Introgression Of Resistance Genes Research Articles

Phenotypical and molecular characterization of new pepper genotypes resistant to Chili pepper mild mottle virus firstly detected in Europe and other tobamoviruses

The tobamoviruses pose a recent threat to local varieties of Gernika pepper (cv. “Derio”) and Ibarra chili (cv. “Ibarroria”), causing a substantial decrease in both yield and fruit quality. Tobamoviruses such as Tomato mosaic virus (ToMV), Tobacco mild green mosaic virus (TMGMV) or Pepper mild mottle virus (PMMoV) are the viruses that cause the greatest impact in pepper crops of northern Spain. The emergence of a novel Tobamovirus, Chili pepper mild mottle virus (CPMMoV; GenBank MN164455.1), firstly identified in Europe, exacerbates these hazards. This situation has jeopardized the ongoing cultivation in some of the virus affected plots. A molecular marker-assisted backcrossing (MABC) breeding program was thus initiated to introduce the L3 and L4 resistance genes into these susceptible local varieties. MABC consisted of one crossing followed by four backcrosses and two self-fertilizations. After each crossbreeding event, the selection criteria of plants were based on plants resistance and fruits resemblance with the original sensitive varieties. This study allowed the homozygous introgression of resistance genes in the new obtained genotypes, reducing the reliance on hybrid seed production and associated costs. The resulting genotypes demonstrated robust resistance when inoculated with PMMoV 1.2, PMMoV 1.2.3, and CPMMoV. In addition, greenhouse yield trials were performed during two consecutive years to identify and select the most productive genotypes harboring the L3 or L4 gene, with the aim of registering some of them as commercial varieties. The productivity of the new selected genotypes did not display significant differences when compared to the original sensitive varieties. The introduction of genetic resistance in these local pepper varieties not only mitigates the immediate hazard posed by Tobamovirus but also fosters the preservation of local agricultural genetic resources, ensuring their continued cultivation and economic sustainability.

Recurrent selection for Fusarium head blight resistance in a durum wheat population

AbstractFusarium head blight (FHB) is a devastating fungal disease of wheat. Since early 1990s, frequent FHB epidemics in major wheat‐growing regions have caused massive economic losses. Developing FHB‐resistant varieties is key to minimize the loss caused by the disease. In durum wheat (Triticum turgidum L. ssp. durum), however, it is challenged by lack of resistant sources. Introgression of resistance genes from wild relatives and bread wheat has resulted in some durum wheat lines with moderate resistance. Due to its complex genetic nature, integrating more resistance genes with moderate and even minor effects promises to provide high and durable FHB resistance. In this study, a base population was developed using diverse resistant lines and elite durum wheat breeding lines as founders and went through three cycles of phenotypic selection from 2019 to 2022, with FHB severity decreased by 34%. Six S0:1 lines in Cycle 2 and Cycle 3 populations exhibited significantly lower FHB severity than the moderately susceptible check variety ND Riveland. The results suggested that recurrent phenotypic selection could effectively improve FHB resistance. Analysis of the founders and Cycle 2 and Cycle 3 populations with 2706 single nucleotide polymorphism markers indicated that there was little decrease in genetic variation due to selection. Genome‐wide association analysis found no markers significantly associated with FHB severity. Genomic prediction accuracies based on cross‐validation for FHB severity, plant height, and days‐to‐flowering were 0.51, 0.69, and 0.61, respectively. Recurrent genomic selection can shorten the select cycle to 4 months and therefore is promising to accelerate genetic improvement of FHB severity.

Genetic study of fruit quality traits in watermelon (<i>Citrullus lanatus</i>) prebred line derived from <i>Citrullus lanatus</i> var. <i>citroid</i>

Fruit quality is most important for commercially cultivated watermelon [Citrullus lanatus (Thunb.) Matsum and Nakai] cultivars and introgression of resistance gene from wild or related species is a major challenge and imperative to study the inheritance of internal and external fruit quality traits for utilizing in resistance breeding programme. Present study was carried out at the research farm of ICAR-Indian Agricultural Research Institute, New Delhi during summer 2020 to 2022 involving 4 seasons for identifying source of resistance, developing F1 and other subsequent generations (F2, BC1P1 and BC1P2) and evaluation of parental lines along with breeding population in watermelon. The resistant line DWM-45 was used as a female parent and crossed with commercially popular sweet watermelon variety Arka Manik to produce F1 and other generation to study the inheritance of internal and external fruit quality traits. Based on the segregation pattern of progeny it is concluded that fruit shape, rind pattern, seed coat colour and colour of flesh at margin near rind and at carpellar region followed monogenic inheritance. Furthermore, our findings revealed a complex genetic control with epistatic interactions for other fruit quality traits such as fruit length, fruit width, fruit weight and total soluble solids. This study provides valuable insights into the genetic basis of various fruit quality traits in watermelon which can have practical applications in breeding programmes, facilitating the development of improved watermelon varieties with desirable fruit characteristics.

