Assessing fitness costs of the resistance of Spodoptera frugiperda (Lepidoptera: Noctuidae) to pyramided Cry1 and Cry2 insecticidal proteins on different host plants

Fall armyworm (FAW), Spodoptera frugiperda (Smith), is one of the major pests targeted by transgenic crops expressing insecticidal proteins from Bacillus thuringiensis (Bt) Berliner. However, FAW presents a high capacity to develop resistance to Bt protein-expressing crop lines, as reported in Brazil, Argentina, Puerto Rico and the southeastern U.S. Here, FAW genotypes resistant to pyramided maize events expressing Cry1F/Cry1A.105/Cry2Ab2 (P-R genotype) and Cry1A.105/Cry2Ab2 (Y-R genotype) from Brazil were used to investigate the interactions between non-Bt hosts (non-Bt maize, non-Bt cotton, millet and sorghum) and fitness costs. We also tested a FAW genotype susceptible to Bt maize and F1 hybrids of the resistant and susceptible genotypes (heterozygotes). Recessive fitness costs (i.e., costs affecting the resistant insects) were observed for pupal and neonate to adult survival of the P-R genotype on non-Bt cotton; larval developmental time of the P-R genotype on millet and sorghum; larval and neonate-to-adult developmental time of the Y-R genotype on non-Bt cotton and sorghum; the fecundity of the Y-R genotype on non-Bt cotton; and mean generation time of both resistant genotypes. However, on non-Bt cotton and non-Bt maize, the P-R genotype had a higher fitness (i.e., fitness benefits), displaying greater fecundity and rates of population increases than the Sus genotype. Non-recessive fitness costs (i.e., costs affecting heterozygotes) were found for fecundity and population increases on millet and sorghum. These findings suggest that, regardless of the disadvantages of the resistant genotypes in some hosts, the resistance of FAW to Cry1 and Cry2 Bt proteins is not linked with substantial fitness costs, and may persist in field conditions once present.

Evaluation of resistant genotypes and their characterization using molecular markers linked for powdery mildew resistance in cucumber (Cucumis sativus L.)

Powdery mildew (PM) is one of the most severe fungal diseases of cucumber that limits its production worldwide. In this study, 140 genotypes of cucumber were screened for disease resistance under field and artificial conditions, and then validated with eight known SSR markers linked to PM resistance. Among these genotypes, genotype GS140 was found resistant (R), whereas GS148, GS16 and GS70 were moderately resistant, and GS169 was found to be tolerant. Of all the eight markers, only C31, C80, C162, SSR16472 and SSR16881 amplified the reported linked allele. The 127 bp allele of SSR16881 was found to be associated with the lowest disease severity of 37.65%. The associated markers could further be verified for their usability using linkage studies and the contrast genotypes in the present study could serve as a tool for selection in future marker-assisted selection breeding strategies for PM resistance.

Inoculation methods and agressiveness of Macrophomina phaseolina isolates in cowpea

ABSTRACT: The fungi Macrophomina phaseolina is the charcoal rot causal agent, one of the most important cowpea crop disease in semiarid regions can causes 100% yield losses. The search for resistant genotypes requires efficient phenotyping. In addition, there is the problem of great variation in aggressiveness between isolates. This study aimed to 1) test three methods of inoculation in semiarid conditions, and 2) to evaluate the aggressiveness of isolates of M. phaseolina. In the first experiment carried out in greenhouse, the inoculations methods were evaluated, using two cowpea lines, three inoculation methods and three pathogen isolates. On the second experiment, fifteen M. phaseolina isolates were inoculated in one cultivar to evaluate their aggressiveness. By assessing the length of the lesions and the severity of the disease using an index, we identified the toothpick inoculation method as the most efficient. Toothpick method allowed to discriminate the genotypes and the aggressiveness of the pathogen.

