Population structure and genetic differentiation analyses reveal high level of diversity and allelic richness in crop wild relatives of AA genome species of rice (Oryza sativa L.) in India.

Crop wild relatives (CWRs) are vital sources of variation for genetic improvement, but their populations are few in genebanks, eroded in natural habitats and inadequately characterized. With a view to explore genetic diversity in CWRs of AA genome rice (Oryza sativa L.) species in India, we analyzed 96 accessions of 10 Oryza species by using 17 quantitative traits and 45 microsatellite markers. The morpho-quantitative traits revealed a high extent of phenotypic variation in the germplasm. Diversity index (H') revealed a high level of within-species variability in O. nivara (H' = 1.09) and O. rufipogon (H' = 1.12). Principal component (PC) analysis explained 79.22% variance with five PCs. Among the traits related to phenology, morphology, and yield, days to heading showed strong positive association with days to 50% flowering (r = 0.99). However, filled grains per panicle revealed positive association with spikelet fertility (0.71) but negative with awn length (- 0.58) and panicle bearing tillers (- 0.39). Cluster analysis grouped all the accessions into three major clusters. Microsatellite analysis revealed 676 alleles with 15.02 alleles per locus. High polymorphism information content (PIC = 0.83) and Shannon's information index (I = 2.31) indicated a high level of genetic variation in the CWRs. Structure analysis revealed four subpopulations; first and second subpopulations comprised only of O. nivara accessions, while the third subpopulation included both O. nivara and O. rufipogon accessions. Population statistics revealed a moderate level of genetic differentiation (FST = 0.14), high gene diversity (HE = 0.87), and high gene flow (Nm = 1.53) among the subpopulations. We found a high level of molecular variance among the genotypes (70%) and low among populations (11%) and within genotypes (19%). The high level of molecular and morphological variability detected in the germplasm of CWRs could be utilized for the improvement of cultivated rice.

Mycorrhizae set the stage for plants to produce a higher production of biomolecules and stress-related metabolites: a sustainable alternative of agrochemicals to enhance the quality and yield of beetroot (Beta vulgaris L.).

Population explosions, environmental deprivation, and industrial expansion led to an imbalanced agricultural system. Non-judicial uses of agrochemicals have decreased agrodiversity, degraded agroecosystems, and increased the cost of farming. In this scenario, a sustainable agriculture system could play a crucial role; however, it needs rigorous study to understand the biological interfaces within agroecosystems. Among the various biological components with respect to agriculture, mycorrhizae could be a potential candidate. Most agricultural crops are symbiotic with arbuscular mycorrhizal fungi (AMF). In this study, beetroot has been chose to study the effect of different AMFs on various parameters such as morphological traits, biochemical attributes, and gene expression analysis (ALDH7B4 and ALDH3I1). The AMF Gm-Funneliformis mosseae (Glomus mosseae), Acaulospora laevis, and GG-Gigaspora gigantean were taken as treatments to study the effect on the above-mentioned parameters in beetroot. We observed that among all the possible combinations of mycorrhizae, Gm+Al+GG performed best, and the Al-alone treatment was found to be a poor performer with respect to all the studied parameters. This study concluded that the more the combinations of mycorrhizae, the better the results will be. However, the phenomenon depends on the receptivity, infectivity, and past nutrient profile of the soil.

Identification of Eight High Yielding Strains via Morpho-Molecular Characterization of Thirty-Three Wild Strains of Calocybe indica.

Calocybe indica, generally referred as milky mushroom, is one of the edible mushroom species suitable for cultivation in the tropical and sub-tropical regions of the world. However, lack of potential high yielding strains has limited its wider adaptability. To overcome this limitation, in this study, the germplasms of C. indica from different geographical regions of India were characterized based on their morphological, molecular and agronomical attributes. Internal transcribed spacers (ITS1 and ITS4)-based PCR amplification, sequencing and nucleotide analysis confirmed the identity of all the studied strains as C. indica. Further, evaluation of these strains for morphological and yield parameters led to the identification of eight high yielding strains in comparison to the control (DMRO-302). Moreover, genetic diversity analysis of these thirty-three strains was performed using ten sequence-related amplified polymorphism (SRAP) markers/combinations. The Unweighted Pair-group Method with Arithmetic Averages (UPGMA)-based phylogenetic analysis categorized the thirty-three strains along with the control into three clusters. Cluster I possesses the maximum number of strains. Among the high yielding strains, high antioxidant activity and phenol content was recorded in DMRO-54, while maximum protein content was observed in DMRO-202 and DMRO-299 as compared with the control strain. The outcome of this study will help the mushroom breeders and growers in commercializing C. indica.

Deciphering the melatonin-mediated response and signalling in the regulation of heavy metal stress in plants.

MAIN CONCLUSION: Melatonin has a protective effect against heavy metal stress in plants by immobilizing HM in cell walls and sequestering them in root cell vacuoles, reducing HM's translocation from roots to shoots. It enhances osmolyte production, increases antioxidant enzyme activity, and improves photosynthesis, thereby improving cellular functions. Understanding the melatonin-mediated response and signalling can sustain crop production in heavy metal-stressed soils. Melatonin is a pleiotropic signal molecule that plays a critical role in plant growth and stress tolerance, particularly against heavy metals in soil. Heavy metals (HMs) are ubiquitously found in the soil-water environment and readily taken up by plants, thereby disrupting mineral nutrient homeostasis, osmotic balance, oxidative stress, and altered primary and secondary metabolism. Plants combat HM stress through inbuilt defensive mechanisms, such as metal exclusion, restricted foliar translocation, metal sequestration and compartmentalization, chelation, and scavenging of free radicals by antioxidant enzymes. Melatonin has a protective effect against the damaging effects of HM stress in plants. It achieves this by immobilizing HM in cell walls and sequestering them in root cell vacuoles, reducing HM's translocation from roots to shoots. This mechanism improves the uptake of macronutrients and micronutrients in plants. Additionally, melatonin enhances osmolyte production, improving the plant's water relations, and increasing the activity of antioxidant enzymes to limit lipid peroxidation and reactive oxygen species (ROS) levels. Melatonin also decreases chlorophyll degradation while increasing its synthesis, and enhances RuBisCO activity for better photosynthesis. All these functions contribute to improving the cellular functions of plants exposed to HM stress. This review aims to gain better insight into the melatonin-mediated response and signalling under HM stress in plants, which may be useful in sustaining crop production in heavy metal-stressed soils.