Indian Institute of Maize Research
Recent publications
Conventional agricultural practices rely heavily on chemical fertilizers to boost production. Among the fertilizers, phosphatic fertilizers are copiously used to ameliorate low-phosphate availability in the soil. However, phosphorus-use efficiency (PUE) for major cereals, including maize, is less than 30%; resulting in more than half of the applied phosphate being lost to the environment. Rock phosphate reserves are finite and predicted to exhaust in near future with the current rate of consumption. Thus, the dependence of modern agriculture on phosphatic fertilizers poses major food security and sustainability challenges. Strategies to optimize and improve PUE, like genetic interventions to develop high PUE cultivars, could have a major impact in this area. Here, we present the current understanding and recent advances in the biological phenomenon of phosphate uptake, translocation, and adaptive responses of plants under phosphate deficiency, with special reference to maize. Maize is one of the most important cereal crops that is cultivated globally under diverse agro-climatic conditions. It is an industrial, feed and food crop with multifarious uses and a fast-rising global demand and consumption. The interesting aspects of diversity in the root system architecture traits, the interplay between signaling pathways contributing to PUE, and an in-depth discussion on promising candidate genes for improving PUE in maize are elaborated.
Cold temperature is a devastating abiotic stress for rice production, especially in the areas where low temperature prevails throughout the crop duration or in particular growth stages. Boro cultivation season in eastern India is such a replica of rice cultivation under occasional colder climate. Therefore, it is imperative to study a large collection of germplasms for potential cold tolerant stocks. In this study, 106 germplasms from eastern India were cultivated during Boro season in field as well as under 10 °C and 28 °C temperature conditions inside plant growth chamber. Six seedling growth parameters were used as phenotypic markers and 56 cold tolerance quantitative trait loci linked simple sequence repeats (SSRs) were utilized as molecular markers. Leaf yellowing and germination index were also incorporated within the framework of cold tolerance screening to enrich the multidimensional approach. Based on the k-means clustering for each morphological parameter in each condition, the genotypes were ranked and the resulting total ranks for each genotype eventually grouped them into four clusters, i.e. highly susceptible, susceptible, moderately tolerant and tolerant as different level of cold tolerance. Among the screened SSRs, only 33 were polymorphic and most informative were RM336, RM566 and RM1349 due to higher marker efficiency threshold. Combining both morphology and molecular analysis, highly tolerant landraces such as Neera, Barnamali, Khaiya Boro and genotypes such as Purbachi, CB1, Gotra, UPR 103-80 were identified which may be of greater use in development of high yielding cold tolerant genotypes.
Drought stress has severely hampered maize production, affecting the livelihood and economics of millions of people worldwide. In the future, as a result of climate change, unpredictable weather events will become more frequent hence the implementation of adaptive strategies will be inevitable. Through utilizing different genetic and breeding approaches, efforts are in progress to develop the drought tolerance in maize. The recent approaches of genomics-assisted breeding, transcriptomics, proteomics, transgenics, and genome editing have fast-tracked enhancement for drought stress tolerance under laboratory and field conditions. Drought stress tolerance in maize could be considerably improved by combining omics technologies with novel breeding methods and high-throughput phenotyping (HTP). This review focuses on maize responses against drought, as well as novel breeding and system biology approaches applied to better understand drought tolerance mechanisms and the development of drought-tolerant maize cultivars. Researchers must disentangle the molecular and physiological bases of drought tolerance features in order to increase maize yield. Therefore, the integrated investments in field-based HTP, system biology, and sophisticated breeding methodologies are expected to help increase and stabilize maize production in the face of climate change.
Modern monoculture oriented intensive maize cultivation is facing multiple biotic and abiotic stresses and various soil fertility linked issues, which compels to adopt sustainable approaches to deal with these yield limiting factors. On the other hand, simultaneous cultivation of two or more plant species in same plot, i.e. polyculture, provides eco-friendly and cost-effective insurance against crop failures in the adverse situations. In addition, maize-based intercropping systems provide better overall yields and monetary returns, diversify the agriculture produce, suppress biotic pressures (weed, pest and disease), improve soil fertility, conserve soil and water and also enhance fodder yield and quality. By providing increased pest control, trap/border crops can be low-cost and environment-friendly option for biotic stress management particularly in organic production systems. Moreover, agroforestry in maize systems enhances the soil fertility and soil carbon status, improves stress resilience and can help in climate change mitigation. However, the success of polyculture depends on environmental factors, compatibility among companion crops and their planting patterns. Co-culture of two different kinds of crops need different sets of skills and some extra efforts, especially during planting and harvesting. Further, intercropping is not much friendly with seed-to-seed mechanization and also put restrictions on chemical weed control, which hinders its adoption in intensive cropping systems. The present review highlights the role of maize-based polyculture systems in enhancing the land productivity and addressing the biotic and abiotic stresses while reducing input-use.