Pyramiding of transgenic immune receptors from primary and tertiary wheat gene pools improves powdery mildew resistance in the field.

Introgression of resistance genes from wild or related species is a common strategy to improve disease resistance of wheat cultivars. Pm17 is a gene that confers powdery mildew resistance in wheat. It encodes an NLR type of immune receptor and was introgressed from rye to wheat as part of the 1RS chromosome arm translocation several decades ago. So far it has not been possible to separate Pm17 from its co-introgressed rye genes due to suppressed recombination. Here we tested in the field transgenic Bobwhite wheat overexpressing Pm17 without any other rye genes. Four transgenic events showed high levels of PM17 protein accumulation, strong powdery mildew resistance, and no pleiotropic effects during three field seasons. We used a combined approach of transgene insertion and cross-breeding to generate lines co-expressing Pm17 and Pm3, or Pm17 and Pm8. Blumeria graminis f. sp. tritici infection tests confirmed additive, race-specific resistance of the two pyramided transgenes in lines Pm17+Pm3b and Pm17+Pm8. Furthermore, pyramided lines showed strong powdery mildew resistance during three field seasons. We conclude that the combination of overexpressed NLR genes from the extended gene pool broadens and diversifies wheat disease resistance.

Screening of Sunflower Genotypes for Reaction to Alternaria Leaf Blight Disease across Multi-environments using Pooled Analysis

Sunflower (Helianthus annuus L.) is an oilseed crop with potential health benefits as a source of oil and dietary fiber. The productivity of sunflower is hampered by both biotic and abiotic stresses caused due to climate changes. So far, the available gene pool is having moderately resistant lines. In the present study, we evaluated two screening methods by artificially challenging the plants with the causative agent A. helianthi. Significant changes in disease severity have been observed across 160 pre-breeding lines of sunflower, including the susceptible check, Morden in three different seasons. Among the160 pre-breeding lines derived from a mutant population of sunflower cv. Morden, 6.25 and 5.63 % of lines showed less leaf blight disease incidence under in vivo and in vitro environments respectively. Moreover, 44.38 % of the sunflower pre breeding lines demonstrated field tolerance with disease severity in the scale of 5. The promising accessions evaluated in our studies by whole plant assay method and detached leaf technique includes KSFI 19, KSFI 24, KSFI 147, KSFI 56, KSFI 120, KSFI 88, KSFI 152, KSFI 51 and KSFI 115. Therefore, these sunflower lines, could be employed for introgression of resistance genes against leaf blight disease in sunflower cultivars through marker assisted breeding strategies.

A rapid method for detection of the root-knot nematode resistance gene, Mi-1.2, in tomato cultivars.

Molecular markers have been widely used in plant breeding to improve the accuracy and efficiency of trait selection. In particular, molecular markers are powerful in facilitating the introgression of resistance genes by circumventing costly and time-consuming infection assays. To achieve their practical use, it is important to ensure the tight linkage between the markers and the traits. Here we report a new cleaved amplified polymorphic sequence (CAPS) marker, Mi1713, for the root-knot nematode resistance gene, Mi-1.2, in cultivated tomato. The Mi1713 marker is designed in the conserved region of Mi-1.2 and its homologs in tomato and other nightshade species. Combined with a single-step procedure for preparing PCR templates, the Mi1713 marker enables rapid and reliable screening for the presence of Mi-1.2. The approach described in this study is applicable in designing CAPS markers for various genes or alleles of interest in tomato and other crops.

