Effect of Low-Temperature Stress on Plant Performance and Adaptation to Temperature Change

Low-temperatures (LT) stress is one of the abiotic stresses in plants that affect cell survival, cell division, photosynthesis, and water transport, negatively affecting plant growth, and eventually constraining crop productivity. LT stress is categorized as, (i) chilling stress where low temperature (0–15°C) causes injury without ice crystal formation in plant tissues, and (ii) freezing stress (<0°C), where ice formation occurs within plant tissues. Both stresses are together termed low temperature or cold stress. In general, plants originating from tropical and subtropical regions are sensitive to LT, whereas temperate plants showed chilling tolerance to variable degrees. Low-temperature stress negatively impacts plants, may affect the survival rate of crop plants, and also affect various processes, including cell division, photosynthesis, plant growth, development, metabolism, and finally reduce the yield of crop plants, especially in the tropics and subtropics. To overcome stress generated by low-temperature exposure, plants trigger a cascade of events that enhance their tolerance by gene expression changes and activation of the ROS scavenging system, thus inducing biochemical and physiological modifications. In this chapter, a detailed discussion of different changes in plants and their tolerance mechanism is done to understand the plant’s response under LT stress

Time course evaluation of provitamin A carotenoids stored under different storage regimens in maize

Yellow maize is natural source of provitamin A components. However, the provitamin A carotenoids are known to degrade fast as a result of oxidation and isomerization due to exposure to heat and oxygen during storage. Keeping this in view, here, we evaluated the provitamin A carotenoids in maize stored under different storage conditions. For this purpose, F2 grains of six hybrids consisting of two provitamin A rich, two QPM and two normal maize were stored in earthen pot, aluminium box, cotton cloth and jute bag for a period of 6 months under ambient temperature and carotenoid components were estimated at monthly interval. Provitamin A components are found to reduce significantly within two to six months under various storage conditions. However, the samples stored in aluminium box exhibited least degradation of β-carotene (73%) and β-cryptoxanthin (81%), whereas those stored in earthen pot exhibited highest degradation of β-carotene (86%) and β-cryptoxanthin (90%), after six months of storage. The provitamin A rich hybrids especially APH27 retained highest concentration of provitamin A carotenoids after six months of storage. The least losses observed in the samples stored in aluminium box may be attributed to reduced oxidation and least light penetration

Nitrogen Use Efficiency in Wheat: Genome to Field

Nitrogen (N), being the most limiting macroelement for optimal plant growth and development needs synthetic N fertilizer usage for uplifting crop yields; nevertheless, an excessive and inefficient use of N fertilizer is a global concern incurring high production costs, environment pollution, and greenhouse gas emissions. Hence, developing crop plants with high nitrogen use efficiency (NUE) is an essential research target to achieve a better agricultural sustainability. NUE being a complex trait depends on our understanding of genetics (G), environment (E), management (M), and their interrelationships (G x E x M). NUE improvement is preceded by key processes such as nitrogen capture, utilization efficiency, nitrogen partitioning, trade-offs between yield and quality aspects, as well as interactions with the capture and utilization of other nutrients. An in-depth knowledge can be attained on NUE mechanisms through the UK Wheat Genetic Improvement Network project (http://www.wgin.org.uk/) using an integrated strategy that look into the physiological, metabolic, molecular, and genetic aspects influencing NUE in wheat. The current book chapter highlights the recent progress in understanding and improving NUE in wheat, focussing on N impact on plant morphology and agronomic performances, using a combination of approaches, including whole-plant physiology and quantitative, forward and reverse genetics

Genetic and molecular understanding for the development of methionine-rich maize: a holistic approach

Maize (Zea mays) is the most important coarse cereal utilized as a major energy source for animal feed and humans. However, maize grains are deficient in methionine, an essential amino acid required for proper growth and development. Synthetic methionine has been used in animal feed, which is costlier and leads to adverse health effects on end-users. Bio-fortification of maize for methionine is, therefore, the most sustainable and environmental friendly approach. The zein proteins are responsible for methionine deposition in the form of δ-zein, which are major seed storage proteins of maize kernel. The present review summarizes various aspects of methionine including its importance and requirement for different subjects, its role in animal growth and performance, regulation of methionine content in maize and its utilization in human food. This review gives insight into improvement strategies including the selection of natural high-methionine mutants, molecular modulation of maize seed storage proteins and target key enzymes for sulphur metabolism and its flux towards the methionine synthesis, expression of synthetic genes, modifying gene codon and promoters employing genetic engineering approaches to enhance its expression. The compiled information on methionine and essential amino acids linked Quantitative Trait Loci in maize and orthologs cereals will give insight into the hotspot-linked genomic regions across the diverse range of maize germplasm through meta-QTL studies. The detailed information about candidate genes will provide the opportunity to target specific regions for gene editing to enhance methionine content in maize. Overall, this review will be helpful for researchers to design appropriate strategies to develop high-methionine maize

