Mechanism of high affinity potassium transporter (HKT) towards improved crop productivity in saline agricultural lands

Chitosan nanoparticles (CSNPs) conferred salinity tolerance in maize by upregulating E3 ubiquitin-protein ligase, P5CS1, HKT1, NHX1, and PMP3 genes

This study explored the transcriptional behaviors of several candidate genes in response to the application of CSNPs (50 and 100 mgl-1) in maize seedlings grown under two salinity levels (NaCl of 0.07 and 0.14 gkg-1soil). Employing CSNPs at both concentrations mitigated the inhibitory role of salinity on the leaf and root fresh weights. The application of CSNPs enhanced the transcription of the E3 ubiquitin-protein ligase gene by an average of threefold, contrasted with the salinity controls. The Δ1-pyrroline-5-carboxylate synthetase (P5CS1) gene was upregulated in response to both individual and mixed treatments of CSNPs and salinity. The transcription of the high-affinity K+ transporter (HKT1) gene displayed an upward trend in response to the CSNPs and salinity treatments. The Na+/H+ exchangers (NHX1) gene exhibited a similar trend to that of the HKT1 gene. The utilization of CSNPs was accompanied by an upregulation in the plasma membrane proteolipid 3 (PMP3) gene, contrasted with the salinity controls. The phenylalanine ammonia-lyase (PAL) activity displayed an upward trend in response to the foliar application of CSNPs. The CSNPs at the 100 mgl-1 concentration were more capable of inducing the ascorbate peroxidase enzyme under both salinity conditions than the 50 mgl-1 dose. The simultaneous exposure of maize seedlings to CSNPs and salinity resulted in the drastic upregulation of the catalase activities. This study provides novel insights into the major mechanisms underlying the stress-mitigating effects of CSNPs, thereby providing a suitable platform for their application in sustainable agricultural practices.

Enhancing Photosynthesis and Plant Productivity through Genetic Modification

Enhancing crop photosynthesis through genetic engineering technologies offers numerous opportunities to increase plant productivity. Key approaches include optimizing light utilization, increasing cytochrome b6f complex levels, and improving carbon fixation. Modifications to Rubisco and the photosynthetic electron transport chain are central to these strategies. Introducing alternative photorespiratory pathways and enhancing carbonic anhydrase activity can further increase the internal CO2 concentration, thereby improving photosynthetic efficiency. The efficient translocation of photosynthetically produced sugars, which are managed by sucrose transporters, is also critical for plant growth. Additionally, incorporating genes from C4 plants, such as phosphoenolpyruvate carboxylase and NADP-malic enzymes, enhances the CO2 concentration around Rubisco, reducing photorespiration. Targeting microRNAs and transcription factors is vital for increasing photosynthesis and plant productivity, especially under stress conditions. This review highlights potential biological targets, the genetic modifications of which are aimed at improving photosynthesis and increasing plant productivity, thereby determining key areas for future research and development.

Comparative adaptability assessment of bread wheat and synthetic hexaploid genotypes under saline conditions using physiological, biochemical, and genetic indices

The tolerance to salinity stress is an intricate phenomenon at cellular and whole plant level that requires the knowledge of contributing physiological and biochemical processes and the genetic control of participating traits. In this context, present study was conducted with objective to evaluate the physiological, biochemical, and genetic responses of different wheat genotypes including bread wheat (BW) and synthetic hexaploids (SHs) under saline and control environment. The experiment was conducted in two factorial arrangement in randomized complete block design (RCBD), with genotypes as one factor and treatments as another factor. A significant decline in physiological traits (chlorophyll, photosynthesis, stomatal conductance, transpiration, and cell membrane stability) was observed in all genotypes due to salt stress; however, this decline was higher in BW genotypes as compared to four SH genotypes. In addition, the biochemical traits including enzymes [superoxide dismutase, catalase, and peroxidase (POD)] activity, proline, and glycine betaine (GB) illustrated significant increase along with increase in the expression of corresponding genes (TaCAT1, TaSOD, TaPRX2A, TaP5CS, and TaBADH-A1) due to salt stress in SHs as compared to BW. Correspondingly, highly overexpressed genes, TaHKT1;4, TaNHX1, and TaAKT1 caused a significant decline in Na+/K+ in SH as compared to BW genotypes under salt stress. Moreover, correlation analysis, principal component analysis (PCA), and heatmap analysis have further confirmed that the association and expression of physiological and biochemical traits varied significantly with salinity stress and type of genotype. Overall, the physiological, biochemical, and genetic evaluation proved SHs as the most useful stock for transferring salinity tolerance to other superior BW cultivars via the right breeding program.

Identification of the High-Affinity Potassium Transporter Gene Family (HKT) in Brassica U-Triangle Species and Its Potential Roles in Abiotic Stress in Brassica napus L

Members of the high-affinity potassium transporter (HKT) protein family regulate the uptake and homeostasis of sodium and potassium ions, but little research describes their roles in response to abiotic stresses in rapeseed (Brassica napus L.). In this study, we identified and characterized a total of 36 HKT genes from the species comprising the triangle of U model (U-triangle species): B. rapa, B. nigra, B. oleracea, B. juncea, B. napus, and B. carinata. We analyzed the phylogenetic relationships, gene structures, motif compositions, and chromosomal distributions of the HKT family members of rapeseed. Based on their phylogenetic relationships and assemblage of functional domains, we classified the HKT members into four subgroups, HKT1;1 to HKT1;4. Analysis of the nonsynonymous substitutions (Ka), synonymous substitutions (Ks), and the Ka/Ks ratios of HKT gene pairs suggested that these genes have experienced strong purifying selective pressure after duplication, with their evolutionary relationships supporting the U-triangle theory. Furthermore, the expression profiles of BnaHKT genes varies among potassium, phytohormone and heavy-metal treatment. Their repression provides resistance to heavy-metal stress, possibly by limiting uptake. Our results systematically reveal the characteristics of HKT family proteins and their encoding genes in six Brassica species and lay a foundation for further exploration of the role of HKT family genes in heavy-metal tolerance.