Moderately Susceptible Research Articles

Screening of Inbred Lines of Maize against Turcicum Leaf Blight (Exserohilum turcicum) under Artificial Epiphytotic Conditions

Aims: Turcicum Leaf Blight (TLB), caused by Exserohilum turcicum, significantly affects maize in Karnataka, leading to yield losses of up to 70% in severe cases. To develop tolerant genotypes against this disease, an experiment was conducted using 100 inbred lines collected from the IMIC maize field day in Hyderabad. Study Design: Investigation was carried using Randomized complete block design with two replication. Place and Duration of Study: Maize Research Centre and Seed Farm, Devihosur during kharif-2022. Methodology: One hundred inbred lines were screened against TLB disease. among them 10 resistant lines were selected based on their maturity, disease reaction, grain yield and per se performance. These inbreds along with the checks (Resistant check CI-4 and Susceptible Check CM-202) were sown in Kharif 2022 at Maize Research Centre and Seed Farm Devihosur, UAS, Dharwad. Artificial inoculation was performed 45 days after sowing in the leaf whorls using infected leaves with TLB and the results were evaluated at the silk drying stage. To assess the disease reaction to TLB, we used 1 to 9 scale as established by the Indian Institute of Maize Research, Ludhiana (Anon., 2016). Lines that received disease scores between 1.0 and 3.0 were classified as resistant (R), scores of 4 to 5 as moderately resistant (MR), scores of 6 to 7 as moderately susceptible (MS), and scores of 8 to 9 as susceptible (S). Results: The performance of these lines were compared with the resistant check CI-4 and susceptible check CM-202. Screening trial revealed that out of hundred inbred lines, eighteen lines Showed highly resistant reaction. This information can be useful for selection of parents and to develop tolerant hybrids in breeding programs or utilize them as source of resistance.

Resistance of spring durum wheat varieties to stem rust on the background of natural infection

The scientific study presents the results and indicators of the cultivation of spring durum wheat in the world, the main varieties of spring durum wheat in the south-east of Kazakhstan, the development of stem rust on durum wheat varieties (Triticum durum Desf.), data on the stability of varieties in grain-bearing regions of the republic. Field experiments were conducted in the conditions of the foothill zone of the Almaty region in 2022. The object of research was 15 varieties of spring durum wheat of various origins: Gordeiforme 254, Nauryz 2, Nauryz 6, Seymour 17, Milana, Salauat, Zhakut 20 (Kazakh Research Institute of Agriculture and Plant Growing), Altyn dala, Asangali 20, Sharifa (Karabalyk Agricultural Station), Damsinskaya jubileinaya (A.I. Barayev Research and Production Centre for Grain Farming), Bezenchukskaya 182, Kanysh (Russia), Berillo (Italy), Kamillaroi (Australia).Under natural conditions, the manifestation of stem rust (Puccinia graminis f. sp. tritici) on spring durum wheat varieties was late, in the phase of flowering and filling of plant grains. In the experience, many varieties of Kazakh and foreign breeding have shown moderate resistance and susceptibility to the disease. In the varieties Salauat and Zhakut 20, the initial and subsequent development of the disease did not exceed 20%, which is a sign of Slow rust development. With a strong lesion of the Nauryz 2 variety (60%), Gordeyforme 254, Milana, Nauryz 6, Damsinskaya jubileinaya, Altyn Dala, Asangali 20, Berillo and Kamillaroi were moderately susceptible. The Seymour 17, Sharifa and Kanysh varieties showed moderate resistance to stem rust.

Disease Indexing of Rapeseed: Mustard Cultivars against Alternaria Blight

In the investigation, 120 rapeseed-mustard genotypes were screened under in vivo conditions for resistance against the foliar disease Alternaria blight. None of the genotypes were found to be immune to the disease. However, three genotypes—JT-1, RVM-3, and Pusa Jagannath—were identified as resistant (R), with disease severity ranging from 1% to 10%. Nine genotypes were classified as moderately resistant (MR), showing disease severity between 11% and 25%. A total of 67 genotypes were rated as moderately susceptible (MS), with disease severity ranging from 26% to 50%. Additionally, 41 genotypes were categorized as susceptible (S), where disease severity was between 51% and 75%. The highly susceptible none of genotypes were found.

