Genome-Wide Analysis of TIR-NBS-LRR Gene Family in Potato Identified StTNLC7G2 Inducing Reactive Oxygen Species in Presence of Alternaria solani

Resistance gene analogs (RGAs) comprising NBS-LRR gene family members are considered prominent candidates in the development of disease-resistant genotypes. NBS-LRR gene family comprised a very large number of genes; therefore, members of one subfamily TIR-NBS-LRR (TNL) are identified in the present study from Solanum tuberosum genome, followed by their bioinformatics characterization. The study identified a total of 44 genes encoding 60 TNL transcripts with two prominent clusters at chromosome 1 and chromosome 11. Expression analysis of 14 TNL genes after Alternaria solani infection at 1, 2, 3, 5, and 7 days post inoculation in two disease-tolerant varieties, Kufri Jyoti and Kufri Pukhraj, and one relatively susceptible variety, Kufri Chandramukhi, showed differential expression of many genes including a high expression (>15-fold) of StTNLC6G2T1 and StTNLC11G9T1. Functional characterization of one such gene, StTNLC7G2, reveals involvement in the generation of reactive oxygen species under A. solani attack, implicating its putative role in plant defense via hypersensitive response.

Soil supplementation with Si, B and Zn and their synergetic effects in reducing severity of wheat blast (Magnaporthe oryzae Triticum)

Wheat blast (Magnaporthe oryzae Triticum) in Bangladesh and South America is recognized as one major limiting factor of wheat production. Its control using chemical pesticides raises concerns about food safety and pesticide resistance, which have dictated the need for alternative blast management approach, nutrient supplementation could be an ecofriendly alternative. Experiments were carried out under confined net house condition for two consecutive cropping seasons. Single doses of the nutrients (Si, B and Zn) were incorporated during soil preparation. Plants of the wheat blast susceptible variety BARI Gom-26 were inoculated with spores (1 x 107 spores ml-1) of Magnaporthe oryzae Triticum at blast vulnerable pre-heading stage of 52 days age. Typical wheat blast symptoms of spike bleaching from top to downward appeared on sight 14 days after inoculation i.e., 66 days age of the crop. Incidence and severity of blast bleaching of spike were scored for four times starting from 68 days age @ three day’s interval. None of the nutrients could stop the incidence of blast on wheat; however, some nutrients reduced the blast incidence significantly. Solo application of Si, B and Zn or combination of two caused significant reduction of spike bleaching. With the mixed application of Si, B and Zn, > 47% reduction of wheat blast severity was obtained. The results revealed that the soil application of silicon, zinc and boron had a synergistic effect on the intensity of blast disease of wheat. Int. J. Agril. Res. Innov. Tech. 11(2): 76-84, Dec 2021

Effect of weather parameters, host resistance and sowing date on disease severity and temporal dynamics of Fusarium wilt in chickpea (Cicer arietinum L.)

Fusarium wilt incited by Fusarium oxysporum f. sp. ciceris is an economically damaging disease of chickpea (Cicer arietinum L.). Field experiments on epidemiological studies revealed that sowing during second fortnight of November curtailed the disease severity index (22.50 and 20.83% during 2018-19 and 2019-20, respectively) whereas, sowing during first fortnight of October enhanced the disease severity index (34.86 and 30.41%). The area under disease progress curve was significantly higher in susceptible variety JG 62 and was the least in resistant variety HC 1. The correlation analysis exhibited positive correlation of disease severity index with maximum and minimum temperature while negative correlation with relative humidity morning and evening, irrespective of date of sowing. The principal component analysis depicted resistance index, sowing time and weather parameters as positional factors in determining Fusarium wilt progression. In susceptible variety, Gompertz model was the best fitted model for simulating the Fusarium wilt epidemic over time.

tRNA-derived fragments from wheat are potentially involved in susceptibility to Fusarium head blight

Background Fusarium head blight (FHB) caused by Fusarium graminearum is a devastating fungal disease of wheat. The mechanism underlying F. graminearum-wheat interaction remains largely unknown. tRNA-derived fragments (tRFs) are RNase-dependent small RNAs derived from tRNAs, and they have not been reported in wheat yet, and whether tRFs are involved in wheat-F. graminearum interactions remains unknown. Results Herein, small RNAs from the spikelets inoculated with F. graminearum and mock from an FHB-susceptible variety Chinese Spring (CS) and an FHB-resistant variety Sumai3 (SM) were sequenced respectively. A total of 1249 putative tRFs were identified, in which 15 tRFs was CS-specific and 12 SM-specific. Compared with mock inoculation, 39 tRFs were significantly up-regulated across both wheat varieties after F. graminearum challenge and only nine tRFs were significantly down-regulated. tRFGlu, tRFLys and tRFThr were dramatically induced by F. graminearum infection, with significantly higher fold changes in CS than those in SM. The expression patterns of the three highly induced tRFs were further validated by stem-loop qRT-PCR. The accumulation of tRFs were closely related to ribonucleases T2 family members, which were induced by F. graminearum challenge. The tRFs’ targets in host were predicted and were validated by RNA sequencing. Conclusion Integrative analysis of the differentially expressed tRFs and their candidate targets indicated that tRFGlu, tRFLys and tRFThr might negatively regulate wheat resistance to FHB. Our results unvealed the potential roles of tRFs in wheat-F. graminearum interactions.