Evaluation of Cultivated and Wild Brinjal Germplasm against Bacterial Wilt Disease with Tollinterleukin-1 Receptors (TIR)-NBS-LRR Type R-gene Specific Degenerate Primer

The experiment was conducted at C-Block Farm of Bidhan Chandra Krishi Viswavidyalaya, Kalyani, West Bengal, India during 2017–18 to screen eight brinjal germplasm lines against BW disease using tollinterleukin-1 receptors (TIR)-NBS-LRR type R-gene specific degenerate primer. The study showed that wild genotype S. torvum was highly resistant to bacterial wilt incidence with no wilting symptom whereas two cultivated genotypes (Utkal Anushree and Utkal Madhuri) and one wild genotype S. sisymbriifolium were found to be resistant to BW disease. Out of the 7 germplasm sequences, 2 had no match with R-genes whereas the remaining 5 sequences have 70-93% homology with R-genes of other plant species submitted in Gene Bank sequence database. Nearly 90% sequence identity of brinjal NBS-LRR RGA was found by analyzing through BLASTn with NBS-LRR RGAs of other solanaceous crops. Two cultivated resistant genotypes (Utkal Madhuri and Utkal Tarini) were similar to the wild resistant type S. sisymbriifloium, while cultivable resistant genotype Utkal Anushree was highly different at sequence level. Two cultivable susceptible genotypes (BCB-30 and Garia) showed high level of similarity among them and they were strongly associated with the wild susceptible genotype S. macrocarpum. Two cultivable genotypes Utkal Anushree and Utkal Madhuri could be utilized in future breeding programme and two wild genotypes S. torvum and S. sisymbriifolium could be used as resistant rootstocks in brinjal grafting.

The Omics Hunt for Novel Molecular Markers of Resistance to Phytophthora infestans

Wild Solanum accessions are a treasured source of resistance against pathogens, including oomycete Phytophthora infestans, causing late blight disease. Here, Solanum pinnatisectum, Solanum tuberosum, and the somatic hybrid between these two lines were analyzed, representing resistant, susceptible, and moderately resistant genotypes, respectively. Proteome and metabolome analyses showed that the infection had the highest impact on leaves of the resistant plant and indicated, among others, an extensive remodeling of the leaf lipidome. The lipidome profiling confirmed an accumulation of glycerolipids, a depletion in the total pool of glycerophospholipids, and showed considerable differences between the lipidome composition of resistant and susceptible genotypes. The analysis of putative resistance markers pinpointed more than 100 molecules that positively correlated with resistance including phenolics and cysteamine, a compound with known antimicrobial activity. Putative resistance protein markers were targeted in an additional 12 genotypes with contrasting resistance to P. infestans. At least 27 proteins showed a negative correlation with the susceptibility including HSP70-2, endochitinase B, WPP domain-containing protein, and cyclase 3. In summary, these findings provide insights into molecular mechanisms of resistance against P. infestans and present novel targets for selective breeding.

The effect of weather conditions in southern Russia on the frost resistance of apricot generative buds

One of the reasons limiting the apricot expansion in the world is the short period of winter dormancy in the plants and the rapid development of generative buds in the spring. Apricot flower buds often die even after small spring return frosts that limit the commercial culture of this fruit crop. The aim of this investigation was to study collection-breeding plantations and select frost-resistant genotypes that have promise for commercial and breeding use. To solve this problem, the frost resistance of generative buds in 50 apricot cultivars and the breeding forms of various origins were studied by freezing treatments of the branches in a climatic chamber. The Czech cultivar ‘Leala’ was selected due to its best frost resistance. In late winter 2020–2021, six cultivars and breeding forms, which kept 41.8 to 65.9% of the generative buds alive, were identified. These genotypes are characterised by a slow development that prevents any negative freezing temperature effects. Thus, the results of the study confirmed the dependence of the adaptation mechanisms in apricot plants on the rates of their morphogenesis and abiotic factor pressures.