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Not AvailableMaize, an important cereal crop, has a poor quality of endosperm protein due to the deficiency of essential amino acids, especially lysine and tryptophan. Discovery of mutants such as opaque-2 led to the development of nutritionally improved maize with a higher concentration of lysine and tryptophan. However, the pleiotropic effects associated with opaque-2 mutants necessitated the development of nutritionally improved hard kernel genotype, the present-day quality protein maize (QPM). The aim of present study was to analyze and compare the temporal profile of lysine and tryptophan in the developing maize kernel of normal, opaque-2 and QPM lines. A declining trend in protein along with tryptophan and lysine content was observed with increasing kernel maturity in the experimental genotypes. However, opaque2 retained the maximum concentration of lysine (3.43) and tryptophan (1.09) at maturity as compared to QPM (lysine3.05, tryptophan-0.99) and normal (lysine-1.99, tryptophan-0.45) lines. Opaque-2 mutation affects protein quality but has no effect on protein quantity. All maize types are nutritionally rich at early stages of kernel development indicating that early harvest for cattle feed would ensure a higher intake of lysine and tryptophan. Two promising lines (CML44 and HKI 1105) can be used for breeding high value corn for cattle feed or human food in order to fill the protein inadequacy gap. Variation in lysine and tryptophan content within QPM lines revealed that differential expression of endosperm modifiers with varying genetic background significantly affects nutritional quality, indicating that identification of alleles affecting amino acid composition can further facilitate QPM breeding programNot Availabl

Assessment of quality of life in glaucoma patients in a tertiary care center in Eastern India

Purpose: The aim of this study is to assess the quality of life (QOL) in glaucoma patients and find out the sociodemographic factors predicting QOL. Methods: A cross-sectional study was conducted in a tertiary care center from August 2021 to February 2022. Subjects diagnosed with glaucoma for at least 6 months were enrolled. After taking informed consent, demographic details and detailed history were collected for all patients. Comprehensive eye examination (visual acuity, intraocular pressure, gonioscopy, fundoscopy, visual field assessment, ocular coherence tomogram assessment) was done for all and they were asked to fill the WHOQOL-BREF questionnaire. Data were collected and analyzed using SPSS 21. Results: One hundred and ninety-nine patients were recruited. Mean age of participants was 57.99 ± 10.76 years. Based on various domains and subgroups, QOL values were significant with respect to income (P = 0.016). Gender-wise QOL in females was lower than that of males with respect to all the domains (P = 0.001). While marital status affected both environmental and social domain, literacy affected only the social domain. A variation in intraocular pressure affected the QOL in the psychological domain. QOL was not significantly associated with the severity of the disease. Gender was the most predominant predictor out of all sociodemographic factors. Conclusion: Chronic diseases affect the QOL of individuals in many ways. Glaucoma being a chronic disease hampers patients' vision irreversibly and by extension the various physical, social, and psychological aspects of the patient's life as well. Hence, knowledge of the change in QOL it brings about can help plan the treatment, counseling, and management of these patients

Comparison of Dexamethasone Implant and Anti-VEGF Agents in the Treatment of Naive Diabetic Macular Oedema: A Prospective Cohort Study