Morphological and Biochemical Responses Associated With Resistance to Earias Vittella Fab. (Lepidoptera: Noctuidae) In Okra Varieties

Response of morphological and biochemical traits against okra shoot and fruit borer in different okra varieties were studied. Among the fifteen okra varieties under test Kashi Satdhari was the most superior variety as it showed lowest (2.60) per cent shoot damage followed by D-1-87-5 (3.62%) and Pusa A-4 (4.24%). On the contrary, in Pusa Sawani highest level of shoot infestation (16.23%) followed by SB-2 (13.74%) as against Kashi Pragati (check) 10.08 per cent were recorded. Further, okra variety Kashi Satdhari (7.87%) showed lowest fruit infestation and was considered as least susceptible variety which was at par with NO-136 (8.77%), D-1-87-5 (9.12%) and Kashi Leela (9.38%). Amongst all the okra varieties evaluated for their susceptibility to fruit infestation, Pusa Sawani and VRO-03 showed relatively higher fruit infestation i.e. 35.17 and 33.41 per cent, respectively and registered as the most inferior varieties against (26.12%) Kashi Pragati (check). The correlation study between fruit infestation and morphological factors implied that primary branching and trichome length adversely affect the borer infestation. Further, phenol and phosphorus availability in host plant also showed negative effect on shoot and fruit borer infestation. Bangladesh J. Bot. 50(4): 1059-1066, 2021 (December)

Efficacy of essential oils in the management of soft rot caused by Pectobacterium aroidearum in lettuce

Lettuce is susceptible to several diseases, especially soft rot caused by bacteria of the genus Pectobacterium. Due to the adaptability of this pathogen and the lack of disease control registered for the crop, the objective of this work was to evaluate the effects of essential oils in the management of soft rot caused by P. aroidearum in lettuce. The study was developed at the Universidade do Estado da Bahia, Juazeiro, BA, Brazil, and the essential oils (EOs) of orange, bergamot, lemongrass, palmarosa, citronella, cloves, tea tree, rosemary, sage, and ginger were used in concentrations of 0.25; 0.5; 0.75 and 1.0% to assess the in vitro growth inhibition of the bacterium. Subsequently, the curative effects of the disease were evaluated by applying the EOs that obtained the best results in vitro in lettuce plants of the susceptible variety “Mônica”. The treatments were applied, via spraying, 12 hours after inoculation using the bite method with bacterial suspension. The best in vivo treatment was selected to assess its preventive and curative activity, as well as to find the ideal concentration for reducing epidemiological variables and chromatographic characterization. The EOs of palmarosa, sage, citronella, lemongrass, and cloves (0.25%), and that of sage (0.75%), inhibited bacterial growth in vitro. The EO of salvia showed the best results in vivo, inhibiting the growth of the disease in concentrations of 0.50 and 0.75%, so it was selected for the preventive and curative control tests alone. The preventive treatment was not efficient for the management of soft rot in lettuce, however, from the regression analysis, a concentration of 0.64% of the salvia EO was found as a potential for curative control of this bacteriosis, as it reduces the incidence and severity of the disease. Linalyl acetate and linalool were found in higher concentrations in the chromatographic analysis. These components, probably, conferred the bactericidal capacity of the EO of sage, being potential for the use in the control of P. aroidearum in lettuce.