ASSESSMENT OF EARLY BLIGHT RESISTANCE IN INDIAN POTATO CULTIVARS AND ASSOCIATED BIOCHEMICAL CHANGES DURING DISEASE DEVELOPMENT

Among the twenty-three varieties of potato screened against early blight disease under field conditions during Rabi 2020-21 and Rabi 2021-22 in Gujarat at Anand agricultural University, Anand, varieties were categorized into resistant (R), moderately resistant (MR), moderately susceptible (MS), susceptible (S) and highly susceptible (HS). For biochemical analysis some varieties disease reaction revealed Kufri Lima as resistant, Kufri Himalini and Kufri Nilkanth as moderately resistant, Kufri Mohan and Kufri Chadramukhi as moderately susceptible Kufri Pukhraj and Kufri Kesar as susceptible and Kufri Lalit as highly susceptible varieties to early blight disease. These varieties biochemical analysis revealed that healthy leaves of resistant, moderately resistant, moderately susceptible, susceptible and highly susceptible varieties showed higher content of moisture, total soluble sugar and total chlorophyll as compared to diseased leaves. While diseased leaves of resistant, moderately resistant, moderately susceptible, susceptible and highly susceptible varieties contained higher content of phenol and true protein compared to healthy leaves.

Oxidative stress dynamics revealed the role of H2O2 in citrus rootstocks sensitivity to Phytophthoranicotianae

Phytophthora nicotianae is a devastating pathogen in citrus and tolerant rootstocks are required for its management. Seven Jatti Khatti (JK, a rough lemon strain; susceptible) × Poncirus trifoliata (PT; tolerant) hybrids were screened against P. nicotianae. In feeder root rot based evaluation, three hybrids were found moderately tolerant (MT) while four were moderately susceptible (MS). The H2O2 in plant pathogen interactions contributes in resistance/susceptibility to the biotrophic/necrotrophic pathogens. To comprehend its role in citrus against Phytophthora (a hemi-biotrophic pathogen), H2O2, lipid peroxidation, and peroxidase (POD) activity were determined in Phytophthora inoculated and non-inoculated roots of JK, PT, three MT and one MS hybrids at 10, 20 and 30 days post inoculation (dpi). The tolerant parent, PT and MT hybrids exhibited lower or stable H2O2 content in Phytophthora inoculated plants at 20 or 30-dpi. Their POD activity increased at 10-dpi, depicting its role in H2O2 homoeostasis. At 30-dpi, JK and MS hybrid showed significantly higher H2O2 content (4.10 and 3.62 μmol g−1 FW), compared to 1.88 μmol g−1 FW in PT. The lipid peroxidation content significantly increased in JK or MS hybrid at 20 or 30-dpi. The susceptible or MS individuals displayed significantly higher (18–25 % higher) electrolyte leakage than their control. A strong positive association (r = 0.89) was found between electrolytes leakage and H2O2 accumulation at 30-dpi. The POD activity and H2O2 at 10-dpi showed strong negative correlation (r = −0.86). Results infer that high H2O2 causes cellular death and contributes to Phytophthora susceptibility in citrus. It can serve as a biomarker for predicting relative sensitivity to Phytophthora.

Studies on inheritance of yellow vein mosaic virus (YVMV) resistance in okra (Abelmoschus esculentus L.) cv. Pusa Bhindi-5 and effect of YVMV disease on fruit nutritional quality