Introduction: Diabetic Retinopathy (DR) is one of the common microvascular complications of diabetes. In patients with DR, the most frequent cause of vision loss is Diabetic Macular oedema (DME). In the present era, anti-Vascular Endothelial Growth Factor (anti-VEGF) agents are the mainstay of treatment for managing DME. A majority of patients show a good response to multiple doses of these agents administered by a pro re nata regimen at regularly spaced fixed intervals. However, the tendency of DME to become chronic and resistant to these agents, as well as the burden of repeated injections, necessitates considering alternative treatment options with similar or better efficacy. As steroids can address these drawbacks of anti-VEGF treatment, the present study compared the efficacy of anti-VEGF agents with dexamethasone implant in the treatment of naïve DME. Aim: To compare the effectiveness of dexamethasone implant with anti-VEGF agents in the treatment of naïve DME. Materials and Methods: A prospective cohort study was conducted in the Department of Ophthalmology at Kalinga Institute of Medical Sciences and Pradyumna Bal Memorial Hospital, Bhubaneswar, Odisha, India from September 2020 to September 2022. A total of 100 eyes with DME, newly diagnosed patients aged 18 years and above, without other macular oedema-causing diseases, were included. A total of 50 eyes in each group were treated with an anti-VEGF agent (Group A) or dexamethasone implant (Group B), and Best Corrected Visual Acuity (BCVA) and Central Foveal Thickness (CFT) were monitored for six months. For statistical analysis, paired t-test and independent t-test were used for within-group and inter-group analysis, respectively. A p-value <0.05 was considered statistically significant. Results: In both groups, post-treatment BCVA showed marked improvement, but there was no significant difference in mean BCVA between the groups (p=0.89) at six months. However, the mean CFT showed significant improvement in Group B at six months. In Group A, the mean CFT reduced from 441.87±54.48 μm to 257.83±25.73 μm, and in Group B, the mean CFT reduced from 464±109.44 μm to 207±22.51 μm at six months (p<0.0001). Adverse events like cataracts and glaucoma were seen in patients treated with the dexamethasone implant and were managed by cataract surgery and topical anti-glaucoma medications, respectively. Conclusion: Dexamethasone implant and anti-VEGF agents are equally effective in improving visual acuity; however, dexamethasone stands superior in reducing macular thickness. Needing fewer injections while treating with a dexamethasone implant improves compliance. The progression of cataract remains a major side-effect with the dexamethasone implant, which is not a concern when treating DME in pseudophakic eye

Image1_Unravelling the genetic framework associated with grain quality and yield-related traits in maize (Zea mays L.).jpeg

Maize serves as a crucial nutrient reservoir for a significant portion of the global population. However, to effectively address the growing world population’s hidden hunger, it is essential to focus on two key aspects: biofortification of maize and improving its yield potential through advanced breeding techniques. Moreover, the coordination of multiple targets within a single breeding program poses a complex challenge. This study compiled mapping studies conducted over the past decade, identifying quantitative trait loci associated with grain quality and yield related traits in maize. Meta-QTL analysis of 2,974 QTLs for 169 component traits (associated with quality and yield related traits) revealed 68 MQTLs across different genetic backgrounds and environments. Most of these MQTLs were further validated using the data from genome-wide association studies (GWAS). Further, ten MQTLs, referred to as breeding-friendly MQTLs (BF-MQTLs), with a significant phenotypic variation explained over 10% and confidence interval less than 2 Mb, were shortlisted. BF-MQTLs were further used to identify potential candidate genes, including 59 genes encoding important proteins/products involved in essential metabolic pathways. Five BF-MQTLs associated with both quality and yield traits were also recommended to be utilized in future breeding programs. Synteny analysis with wheat and rice genomes revealed conserved regions across the genomes, indicating these hotspot regions as validated targets for developing biofortified, high-yielding maize varieties in future breeding programs. After validation, the identified candidate genes can also be utilized to effectively model the plant architecture and enhance desirable quality traits through various approaches such as marker-assisted breeding, genetic engineering, and genome editing.</p

Table7_Unravelling the genetic framework associated with grain quality and yield-related traits in maize (Zea mays L.).XLSX

Maize serves as a crucial nutrient reservoir for a significant portion of the global population. However, to effectively address the growing world population’s hidden hunger, it is essential to focus on two key aspects: biofortification of maize and improving its yield potential through advanced breeding techniques. Moreover, the coordination of multiple targets within a single breeding program poses a complex challenge. This study compiled mapping studies conducted over the past decade, identifying quantitative trait loci associated with grain quality and yield related traits in maize. Meta-QTL analysis of 2,974 QTLs for 169 component traits (associated with quality and yield related traits) revealed 68 MQTLs across different genetic backgrounds and environments. Most of these MQTLs were further validated using the data from genome-wide association studies (GWAS). Further, ten MQTLs, referred to as breeding-friendly MQTLs (BF-MQTLs), with a significant phenotypic variation explained over 10% and confidence interval less than 2 Mb, were shortlisted. BF-MQTLs were further used to identify potential candidate genes, including 59 genes encoding important proteins/products involved in essential metabolic pathways. Five BF-MQTLs associated with both quality and yield traits were also recommended to be utilized in future breeding programs. Synteny analysis with wheat and rice genomes revealed conserved regions across the genomes, indicating these hotspot regions as validated targets for developing biofortified, high-yielding maize varieties in future breeding programs. After validation, the identified candidate genes can also be utilized to effectively model the plant architecture and enhance desirable quality traits through various approaches such as marker-assisted breeding, genetic engineering, and genome editing.</p