Evaluation of biophysical, anatomical and biochemical traits of resistance to Sitophilus oryzae L (Coleoptera: Curculionidae) in stored maize

Sitophilus oryzae L is the most destructive insect pest of stored maize and is widely distributed in tropical regions. In the present study, eighteen maize genotypes were screened for several susceptibility parameters against S. oryzae by using «No Choice method». Biophysical traits (test weight, thousand kernel weight, kernel hardness), anatomical fractions (tip cap, germ, pericarp, endosperm), biochemical variants (starch, protein, oil, sugar) were correlated with insect susceptibility parameters. There is significant relationship among test weight, kernel hard- ness, and insect susceptibility parameters. Pericarp was positively correlated while endosperm, starch content were negatively correlated with median development period but were non-significant. Majority of the maize geno- types containing harder kernels and thick pericarp showed less susceptibility to S. oryzae. The results indicated that the biophysical, anatomical and biochemical traits are responsible for varying levels of resistance to S. oryzae

Role of soluble, cell wall bound phenolics, tannin and flavonoid contents in maize resistance to pink stem borer Sesamia inferens Walker

The pink stem borer Sesamia inferens Walker is an important pest of winter maize which causes significant yieldlosses. In an attempt to identify the biochemical basis of resistance against S. inferens, total soluble phenolics, boundphenolics, cell wall-bound hydroxycinnamic acids-p-coumaric acid (p-CA), ferulic acid (FA), total tannin contentand total flavonoid contents, were measured in leaf at 10, 20 days after germination (DAG); stem at 20, 40 DAG;pith and rind tissues at 60 DAG (stem differentiated). From the present study, it was found that bound phenolics,p-CA, ferulic acid and total tannin contents contribute to the maize defense mechanism against S. inferens. Totalbound phenolic content showed negative correlation with Leaf Injury Rating (LIR). Highly significant strong positivecorrelation (+0.9750) was observed between LIR and total soluble phenolics in leaf tissue at 20 DAG. Similarlyhighly significant strong positive correlation between LIR and total tannins (+0.9354**) and flavonoids (+0.9582**)in pith at 60 DAG was observed. Further, a strong significant positive correlation was also observed between LIRand p-CA (+0.9199*) in pith at 60 DAG and total ferulic acid (+0.9051*) in rind at 60 DAG. The significant strong negativecorrelation between LIR and p-CA (-0.8441*) in stem at 40 DAG was observed. The total bound phenolicsin rind at 60 DAG (0.756), in leaf at 20 DAG (0.681), and total soluble phenolics in the stem at 20 DAG (0.685) showedhigher loadings with PC1, PC2, and PC3, respectively. Genotype-by-biochemical factor biplot showed that thedata of biochemical parameters measured in different tissues and stages could be able to group the genotypesaccording to their reaction to S. inferens

Strategic selection of white maize inbred lines for tropical adaptation and their utilization in developing stable, medium to long duration maize hybrids

White maize plays an important role in human diet, especially in traditional crop growing regions of northern hill region, north-eastern states and central-western parts of India. Breeding efforts to enhance the genetic potential of white maize was not so prominent as compared to yellow maize in the country. As a result, genetic base of the material utilized in white maize breeding program in India is very narrow and majorly contains indigenous germplasm and few introductions. Hence, efforts were made to use 365 white maize inbred lines from CIMMYT, Mexico, for breeding program. These new inbred lines were grown at winter nursery center, Indian Institute of Maize Research, New Delhi for its tropical adaptation. After preliminary evaluation, a total 47 inbred lines were selected and evaluated in randomized complete block design with two replications at Regional Maize Research and Seed Production Centre, Begusarai, Bihar, during rabi 2014. Out of this top performing 12 inbred lines viz, CML 47, CML 95, CML 314, CML 319, CML 377, CML 488, CML 494, CML 504, CML 517, CML 522, CML 531 and CML 538 were selected and were crossed in diallel manner to obtain 66 medium to long duration experimental hybrids. Stability analysis using AMMI model was done to identify adaptive hybrids with high yielding potentiality. According to the ASVi value obtained, the hybrid G38 appeared to be stable followed by G50 and G44. On the other hand, the hybrid G25 appeared as location specific hybrid suitable for high input conditions