The present investigation was carried out by involving six generations of okra, i.e., P1, P2, F1, F2, B1 (F1 × Pusa Bhindi-5) and B2 (F1 × Pusa Sawani) developed from two contrasting parents, one susceptible cultivar Pusa Sawani (P1) and another newly developed Bhendi yellow vein mosaic virus (YVMV) resistant variety Pusa Bhindi-5 (P2). The experimental data showed the maximum PDI (percent disease incidence) in susceptible parent Pusa Sawani (95.56%) followed by B2 (47.5%) and F2 (29%) after 90 days of sowing, whereas Pusa Bhindi-5, B1 and F1 were recorded highly resistant to YVMV disease even after 90 days of sowing. Backcross population B2 and F2 fell into the moderately susceptible (MS) category, whereas parent Pusa Sawani was recorded as highly susceptible (HS). Based on F2 and backcross data, the nature of inheritance of YVMV resistance in Pusa Bhindi-5 was found to be monogenic dominant. Analysis of t-test for the significance of the difference between the mean values of infected and healthy fruits was found to be highly significant with higher probability (p-value <0.05), indicating that the viral infection caused changes in the biochemical/nutrient contents such as protein, carbohydrate, dietary fiber, total ash and minerals. Most of the nutrients were negatively affected by the YVMV. Thus, this study ascertained the qualitative damage caused by this virus.

Grain Yield and Quality Losses Caused by Tan Spot in Wheat Cultivars in Australia

Tan spot (TS), known in Australia as yellow leaf spot, is caused by the fungal pathogen Pyrenophora tritici-repentis, a major foliar disease of wheat. Four experiments were conducted between 2016 and 2017 in two different climatic zones of southeastern Australia to determine the impact of TS on grain yield and quality in six wheat cultivars with different resistance ratings. In each experiment, high and low TS disease scenarios were applied to each cultivar. Disease severity was assessed as either whole-plot percentage leaf area affected (%LAA) or top three leaf (flag to flag-2) %LAA. Whole-plot %LAA was analyzed using both repeated measurements and area under the disease progress curve (AUDPC). For whole-plot %LAA, the repeated measurements identified differences in epidemic progression at key growth stages not identified through AUDPC. Both AUDPC and end-of-season flag to flag-2 %LAA were negatively correlated with grain yield and screenings. Increased rainfall impacting disease development and number of rain days above 5 mm increased TS severity across both climatic zones. Cultivar resistance ratings influenced grain yield loss, with moderately resistant, moderately susceptible, and susceptible cultivars losing up to 6, 18, and 24% grain yield, respectively. High disease significantly increased screenings by up to 1, 3, and 5% for moderately resistant, moderately susceptible, and susceptible cultivars, respectively. This study demonstrated that TS can cause significant grain yield losses in southeastern Australia, and a minimum cultivar rating of moderate resistance to moderate susceptibility was required to prevent severe TS and associated grain yield and quality losses. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Comprehensive Assessment of Aphid (Lipaphis erysimi (Kalt.) Resistance in Mustard Cultivars

The study focuses on mustard (Brassica spp.) crops, crucial rabi oilseed crops in India. This study aimed to assess the susceptibility of 45 mustard crop cultivars to Lipaphis erysimi Kaltenbach, commonly known as the mustard aphid, a significant biotic stressor affecting Indian mustard (Brassica juncea). The necessity of this study lies in the importance of identifying aphid-resistant cultivars to enhance pest management strategies and improve mustard crop yields. Field experiments were conducted at Jawaharlal Nehru Krishi Vishwavidyalaya in Jabalpur, Madhya Pradesh, India during the rabi season, using a Randomized Block Design. The study utilized a mean aphid index-based scoring scheme to categorize the cultivars into different susceptibility levels, ranging from highly resistant to highly susceptible. The classification was determined based on normal distribution values, including highly resistant (HR), resistant (R), moderately resistant (MR), moderately susceptible (MS), susceptible (S), and highly susceptible (HS). The results revealed that none of the cultivars fell into the highly resistant category, but five cultivars demonstrated resistance, with mean aphid index values below 0.34. Thirty cultivars were classified as moderately resistant, displaying mean aphid index values between 0.34 and 0.66. Six cultivars exhibited moderate susceptibility (mean aphid index between 0.66 and 0.82), while four cultivars were categorized as susceptible (mean aphid index between 0.82 and 0.98). Notably, none of the cultivars were highly susceptible. The study underscores the importance of identifying aphid-resistant cultivars to enhance pest management strategies and improve mustard crop yields. The results provide valuable insights into the susceptibility levels of different cultivars, guiding farmers in selecting appropriate varieties for cultivation. The research also emphasizes the significance of environmentally friendly pest management options, considering the potential risks associated with pesticide use. Overall, this study contributes to the development of sustainable Integrated Pest Management (IPM) techniques for Indian mustard cultivation.

