Plant hormones and secondary metabolites under environmental stresses: Enlightening defense molecules

The climatic changes have great threats to sustainable agriculture and require efforts to ensure global food and nutritional security. In this regard, the plant strategic responses, including the induction of plant hormones/plant growth regulators (PGRs), play a substantial role in boosting plant immunity against environmental stress-induced adversities. In addition, secondary metabolites (SMs) have emerged as potential 'stress alleviators' that help plants to adapt against environmental stressors imposing detrimental impacts on plant health and survival. The introduction of SMs in plant biology has shed light on their beneficial effects in mitigating environmental crises. This review explores SMs-mediated plant defense responses and highlights the crosstalk between PGRs and SMs under diverse environmental stressors. In addition, genetic engineering approaches are discussed as a potential revenue to enhance plant hormone-mediated SM production in response to environmental cues. Thus, the present review aims to emphasize the significance of SMs implications with PGRs association and genetic approachability, which could aid in shaping the future strategies that favor agro-ecosystem compatibility under unpredictable environmental conditions.

Mineral nutrients in plants under changing environments: A road to future food and nutrition security

Plant nutrition is an important aspect that contributes significantly to sustainable agriculture, whereas minerals enrichment in edible source implies global human health; hence, both strategies need to be bridged to ensure "One Health" strategies. Abiotic stress-induced nutritional imbalance impairs plant growth. In this context, we discuss the molecular mechanisms related to the readjustment of nutrient pools for sustained plant growth under harsh conditions, and channeling the minerals to edible source (seeds) to address future nutritional security. This review particularly highlights interventions on (i) the physiological and molecular responses of mineral nutrients in crop plants under stressful environments; (ii) the deployment of breeding and biotechnological strategies for the optimization of nutrient acquisition, their transport, and distribution in plants under changing environments. Furthermore, the present review also infers the recent advancements in breeding and biotechnology-based biofortification approaches for nutrient enhancement in crop plants to optimize yield and grain mineral concentrations under control and stress-prone environments to address food and nutritional security.

A Chromosome-length Assembly of the Black Petaltail (Tanypteryx hageni) Dragonfly

We present a chromosome-length genome assembly and annotation of the Black Petaltail dragonfly (Tanypteryx hageni). This habitat specialist diverged from its sister species over 70 million years ago, and separated from the most closely related Odonata with a reference genome 150 million years ago. Using PacBio HiFi reads and Hi-C data for scaffolding we produce one of the most high-quality Odonata genomes to date. A scaffold N50 of 206.6 Mb and a single copy BUSCO score of 96.2% indicate high contiguity and completeness.

Tinospora cordifolia (Willd.) Hook.f. & Thomson polysaccharides: A review on extraction, characterization, and bioactivities

Human awareness of the need for health and wellness practices that enhance disease resilience has increased as a result of recent health risks. Plant-derived polysaccharides with biological activity are good candidates to fight diseases because of their low toxicity. Tinospora cordifolia (Willd.) Hook.f. & Thomson polysaccharides extract from different plant parts have been reported to possess significant biological activity such as anti-oxidant, anti-cancer, immunomodulatory, anti-diabetic, radioprotective and hepatoprotective. Several extraction and purification techniques have been used to isolate and characterize T. cordifolia polysaccharides. Along with hot-water extraction (HWE), other novel techniques like microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), pulsed electric field (PEF), supercritical-fluid extraction (SFE), and enzyme-assisted extraction (EAE) are used to extract T cordifolia polysaccharides. SFE is a revolutionary technology that gives the best yield and purity of low-molecular-weight polysaccharides. According to the findings, polysaccharides extracted and purified from T. cordifolia have a significant impact on their structure and biological activity. As a result, the methods of extraction, structural characterization, and biological activity of T. cordifolia polysaccharides are covered in this review. Research on T. cordifolia polysaccharides and their potential applications will benefit greatly from the findings presented in this review.

