Silicon nanoparticles confer hypoxia tolerance in citrus rootstocks by modulating antioxidant activities and carbohydrate metabolism.

Citrus is a remarkable fruit crop, extremely sensitive to flooding conditions, which frequently trigger hypoxia stress and cause severe damage to citrus plants. Silicon nanoparticles (SiNPs) are beneficial and have the potential to overcome this problem. Therefore, the present study aimed to investigate the effect of silicon nanoparticles to overcome hypoxia stress through modulating antioxidant enzyme activity and carbohydrate metabolism. Three citrus rootstocks (Carrizo citrange, Roubidoux, and Rich 16-6) were exposed to flooding (with and without oxygen) through different SiNP treatments via foliar and root zone. SiNPs applied treatment plants showed a significant increase in photosynthesis, leaf greenness, antioxidant enzymes, and carbohydrate metabolic activities, besides the higher accumulation of proline and glycine betaine. The rate of lipid peroxidation was drastically higher in flooded plants; however, SiNPs application reduced it significantly, ultimately reducing oxidative damage. Overall, Rich16-6 rootstock showed good performance via root zone application compared to other rootstocks, possibly due to genotypical variation in silicon uptake. Our outcomes demonstrate that SiNPs significantly affect plant growth during hypoxia stress conditions, and their use is an optimal strategy to overcome this issue. This study laid the foundation for future research to use at the commercial level to overcome hypoxia stress and a potential platform for future research.

Identification and characterization of Glycolate oxidase gene family in garden lettuce (Lactuca sativa cv. 'Salinas') and its response under various biotic, abiotic, and developmental stresses.

Glycolate oxidase (GLO) is an FMN-containing enzyme localized in peroxisomes and performs in various molecular and biochemical mechanisms. It is a key player in plant glycolate and glyoxylate accumulation pathways. The role of GLO in disease and stress resistance is well-documented in various plant species. Although studies have been conducted regarding the role of GLO genes from spinach on a microbial level, the direct response of GLO genes to various stresses in short-season and leafy plants like lettuce has not been published yet. The genome of Lactuca sativa cultivar 'Salinas' (v8) was used to identify GLO gene members in lettuce by performing various computational analysis. Dual synteny, protein-protein interactions, and targeted miRNA analyses were conducted to understand the function of GLO genes. The identified GLO genes showed further clustering into two groups i.e., glycolate oxidase (GOX) and hydroxyacid oxidase (HAOX). Genes were observed to be distributed unevenly on three chromosomes, and syntenic analysis revealed that segmental duplication was prevalent. Thus, it might be the main reason for GLO gene diversity in lettuce. Almost all LsGLO genes showed syntenic blocks in respective plant genomes under study. Protein-protein interactions of LsGLO genes revealed various functional enrichments, mainly photorespiration, and lactate oxidation, and among biological processes oxidative photosynthetic carbon pathway was highly significant. Results of in-depth analyses disclosed the interaction of GLO genes with other members of the glycolate pathway and the activity of GLO genes in various organs and developmental stages in lettuce. The extensive genome evaluation of GLO gene family in garden lettuce is believed to be a reference for cloning and studying functional analyses of GLO genes and characterizing other members of glycolate/glyoxylate biosynthesis pathway in various plant species.

Genome-Wide Identification and Characterization of the Biosynthesis of the Polyamine Gene Family in Citrus unshiu.

Polyamines (PAs) contribute to diverse plant processes, environmental interaction, and stress responses. In citrus, the mechanism underlying the biosynthesis of polyamines is poorly understood. The present study aims to identify the biosynthesis of PA gene family members in satsuma mandarin (Citrus unshiu) and investigate their response against various stresses. The identified biosynthesis of PA genes in C. unshiu showed clustering in six groups, i.e., SPMS, SPDS, ACL5, ADC, ODC, and SAMDC. Syntenic analysis revealed that segmental duplication was prevalent among the biosynthesis of PA genes compared to tandem duplication. Thus, it might be the main reason for diversity in the gene family in C. unshiu. Almost all biosynthesis of PA gene family members in C. unshiu showed syntenic blocks in the genome of Arabidopsis, Citrus sinensis, Poncirus trifoliata, and Citrus reticulata. Analysis of Cis-regulatory elements (CREs) indicated the occurrence of hormones, light, defense, and environmental stress responses as well as the development and other plant mechanisms-related elements in the upstream sequence of the biosynthesis of PA genes. Expression profiling revealed that the biosynthesis of PA gene expression modulates in different organs during various developmental stages and stress in C. unshiu. This information will provide a deep understanding of genomic information and its expression in multiple tissues to better understand its potential application in functional genomics.