Rice Resistance Buffers against the Induced Enhancement of Brown Planthopper Fitness by Some Insecticides

The brown planthopper, Nilaparvata lugens (Stål)[BPH], is a damaging pest of rice in Asia. Insecticides and rice varietal resistance are widely implemented BPH management practices. However, outbreaks of BPH have been linked to excessive insecticide use—challenging the compatibility of these two management practices. IR62 is a variety with resistance against BPH, the whitebacked planthopper, Sogatella furcifera Horváth [WBPH], and the green leafhopper, Nephotettix virescens (Distant)[GLH]. We compared BPH responses to IR62 and to the susceptible variety IR64 treated with buprofezin, carbofuran, cartap hydrochloride, cypermethrin, deltamethrin, fipronil, or thiamethoxam + chlorantraniliprole. In greenhouse bioassays, cypermethrin, fipronil and thiamethoxam + chlorantraniliprole reduced egg laying on both varieties, and, together with buprofezin, reduced nymph survival to zero. Buprofezin, carbofuran, and cartap hydrochloride stimulated egg laying, and carbofuran increased nymph biomass, but these effects were reduced on IR62. Planthopper populations were ten times higher on deltamethrin-treated rice than untreated rice in a screenhouse experiment. Host resistance failed to buffer against this insecticide-induced resurgence in BPH and WBPH. However, IR62 reduced the effect in GLH. Rice treated with cypermethrin and fipronil had reduced yields compared to untreated controls, suggesting possible phytotoxic effects. We found little evidence of synergies between the two management practices; but host resistance did buffer against the undesirable effects of some insecticides.

Generation Mean Analysis for Yield and Drought Tolerant Traits under Rainfed and Irrigated Conditions in Rice (Oryza sativa L.)

Generation mean analysis was carried out using two crosses, involving a high yielding drought susceptible variety NDR 359 and drought tolerant rainfed cultivars Nagina 22 and Vandana. Six generations namely P1, P2, F1, F2, BC1 and BC2 were grown under both rainfed and irrigated environment to study the gene action for various yield and drought tolerance traits. Scaling test revealed the presence of epistasis for most of the yield and drought tolerance traits in both the crosses. Hence, six parameter model was adopted for these traits and for few traits where epistasis was absent, three parameter model was used. The results revealed that dominance gene effect along with non-allelic interactions had profound effect on the genetic control of majority of the yield traits. Therefore, early generation selection will be misleading for these traits. However, the drought tolerance related traits like proline content and stomatal conductance were governed by additive component as well. Duplicate epistasis was observed for majority of the traits. Hence, present study indicates that, epistasis has a key role in the expression of almost all the traits in both the environment.

Metabolomics Differences of Glycine max QTLs Resistant to Soybean Looper

Quantitative trait loci (QTLs) E and M are major soybean alleles that confer resistance to leaf-chewing insects, and are particularly effective in combination. Flavonoids and/or isoflavonoids are classes of plant secondary metabolites that previous studies agree are the causative agents of resistance of these QTLs. However, all previous studies have compared soybean genotypes that are of dissimilar genetic backgrounds, leaving it questionable what metabolites are a result of the QTL rather than the genetic background. Here, we conducted a non-targeted mass spectrometry approach without liquid chromatography to identify differences in metabolite levels among QTLs E, M, and both (EM) that were introgressed into the background of the susceptible variety Benning. Our results found that E and M mainly confer low-level, global differences in distinct sets of metabolites. The isoflavonoid daidzein was the only metabolite that demonstrated major increases, specifically in insect-treated M and EM. Interestingly, M confers increased daidzein levels in response to insect, whereas E restores M’s depleted daidzein levels in the absence of insect. Since daidzein levels do not parallel levels of resistance, our data suggest a novel mechanism that the QTLs confer resistance to insects by mediating changes in hundreds of metabolites, which would be difficult for the insect to evolve tolerance. Collective global metabolite differences conferred by E and M might explain the increased resistance of EM.

Characterization of Elite Genotypes for Fusarium Wilt Resistance in Pigeonpea [Cajanus cajan (L.) Millspaugh]

Background: The development of Fusarium wilt resistant varieties is a major challenge in pigeonpea breeding and need to be addressed on priority basis. In this study, efforts had been made to characterize the elite pigeonpea genotypes for Fusarium wilt resistance at morphological and molecular level. Methods: The present study was undertaken during kharif season of year 2018-19 at NEB, Crop Research Centre, G.B.P.U.A and T, Pantnagar. The experimental materials for present study consisted of 15 elite pigeonpea genotypes and three commercially grown popular varieties as checks. The molecular analysis was conducted during year 2019-20 and a susceptible variety BAHAR was used as check. The nine yield based indices were used for morphological analysis. The molecular analysis was carried out by using five already reported Fusarium wilt linked SSR markers. Result: The results revealed that the marker ASSR 363, ASSR 366, ASSR 1, ASSR 23 and ASSR 148 were highly effective in differentiating the resistant and susceptible genotypes of pigeonpea for wilt disease. On the basis of morphological and molecular studies, it was concluded that the genotype PA 626 was the most superior genotype as it not only yielded higher than all the three checks but also shown resistance against wilt at both phenotypic and genotypic level.