Marker Assisted Introgression of Resistance Genes and Phenotypic Evaluation Enabled Identification of Durable and Broad-Spectrum Blast Resistance in Elite Rice Cultivar, CO 51

Across the globe, rice cultivation is seriously affected by blast disease, caused by Magnaporthe oryzae. This disease has caused heavy yield loss to farmers over the past few years. In this background, the most affordable and eco-friendly strategy is to introgress blast-resistant genes from donors into elite rice cultivars. However, it is not only challenging to evolve such resistance lines using conventional breeding approaches, but also a time-consuming process. Therefore, the marker-assisted introduction of resistance genes has been proposed as a rapid strategy to develop durable and broad-spectrum resistance in rice cultivars. The current study highlights the successful introgression of a blast resistance gene, i.e., Pi9, into CO 51, an elite rice cultivar which already has another resistance gene named Pi54. The presence of two blast resistance genes in the advanced backcross breeding materials (BC2F2:3) was confirmed in this study through a foreground selection method using functional markers such as NBS4 and Pi54MAS. The selected positive introgressed lines were further genotyped for background selection with 55 SSR markers that are specific to CO 51. Consequently, both Pi9 as well as Pi54 pyramided lines, with 82.7% to 88.1% of the recurrent parent genome recovery, were identified and the selected lines were evaluated under hotspot. The analysis outcomes found that both the lines possessed a high level of resistance against blast disease during the seedling stage itself. In addition to this, it was also noticed that the advanced breeding rice lines that carry Pi9 + Pi54 were effective in nature and exhibited a higher degree of resistance against blast disease compared to the lines that were introgressed with a single blast resistance gene. Thus, the current study demonstrates a rapid and a successful introgression and pyramiding of two blast resistance genes, with the help of markers, into a susceptible yet high-yielding elite rice cultivar within a short period of time. Those gene pyramided rice lines can be employed as donors to introgress the blast-resistant genes in other popular susceptible cultivars.

The broad use of the Pm8 resistance gene in wheat resulted in hypermutation of the AvrPm8 gene in the powdery mildew pathogen

BackgroundWorldwide wheat production is under constant threat by fast-evolving fungal pathogens. In the last decades, wheat breeding for disease resistance heavily relied on the introgression of chromosomal segments from related species as genetic sources of new resistance. The Pm8 resistance gene against the powdery mildew disease has been introgressed from rye into wheat as part of a large 1BL.1RS chromosomal translocation encompassing multiple disease resistance genes and yield components. Due to its high agronomic value, this translocation has seen continuous global use since the 1960s on large growth areas, even after Pm8 resistance was overcome by the powdery mildew pathogen. The long-term use of Pm8 at a global scale provided the unique opportunity to study the consequences of such extensive resistance gene application on pathogen evolution.ResultsUsing genome-wide association studies in a population of wheat mildew isolates, we identified the avirulence effector AvrPm8 specifically recognized by Pm8. Haplovariant mining in a global mildew population covering all major wheat growing areas of the world revealed 17 virulent haplotypes of the AvrPm8 gene that grouped into two functional categories. The first one comprised amino acid polymorphisms at a single position along the AvrPm8 protein, which we confirmed to be crucial for the recognition by Pm8. The second category consisted of numerous destructive mutations to the AvrPm8 open reading frame such as disruptions of the start codon, gene truncations, gene deletions, and interference with mRNA splicing. With the exception of a single, likely ancient, gain-of-virulence mutation found in mildew isolates around the world, all AvrPm8 virulence haplotypes were found in geographically restricted regions, indicating that they occurred recently as a consequence of the frequent Pm8 use.ConclusionsIn this study, we show that the broad and prolonged use of the Pm8 gene in wheat production worldwide resulted in a multitude of gain-of-virulence mechanisms affecting the AvrPm8 gene in the wheat powdery mildew pathogen. Based on our findings, we conclude that both standing genetic variation as well as locally occurring new mutations contributed to the global breakdown of the Pm8 resistance gene introgression.