Induction of PR-Proteins and Oxidative Isozymes in Tomato Genotypes Resistant and Susceptible to Tomato Mosaic Virus and Tomato Spotted wilt Virus

Tomato spotted wilt virus (TSWV) and Tomato mosaic virus (ToMV) are two of the most common viruses that threaten tomato crops in Egypt and worldwide. The purpose of this study was to investigate the role of PRs, and oxidative isozymes in the protection of tomato plants from oxidative damage induced by viral infection in 16 tomato genotypes. A total of 16 tomato genotypes were evaluated against TSWV and ToMV separately. Changes in the content of protein and defense enzymes were studied in tomato genotypes resistant and susceptible to TSWV or ToMV. The results of the investigation showed that 16 tomato lines gave different responses to infection with TSWV or ToMV [highly resistant (HR), resistant (R), moderately resistant (MR), moderately susceptible (MS), and susceptible (S)]. In this study, the total soluble protein profiles, polyphenol oxidase (PPO), and peroxidase (POX) isozymes of the healthy tomato plants and the TSWV or ToMV infected ones were estimated by electrophoresis in Polyacrylamide gel electrophoresis (PAGE). The results showed quantitative and qualitative differences in the number of bands among the 16 tomato genotypes. Thus, the protein content and isozyme activities were increased or decreased or not changed in inoculated tomato plants with TSWV or ToMV, compared with the un-inoculated plants, depending on the genotype, virus, and degree of resistance. On the other hand, it was found a negative or low-positive correlation between disease incidence and (protein content and isozyme activities). Therefore, it is important that to understand the defense strategy of plants against viruses and how tomato plants defend themselves from virus invasion. Therefore, tomato genotypes resistant to TSWV or ToMV could be used in the tomato breeding programs to prevent viral infection

A source of resistance against yellow mosaic disease in soybeans correlates with a novel mutation in a resistance gene

Yellow mosaic disease (YMD) is one of the major devastating constraints to soybean production in Pakistan. In the present study, we report the identification of resistant soybean germplasm and a novel mutation linked with disease susceptibility. Diverse soybean germplasm were screened to identify YMD-resistant lines under natural field conditions during 2016-2020. The severity of YMD was recorded based on symptoms and was grouped according to the disease rating scale, which ranges from 0 to 5, and named as highly resistant (HR), moderately resistant (MR), resistant (R), susceptible (S), moderately susceptible (MS), and highly susceptible (HS), respectively. A HR plant named “NBG-SG Soybean” was identified, which showed stable resistance for 5 years (2016-2020) at the experimental field of the National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan, a location that is a hot spot area for virus infection. HS soybean germplasm were also identified as NBG-47 (PI628963), NBG-117 (PI548655), SPS-C1 (PI553045), SPS-C9 (PI639187), and cv. NARC-2021. The YMD adversely affected the yield and a significant difference was found in the potential yield of NBG-SG-soybean (3.46 ± 0.13a t/ha) with HS soybean germplasm NARC-2021 (0.44 ± 0.01c t/ha) and NBG-117 (1.12 ± 0.01d t/ha), respectively. The YMD incidence was also measured each year (2016-2020) and data showed a significant difference in the percent disease incidence in the year 2016 and 2018 and a decrease after 2019 when resistant lines were planted. The resistance in NBG-SG soybean was further confirmed by testing for an already known mutation (SNP at 149th position) for YMD in the Glyma.18G025100 gene of soybean. The susceptible soybean germplasm in the field was found positive for the said mutation. Moreover, an ortholog of the CYR-1 viral resistance gene from black gram was identified in soybean as Glyma.13G194500, which has a novel deletion (28bp/90bp) in the 5`UTR of susceptible germplasm. The characterized soybean lines from this study will assist in starting soybean breeding programs for YMD resistance. This is the first study regarding screening and molecular analysis of soybean germplasm for YMD resistance.