The northwestern Himalayas (NWH) in India have low rice productivity (∼2 t ha−1) and quality due to poor crop and nutrient management in predominantly Zn-deficient soils. Hence, a field experimentation in the NWH compared the conventionally transplanted rice (CTR) and the system of rice intensification (SRI) under three nutrient management practices (NMPs), viz., 1) farmers’ fertilization practice, FYM @ 5 t ha−1 + N:P2O5:K2O @ 50:40:20 kg ha−1 (FFP); 2) recommended dose of fertilization, FYM @ 10 t ha−1 + N:P2O5:K2O @ 90:40:40 kg ha−1 (RDF); and 3) RDF + Zn fertilization using ZnSO4 @ 25 kg ha−1 (RDF + Zn). The results revealed that SRI practice harnessed a significantly higher rice yield under different NMPs (6.59–8.69 t ha−1) with ∼1.3–1.4- and ∼3.3–4.3-fold enhancements over the CTR and average rice productivity in NWH, respectively. SRI had the greatest improvement in panicle number hill−1 by ∼2.4 folds over the CTR. RDF + Zn had a significantly higher grain (10.7; 7.9%) and straw yield (28.9; 19.7%) over FFP and RDF, respectively, with significant augmentation of Zn biofortification in grains (11.8%) and Zn uptake (23.9%) over the RDF. SRI also enhanced the Zn concentrations in rice grains and straws by ∼4.0 and 2.7% over CTR with respective increases of 36.9 and 25.9% in Zn uptake. The nutrient harvest index and partial factor productivity of applied nutrients (NPK) had a higher magnitude under SRI and RDF + Zn over their respective counterparts, i.e., CTR and RDF. In addition, SRI had higher AE-Zn, CRE-Zn, and PE-Zn to the tune of 119.6, 63.4, and 34%, respectively, over the CTR. Overall, SRI coupled with RDF + Zn in hybrid rice assumes greater significance in enhancing the rice productivity with better Zn-biofortified grains besides higher nutrient use efficiencies to combat widespread malnutrition and acute Zn deficiencies in humans and livestock in the northwestern Himalayas.
Wheat (Triticum aestivum L. AABBDD; Family Poaceae) is a prime dietary cultivated cereal that is consumed worldwide by nearly 20% of the world population. However, due to cosmopolitan distribution, there are a wide plethora of biological variables that seriously threaten wheat productivity around the world. Out of 31 major pathogens and pests reported, the fungal smut and bunt causing agents put serious threat and have drawn much wider attention in the last few decades. These seed-targeted diseases damage seed quality and quantity and are managed through improved agronomic approaches and resistant varieties. However, maintaining multiple resistances in particular single-wheat cultivars has to be a high priority especially during disease epidemics. Therefore, in order to shape the breeding efforts as well as more precise, sustainable, and effective disease management, the present chapter highlights the biology of smut and bunts, management strategies including physical, chemical, biological, cultural, integrated methods, and molecular diagnostics in a detailed manner.