Insight of PBZ mediated drought amelioration in crop plants

Water scarcity is a significant environmental limitation to plant productivity as drought-induced crop output losses are likely to outnumber losses from all other factors. In this context, triazole compounds have recently been discovered to act as plant growth regulators and multi-stress protectants such as heat, chilling, drought, waterlogging, heavy metals, etc. Paclobutrazol (PBZ) [(2RS, 3RS)-1-(4-chlorophenyl)- 4, 4-dimethyl-2-(1H-1, 2, 4-trizol-1-yl)-pentan-3-ol)] disrupts the isoprenoid pathway by blocking ent-kaurene synthesis, affecting gibberellic acid (GA) and abscisic acid (ABA) hormone levels. PBZ affects the level of ethylene and cytokinin by interfering with their biosynthesis pathways. Through a variety of physiological responses, PBZ improves plant survival under drought. Some of the documented responses include a decrease in transpiration rate (due to reduced leaf area), higher diffusive resistance, relieving reduction in water potential, greater relative water content, less water use, and increased antioxidant activity. We examined and discussed current findings as well as the prospective application of PBZ in regulating crop growth and ameliorating abiotic stresses in this review. Furthermore, the influence of PBZ on numerous biochemical, physiological, and molecular processes is thoroughly investigated, resulting in increased crop yield.

Phosphorus homeostasis: acquisition, sensing, and long-distance signaling in plants

Phosphorus (P), an essential nutrient required by plants often becomes the limiting factor for plant growth and development. Plants employ various mechanisms to sense the continuously changing P content in the soil. Transcription factors, such as SHORT ROOT (SHR), AUXIN RESPONSE FACTOR19 (ARF19), and ETHYLENE-INSENSITIVE3 (EIN3) regulate the growth of primary roots, root hairs, and lateral roots under low P. Crop improvement strategies under low P depend either on improving P acquisition efficiency or increasing P utilization. The various phosphate transporters (PTs) are involved in the uptake and transport of P from the soil to various plant cellular organelles. A plethora of regulatory elements including transcription factors, microRNAs and several proteins play a critical role in the regulation of coordinated cellular P homeostasis. Among these, the well-established P starvation signaling pathway comprising of central transcriptional factor phosphate starvation response (PHR), microRNA399 (miR399) as a long-distance signal molecule, and PHOSPHATE 2 (PHO2), an E2 ubiquitin conjugase is crucial in the regulation of phosphorus starvation responsive genes. Under PHR control, several classes of PHTs, microRNAs, and proteins modulate root architecture, and metabolic processes to enable plants to adapt to low P. Even though sucrose and inositol phosphates are known to influence the phosphorus starvation response genes, the exact mechanism of regulation is still unclear. In this review, a basic understanding of P homeostasis under low P in plants and all the above aspects are discussed.

Impacts, Tolerance, Adaptation, and Mitigation of Heat Stress on Wheat under Changing Climates

Heat stress (HS) is one of the major abiotic stresses affecting the production and quality of wheat. Rising temperatures are particularly threatening to wheat production. A detailed overview of morpho-physio-biochemical responses of wheat to HS is critical to identify various tolerance mechanisms and their use in identifying strategies to safeguard wheat production under changing climates. The development of thermotolerant wheat cultivars using conventional or molecular breeding and transgenic approaches is promising. Over the last decade, different omics approaches have revolutionized the way plant breeders and biotechnologists investigate underlying stress tolerance mechanisms and cellular homeostasis. Therefore, developing genomics, transcriptomics, proteomics, and metabolomics data sets and a deeper understanding of HS tolerance mechanisms of different wheat cultivars are needed. The most reliable method to improve plant resilience to HS must include agronomic management strategies, such as the adoption of climate-smart cultivation practices and use of osmoprotectants and cultured soil microbes. However, looking at the complex nature of HS, the adoption of a holistic approach integrating outcomes of breeding, physiological, agronomical, and biotechnological options is required. Our review aims to provide insights concerning morpho-physiological and molecular impacts, tolerance mechanisms, and adaptation strategies of HS in wheat. This review will help scientific communities in the identification, development, and promotion of thermotolerant wheat cultivars and management strategies to minimize negative impacts of HS.

