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Chloroplasts and photosynthesis are the physiologically fateful arenas of salinity stress. Morphological and anatomical alterations in the leaf tissue, ultrastructural changes in the chloroplast, compromise in the integrity of the three-layered chloroplast membrane system, and defects in the light and dark reactions during the osmotic, ionic, and oxidative phases of salt stress are conversed in detail to bring the salinity-mediated physiological alterations in the chloroplast on to a single platform. Chloroplasts of salt-tolerant plants have evolved highly regulated salt-responsive pathways. Thylakoid membrane remodeling, ion homeostasis, osmoprotection, upregulation of chloroplast membrane and stromal proteins, chloroplast ROS scavenging, efficient retrograde signalling, and differential gene and metabolite abundance are the key attributes of optimal photosynthesis in tolerant species. This review throws light into the comparative mechanism of chloroplast and photosynthetic response to salinity in sensitive and tolerant plant species. [ABSTRACT FROM AUTHOR]

Stay-green is an integrated drought adaptation trait characterized by a green leaf phenotype during grain filling under terminal drought. Ethylene is the key hormone for regulating the leaf senescence pathway under natural and stress conditions. The present study was conducted to assess the associative function of ethylene in regulating chlorophyll degrading enzymes viz., chlorophyllase (TaCHLase) and pheophorbide a oxygenase (TaPaO) in wheat (Triticum aestivum L.) under drought stress. Three wheat genotypes (HW 4059, HW 4022 and HW 2078) differing in drought tolerance efficiency were subjected to drought stress for ten days at the reproductive stage. A decline in stay-green traits was found in susceptible genotypes (HW 4059) with yield losses compared to tolerant ones (HW 4022 and HW 2078). The expression level of TaCHLase1 and TaPaO was higher in susceptible genotypes than tolerant ones under drought/osmotic stress. Ethylene upregulated, while ethylene inhibitors downregulated the gene expression. In this study, a novel gene annotated as TaCHLase1 was cloned. The complete cDNA sequence of TaCHLase1 is composed of 1054 bp nucleotides containing an open reading frame of 960 bp encoding 319 amino acids. The encoded protein contained conserved residues such as lipase motif GXSXGG at position 143-148 and putative active site Ser145. Sequence alignment showed TaCHLase1 shares a higher degree of identity with other species. The result suggested that ethylene upregulates the expression of TaCHLase1 gene, inducing chlorophyll degradation. The study further helps in understanding the mechanism of stay-green trait-induced drought tolerance mechanism in wheat. [ABSTRACT FROM AUTHOR]

An investigation was undertaken during 2018-19 in Southern zone of A.P. to study the Status of available phosphorus and forms of Phosphorus in soil under major cropping systems of chittoor district. The soils were strongly acidic to neutral in reaction, non-saline and below the critical limits, free lime content indicates that these soils were non calcareous. The highest mean values for available P2O5 (189.66 kg ha-1), saloid P (16.35 mg kg-1), Fe-P (50.24 mg kg-1) were obtained in groundnut monocropping system and Al-P (40.71 mg kg-1), total-P (574.07 mg kg-1), Ca-P (39.56 mg kg-1) and other forms of P (434.86 mg kg-1) were obtained in groundnut+redgram cropping system. Under all the cropping systems, all forms of P had positive and significant correlation with pH and EC. Free CaCO3 showed positive and significant relation with Ca-P (r = 0.539*). Available P2O5 showed highly significant and positive correlation with saloid-P (r = 0.781**), Al-P (r = 0.809**), Fe-P (r = 0.611**) and Ca-P (r = 0.709**). Whereas saloid-P showed significant and positive correlation with Fe-P (r = 0.694**) and Al-P (r = 0.749**), Fe-P showed positive and significant correlation with Ca-P (r = 0.747**), and Al-P showed positive and significant relation with total-P (0.627**). [ABSTRACT FROM AUTHOR]

Summary Tetraspanins (TETs) are integral membrane proteins, characterized by four transmembrane domains and a unique signature motif in their large extracellular loop. They form dynamic supramolecular complexes called tetraspanin‐enriched microdomains (TEMs), through interactions with partner proteins. In plants, TETs are involved in development, reproduction and immune responses, but their role in defining abiotic stress responses is largely underexplored. We focused on OsTET5, which is differentially expressed under various abiotic stresses and localizes to both plasma membrane and endoplasmic reticulum. Using overexpression and underexpression transgenic lines we demonstrate that OsTET5 contributes to salinity and drought stress tolerance in rice. OsTET5 can interact with itself in yeast, suggesting homomer formation. Immunoblotting of native PAGE of microsomal fraction enriched from OsTET5‐Myc transgenic rice lines revealed multimeric complexes containing OsTET5, suggesting the potential formation of TEM complexes. Transcriptome analysis, coupled with quantitative PCR‐based validation, of OsTET5‐altered transgenic lines unveiled the differential expression patterns of several stress‐responsive genes, as well as those coding for transporters under salt stress. Notably, OsTET5 plays a crucial role in maintaining the ionic equilibrium during salinity stress, particularly by preserving an elevated potassium‐to‐sodium (K+/Na+) ratio. OsTET5 also regulates reactive oxygen species homeostasis, primarily by modulating the gene expression and activities of antioxidant pathway enzymes and proline accumulation. Our comprehensive investigation underscores the multifaceted role of OsTET5 in rice, accentuating its significance in developmental processes and abiotic stress tolerance. These findings open new avenues for potential strategies aimed at enhancing stress resilience and making valuable contributions to global food security. [ABSTRACT FROM AUTHOR]