Global climate change leads to the con- currence of a number of abiotic stresses including moisture stress (drought, waterlogging), temperature stress (heat, cold), and salinity stress, which are the major factors afecting maize production. To develop abiotic stress tolerance in maize, many quantitative trait loci (QTL) have been identifed, but very few of them have been utilized successfully in breeding programs. In this context, the meta-QTL analysis of the reported QTL will enable the identifcation of sta- ble/real QTL which will pave a reliable way to intro- gress these QTL into elite cultivars through marker- assisted selection. In this study, a total of 542 QTL were summarized from 33 published studies for toler- ance to diferent abiotic stresses in maize to conduct meta-QTL analysis using BiomercatorV4.2.3. Among those, only 244 major QTL with more than 10% phe- notypic variance were preferably utilised to carry out meta-QTL analysis. In total, 32 meta-QTL pos- sessing 1907 candidate genes were detected for dif- ferent abiotic stresses over diverse genetic and envi- ronmental backgrounds. The MQTL2.1, 5.1, 5.2, 5.6, 7.1, 9.1, and 9.2 control diferent stress-related traits for combined abiotic stress tolerance. The candidate genes for important transcription factor families such as ERF, MYB, bZIP, bHLH, NAC, LRR, ZF, MAPK, HSP, peroxidase, and WRKY have been detected for diferent stress tolerances. The identifed meta-QTL are valuable for future climate-resilient maize breed- ing programs and functional validation of candidate genes studies, which will help to deepen our under- standing of the complexity of these abiotic stresses.
Wheat and barley are the main staple food crops all over the world. In present scenario of ever growing world population, there is a need of continuous increase in wheat and barley production. Unfortunately, both these crops experienced plethora of problems in successful cultivation mainly biotic and abiotic stresses. A lot of attempts have been made to fine tune the agronomic and breeding strategies to cope the stress problems in wheat and barley for attaining maximum potential production. However, these have some constraints and limitations in existing technologies. In this context, there is constant need for practical, rational and accurate technique like nanotechnology which can beat these limitations. A flood of literature demonstrating the application of nanotechnology in the management of biotic and abiotic stress problems in agricultural crops are being published, but very little and fragmentary information in relation to wheat and barley crops is available. In this chapter, attempts have been made to highlight the potential of nanotechnology as a management solution to combat wheat and barley stresses. The chapter specifically describes the potential mechanisms underlying the interactions of nanoparticles with wheat and barley and explores the potential role of engineered nanoparticles. Further, discussion in light of the available literature, as well as the challenges and research gaps that may be instrumental to plan future strategy for timely management of biotic and abiotic stresses have been covered.
The conventionally managed cereal-based cropping systems in the Indo-Gangetic Plains (IGP) of South Asia are most energy-consuming that overwhelm the farm profits and the environment. This research addresses a complex nexus between yield-energy-water-GHG footprints-economics of conservation agriculture (CA)-based intensified maize-wheat-mungbean rotation. This study evaluated the effect of long-term CA (2012–2020) with optimum nutrient management (2017–20) on energy budgeting, productivity, water and C-footprints, Water productivity (WP), and economics of the CA-based maize-wheat-mungbean system. CA-based permanent bed- and zero tillage flatbed with preceding crop residue retention were compared with the conventional till with preceding crop residue incorporation. These treatments were factored over three-nutrient management alternatives, i.e., GreenSeeker®-guided-N, site-specific nutrient management (SSNM), and recommended fertilizers' dose (Ad-hoc), were compared with farmers' fertilizers practices (FFP). Permanent bed and zero tillage treatments registered higher systems' productivity (18.2 and 12.0%), net returns (44.7 and 34.7%), WP (35.6% and 22.1%), and C-sequestration (54.8 and 62.3%), respectively, over conventional till. Permanent bed- and zero tillage treatments increased the systems' net energy (NE), energy use efficiency (EUE), energy productivity (EP), and energy intensity (EI) by 22.6 and 14.0; 10.1 and 5.6; 9.7 and 5.4; 28.3 and 24.0%, respectively, over conventional till. Conventional till recorded higher net CO2-eq emission (26.5 and 27.2%), C-footprint (20.8 and 14.5%), and water footprint (27.3 and 18.0%) than permanent bed- and zero tillage treatments. SSNM increased the system's productivity, WP, and EUE, while reducing the system's water- and C-footprints and net CO2-eq emission. Thus, adopting permanent beds as a crop establishment method with SSNM could be a feasible alternative to attain higher productivity, profitability, and resource use efficiency in the maize-wheat-mungbean system in northwest India.