Identification of Tetranychus neocaledonicus (Acari: Tetranychidae) resistant genotypes in Phaseolus lunatus

The spider mite Tetranychus neocaledonicus André (Acari: Tetranychidae) is a potential threat to the cultivation of lima bean (Phaseolus lunatus L.). In many countries, lima beans are grown by small-holder farmers with limited access to inputs and technologies. In such systems, the implementation of control practices, such as chemical treatments that require costly equipment and supplies, becomes unviable. Therefore, the development and use of resistant plant genotypes could provide a promising alternative for small producers. Accordingly, the present study aimed to identify and evaluate T. neocaledonicus-resistant genotypes of lima bean. A total of 30 lima bean genotypes were evaluated using the instantaneous increase rate (ri) of T. neocaledonicus reared on individual host genotypes, and T. neocaledonicus fertility life tables were generating by rearing mites on host genotypes with the two highest ri values (IFCE-085 and IFCE-091, considered highly susceptible) and two lowest ri values (IFCE-084 and IFCE-090, considered resistant). Only the IFCE-090 genotype adversely affected immature T. neocaledonicus individuals, by reducing their survival rate, net reproductive rate (Ro), finite rate of increase (λ), and intrinsic rate of increase (rm) and by increasing their mean generation time (T) and time to reach adulthood. The results demonstrate the variation in the susceptibility of lima bean genotypes to T. neocaledonicus and identify the IFCE-090 genotype as a potential source of mite resistance.

IDENTIFICATION OF COWPEA GENOTYPES RESISTANT TO FUSARIUM WILT1

ABSTRACT Fusarium wilt, caused by soil-borne Fusarium oxysporum f. sp. tracheiphilum (Fot), can reduce cowpea bean yield. Considering that genetic control through resistant genotypes is pivotal for Fusarium wilt control, the aim of the present study was to identify cowpea genotypes that are resistant to Fot from the Germplasm Bank of the Pernambuco Agronomic Institute, Embrapa Middle North, and other producing areas in the North and Northeast regions of Brazil. The cultivar BR-17 Gurguéia was used as a susceptible control and MNC01-649F-2-1 was used as a resistant control. Two experiments were carried out in a completely randomized design in the greenhouse of the Department of Agronomy of the University Federal Rural of Pernambuco. Plants with the first pair of expanded leaves were inoculated with a conidial suspension (106 conidia/mL) using the conidia root-immersion methodology. Fusarium wilt severity in plants was assessed 21 d after inoculation, with the aid of a descriptive scale. In the first experiment, we evaluated the resistance of 38 cowpea genotypes, of which 19 (5 moderately resistant and 14 resistant) were selected for the second experiment. In the first experiment, four genotypes (Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante) did not show any symptoms of Fusarium wilt. In the second, 15 genotypes showed high resistance to Fot, including Canapu PE and Miranda IPA 207, which again had no symptoms of Fusarium wilt. In conclusion, this study identified that the genotypes, Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante have greater resistance to Fusarium wilt.

Screening of French Bean (Phaseolus vulgaris L.) Genotypes against Alternaria Leaf Spot Caused by (Alternaria alternata) under Dryland Conditions of Kashmir

Sixty-three genotypes of french bean was screened against leaf spot (Alternaria alternata) in sick plots at Research Farm of Dryland Agriculture Research Srinagar, Rangreth during Kharif 2018 and 2019. The highest mean disease incidence ranged from 0.00 to 85.00 per cent with the mean disease intensity ranged from 0.00 to 53.26 per cent .One genotype namely ‘Local Pulwama’ was highly susceptible in their disease reaction. Among the screened germplasm, ‘Highly Resistant’ genotypes was SKU-R-601, SKUA-R-105, SKU-R-927, DARS-25, DARS-66, DARS-R-615, while as ‘Susceptible’ genotypes was DARS-8, DARS-12, DARS-11, SKUAST-R-155, SKU-R-928, DARS-7, DARS-R-4, Bhaderwah (L), Local Kupwara black and Raj Jawala. Local Pulwama was found to be a highly susceptible (HS) genotype. Twenty nine genotypes namely., DARS-16, DARS-9, DARS-54, DARS-39, VL-125, DARS-63, ENTO-504, SKUAST-204,SKU-R-925, DARS-60, DARS-109, DARS-43, DARS-44, SKU-R-23, DARS-4, DARS-74, SKU-R-105, DARS-40, DARS-23, DARS-18, SKU-R-71, WB-341, SKU-R-605, Uri local, Shopian (L), SKU-R-23, DARS-71, SSGB-729, DARS-R-19 showed resistant reaction to disease. The selection for resistance was based on the reaction of varieties on leaves.