Resistance to Pythium root rot and anthracnose among Kenyan common bean genotypes and marker-assisted introgression of resistance genes

ABSTRACT Common bean (Phaseolus vulgaris L.) is an important food legume crop and major protein source in Kenya and many parts of the world. However, the yields are low due to the diseases like anthracnose caused by Colletotrichum lindemunthianum and Pythium root rots. The study, therefore, sought to screen Kenyan common bean genotypes for anthracnose and Pythium resistance and to improve the resistance of local landraces to the two diseases. Local landraces and commercial cultivars were screened for resistance under greenhouse conditions for Pythium and in vitro for anthracnose. The results showed that majority of the landraces were moderately resistant to anthracnose and Pythium root rot. The study further utilized molecular markers linked to anthracnose and Pythium resistance, respectively, to determine their potential to detect specific resistance genes among the test genotypes. None of the markers amplified the test genotypes except the control genotypes pointing toward different resistance genes. Further, cultivars G2333 and KK8 were used as donor parents for anthracnose and Pythium resistance, respectively, in a marker-assisted backcross breeding program involving three high-yielding farmer-preferred landraces. A number of lines were developed that carry both resistance genes. These lines can be advanced for release as new cultivars to enhance common bean production in Kenya.

Fall Armyworm Infestation and Development: Screening Tropical Maize Genotypes for Resistance in Zambia.

Knowledge of fall armyworm (FAW) (Spodoptera frugiperda J.E. Smith) rearing, infestation and development and precision screening protocols are preconditions for the successful introgression of resistance genes into farmer-preferred varieties. We aimed to determine FAW developmental stages, screen tropical maize and select resistant lines under controlled conditions in Zambia. Field-collected FAW samples constituting 30 egg masses and 60 larvae were reared using maize leaf- and stalk-based and soy- and wheat flour-based diets at 27 ± 1 °C, 60 ± 5% relative humidity and 12 h day length. The resulting neonates were separated into sets A and B. The life cycles of set A and field-collected larvae were monitored to document the FAW developmental features. Set B neonates were used to infest the seedlings of 63 diverse tropical maize genotypes. Egg, larva, pupa and adult stages had mean durations of 2, 24, 20 and 12 days, respectively. Test maize genotypes revealed significant differences (p < 0.05) based on FAW reaction types, with lines TL13159, TL02562, TL142151, VL050120 and CML548-B exhibiting resistance reactions, while CML545-B, CZL1310c, CZL16095, EBL169550, ZM4236 and Pool 16 displayed moderate resistance. These genotypes are candidate sources of FAW resistance for further breeding. This study will facilitate controlled FAW rearing for host screening in the integration of FAW resistance into market-preferred maize lines.

Introgression of Asian soybean rust resistant genes into elite soybean lines from Uruguay

Soybean is the main agricultural crop in Uruguay. One of the diseases with the greatest damage potential is Asian soybean rust, with estimated grain yield losses up 80% in the region. Throughout history, different authors have stated the importance of genetic resistance as a fundamental tool to decrease the adverse effects of phytopathogens, leading to agriculture sustainability. The objective of this work was to introduce rust resistance genes into elite lines of INIA’s soybean breeding program and to evaluate the enhanced resistance. Introgression of resistant genes was carried out in a greenhouse, through three backcrosses from F1. Two donors: Py7-1-47 and No6-12-B handed by JIRCAS with two resistant genes combinations (Rpp1-b + Rpp5 and Rpp4 + Rpp5, respectively) and three elite lines: SJ10-122-040, SJ10-158-039, and SJ10-173-072 from INIA’s breeding program were used. After each backcross, plants carrying both genes were selected with marker assisted selection. Each third backcross was self-pollinated (BC3F2) and single plant families were inoculated in the greenhouse. Percentage of rust resistant plants within the introgressed families ranged from 42% to 98%, compared to fully susceptible recurrent parents.

Relationship between Acylsugars and Leaf Trichomes: Mediators of Pest Resistance in Tomato.

Simple SummarySeveral pests have the potential to cause major damage to tomatoes. The two-spotted spider mite and whitefly are examples of pests that attack tomato crops. Management of these pests involves several techniques; the use of chemical products is the most adopted strategy. However, growing resistant genotypes is a promising strategy in pest management, reducing the use of chemical products. In this work, we sought to identify genotypes more resistant to the mite and whitefly using advanced populations of tomato (F2BC3) obtained from the cross between S. lycopersicum “Redenção” and S. pennellii, accession LA-716. Results indicated a greater resistance in the genotypes with high levels of acylsugars, a chemical compound commonly found in S. pennellii tomatoes. Consequently, genotypes with increased levels of acylsugar can be used in breeding programs for pest resistance.Tomato plants are highly susceptible to pests. Among the control methods, genetic improvement with introgression of resistance genes from wild accessions into commercial tomato lines is the best alternative for an integrated pest management (IPM). Thus, the objective of this study was to select tomato genotypes in advanced populations (F2BC3), with higher levels of acylsugar content, greater recurrent parent genome recovery, and resistance to Tetranychus urticae and Bemisia tabaci inherited from Solanum pennellii. For pest resistance, bioassays were assessed: nine high-acylsugar genotypes, four low-acylsugar genotypes, and the parents, Solanum lycopersicum or ‘Redenção’, and Solanum pennellii LA-716. Glandular and non-glandular trichomes were quantified. A negative correlation was measured between acylsugar content in the leaflets and pest behavior. Pest resistance was found in the selected F2BC3 genotypes with high-acylsugar content, indicating that this allelochemical was efficient in controlling the arthropod pests.