Evaluation of Host Plant Susceptibility Indices and Screening of Sugarcane Promising Lines for Resistance Potential Against Whitefly, Aleurolobus barodensis (Maskell) in Sindh, Pakistan.

The whiteflies are polyphagous, host, and feed on the sap of sugarcane leaves may cause a loss in yield production. This study was designed to screen out the fifteen sugarcane genotypes to recognize their comparative resistance/susceptibility during 2014-15 and 2015-16. The whitefly attack was first found in June, rapidly increased in August, and reached its maximum population in October. After that, the population gradually declined from November to December. The highest 1.80 per cm2 leaf-1 population of whitefly (nymph + puparia) was recorded on YT-53, followed by 1.56 per cm2 leaf-1 in S-2007-AUS-384, which showed moderate susceptibility. The genotypes Hoth-127, NARC-1, and CP-TJ-349, exhibited less susceptible responses with an average range of 1.01-1.50 per cm2 leaf-1. The other genotypes, i.e., CP-TJ-349, Hoth-326, Th-910, S-2005-CSSG-33, S-2007-AUS-384, Hoth-2109, LAM-76/TJ-803, Th-1201, S-2009-CPSG-06, S-1996-NSG-197, NARC-2, and Th-1210 showed resistance response with an average range of 0.01-1.00 per cm2 leaf-1. The maximum Host Plant Susceptibility Indices (HPSIs) during 2015 (16% and 15%), 2016 (13% and 14%), and cumulative (16% and 14%) were recorded in YT-53 and S-2007-AUS-384, respectively. Based on the cumulative result of HPSIs, these genotypes keep in the moderately susceptible category. Similarly, the genotypes Hoth-127, NARC-1, and CP-TJ-349 showed intermediate HPSIs (12, 11, and 9% respectively, found to be less susceptible. While the genotypes, i.e., Hoth-326, Th-910, S-2005-CSSG-33, LAM-76/TJ-803, Hoth-2109, Th-1201, S-1996-NSG-197, S-2009-CPSG-06, NARC-2, and Th-1210 were recorded minimum HPSIs in the range of 1-8% possibly found to be resistant.

BIOCHEMICAL AND HISTOPATHOLOGICAL CHANGES IN CHICKPEA (CICER ARIETINUM L.) DURING PATHOGENESIS OF COLLAR ROT FUNGI (SCLEROTIUM ROLFSII SACC)

Sclerotium rolfsii (Sacc.), causing collar rot (CR) of chickpea is one of the most perilous soil-borne pathogens that parasitize chickpea at a very early stage, therefore, leading to huge yield loss. The present experiment aimed to study the relative changes in defence-related enzymes and phenolics which take place in chickpea (both in resistant and susceptible genotypes) upon CR infection. Emphasis was given to study the changes in total soluble proteins, peroxidase and total phenol content at 7, 14, and 21-days post inoculation (dpi). The experiment was set up by taking moderately resistant (MR), moderately susceptible (MS), susceptible (S) and highly susceptible (HS) genotypes and the experiment was conducted under both inoculated and non-inoculated conditions. The results indicated that total phenol content was signicantly higher (3 folds) at 7dpi and then declined gradually upto 21dpi. MR cultivars had higher phenol content than the (MS) and the susceptible non-inoculated control. Total soluble protein content decreased with the days after post-inoculation and this reduction is greater in the susceptible cultivar as compared to the MR cultivars. Total soluble protein content was 3 times higher in the inoculated cultivars than in the in-inoculated control. Peroxidase (POD) activity was also decreased from 7dpi to 21dpi and maximum POD activity was recorded at 7dpi in MR cultivars (12.61 g-1 fresh wt.) than the susceptible one (1.31 g-1 fresh wt.). Scanning electron microscopy (SEM) was also done to compare the extent of the mycelial network within the xylem vessels of inoculated MR, MS and susceptible cultivars.