In recent years, deep learning techniques have shown impressive performance in the field of identification of diseases of crops using digital images. In this work, a deep learning approach for identification of in-field diseased images of maize crop has been proposed. The images were captured from experimental fields of ICAR-IIMR, Ludhiana, India, targeted to three important diseases viz. Maydis Leaf Blight, Turcicum Leaf Blight and Banded Leaf and Sheath Blight in a non-destructive manner with varied backgrounds using digital cameras and smartphones. In order to solve the problem of class imbalance, artificial images were generated by rotation enhancement and brightness enhancement methods. In this study, three different architectures based on the framework of ‘Inception-v3’ network were trained with the collected diseased images of maize using baseline training approach. The best-performed model achieved an overall classification accuracy of 95.99% with average recall of 95.96% on the separate test dataset. Furthermore, we compared the performance of the best-performing model with some pre-trained state-of-the-art models and presented the comparative results in this manuscript. The results reported that best-performing model performed quite better than the pre-trained models. This demonstrates the applicability of baseline training approach of the proposed model for better feature extraction and learning. Overall performance analysis suggested that the best-performed model is efficient in recognizing diseases of maize from in-field images even with varied backgrounds.
The development of low glycaemic index maize varieties requires screening of a large number of inbreds in shortest time. Conventional amylose estimation methods are tedious, time consuming and involve high reagent costs. A simple and rapid screening method has been designed for amylose estimation in maize kernels, which is based on the principle of amylose-iodine complex formation. The method is named as cut grain dip method (CGD). The CGD method involved cutting of maize kernel longitudinally to expose the endosperm, followed by treatment with optimized potassium iodide:iodine (2:1) solution on the cut end and recording the time involved for maximum colouration. It was observed that time taken for iodine to reach its maximum colouration had an inverse relation to the amylose content (AC) in maize kernel. The method was validated in a large set of maize samples with varied amylose content and automation was also done with the use of AlphaView SA software. The proposed CGD method is a rapid and simple for screening of maize kernels with varied AC. The method does not rely upon costly reagents and gets completed in 1 min, therefore is suitable for large-scale screening of maize germplasm including mutants and wild types.
Background: The occurrence of Spodoptera frugiperda (J.E. Smith) in Asia was reported for the first time from Karnataka in 2018. This pest is widely distributed in India, causing significant damage to maize. Management of this recent invasive pest in maize growing regions of India relies upon chemical control. Resistance is the greatest obstacle to the successful use of chemical insecticides to control this pest. Indiscriminate use of chemical insecticides destroys beneficial natural enemies. Therefore effective and sustainable alternative control strategies are needed. In this case, the use of biological control agents is the alternative option to mitigate this pest. Thus, this study aimed to select virulent entomopathogenic nematodes (EPN) isolates based on the laboratory assay and further to test the efficacy of virulent isolates in the field condition along with commonly used chemical insecticide emamectin benzoate against S. frugiperda. Results: Laboratory results revealed that both Heterorhabditis indica 1 NBAIIH38 and Steinernema carpocapsae NBAIRS59 caused 100% mortality in third- and fourth-instar larvae of S. frugiperda, while these two species caused 82.5 and 75.0% mortality in pupae, respectively. When pupae of S. frugiperda were exposed to EPNs, pupae died after metamorphosis to malformed adult. All the nematode species were able to penetrate and reproduce within S. frugiperda larvae, but the reproduction rate for Heterorhabditids was higher than those of Steinernematids. Field trial results showed that H. indica 1 NBAIIH38 significantly reduced the number of larvae and leaf damage scores than S. carpocapsae NBAIRS59. Emamectin benzoate was more effective in reducing the larval population compared to EPNs species. The cob yield was significantly higher in EPN-and emamectin benzoate-treated plots than untreated control plots. Conclusion: Overall, these experiments suggest H. indica 1 NBAIIH38 to be a promising biocontrol agent against S. frugiperda in maize production. This article is protected by copyright. All rights reserved.