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Not AvailableGlobally, maize is an important cereal food crop with the highest production and productivity. Among the biotic constraints that limit the productivity of maize, the recent invasion of fall armyworm (FAW) in India is a concern. The first line of strategy available for FAW management is to evaluate and exploit resistant genotypes for inclusion in an IPM schedule. Screening for resistant maize genotypes against FAW is in its infancy in India, considering its recent occurrence in the country. The present work attempts to optimize screening techniques suited to Indian conditions, which involve the description of leaf damage rating (LDR) by comparing injury levels among maize genotypes and to validate the result obtained from the optimized screening technique by identification of lines potentially resistant to FAW under artificial infestation. Exposure to 20 neonate FAW larvae at the V 5 phenological stage coupled with the adoption of LDR on a 1–9 scale aided in preliminary characterize maize rize maize genotypes as potentially resistant, moderately resistant, and susceptible. The LDR varies with genotype, neonate counts, and days after infestation. The genotypes, viz., DMRE 63, DML-163-1, CML 71, CML 141, CML 337, CML 346, and wild ancestor Zea mays ssp. parviglumis recorded lower LDR ratings against FAW and can be exploited for resistance breeding in maize.ICAR-NAS

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Not AvailableA Decision Support System (DSS) for efficient utilization of maize inbred line germplasm has been developed using the latest version of Drupal (7.34); Hypertext Preprocessor (PHP) was used for frontend development and database (backend) was developed in My Structured Query Language (MySql). The DSS houses a database with information on 12 traits viz. days to 50% anthesis, days to 50% silk emergence, density of spikelets, number of kernel rows, grain type, plant height, ear placement height, anthocyanin colouration at base of glume, anthocyanin colouration of anthers, anthocyanin colouration of silks, kernel row arrangement and 1000-kernel weight against each inbred lines in addition it has Image Library feature which displays ear and tassel images of the maize inbred lines. The system was designed as per the requirements and available at http://wnciimr.org. The DSS is first of its kind developed for maize in India. It helps in taking informed decision to accelerate the utilization of germplasm. It significantly reduces the duplicity of experiments to generate information on simply inherited traits and thus, enhances the scientific productivity to a great extent.Not Availabl

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Not AvailableBreeding stress-resilient cereals is a prerequisite to sustaining the food and nutritional security in the era of climate change. The number of cereal genome sequences and the number of genomic resources are growing with the advent of a technological revolution in genomics and molecular biology. These genomic innovations resulted in advanced next-generation cereal breeding methods to improve the genetic gain per unit time. Many contemporary next-generation breeding methods necessitate the genetic and genomic resources for target trait improvement. Therefore, the cereal genetic resources are a substantial opportunity for stress-resilient cereal breeding, preservation, and maintenance of genetic diversity. Interestingly, broad genetic variability for stress-resilient traits in cultivated varieties, landraces, and wild relatives is preserved and actively used in the breeding pipeline. Further, contemporary cereal breeding techniques, viz. genome-wide association mapping, genomic selection, and genome editing, have resulted in various sequence resources, databases, and software packages. These genomic resources are assisting the translational cereal genomics in addition to the promotion of comparative genomics to accelerate discovery and functional analyses of genes in cereals and model plants. Additionally, various bioinformatic platforms and associated databases for stress-resilient cereal breeding are expected to play key roles in designing effective breeding strategies to make the best use of genomic resources in cereals. Here, we summarised genomic resources, bioinformatic tools, and databases made available in cereal omics towards their possible utility in the next-generation cereal breeding for stress resilience.Not Availabl

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Not AvailableThe pink stem borer Sesamia inferens Walker is an important pest of winter maize, causing dead hearts and significant yield losses. In an attempt to decipher biochemical basis of resistance against S. inferens, total soluble phenolics, bound phenolics, total tannin content, total flavonoid content, cell wall bound hydroxycinnamic acids-p-coumaric acid (p-CA) and ferulic acid were measured in leaf at 10, 20 days after germination(DAG); stem at 20,40 DAG; pith and rind tissues at 60 DAG (stem differentiated). Higher quantities of phenolic compounds except total soluble phenolics and total flavonoid contents were found in either resistant (DMRE63) or moderately resistant lines (WNZPBTL3,WNZExotic Pool) compared to susceptible genotypes (BML6, CM202). Significant negative correlation (r=-0.8441*) between leaf injury rating and p-CA content in stem tissues at 40 DAG indicated its role in expression of resistance to S. inferens. The proportion of spread of various biochemical constituents of different genotypes ranged from 50.59 to 19.19% as determined according to Eigen analysis. From the results, it can be concluded that higher concentrations of p-CA, ferulic acid and total tannin content are the possible biochemical defense mechanisms in maize against S.inferens.Not Availabl