Improvement of the selection method for potato breeding for resistance to the Colorado potato beetle

Создание сортов картофеля, устойчивых к повреждению колорадским жуком, – основное направление стабилизации картофельных агроценозов в долгосрочной перспективе. Цель настоящих исследований – совершенствование методики отбора генотипов с относительно высокой устойчивостью к повреждению колорадским жуком. Предложена методика отбора по фенотипическому признаку интенсивности проявления реакции сверхчувствительности (СВЧ) листовой пластинки листьев картофеля к яйцекладкам колорадского жука. Чтобы исключить зависимость селекционного отбора от наличия кладки насекомого на листовой пластинке из состава химических соединений, находящихся на поверхности хориона откладываемых яиц, был выделен эффектор, запускающий реакцию сверхчувствительности (СВЧ-реакцию) к появлению на поверхности листовой пластинки яиц колорадского жука. На основе результатов двухлетних полевых опытов на большом количестве сортообразцов установлено наличие положительной корреляционной зависимости средней степени (коэффициент 0,451) между интенсивностью образования некроза в ответ на обработку листовой пластинки эффектором СВЧ-реакции и уровнем устойчивости растений картофеля к фитофагу. Использование эффектора, запускающего СВЧ-реакцию на кладки яиц колорадского жука, позволяет оценивать гибриды в младших питомниках в отсутствии фитофага. В статье приводится подробное описание усовершенствованной методики оценки и отбора устойчивых к насекомому генотипов с использованием эффектора, запускающего СВЧ-реакцию на кладки яиц колорадского жука. Воспроизводимость СВЧ-реакции листьев картофеля на кладки яиц колорадского жука в полевых условиях при использовании биохимического эффектора позволяет провести визуализацию наличия устойчивости растений к вредителю, значительно облегчить оценку и отбор устойчивых генотипов, что в конечном счете существенно повышает результативность селекционного процесса. Creation of resistant potato varieties to damage by the Colorado potato beetle is the main direction of stabilization of potato fields in the long term. The aim of these studies is to improve the methodology for the selection of genotypes with a relatively high resistance to damage by the Colorado potato beetle. A method is proposed for the selection of genotypes with a relatively high resistance to damage by the Colorado potato beetle according to the phenotypic sign of the intensity of the hypersensitivity reaction (HR) of the leaf blade of potato leaves to the clutches of eggs of the Colorado potato beetle. In order to exclude the dependence of the selection screening on the presence of an insect clutch on the leaf blade, an effector that triggers a HR – response to clutches was isolated from the composition of chemical compounds on the chorion surface of the laid eggs. On the basis of two-year field experiments on a large number of cultivars, the presence of a positive correlation dependence of the average degree (coefficient 0.451) between the intensity of necrosis formation in response to the treatment of the leaf blade by the effector that triggers a HR – response and the level of resistance of potato plants to phytophagous was established. The use of the triggering effector HR – the reaction to the egg clutches of the Colorado potato beetle makes it possible to evaluate hybrids in younger nurseries in the absence of a phytophages. The article provides a detailed protocol of an improved methodology for assessing and selecting insect-resistant genotypes using the triggers effector HR – response to egg clutches of the Colorado potato beetle. Stable repeatability of the HR – response of potato leaves to clutches of Colorado potato beetle eggs in the field using the microwave response effector allows visualizing the presence of plant resistance to the pest, greatly facilitating the assessment and selection of resistant genotypes, which ultimately significantly increases the effectiveness of the breeding process.