Magnetofection approach for the transformation of okra using green iron nanoparticles.

Climate change, pesticide resistance, and the need for developing new plant varieties have galvanized biotechnologists to find new solutions in order to produce transgenic plants. Over the last decade scientists are working on green metallic nanoparticles to develop DNA delivery systems for plants. In the current study, green Iron nanoparticles were synthesized using leaf extract of Camellia sinensis (green tea) and Iron Chloride (FeCl3), the characterization and Confirmation was done using UV-VIS Spectroscopy, FTIR, SEM, and TEM. Using these nanoparticles, a novel method of gene transformation in okra plants was developed, with a combination of different Magnetofection factors. Maximum gene transformation efficiency was observed at the DNA to Iron-nanoparticles ratio of 1:20, by rotation of mixture (Plasmid DNA, Iron-nanoparticles, and seed embryo) at 800 rpm for 5 h. Using this approach, the transformation of the GFP (green fluorescent protein) gene was successfully carried out in Abelmoschus esculentus (Okra plant). The DNA transformation was confirmed by observing the expression of transgene GFP via Laser Scanning Confocal Microscope (LSCM) and PCR. This method is highly economical, adaptable, genotype independent, eco-friendly, and time-saving as well. We infer that this approach can be a potential solution to combat the yield and immunity challenges of plants against pathogens.

Interaction between bacterial endophytes and host plants.

Endophytic bacteria are mainly present in the plant's root systems. Endophytic bacteria improve plant health and are sometimes necessary to fight against adverse conditions. There is an increasing trend for the use of bacterial endophytes as bio-fertilizers. However, new challenges are also arising regarding the management of these newly discovered bacterial endophytes. Plant growth-promoting bacterial endophytes exist in a wide host range as part of their microbiome, and are proven to exhibit positive effects on plant growth. Endophytic bacterial communities within plant hosts are dynamic and affected by abiotic/biotic factors such as soil conditions, geographical distribution, climate, plant species, and plant-microbe interaction at a large scale. Therefore, there is a need to evaluate the mechanism of bacterial endophytes' interaction with plants under field conditions before their application. Bacterial endophytes have both beneficial and harmful impacts on plants but the exact mechanism of interaction is poorly understood. A basic approach to exploit the potential genetic elements involved in an endophytic lifestyle is to compare the genomes of rhizospheric plant growth-promoting bacteria with endophytic bacteria. In this mini-review, we will be focused to characterize the genetic diversity and dynamics of endophyte interaction in different host plants.

Citrus Canker Pathogen, Its Mechanism of Infection, Eradication, and Impacts.

Citrus canker is a ravaging bacterial disease threatening citrus crops. Its major types are Asiatic Canker, Cancrosis B, and Cancrosis C, caused by Xanthomonas citri pv. citri (Xcc), Xanthomonas citri pv. aurantifolii pathotype-B (XauB), and pathotype-C (XauC), respectively. The bacterium enters its host through stomata and wounds, from which it invades the intercellular spaces in the apoplast. It produces erumpent corky necrotic lesions often surrounded by a chlorotic halo on the leaves, young stems, and fruits, which causes dark spots, defoliation, reduced photosynthetic rate, rupture of leaf epidermis, dieback, and premature fruit drop in severe cases. Its main pathogenicity determinant gene is pthA, whose variants are present in all citrus canker-causing pathogens. Countries where citrus canker is not endemic adopt different methods to prevent the introduction of the pathogen into the region, eradicate the pathogen, and minimize its dissemination, whereas endemic regions require an integrated management program to control the disease. The main aim of the present manuscript is to shed light on the pathogen profile, its mechanism of infection, and fruitful strategies for disease management. Although an adequate method to completely eradicate citrus canker has not been introduced so far, many new methods are under research to abate the disease.