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Not AvailableMaize (Zea mays L.) is the third most important cereal food crop after wheat and rice, grown in an area of 9.2 million ha with the production of 30.2 million MT (DES, 2021). Pink stem borer (PSB), Sesamia inferens Walker is one of the major insect pests in the winter maize resulting in 25.7-78.9 percent yield losses (Siddiqui and Marwaha 1993). The larvae feed inside the leaf sheath in groups and subsequently bore into the central shoot resulting in the formation of dead hearts. Understanding the mechanisms of Host Plant Resistance (HPR) can provide an opportunity to manage PSB. HPR is an economically viable, environmentally friendly, and sustainable strategy and is one of the most effective components of integrated pest management (IPM) modules. Understanding the plant-insect interactions is of utmost importance for developing effective pest management approaches. Therefore, the present study was undertaken to study whether the resistance was inducted in response to plant-insect and/or non-insect interactions. Materials and methods The experiment was conducted in two different sets one each to record the response of genotypes upon PSB infestation and defense responses of the genotypes against different treatments in field and pot, respectively. To investigate the maize defense responses, five treatments were designed including insect and non-insect interactions namely (i) control (untreated plants) (ii) PSB larvae infestation, (iii) mechanical wounding, (iv) mechanical wounding plus PSB regurgitation, (v) exposure to methyl jasmonate. The treatments were imposed at two stages i.e.V3 and V6 stages in resistant, moderately resistant and susceptible genotypes. Maize genotypes were categorized The quantification of two major defense related cell wall bound phenolic compounds namely p-Coumaric acid (p-CA) and ferulic acid (FA) was carried out through ultra-fast liquid chromatography (UFLC). The effect of induced treatments on p-CA and FA content at each sampling time were subjected to two-way ANOVA by using a general linear model (PROC GLM) using SAS version 9.3. Results and Discussion The p-CA content induced in leaf tissues of maize genotypes were intrinsically higher when challenged by PSB attack at V3 and V6 stages in short- and long-term responses. Higher p-CA content was observed in stalk tissues upon wounding and regurgitation in short- and long-term responses at V3 and V6 stages. Significant accumulation of FA content was also observed in leaf tissues in response to PSB feeding at V3 stage in long-term response while at V6 stage it was observed both in short- and long-term responses. In stalk tissues, methyl jasmonate induced higher FA content in short-term response at V3 stage. However, at V6 stage PSB feeding induced FA accumulation in the short-term while, wounding and regurgitation treatment-induced defense responses in the long-term. The study indicates that phenolic mediated defense responses in maize are induced by PSB attack followed by wounding and regurgitation and the response observed was more in resistant genotypes compared to susceptible ones. Breeding for the restoration of these defense chemicals or cross species transfer of defense metabolite production may harness the chemical defense capabilities of maize resulting in effective pest management.Not Availabl

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Not Availablesignificant implications for sustainable pest management. The present study demonstrated that PSB feeding, mechanical wounding, a combination of mechanical wounding and PSB regurgitation and exogenous application of methyl jasmonate have induced phenolic compound mediated defense responses both at short term (within 2 days of treatment) and long term (in 15 days of treatment) in leaf and stalk tissues of maize. The quantification of two major defense related phenolic compounds namely p-Coumaric acid (p-CA) and ferulic acid (FA) was carried out through ultra-fast liquid chromatography (UFLC) at 2 and 15 days after imposing the above treatments. The p-CA content induced in leaf tissues of maize genotypes were intrinsically higher when challenged by PSB attack at V3 and V6 stages in short- and long-term responses. Higher p-CA content was observed in stalk tissues upon wounding and regurgitation in short- and long-term responses at V3 and V6 stages. Significant accumulation of FA content was also observed in leaf tissues in response to PSB feeding at V3 stage in long-term response while at V6 stage it was observed both in short- and long-term responses. In stalk tissues, methyl jasmonate induced higher FA content in short-term response at V3 stage. However, at V6 stage PSB feeding induced FA accumulation in the short-term while, wounding and regurgitation treatment-induced defense responses in the long-term. In general, the resistant (DMRE 63, CM 500) and moderately resistant genotypes (WNZ ExoticPool) accumulated significantly higher contents of p-CA and FA content than susceptible ones (CM 202, BML 6) in most of the cases. The study indicates that phenolic mediated defense responses in maize are induced by PSB attack followed by wounding and regurgitation compared to the other induced treatments. Furthermore, the study confirmed that induced defense responses vary with plant genotype, stage of crop growth, plant tissue and short and long-term responses. The results of the study suggested that the Phenolic acids i.e. p-CA and FA may contribute to maize resistance mechanisms in the maize-PSB interaction system.Not Availabl