Regulatory hubs and strategies for improving heavy metal tolerance in plants: Chemical messengers, omics and genetic engineering

Heavy metal (HM) accumulation in the agricultural soil and its toxicity is a major threat for plant growth and development. HMs disrupt functional integrity of the plants, induces altered phenological and physiological responses and slashes down qualitative crop yield. Chemical messengers such as phytohormones, plant growth regulators and gasotransmitters play a crucial role in regulating plant growth and development under metal toxicity in plants. Understanding the intricate network of these chemical messengers as well as interactions of genes/metabolites/proteins associated with HM toxicity in plants is necessary for deciphering insights into the regulatory circuit involved in HM tolerance. The present review describes (a) the role of chemical messengers in HM-induced toxicity mitigation, (b) possible crosstalk between phytohormones and other signaling cascades involved in plants HM tolerance and (c) the recent advancements in biotechnological interventions including genetic engineering, genome editing and omics approaches to provide a step ahead in making of improved plant against HM toxicities.

Delineating the inherent functional descriptors and biofunctionalities of pectic polysaccharides

Pectin is a plant-based heteropolysaccharide macromolecule predominantly found in the cell wall of plants. Pectin is commercially extracted from apple pomace, citrus peels and sugar beet pulp and is widely used in the food industry as a stabilizer, emulsifier, encapsulant, and gelling agent. This review highlights various parameters considered important for describing the inherent properties and biofunctionalities of pectins in food systems. These inherent descriptors include monosaccharide composition, galacturonic acid content, degree of esterification, molecular weight, structural morphology, functional group analysis, and functional properties, such as water and oil holding capacity, emulsification, foaming capacity, foam stability, and viscosity. In this study, we also delineate their potential as a nutraceutical, prebiotic, and carrier for bioactive compounds. The biofunctionalities of pectin as an anticancer, antioxidant, lipid-lowering, and antidiabetic agent are also conceptually elaborated in the current review. The multidimensional characteristics of pectin make it a potential candidate for use in food and biomedical science.

Improving drought tolerance in rice: Ensuring food security through multi-dimensional approaches

Drought has been highly prevalent around the world especially in Sub-Saharan Africa and South-East Asian countries. Consistent climatic instabilities and unpredictable rainfall patterns are further worsening the situation. Rice is a C₃ staple cereal and an important food crop for the majority of the world's population and drought stress is one of the major growth retarding threats for rice that slashes down grain quality and yield. Drought deteriorates rice productivity and induces various acclimation responses that aids in stress mitigation. However, the complexity of traits associated with drought tolerance has made the understanding of drought stress-induced responses in rice a challenging process. An integrative understanding based on physiological adaptations, omics, transgenic and molecular breeding approaches successively backed up to developing drought stress-tolerant rice. The review represents a step forward to develop drought-resilient rice plants by exploiting the knowledge that collaborates with omics-based developments with integrative efforts to ensure the compilation of all the possible strategies undertaken to develop drought stress-tolerant rice.

Targeted knockdown of ribulose-1, 5-bisphosphate carboxylase-oxygenase in rice mesophyll cells

We generated antisense constructs targeting two of the five Rubisco small subunit genes (OsRBCS2 and 4) which account for between 30-40 % of the RBCS transcript abundance in leaf blades. The constructs were driven by a maize phosphoenolpyruvate carboxylase (PEPC) promoter known to have enriched expression in mesophyll cells (MCs). In the resulting lines leaf, Rubisco protein content was reduced by between 30-50 % and CO₂ assimilation rate was limited under photorespiratory and non-photorespiratory conditions. A relationship between Rubisco protein content and CO₂ assimilation rate was found. This was associated with a significant reduction in dry biomass accumulation and grain yield of between 37-70%. In addition to serving as a resource for reducing Rubisco accumulation in a cell-preferential manner, these lines allow us to characterize gene function and isoform specific suppression on photosynthesis and growth. Our results suggest that the knockdown of multiple genes is required to completely reduce Rubisco accumulation in MCs.

