purpose. Primarily, the pedigree of black rot resistance donors was reconstructed based on the collection of phenotypic historical data, highlighting unexplored sources of black rot resistance. Strains used for artificial infections were isolated, genetically characterized and mixed to avoid race-specific resistance selection. A new inoculation protocol based on the use of leaf mature lesions was developed. Ex vivo inoculation on detached leaves was effective for the evaluation of conidia germination and hyphal growth, but not for disease progression. Finally, the pedigree was used for the identification of 23 genotypes to be tested. Two breeding selections (NY39 and NY24) resulted symptomless in all assessments and a third one (F25P52) also showed very high resistance, although with a greater variability. Other two genotypes (F12P19 and ‘Charvir’) fell within the medium resistance category, making them good candidates in a regime of well-timed preventive treatments. In conclusion, this work was effective to a comprehensive parental line characterization and preparatory towards grapevine breeding programs for black rot resistance.

Development and molecular cytogenetic identification of a new wheat-rye 6RL ditelosomic addition and 1R (1B) substitution line with powdery mildew resistance

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a serious disease that critically threatens the yield and quality of wheat (Triticum aestivum L.). Using effective powdery mildew resistance genes is considered to be the optimal choice for controlling this disease. Against the background of high homogeneity among the modern commercial cultivars that are mainly derived from conventional interbreeding, the resistance genes from wheat relatives have especially prominent advantages. Octoploid triticale, produced by common wheat and rye (Secale cereale L.) through distant hybridization, is a new synthetic species and valuable gene donor for wheat improvement. In this study, we developed a wheat-rye line YT5 through the hybridization of octoploid triticale and two wheat lines. YT5 was confirmed to be a 6RL ditelosomic addition and 1R (1B) substitution line using genomic in situ hybridization (GISH), multicolor fluorescence in situ hybridization (mc-FISH), multicolor GISH (mc-GISH) and molecular marker analysis. Genetic analysis showed that the powdery mildew resistance in YT5 was derived from the rye chromosome arm 6RL. After inoculation with different Bgt isolates at the seedling stage, YT5 had compound reaction patterns with both obvious spores and hypersensitivity and gradually became highly resistant until the adult-plant stage, thus showing a resistance response significantly different from the reported Pm genes from rye chromosome 6RL. Meanwhile, YT5 showed promising agronomic performance and hence is expected to be an elite resistance donor for wheat improvement. To promote the transfer of the chromosome arm 6RL of YT5 in marker-assisted selection breeding, we selected and verified two 6RL-specific kompetitive allele-specific PCR markers that can be applied to efficiently detect this chromosome arm in different wheat backgrounds.

Wheat (Triticum aestivum) chromosome 6D harbours the broad spectrum common bunt resistance gene Bt11

Key messageA major QTL on chromosome 6DL corresponding to bunt resistance gene Bt11 was identified in four mapping populations generated through crosses with Bt11-carriers PI 166910 and M822123.Common bunt in wheat has witnessed a renaissance with the rise of organic agriculture that began in the 1980s. The abandonment of systemic fungicides in organic farming, together with a lack of resistant cultivars, has led to wide-spread problems due to common bunt infections. Knowledge about genetic sources for resistance is still scarce and only few of the known bunt resistance factors are currently used in breeding. We therefore aimed to map the resistance factor harboured by the Turkish landrace PI 166910, which is the resistance donor for the Bt11 bunt differential line. Four mapping populations (MPs) with 96–132 recombinant inbred lines (RILs) were phenotyped for common bunt resistance over 2, 3 or 4 years with one or two local bunt populations and genotyped with the 25K SNP array. A major bunt resistance locus on the distal end of chromosome 6D designated QBt.ifa-6DL was identified in all MPs and experiments. Additional QTL contributing to resistance were detected on chromosomes 4B, 1A, 1B, 2A and 7B. QBt.ifa-6DL mapped to a region overlapping with the Bt9-locus identified in previous studies, but results indicate that QBt.ifa-6DL is different from Bt9 and convincing evidence from haplotype comparisons suggests that it represents the Bt11 resistance allele. Markers for the distal region of chromosome 6D between 492.6 and 495.2 Mbp can be used to select for QBt.ifa-6DL. This resistance factor confers high and stable resistance against common bunt and should be integrated into organic and low-input wheat breeding programs.

Field Screening for Powdery Mildew Resistance (Erysiphe polygoni DC) in Cowpea

Aim: The present study was conducted to identify the cowpea genotypes resistant to powdery mildew.
 Study Design: One hundred and nine cowpea genotypes were laid out in Augmented Block Design in a single row plot of 4m length and 60cm distance between the rows.
 Place and Duration of Study: In total 109 genotypes of cowpea were screened for powdery mildew under field conditions during winter 2018 and winter 2019.
 Methodology: All these genotypes were screened under field conditions along with susceptible line VRCP-1444-5 as infector row.
 Results: During winter powdery mildew incidence in cowpea was high under Varanasi conditions when cowpea is under maturity stage. Powdery mildew incidence was severe in winter months especially from second fortnight of November to January. Each genotype was grown in a single row. Scoring was done in 0-5 scale. The genotypes that had shown resistance to powdery mildew during winter 2018 were sown again in 2019 for identifying suitable resistant genotypes. Results showed that, 2 genotypes namely IC202280 and EC528412 were completely free from disease during both the seasons of screening and they falls under the category of immune.
 Conclusion: Hence these genotypes may be used as resistant donor for development of varieties/lines resistant to powdery mildew.