Resistance of pea (Pisum sativum L.) varieties to fungal diseases and their productivity in the South-East of Kazakhstan

In Kazakhstan, fungal diseases root rot and Ascochyta strongly affect the growth and yield of peas. Traditional breeding practices have resulted in improved resistance to these diseases in adapted varieties and lines, which is the main way to minimize yield losses. The global problem for breeders is to identify genes for disease resistance and use them in breeding programs. At the moment, promising, highly resistant to fungal diseases have been identified. In this work, modern methods of experiment, observation and accounting, selection and preparation of land plots, laying and experimenting with physiological and biological parameters of pea samples were used. Monitoring was carried out to determine the phytopathological and immunological evaluation of 59 varieties and lines of peas to fungal diseases was carried out. As a result of the analysis, 16 genotypes were highly resistant (I), 32 resistant (R) and 11 moderately resistant (MR) to Ascochyta in the natural background of the disease. At the same time, 21 genotypes were highly resistant (I), 26 resistant (R), 5 moderately resistant (MR), 6 moderately susceptible (MS) and 1 susceptible (S) to root rot on a natural background. On an artificial infectious background, the result showed that 9 genotypes were highly resistant (I), 43 resistant (R), and 7 moderately resistant to Ascochyta. And 19 genotypes were highly resistant (I), 33 resistant (R), 3 moderately resistant (MR), 2 moderately susceptible (MS) and 2 susceptible (S) to root rot. As a result of phenological analysis, in most pea samples, ascochitosis disease and root rot were pronounced, but with the least damage. The vegetation period was 112 days in 2021, and up to 93 days in 2022. According to the analysis indicators, all pea samples are very useful for identifying donors and can be included in breeding programs for hybridization to create new productive and resistant varieties.

Impact of Gibberella Ear Rot on Grain Quality and Yield Components in Maize as Influenced by Hybrid Reaction.

The impact of Gibberella ear rot (GER; caused by Fusarium graminearum) on deoxynivalenol (DON) contamination of grain and yield components in maize were investigated using data from 30 environments in Ohio (3 years by 10 locations). Fifteen hybrids, later classified as susceptible (SU), moderately susceptible (MS), or moderately resistant (MR), based on the magnitude of differences in mean arcsine square-root-transformed GER severity (arcSEV) and log-transformed DON (logDON) relative to a reference SU check, were planted in each environment, and 10 ears per hybrid were inoculated with a spore suspension of F. graminearum. Relationships between GER severity and DON were well described by a Kono-Sugino-type nonlinear equation. Estimated parameters representing height (A) and steepness (β) of the curves were significantly higher for SU than MS and MR hybrids but A was not significantly different between MS and MR. Results from a surrogacy analysis showed that GER was a moderate trial- and individual-level surrogate for DON. Both grain weight per ear and ear diameter decreased with increasing arcSEV but the regression slopes varied among resistance classes. The rates of reduction in both yield components per unit increase in arcSEV were significantly greater for SU than for MS and MR. An estimated 50% reduction in grain weight occurred at 62% GER severity for SU, compared with 77% severity for MS and 83% for MR. These results show that GER severity can be used as a surrogate for early estimation of DON contamination and yield loss to help guide grain handling and marketing decisions.

Susceptibility of dairy cows to subacute ruminal acidosis is reflected in both prepartum and postpartum bacteria as well as odd- and branched-chain fatty acids in feces

