Akhtar Ali

High-salinity stress induces severe oxidative damage in plants, leading to growth inhibition through cellular redox imbalance. Chalcone synthase (CHS), a pivotal enzyme in the flavonoid biosynthesis pathway, plays critical roles in plant stress adaptation. However, the molecular mechanisms underlying CHS-mediated salt tolerance remain uncharacterized in Areca catechu L., a tropical crop of high economic and ecological significance. Here, we systematically identified the CHS gene family in A. catechu and revealed tissue-specific and salt-stress-responsive expression patterns, with AcCHS5 exhibiting the most pronounced induction under salinity. Transgenic Arabidopsis overexpressing AcCHS5 displayed enhanced salt tolerance compared to wild-type plants, characterized by elevated activities of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), increased flavonoid accumulation, and reduced reactive oxygen species (ROS) accumulation. Furthermore, we identified the transcription factor AcMYB176 as a direct activator of AcCHS5 through binding to its promoter. Our findings demonstrate that the AcMYB176-AcCHS5 regulatory module enhances salt tolerance by orchestrating flavonoid biosynthesis and ROS scavenging. This study provides functional evidence of CHS-mediated salt adaptation in A. catechu and highlights its potential for improving stress resilience in tropical crops.

The basic helix-loop-helix (bHLH) transcription factor (TF) family, the second-largest among eukaryotes, is known for its evolutionary and functional diversity across plant species. However, bHLH genes have not yet been characterized in Areca catechu. In this study, we identified 76 AcbHLH genes, which exhibit a variety of physicochemical properties. Phylogenetic analysis revealed evolutionary relationships between Arabidopsis thaliana bHLH genes (AtbHLH) and their counterparts in A. catechu (AcbHLH). These analyses also highlighted conserved amino acid motifs (S, R, K, P, L, A, G, and D), conserved domains, and evolutionary changes, such as insertions, deletions, and exon gains or losses. Promoter analysis of AcbHLH genes revealed 76 cis-elements related to growth, phytohormones, light, and stress. Gene duplication analysis revealed four tandem duplications and twenty-three segmental duplications, while AcbHLH63 in the Areca genome exhibited significant synteny with bHLH genes from A. thaliana, Vitis vinifera, Solanum lycopersicum, Brachypodium distachyon, Oryza sativa, and Zea mays. Furthermore, relative expression analysis showed that under drought stress (DS), AcbHLH22, AcbHLH39, AcbHLH45, and AcbHLH58 showed distinct upregulation in leaves at specific time points, while all nine AcbHLH genes were upregulated in roots. Under salt stress (SS), AcbHLH22, AcbHLH39, AcbHLH45, and AcbHLH58 were upregulated in leaves, and AcbHLH22, AcbHLH34, and AcbHLH39 exhibited differential expression in roots at various time points. This study provides valuable insights into the bHLH superfamily in A. catechu, offering a solid foundation for further investigation into its role in responding to abiotic stresses.

The basic helix-loop-helix (bHLH) transcription factor family, is the second-largest superfamily in plants after MYB, which plays a significant role in the physiological processes of plant growth, tissue development, and environmental variation. However, the systematized study of the bHLH transcription factor family has not yet been conducted in A. catechu. Herein, we conducted genome genome-wide investigation of AcbHLH genes located on 16 chromosomes of A. catechu. A phylogenic tree was constructed to adjudge their homology of genes, and 24 subgroups were identified. Finally, we analyzed the dynamic changes of gene-expression levels of nine AcbHLH genes in response to drought and salt in leaves and roots. The expression patterns of 9 AcbHLH genes show differences in leaves and roots. Under stress conditions induced by salt and drought, AcbHLH22, AcbHLH62 and AcbHLH45 are significantly upregulated in both leaves and roots. In conclusion, this study will substantially contribute to the foundation for exploring the role of the bHLH superfamily in A.catechu in dealing with abiotic stresses.

Straw returning is an environmentally friendly method to improve soil health and agricultural productivity by reusing organic waste products. However, fields are often also treated with inorganic fertilizers, and the effect of the interaction between phosphate fertilizer application and straw return on crop yield remains unclear. Therefore, a full-factorial, two-year field experiment was conducted on sweet corn (NARC-16 in late 2021 and Kashmeri-19 in early 2022) to explore how crop yield may be optimized by combining straw return with efficient phosphate fertilization. The experiment involved the application of DAP, SSP, and NP (three different types of phosphates) and the application of crop waste byproducts, namely the residual stover left after sorghum and maize harvesting. We compared control fields with no crop waste or phosphate addition (CR0 and PS0) to experimental plots treated with various phosphates and straw return. Growth parameters such as days to emergence, tasseling, silking and maturity, emergence rate (emergence m⁻²), height of plant, number of leaves, leaf area per plant, and yield were evaluated, and the influence of the treatment on the economic value of crops was estimated. Phosphorus and straw return were applied at rates of 90 kg per hectare and 5 tons per hectare, respectively. The best P-crop straw combination treatment involved DAP (90 kg ha⁻¹) with the incorporation of 5 tons’ ha⁻¹ of maize straw, which resulted in delayed tasseling (50 days), early silking (68 days), taller plants (178 cm), improved thousand-grain weight (233 g), maximum biological yield (11,349 kg ha⁻¹) and grain yield (3760 kg ha⁻¹). The application of DAP with maize straw return resulted in the highest plant height, biological yield, and grain yield of sweet corn during the second year of the experiment, despite the first year’s yield being influenced by a natural disaster. This combined management strategy (using either DAP or crop residuals) was found to have a more a favorable cost–benefit ratio (BCR) efficiency. In conclusion, increasing the use of crop residuals can help reduce the expensive application of synthetic mineral fertilizers like SSP and NP, while significantly increasing sweet corn production and improving profit margins. Considering the importance of environmental friendliness and sustainable agriculture, the combined use of DAP and straw return is considered a viable method.