Pyramiding Fusarium head blight resistance QTL from T. aestivum, T. dicoccum and T. dicoccoides in durum wheat

Key messageFHB resistance of durum wheat was improved by introgression of Fhb1 and resistance genes from emmer wheat and by selection against adverse alleles of elite durum wheat.Durum wheat is particularly susceptible to Fusarium head blight (FHB) and breeding for resistance is impeded by the low genetic variation within the elite gene pool. To extend the genetic basis for FHB resistance in durum wheat, we analyzed 603 durum wheat lines from crosses of elite durum wheat with resistance donors carrying resistance alleles derived from Triticum aestivum, T. dicoccum and T. dicoccoides. The lines were phenotyped for FHB resistance, anthesis date, and plant height in artificially inoculated disease nurseries over 5 years. A broad variation was found for all traits, while anthesis date and plant height strongly influenced FHB severities. To correct for spurious associations, we adjusted FHB scorings for temperature fluctuations during the anthesis period and included plant height as a covariate in the analysis. This resulted in the detection of seven quantitative trait loci (QTL) affecting FHB severities. The hexaploid wheat-derived Fhb1 QTL was most significant on reducing FHB severities, highlighting its successful introgression into several durum wheat backgrounds. For two QTL on chromosomes 1B and 2B, the resistance alleles originated from the T. dicoccum line Td161 and T. dicoccoides accessions Mt. Hermon#22 and Mt. Gerizim#36, respectively. The other four QTL featured unfavorable alleles derived from elite durum wheat that increased FHB severities, with a particularly negative effect on chromosome 6A that simultaneously affected plant height and anthesis date. Therefore, in addition to pyramiding resistance genes, selecting against adverse alleles present in elite durum wheat could be a promising avenue in breeding FHB-resistant durum wheat.

Problems of creation of breeding material of the subgenus <i>Cerasus</i> (Mill.) A. Gray with resistance to coccomycosis (<i>Blumeriella jaapii</i> (Rehm) Arx)

Currently, the problem of ecological production is becoming more relevant. One of the ways to solve it is the use of varieties that combine high productivity with sufficient adaptability to environmental conditions, have high taste and commercial qualities of fruits, are resistant to diseases, and significantly affect fruit quality and yield. The purpose of the work is to identify the problem and determine directions in the creation of breeding material for cherries and sweet cherries resistant to coccomycosis based on a literature review. When performing the work, open sources were studied and used, containing information on the distribution, etiology of coccomycosis, methods of its infection and spread, the stability of the assortment of cherries approved for use in the Russian Federation, as well as electronic scientific libraries. It was revealed that the main problem of creating such an assortment of the subgenus Cerasus (Mill.) A. Gray is the ability of Blumeriella jaapii (Rehm) Arx to overcome the resistance of the host, which is determined by its reproductive and population characteristics. Resistance to B. jaapii in the breeding material of the subgenus under study usually dominates and is controlled mono-, oligo-, and polygenic. It can be obtained with the involvement of donors of resistance to cocomycosis (13 species) in the selection process. Modern varieties and forms were created with the participation of a donor – Prunus maackii Rupr. and P. lannesiana (Carr) E. H. Wilson. The use of genetic methods in the work on the creation of breeding material of the subgenus Cerasus with resistance to coccomycosis will allow its intensification due to more accurate selection of forms with this trait.F

Variability of Sarocladium oryzae [(Sawada) Games & Hawksworth] and identification of novel donors for sheath rot resistance among temperate germplasm lines of rice

AbstractSheath rot is one of the most destructive emerging diseases of rice in Asia and a significant loss (20–85%) to rice production is caused by this disease under temperate agro-climatic conditions of Kashmir. Disease is more prevalent in higher belts of valley where Japonica rice cultivation is more common. Also, late-maturing varieties are more likely to be attacked by sheath rot disease of rice. Information regarding the occurrence and distribution of any pathogen and its variability in the field is very much essential to devise a suitable disease management programme against the particular pathogen. The isolates of Sarocladium oryzae tested in the present study exhibited considerable variation in cultural characteristics, morphology and pathogenicity. The resistant sources for sheath rot disease of rice were identified among the temperate germplasm of rice under a relatively high inoculum concentration and disease pressure of all the variable isolates of S. oryzae. Among 219 rice genotypes screened for resistance against S. oryzae under field conditions, 42 genotypes were further evaluated under controlled epiphytotic conditions against all the 18 isolates of S. oryzae. Four genotypes (SKUA-354, ORN-V4, GS-183, GS357) were finally selected with high resistance against sheath rot disease of rice which can be utilized as potential donors for the development of disease-resistant varieties of rice against sheath rot.