The development of quality protein maize (QPM) was considered a significant leap toward improvement in the nutritional status of rural masses in developing countries. The nutritional quality of QPM is attributed to the higher concentration of essential amino acids, particularly lysine and tryptophan, in its kernel endosperm. However, the similarity in the grains of QPM and normal maize necessitates the development of a standard protocol to assess the protein quality of maize. The present study aimed at improving the protocol of protein quality assessment in QPM. For this purpose, endosperm defatting and protein estimation procedures were restandardized and optimized with respect to the protocol duration and its amenability for high-throughput analysis. Unlike normal maize, QPM and opaque-2 mutants were completely defatted within a 48 h period. It was observed that the tryptophan content, calculated at each defatting interval, increased in the samples defatted for a longer duration. No significant differences were observed in the tryptophan content analyzed in the samples defatted for 48 and 72 h. Moreover, the endosperm protein estimated by using the Bradford method with certain modifications strongly correlated with the micro-Kjeldahl method (r = 0.9). Relative to the micro-Kjeldahl method, the Bradford method was found to be precise, rapid, and hazard-free. The present findings enable a testing protocol of reduced time duration that can be used in resource-poor settings for the determination of a protein quality assay in QPM. Overall, the present study effectively helped in reducing the defatting time by 24 h and protein estimation by 3 h as compared to the already established International Maize and Wheat Improvement Center protocol. This is expected to enable the aggregation of high-protein-quality maize to facilitate its commercialization.
Citation: Kumar, B.; Choudhary, M.; Kumar, P.; Kumar, K.; Kumar, S.; Singh, B.K.; Lahkar, C.; M.; Kumar, P.; Dar, Z.A.; et al. Population Structure
Advances in sequencing technologies and bioinformatics tools have fueled a renewed interest in whole genome sequencing efforts in many organisms. The growing availability of multiple genome sequences has advanced our understanding of the within-species diversity, in the form of a pangenome. Pangenomics has opened new avenues for future research such as allowing dissection of complex molecular mechanisms and increased confidence in genome mapping. To comprehensively capture the genetic diversity for improving plant performance, the pangenome concept is further extended from species to genus level by the inclusion of wild species, constituting a super-pangenome. Characterization of pangenome has implications for both basic and applied research. The concept of pangenome has transformed the way biological questions are addressed. From understanding evolution and adaptation to elucidating host-pathogen interactions, finding novel genes or breeding targets to aid crop improvement to design effective vaccines for human prophy-laxis, the increasing availability of the pangenome has revolutionized several aspects of biological research. The future availability of high-resolution pangenomes based on reference-level near-complete genome assemblies would greatly improve our ability to address complex biological problems .
Several maize breeding programs in India have developed numerous inbred lines but the lines have not been characterized using high-density molecular markers. Here, we studied the molecular diversity, population structure, and linkage disequilibrium (LD) patterns in a panel of 314 tropical normal corn, two sweet corn, and six popcorn inbred lines developed by 17 research centers in India, and 62 normal corn from the International Maize and Wheat Improvement Center (CIMMYT). The 384 inbred lines were genotyped with 60,227 polymorphic single nucleotide polymorphisms (SNPs). Most of the pair-wise relative kinship coefficients (58.5%) were equal or close to 0, which suggests the lack of redundancy in the genomic composition in the majority of inbred lines. Genetic distance among most pairs of lines (98.3%) varied from 0.20 to 0.34 as compared with just 1.7% of the pairs of lines that differed by <0.20, which suggests greater genetic variation even among sister lines. The overall average of 17% heterogeneity was observed in the panel indicated the need for further inbreeding in the high heterogeneous genotypes. The mean nucleotide diversity and frequency of polymorphic sites observed in the panel were 0.28 and 0.02, respectively.The model-based population structure, principal component analysis, and phylogenetic analysis revealed three to six groups with no clear patterns of clustering by center-wise breeding lines, types of corn, kernel characteristics, maturity, plant height, and ear placement. However, genotypes were grouped partially based on their source germplasm from where they derived.
Key message Improving crop resistance against insect pests is crucial for ensuring future food security. Integrating genomics with modern breeding methods holds enormous potential in dissecting the genetic architecture of this complex trait and accelerating crop improvement. Abstract Insect resistance in crops has been a major research objective in several crop improvement programs. However, the use of conventional breeding methods to develop high-yielding cultivars with sustainable and durable insect pest resistance has been largely unsuccessful. The use of molecular markers for identification and deployment of insect resistance quantitative trait loci (QTLs) can fastrack traditional breeding methods. Till date, several QTLs for insect pest resistance have been identified in field-grown crops, and a few of them have been cloned by positional cloning approaches. Genome editing technologies, such as CRISPR/Cas9, are paving the way to tailor insect pest resistance loci for designing crops for the future. Here, we provide an overview of diverse defense mechanisms exerted by plants in response to insect pest attack, and review recent advances in genomics research and genetic improvements for insect pest resistance in major field crops. Finally, we discuss the scope for genomic breeding strategies to develop more durable insect pest resistant crops.