Guava (Psidium guajava L.) Leaves: Nutritional Composition, Phytochemical Profile, and Health-Promoting Bioactivities

Psidium guajava (L.) belongs to the Myrtaceae family and it is an important fruit in tropical areas like India, Indonesia, Pakistan, Bangladesh, and South America. The leaves of the guava plant have been studied for their health benefits which are attributed to their plethora of phytochemicals, such as quercetin, avicularin, apigenin, guaijaverin, kaempferol, hyperin, myricetin, gallic acid, catechin, epicatechin, chlorogenic acid, epigallocatechin gallate, and caffeic acid. Extracts from guava leaves (GLs) have been studied for their biological activities, including anticancer, antidiabetic, antioxidant, antidiarrheal, antimicrobial, lipid-lowering, and hepatoprotection activities. In the present review, we comprehensively present the nutritional profile and phytochemical profile of GLs. Further, various bioactivities of the GL extracts are also discussed critically. Considering the phytochemical profile and beneficial effects of GLs, they can potentially be used as an ingredient in the development of functional foods and pharmaceuticals. More detailed clinical trials need to be conducted to establish the efficacy of the GL extracts.

Human-interpretable image features derived from densely mapped cancer pathology slides predict diverse molecular phenotypes

Computational methods have made substantial progress in improving the accuracy and throughput of pathology workflows for diagnostic, prognostic, and genomic prediction. Still, lack of interpretability remains a significant barrier to clinical integration. We present an approach for predicting clinically-relevant molecular phenotypes from whole-slide histopathology images using human-interpretable image features (HIFs). Our method leverages >1.6 million annotations from board-certified pathologists across >5700 samples to train deep learning models for cell and tissue classification that can exhaustively map whole-slide images at two and four micron-resolution. Cell- and tissue-type model outputs are combined into 607 HIFs that quantify specific and biologically-relevant characteristics across five cancer types. We demonstrate that these HIFs correlate with well-known markers of the tumor microenvironment and can predict diverse molecular signatures (AUROC 0.601-0.864), including expression of four immune checkpoint proteins and homologous recombination deficiency, with performance comparable to 'black-box' methods. Our HIF-based approach provides a comprehensive, quantitative, and interpretable window into the composition and spatial architecture of the tumor microenvironment.

Mango (Mangifera indica L.) Leaves: Nutritional Composition, Phytochemical Profile, and Health-Promoting Bioactivities

Mangifera indica L. belongs to the family of Anacardiaceae and is an important fruit from South and Southeast Asia. India, China, Thailand, Indonesia, Pakistan, Mexico, Brazil, Bangladesh, Nigeria, and the Philippines are among the top mango producer countries. Leaves of the mango plant have been studied for their health benefits, which are attributed to a plethora of phytochemicals such as mangiferin, followed by phenolic acids, benzophenones, and other antioxidants such as flavonoids, ascorbic acid, carotenoids, and tocopherols. The extracts from mango leaves (MLs) have been studied for their biological activities, including anti-cancer, anti-diabetic, anti-oxidant, anti-microbial, anti-obesity, lipid-lowering, hepato-protection, and anti-diarrheal. In the present review, we have elaborated on the nutritional and phytochemical profile of the MLs. Further, various bioactivities of the ML extracts are also critically discussed. Considering the phytochemical profile and beneficial effects of the MLs, they can be used as a potential ingredient for the development of functional foods and pharmaceutical drugs. However, more detailed clinical trials still needed to be conducted for establishing the actual efficacy of the ML extracts.