Agave, monocotyledonous succulent plants, is endemic to arid regions of North America, exhibiting exceptional tolerance to their xeric environments. They employ various strategies to overcome environmental constraints, such as crassulacean acid metabolism, wax depositions, and protective leaf morphology. Genomic resources of Agave species have received little attention irrespective of their cultural, economic and ecological importance, which so far prevented the understanding of the molecular bases underlying their adaptations to the arid environment. In this study, we aimed to elucidate molecular mechanism(s) using transcriptome sequencing ofA. sisalana. Ade novoapproach was applied to assemble paired-end reads. The expression study unveiled 3,095 differentially expressed unigenes between well-irrigated and drought-stressed leaf samples. Gene ontology and KEGG analysis specified a significant number of abiotic stress responsive genes and pathways involved in processes like hormonal responses, antioxidant activity, response to stress stimuli, wax biosynthesis, and ROS metabolism. We also identified transcripts belonging to several families harboring important drought-responsive genes. Our study provides the first insight into the genomic structure ofA. sisalanaunderlying adaptations to drought stress, thus providing diverse genetic resources for drought tolerance breeding research.

Guava (Psidium guajavaL.), a major fruit crop of the sub-tropical region, is facing a production decline due to drought stress. Morphophysiological responses to drought stress and underlying transcriptional regulations in guava are, largely, unknown. This study evaluated the drought stress tolerance of two guava cultivars,viz. “Gola” and “Surahi,” at morphological and physiological levels regulated differentially by ESTs (Expressed Sequence Tags). The treatments comprises three moisture regimes,viz. T_o= 100% (control), T₁= 75%, and T₂= 50% of field capacity. There was an overall decrease in both morphological and physiological attributes of studied guava cultivars in response to drought stress. Nonetheless, the water use efficiency of the “Surahi” cultivar increased (41.86%) speculating its higher drought tolerance based on enhanced peroxidase (402%) and catalase (170.21%) activities under 50% field capacity (T₂). Moreover, higher proline and flavonoid contents reinforced drought stress retaliation of the “Surahi” cultivar. The differential expression of a significant number of ESTs in “Surahi” (234) as compared to “Gola” (117) cultivar, somehow, regulated its cellular, biological, and molecular functions to strengthen morphophysiological attributes against drought stress as indicated by the upregulation of ESTs related to peroxidase, sucrose synthase (SUS), alcohol dehydrogenase (ADH), and ubiquitin at morphological, biochemical, and physiological levels. In conclusion, the drought stress acclimation of pear-shaped guava cultivar “Surahi” is due to the increased activities of peroxidase (POD) and catalase (CAT) complimented by the upregulation of related ESTs.

Plants are under the threat of climatic changes and there is a reduction in productivity and deterioration in quality. The application of nanoparticles is one of the recent approaches to improve plant yield and quality traits. A number of nanoparticles, such as zinc nanoparticles (ZnO NPs), iron nanoparticles (Fe2O3 NPs), silicon nanoparticles (SiO2 NPs), cerium nanoparticles (CeO2 NPs), silver nanoparticles (Ag NPs), titanium dioxide nanoparticles (TiO2 NPs), and carbon nanoparticles (C NPs), have been reported in different plant species to play a role to improve the plant physiology and metabolic pathways under environmental stresses. Crop plants readily absorb the nanoparticles through the cellular machinery of different tissues and organs to take part in metabolic and growth processes. Nanoparticles promote the activity of a range of antioxidant enzymes, including catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), in plant species, which in turn improve the growth and development under stressful conditions. The present review focuses on the mode of action and signaling of nanoparticles to the plant systems and their positive impact on growth, development, and ROS scavenging potential. The appropriate elucidation on mechanisms of nanoparticles in plants leads to better growth and yields under stress conditions, which will ultimately lead to increased agricultural production.