Maize is an important crop for billions of people globally. The existing immature embryo-based regeneration protocol of maize has major limitations due to the non-availability of explants throughout the year, limited durability for culturing, and its laborious nature. Mature embryos, especially in tropical maize, are considered recalcitrant towards tissue culture. Therefore, standardization of a robust regeneration and transformation protocol in tropical maize using mature embryos or seeds as starting material is long envisaged. Considering this, in this study, 28 diverse tropical maize genotypes were evaluated for their embryogenic callus induction potential using two different explants (nodal explants and split embryo region) under two different callusing media. Out of 28 genotypes, better callus induction was achieved in four genotypes (BML 6, DHM 117, DMRH 1301, and DMRH 1308) from nodal explants. Further, in vitro regeneration was standardized using 22 different combinations of various auxins and cytokinins. Out of 28 genotypes, two recently commercialized and high-yielding cultivars (DMRH 1301 and DMRH 1308) demonstrated the best callusing and regeneration capability with an average regeneration percentage of 60.4% and 53.6%, respectively. Using the nodal explants-derived embryogenic calli, the genetic transformation was successfully carried out using the ‘Biolistic’ approach, and up to ~ 5% transformation efficiency was achieved. This efficient regeneration and transformation protocol can overcome the major limitations associated with the existing immature embryo-based protocol in tropical maize as mature seeds can be obtained easily in ample quantity round the year. Such a generalized and reproducible protocol has the potential to be a major tool for maize improvement using transgenic and genome-edited techniques.
Salinity stress adversely affects plant growth and causes considerable losses in cereal crops. Salinity stress tolerance is a complex phenomenon, imparted by the interaction of compounds involved in various biochemical and physiological processes. Conventional breeding for salt stress tolerance has had limited success. However, the availability of molecular marker-based high-density linkage maps in the last two decades boosted genomics-based quantitative trait loci (QTL) mapping and QTL-seq approaches for fine mapping important major QTL for salinity stress tolerance in rice, wheat, and maize. For example, in rice, ‘Saltol’ QTL was successfully introgressed for tolerance to salt stress, particularly at the seedling stage. Transcriptomics, proteomics and metabolomics also offer opportunities to decipher and understand the molecular basis of stress tolerance. The use of proteomics and metabolomics-based metabolite markers can serve as an efficient selection tool as a substitute for phenotype-based selection. This review covers the molecular mechanisms for salinity stress tolerance, recent progress in mapping and introgressing major gene/QTL (genomics), transcriptomics, proteomics, and metabolomics in major cereals, viz., rice, wheat and maize.
Flour of millets is nutritionally better, as compared to cereals, but has problem of low shelf-life. Here, we analyzed the nutritional density, and shelf-life of flours of millets (pearl millet, foxtail millet), and cereals (wheat, maize) stored for different durations. We observed maximum starch content in cereals (70–80%) compared with millets (48–72%). The maximum resistant starch (1.2–3.2%), micronutrients (15–72 ppm) and balanced essential amino acids were observed in millets, as compared to cereals. Total lipid and fatty acids were observed maximum in pearl millet cv. Dhanshakti and minimum in wheat cv. HD2329. Percent decrease in the lipid and increase in the FFAs upon storage was observed maximum in pearl millet and minimum in wheat. Oxidative markers like AV and PV showed significant decrease with increase in storage of flours in millets and cereals. Lipase activity was observed maximum in millets followed by wheat, whereas it was negligible in maize. LOX, GPX and PPO activities were observed maximum in foxtail millet cv. DHFT and minimum in cereals. Millets and cereals showed increase in the activities of rancidity causing enzymes initially (up to 10 DAM) and further, decrease was observed. The information generated can be used to develop nutrient-dense pre-mixes with better keeping quality in order to achieve the supremacy of millets in real sense.
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25 members
N. Sunil
  • Winter Nursery Centre, Hyderabad
Dharam Chaudhary
  • Department of Biochemistry
Abhijit Das
  • Department of Genetics
Bharat Bhushan Nehru
  • Department of Biochemistry
J. C. Sekhar
Ludhiāna, India