Assessment of gene pool of black currant Federal Horticultural Center for Breeding, Agrotechnology and Nursery by resistance to currant gall mite in the Bryansk Region

Since controlling currant gall mite (Cecidophyopsis ribis Westw.) is a challenging and ineffective task, developing genetic resistance to the pest is one of the main priorities in breeding programs for Ribes nigrum both in Russia and abroad. The task was assigned at the FSBSO “Federal Horticultural Center for Breeding, Agrotechnology and Nursery” to combine efficiently the positive economic and biological traits of previously developed varieties with resistance to phytophagous pests in hybrid progeny. The study evaluates the genetic collection and hybrid material of black currant for resistance to currant gall mite, as well as identifies the most promising parent pairs for mite-resistant progeny. The research objects included 107 varieties of various genetic origins, 30 of which were of foreign breeding. An assessment of the genetic collection carried out for ten years (since 2012) during the seasons of mass manifestation of the currant gall mite and reversion, is presented. Approximately 1,200 seedlings, planted in 2017, were studied. The methodologies for studying fruit, berry, and nut crops were used to assess the degree of incidence of the currant gall mite. The statistical processing of experimental results was performed using the Microsoft Excel program. As a result, the genetic sources and donors of resistance to the currant gall mite were identified (Barmaley, Dar Smolyaninovoi, Kipiana, Svityazyanka, Chernooka, Wonderful Moment, Ben Hope, Big Ben, etc.). The promising combinations of crosses were identified based on the yield of seedlings resistant to Cecidophyopsis ribis: Ben Hope×Kipiana, Ben Hope×Dar Smolyaninovoi, Kipiana×Dar Smolyaninovoi, Barmalei×Dar Smolyaninovoi, Ben Tirran×Kipiana, 9-28-1/02×Bryansk Agate, Dar Smolyaninovoi×33-27-1, 33-27-1×Kipiana. In the progeny of these parental forms, the selected forms were identified (3-63-01, 3-63-02, 9-197-3, 3-16-1, 7-28-01, 8-123-1), which combine resistance to the currant gall mite with large fruits and tolerance to fungal diseases.

Use of plant essential oils for the management of sheath blight disease in rice

Sheath blight caused by Rhizoctonia solani Kuhn is one of the most important diseases on the major high yielding rice varieties. Because of lack of resistant donor lines, no variety is completely immune to the disease. Till now, chemical control is the most widely used means to manage the disease which may have several adverse effects on the environment. Plant essential oils are among the most promising compounds for bio rational pest management. As highly volatile compounds are found in essential oils, they therefore cause no residue problems either in crop or in soil and are less subject to resistance. Keeping these factors in view, a field experiment was conducted at All India Co-Ordinated Rice Improvement Project, Chiplima, Sambalpur, Odisha during kharif and rabi seasons of 2019-20 and 2020-21 respectively to assess the effect of seven essential oils for the management of sheath blight disease in rice. They were sprayed twice at weekly interval starting from the third day of inoculation. Among all the essential oils, citronella oil @ 2ml l-1 was found best to manage the disease during both the years of experiment. It gave 36% disease control compared to check plots. Under invitro condition also, citronella oil @ 500 ppm proved to be the best of all the essential oils. Though the chemical check carbendazim gave the highest disease control (47.25%) but considering the environmental point of view, citronella oil @ 2ml l-1 can be recommended as an alternative to manage sheath blight disease in rice without any toxic effect on the crop.

QTL mapping and improvement of pre-harvest sprouting resistance using japonica weedy rice.

The stability of cultivation and production in terms of crop yield has been threatened by climate change due to global warming. Pre-harvest sprouting (PHS) is a threat to crops, especially staple foods, including rice, because of reductions in yield and quality. To address the problem of precocious germination before harvest, we performed quantitative trait loci (QTL) analysis for PHS using F8 RILs populations derived from japonica weedy rice in Korea. QTL analysis revealed that two stable QTLs, qPH7 and qPH2, associated with PHS resistance were identified on chromosomes 7 and 2, respectively, explaining approximately 38% of the phenotypic variation. The QTL effect in the tested lines significantly decreased the degree of PHS, based on the number of QTLs included. Through fine mapping for main QTL qPH7, the region for the PHS was found to be anchored within 23.575-23.785 Mbp on chromosome 7 using 13 cleaved amplified sequence (CAPS) markers. Among 15 open reading frames (ORFs) within the detected region, one ORF, Os07g0584366, exhibited upregulated expression in the resistant donor, which was approximately nine times higher than that of susceptible japonica cultivars under PHS-inducing conditions. Japonica lines with QTLs related to PHS resistance were developed to improve the characteristics of PHS and design practical PCR-based DNA markers for marker-assisted backcrosses of many other PHS-susceptible japonica cultivars.