MusaRgeneDB: an online comprehensive database for disease resistance genes in Musa spp.

Banana is one of the major food crops and its production is subject to many pests and diseases. Banana breeding exploits wild relatives and progenitor species for the introgression of resistant genes (R) into cultivated varieties to overcome these hurdles. With advances in sequencing technologies, whole-genome sequences are available for many Musa spp. and many of them are potential donors of disease resistance genes. Considering their potential role, R genes from these species were explored to develop an user-friendly open-access database that will be useful for studying and implementing disease resistance in bananas. MusaRgene database is complemented with complete details of 3598 R genes identified from eight Musa spp. and rice, Arabidopsis, sorghum along with its classification and separate modules on its expression under various stresses in resistant and susceptible cultivars and corresponding SSRs are also provided. This database can be regarded as the primary resource of information on R genes from bananas and their relatives. R genes from other allele mining studies are also incorporated which will enable the identification of its homolog in related Musa spp. MusaRgene database will aid in the identification of genes and markers associated, cloning of full-length R genes, and genetic transformation or gene editing of the R genes in susceptible cultivars. Multiple R genes can also be identified for pyramiding the genes to increase the level of resistance and durability. Overall, this database will facilitate the understanding of defense mechanisms in bananas against biotic or abiotic stresses leading to the development of promising disease-resistant varieties.

Genome wide association study for stripe rust resistance in spring bread wheat (Triticum aestivum L.)

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst) is one of the most destructive diseases of wheat (Triticum aestivum L.) worldwide causing huge yield losses every year. Development and deployment of resistant varieties is the most economical and environment friendly approach for controlling this disease. However, because of the continuous evolution of the pathogen, resistant genes are easily overcome by new virulent Pst races, which necessitates a continuous identification and introgression of resistance genes to develop resistant wheat varieties. To identify effective source of resistance, a genome-wide association study was performed using 426 elite bread wheat genotypes based on 5176 polymorphic Diversity Arrays Technology (DArT) markers. Adult-plant-resistance was evaluated under field conditions for yellow rust resistance for two consecutive years (2014 and 2015) at ICARDA Merchouch station, Morocco. Out of the 426 genotypes, 51.17% were highly resistant with 5–10% level of severity to yellow rust. Genome wide association studies (GWAS) using a mixed linear model (MLM) identified three DArT markers on chromosomes 1B, 2B and 7B which are significantly associated with stripe rust resistance at false discovery rate p ≤ 0.05. BLAST analysis confirmed that the marker 412,394 in chromosome 2B overlapped with two previously reported QTLs (QYrlu.cau-2BS1 Luke and QYrid.ui-2B.1_IDO444). However, the two other markers 542,318 (1B) and 583,038 (5B) were not mapped within any of the previously reported gene/QTL regions; therefore, these markers may represent novel resistance loci for yellow rust. The highly resistant elite genotypes and linked molecular markers are recommended for further gene introgression and pyramiding purposes in the wheat breeding programs after validation.

Genomics Enabled Breeding Strategies for Major Biotic Stresses in Pea (Pisum sativum L.).