BackgroundThe transition period is a challenging period for high-producing dairy cattle. Cows in early lactation are considered as a group at risk of subacute ruminal acidosis (SARA). Variability in SARA susceptibility in early lactation is hypothesized to be reflected in fecal characteristics such as fecal pH, dry matter content, volatile and odd- and branched-chain fatty acids (VFA and OBCFA, respectively), as well as fecal microbiota. This was investigated with 38 periparturient dairy cows, which were classified into four groups differing in median and mean time of reticular pH below 6 as well as area under the curve of pH below 6. Furthermore, we investigated whether fecal differences were already obvious during a period prior to the SARA risk (prepartum).ResultsVariation in reticular pH during a 3-week postpartum period was not associated with differences in fecal pH and VFA concentration. In the postpartum period, the copy number of fecal bacteria and methanogens of unsusceptible (UN) cows was higher than moderately susceptible (MS) or susceptible (SU) cows, while the genera Ruminococcus and Prevotellacea_UCG-001 were proportionally less abundant in UN compared with SU cows. Nevertheless, only a minor reduction was observed in iso-BCFA proportions in fecal fatty acids of SU cows, particularly iso-C15:0 and iso-C16:0, compared with UN cows. Consistent with the bacterial changes postpartum, the lower abundance of Ruminococcus was already observed in the prepartum fecal bacterial communities of UN cows, whereas Lachnospiraceae_UCG-001 was increased. Nevertheless, no differences were observed in the prepartum fecal VFA or OBCFA profiles among the groups. Prepartum fecal bacterial communities of cows were clustered into two distinct clusters with 70% of the SU cows belonging to cluster 1, in which they represented 60% of the animals.ConclusionsInter-animal variation in postpartum SARA susceptibility was reflected in post- and prepartum fecal bacterial communities. Differences in prepartum fecal bacterial communities could alert for susceptibility to develop SARA postpartum. Our results generated knowledge on the association between fecal bacteria and SARA development which could be further explored in a prevention strategy.Graphical abstract

Population structure, genetic diversity and bakanae disease resistance among rice varieties

AbstractAvailability of resistance sources among cultivated varieties helps in easy utilization as donor owing to no deleterious linkage drag. In the present investigation, 121 rice varieties were screened for their resistance against a virulent isolate ofFusarium fujikuroi(Ff-10) and genotyped using reported microsatellite markers. Among 121 varieties, only eight varieties, namely Luna Sankhi, Improved Tapaswini, Sarasa, Sadabahar, CR-311, Kshira, Wifa-10 and Binadhan-8, were found to be highly resistant (HR), seven varieties were resistant (R), 31 were moderately resistant (MR), 10 were moderately susceptible (MS), 11 were susceptible (S) and the rest 54 were highly susceptible (HS). The allele diversity of molecular markers classified the population into three clusters. The highly resistant varieties were grouped in major clusters II and III, whereas the remaining genotypes were distributed in all three clusters. Analysis of molecular variance (AMOVA) resulted in 95% of the maximum diversity within the test population and 5% diversity between populations. Population structure analysis grouped the genotypes into two sub-populations based on relatedness, where most of the resistant genotypes were grouped into one sub-population and other genotypes were distributed among sub-populations. Re-examination of reported markers' trait associations with bakanae resistance in the experimental population identified marker RM-3698 as associated with resistance accounting 8.4% explained phenotypic variation. This study shows that simple sequence repeat markers can be used to assess allelic diversity and population structure of bakanae resistance in rice varieties. The highly resistant genotypes, along with resistance markers, could be used as donors in marker-assisted bakanae improvement breeding programmes.

Screening of Mungbean Genotypes Against Whitefly <i>Bemisia tabaci</i> (Genn.) And Thrips <i>Megalurothrips distalis</i> (Karny)

Ten green gram genotypes (K 851, GM 4, Meha, VMS 6 (GM-5), IPM 205-7 (Virat), Vaibhav, AKM-6802, CO-5, AKM-8803 and PM-2) were screened for their resistance to the sucking pests. The field experiment was conducted at the Instructional Farm, JAU, Junagadh during summer 2018. None of the varieties proved highly resistant to the whitefly Bemisia tabaci (Genn.) and thrips Megalurothrips distalis (Karny); however, Meha, IPM 205-7 (Virat), and VMS 6 (GM-5) were found resistant. The varieties Vaibhav, CO-5 and PM-2 have been classified as moderately resistant (MR) to B. tabaci and AKM- 6802 was moderately susceptible (MS) to both the pests. The susceptible (S) category included the AKM-8803, GM-4, and K-851 varieties.