Pea (Pisum sativum L.) is one of the most important and productive cool season pulse crops grown throughout the world. Biotic stresses are the crucial constraints in harnessing the potential productivity of pea and warrant dedicated research and developmental efforts to utilize omics resources and advanced breeding techniques to assist rapid and timely development of high-yielding multiple stress-tolerant–resistant varieties. Recently, the pea researcher’s community has made notable achievements in conventional and molecular breeding to accelerate its genetic gain. Several quantitative trait loci (QTLs) or markers associated with genes controlling resistance for fusarium wilt, fusarium root rot, powdery mildew, ascochyta blight, rust, common root rot, broomrape, pea enation, and pea seed borne mosaic virus are available for the marker-assisted breeding. The advanced genomic tools such as the availability of comprehensive genetic maps and linked reliable DNA markers hold great promise toward the introgression of resistance genes from different sources to speed up the genetic gain in pea. This review provides a brief account of the achievements made in the recent past regarding genetic and genomic resources’ development, inheritance of genes controlling various biotic stress responses and genes controlling pathogenesis in disease causing organisms, genes/QTLs mapping, and transcriptomic and proteomic advances. Moreover, the emerging new breeding approaches such as transgenics, genome editing, genomic selection, epigenetic breeding, and speed breeding hold great promise to transform pea breeding. Overall, the judicious amalgamation of conventional and modern omics-enabled breeding strategies will augment the genetic gain and could hasten the development of biotic stress-resistant cultivars to sustain pea production under changing climate. The present review encompasses at one platform the research accomplishment made so far in pea improvement with respect to major biotic stresses and the way forward to enhance pea productivity through advanced genomic tools and technologies.

Detection of Maternal and Cytoplasmic Effects on Resistance to Zymoseptoria tritici in Durum Wheat.

Septoria tritici blotch (STB) is a major disease problem of wheat worldwide. To optimize the introgression of resistance genes in elite genotypes throughout traditional or molecular breeding programs, a full understanding of the quantitative inheritance of resistance to Zymoseptoria tritici, plant height (PH), and thousand kernel weight (TKW) is needed. In this study, maternal and cytoplasmic effects of resistance to STB were investigated using P1 (susceptible, high-yielding line) and P2 (resistant, low-yielding line) durum wheat lines and their F1, RF1, F2, RF2, BC1, RBC1, BC2, and RBC2 progeny, assessed for resistance to STB during three growing seasons. Duncan mean's analysis revealed significant differences between generation means for STB, PH, and TKW. The two parents had an extreme pattern. The F1 and RF1 segregated close to their respective parents, suggesting the presence of cytoplasmic and maternal genetic effects for Z. tritici resistance, PH, and TKW. Separate generation mean's analysis confirmed the results of the Duncan test. A three-parameter model was found to be not adequate for all traits in all three growing years; while a digenic epistatic model with cytoplasmic or/and maternal effect was adequate for all cases. Narrow-sense heritability was in the range of 50–60%, 30–69%, and 28–31% for STB, PH, and TKW, respectively. For STB, high heritability and the presence of fixable epistatic effect is encouraging and could lead to creating varieties with the right female parent to exploit cytoplasmic and maternal effects in order to improve resistance to Z. tritici in durum wheat.

Grapevine DMR6-1 Is a Candidate Gene for Susceptibility to Downy Mildew.

Grapevine (Vitis vinifera) is a valuable crop in Europe for both economical and cultural reasons, but highly susceptible to Downy mildew (DM). The generation of resistant vines is of critical importance for a sustainable viticulture and can be achieved either by introgression of resistance genes in susceptible varieties or by mutation of Susceptibility (S) genes, e.g., by gene editing. This second approach offers several advantages: it maintains the genetic identity of cultivars otherwise disrupted by crossing and generally results in a broad-spectrum and durable resistance, but it is hindered by the poor knowledge about S genes in grapevines. Candidate S genes are Downy mildew Resistance 6 (DMR6) and DMR6-Like Oxygenases (DLOs), whose mutations confer resistance to DM in Arabidopsis. In this work, we show that grapevine VviDMR6-1 complements the Arabidopsis dmr6-1 resistant mutant. We studied the expression of grapevine VviDMR6 and VviDLO genes in different organs and in response to the DM causative agent Plasmopara viticola. Through an automated evaluation of causal relationships among genes, we show that VviDMR6-1, VviDMR6-2, and VviDLO1 group into different co-regulatory networks, suggesting distinct functions, and that mostly VviDMR6-1 is connected with pathogenesis-responsive genes. Therefore, VviDMR6-1 represents a good candidate to produce resistant cultivars with a gene-editing approach.

New genetic tools for plant defense against parasitic nematodes

Нематоды относятся к числу значимых вредителей сельскохозяйственных растений. В обзоре рассмотрены последние данные о молекулярных механизмах устойчивости растений к цистообразующим и галловым нематодам, среди которых одни из наиболее вредоносных видов: Globodera rostochiensis, G. pallida, Heterodera schachtii, Meloidogyne chitwoodi и M. incognita. Например, золотистая картофельная нематода G. rostochiensis, зарегистрированная в 61 субъекте РФ на общей площади 1.8 млн га, способна приводить к потере от 19 до 90 % урожая картофеля. Биологические особенности нематод затрудняют разработку агротехнических способов борьбы с ними: цисты G. rostochiensis сохраняют жизнеспособность в почве в течение многих лет, нематициды токсичны или малоэффективны, поэтому предпочтительным методом борьбы с ними является интрогрессия генов устойчивости от родственных культурных и дикорастущих видов. Стратегия жизненного цикла цистообразующих и галловых нематод основана на способности личинок проникать в корни восприимчивых видов растений, репрограммировать клетки растения-хозяина, формирующие гигантские клетки или синцитии в качестве питающих структур, а также ингибировать иммунный ответ. Молекулярные механизмы, лежащие в основе такого взаимодействия в системе «патоген–хозяин», вызывают значительный интерес как с точки зрения управления морфогенезом растений, так и в аспекте разработки безопасных и эффективных способов борьбы с паразитическими нематодами. В обзоре рассмотрены данные об эффекторах, с помощью которых разные виды нематод контролируют иммунный ответ растения-хозяина, а также гены устойчивости (R-гены) и некоторые молекулярные механизмы, прерывающие формирование питающих структур и развитие паразита. Приведены новые данные о способах генетического контроля, основанных на одном из активно обсуждаемых в последнее время варианте механизма РНК-интерференции – HIGS (host induced gene silencing), представляющем собой адресное выключение экспрессии гена-мишени в клетках личинки нематоды с помощью специфических двуцепочечных РНК, синтезирующихся в клетках растения-хозяина. Индукция РНК-интерференции в клетках растений приводит к появлению молекул-медиаторов, способных инициировать аналогичный процесс в клетках фитофагов, взаимодействующих с растением, в том числе у личинок нематод. Описаны случаи, в которых такое адресное выключение экспрессии генов-мишеней приводило к нарушениям развития личинок и высокому уровню защиты сельскохозяйственных растений от наиболее опасных видов нематод.

Genotypic selection of multispecific hybrids obtained through crosses between commercial Passiflora edulis and wild passiflora species

Abstract The interspecific introgression of resistance genes to diseases in commercial varieties through interspecific crosses has been adopted as a strategy in breeding programs of sour passion fruit. This work aimed to evaluate 11 progenies of multispecific hybrids obtained from crosses involving seven Passiflora species, in addition to four commercial cultivars, using the REML/BLUP method. The experiment was carried out as a randomized block design with six repetitions and three plants per plot. Ten fruit traits were evaluated. The additive, multiplicative, and sum of ranks indexes were applied to determine the most appropriate selective strategy in the simultaneous increase of fruit weight, number of fruits, and yield. Plants from the 325 x VAO progeny showed a lower bacterial defoliation index and better means predicted for the traits number of fruits and productivity. The progenies 325 x LD4, PL3 x LD4, and the controls CSB-Marília and BRS-Gigante Amarelo showed plants with better-predicted means for traits related to fruit quality. The genetic gains demonstrated good prospects for the use of wild species in sour passion fruit genetic breeding.

Immunogenic breeding program. Stage I-phytopathological screening of the grape gene pool

At the present stage of science development it is necessary to develop and implement the grape breeding programs for immunity basing on the international level of knowledge about the genetics of immunity to pathogens that cause culture diseases. The extensive material on genes of grape resistance to Plasmopara viticola and Erysiphe necator (Uncinula necator), which cause mildew and oidium diseases, has been collected thanks to the MAS technology. There is an evidence of necessity to pyramidize genes of resistance to these pathogens in one progeny genome for consistent field resistance to the complex of these pathogens. However, even at present, the issue of study the transfer of specific genes of resistance from parents to the progeny, their combining ability in one genome, and gene expression during pathogenesis remains relevant. This publication discusses the formation of grape breeding program in the FSBSI Institute Magarach of the RAS on introgression of resistance genes of the species Vitis rotundifolia (Muscadinia rotundifolia), and also presents the results of phytopathological screening of populations resulting from crossing with this species.