Management of Chili leaf curl disease (ChiLCD) through resistant germplasm and Nutrients in relation to Environmental Factors

The aim of present study was to evaluate the selected germplasm against chili leaf curl virus disease (ChiLCVD) and its management through nutrients. The chili varieties i.e., Zinia F1, Desi (Jalalpuri), Desi (Jalalpuri 2), Wonder Hot, Summer Queen F1 and Faisalabad Selection was evaluated against the ChiLCVD. After screening, Wonder Hot and Summer Queen F1 showed moderately resistant (MR) response whereas, 3 varieties i.e., Zinia F1, Desi (Jalalpuri) and Desi (Jalalpuri 2) had a moderately susceptible (MS) response and only a single variety (Faisalabad Selection) expressed resistant (R) response. Four varieties; Desi (Jalalpuri), Desi (Jalalpuri 2), Zinia F1 and Wonder Hot, were used for management experiment with 4 nutrients combinations, T1 (ZnSO4 + CuSO4), T2 (MnSO4 + CuSO4), T3 (Boric Acid + CuSO4) and T4 (ZnSO4 + CuSO4 + MnSO4 + Boric Acid). When compared to control (58.14%), only T4 demonstrated minimum disease severity (11.63%). In case of disease incidence, T4 gave the best results with minimum disease incidence (35.65%) as compared to control (92.59%). Treatments reduced disease progression even during favorable environmental conditions. There was significant (p?0.05) but positive correlation between wind speed and disease severity. Wind speed was highly correlated with the disease severity of variety Wonder Hot (r=0.91). It could be concluded that the application of nutrients activates the plant defense system and at suppress the vector infestation. Keywords: Management, Nutrients, Whitefly, Epidemiology.

Phenotypic Screening of F3 Rice (Oryza sativa L.) Population Resistance Associated with Sheath Blight Disease

The experiment was conducted during July–December, 2019 in the Agricultural Research Farm Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India. One hundred and twenty-two F3 rice populations from the cross made between IC277332 (susceptible parent)×IC277275 (moderately resistant parent) were evaluated against sheath blight disease under field conditions. The area under disease progress curve (AUDPC) values categorized rice population into four groups viz., moderately resistant (24), moderately susceptible (38), susceptible (40), and highly susceptible (20). A moderate resistance level to the disease was identified during the study in 24 lines (19.6%) with a mean Percentage Disease Index (PDI) of 12.22%−36.6%. Furthermore, 38 individuals showed moderate susceptibility with AUDPC values (1012−1446 day-1). The maximum PDI and AUDPC value were 76.11 and 2325.56, and the minimum PDI and AUDPC values were 22.78 and 622.22, respectively. The principal component (PCA) biplot analysis showed 71.62% and 12.05% variation, respectively. Unweighted Pair Group Method of Arithmetic Means (UPGMA) cluster analysis grouped the 122 individuals into two major clusters, A and B and sub-clusters. These findings indicated that no rice line resistant to sheath blight had been identified. However, few population lines exhibited moderate resistance, which can be utilized as donor lines to generate sheath blight-resistant rice cultivars. These findings will provide a solid basis for our future breeding and screening activities at the institution.

Evaluation of black gram (Vigna mungo) genepool against Callosobruchus maculatus and diversity analysis inter se

The present study was carried out at ICAR-National Bureau of Plant Genetic Resources, New Delhi during 2020–21to evaluate the differential reaction of 69 germplasm accessions representing black gram [Vigna mungo (L.) Hepper] landraces and its crop wild relatives for resistance against Callosobruchus maculatus (Fab.) under artificial infestation et-up using ‘No-choice test’ method and analyze their genetic diversity using SSR markers. After emergence of adult beetles, the accessions were studied for the growth parameters like total oviposition, exit holes, adult emergence (AE), per cent seed weight loss (PSWL) and growth index (GI), which varied significantly. Based on the key traits, viz. AE and PSWL, the accessions were categorized into six groups, viz. immune (I), resistant (R), moderately resistant (MR), moderately susceptible (MS), susceptible (S) and highly susceptible (HS). Accessions IC259504 (Vigna vexillata) and IC424616 (Vigna mungo) were immune and resistant to bruchid infestation respectively. Moreover, the genetic diversity parameters such as allele number, PIC values and observed heterozygosity indicated considerable diversity among the accessions. The reported immune and resistant accessions could be used as donor parents in the Vigna breeding programme for transferring bruchid resistance factor(s) to agronomically superior cultivars.