Transcriptomic analysis towards identification of defence-responsive genes and pathways upon application of Sargassum seaweed extract on tomato plants infected with Macrophominaphaseolina.

The charcoal-rot caused by Macrophomina phaseolina is one of the major disease in many economically important crop plants including tomato. The molecular responses of the host plant against the M. phaseolina are poorly stated. In the present study, for the first time the molecular insight of tomato-Macrophomina interaction and Sargassum tenerrimum extract (SE) toward managing disease through RNA-seq approach is established. A total of 449 million high-quality reads (HQRs) were obtained and aligned to the tomato genome with an average mapping of 89.12%. The differentially expressed genes (DEGs) regulated across the different treatment pairs were identified. Several DEGs, such as receptor-like kinases (SlRLKs), transcription factors including SlWRKY70, SlGRAS4, SlERF4, SlERF25, pathogenesis related-1 (SlPR1), SlPR2, endochitinase and peroxidase were significantly up-regulated in SE + Macrophomina treated sample as compared to only Macrophomina treated sample. The crosstalk between salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) was a key factor to regulate resistance in tomato during SE + Macrophomina treatment. The KEGG pathway including plant hormone signal transduction, plant-pathogen interaction and mitogen-activated protein kinase (MAPK) signaling pathway were significantly enriched. The RNA-seq data were validated through qPCR using 12 disease-responsive genes and correlated significantly with R2 = 0.73. The present study suggests that SE act as an elicitor molecule and activate the defence-related pathways similar to PAMP-triggered immunity in tomato. The jasmonic acid (JA) mediated signaling pathway was identified as a key factor to induce resistance in tomato against Macrophomina infection. The present study depicts the beneficial effects of SE by regulating molecular mechanism towards defence responses in tomato against Macrophomina infection. The application of SE brings out new prospects to induce disease tolerance in the agricultural crops. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03565-4.

An integrated effluent free process for the production of 5-hydroxymethyl furfural (HMF), levulinic acid (LA) and KNS-ML from aqueous seaweed extract.

This paper demonstrates an integrated zero liquid discharge (ZLD) process for time-dependent recovery of 5-hydroxymethyl furfural (HMF), levulinic acid (LA) and potassium, nitrogen and sulphur rich mother liquor (KNS-ML) - manure from agar/agarose containing seaweed aqueous solution using transition metal-free KHSO4 as an eco-friendly and reusable catalyst. The selectivity of HMF is higher at 115 °C in 3 h and favorable to LA in 6 h in autoclave conditions. The proposed concept could be fine-tuned for the selective production of 5-HMF (up to 91% yield) or levulinic acid (56% yield) in the presence of the KHSO4 catalyst. We have also achieved recyclability of KHSO4 up to nine (09) cycles and the gram-scale reaction has been demonstrated. The (KNS-ML) obtained after nine cycles followed by neutralization with ammonia solution utilized for manure makes the process zero-liquid discharge and more cost-effective. The efficacy of the KNS-ML after nine cycles has been tested on groundnut plants.

SbMYB15 transcription factor mitigates cadmium and nickel stress in transgenic tobacco by limiting uptake and modulating antioxidative defence system.

Plants require different inorganic minerals in an appropriate amount for growth; however, imbalance can limit growth and productivity. Heavy metal accumulation causes toxicity and generates signalling crosstalk with reactive oxygen species (ROS), phytohormones, genes and transcription factors (TFs). The MYB (myeloblastoma) TFs participate in plant processes such as metabolism, development, cell fate, hormone pathways and responses to stresses. This is the first report towards characterisation of R2R3-type MYB TF, SbMYB15, from succulent halophyte Salicornia brachiata Roxb. for heavy metal tolerance. The SbMYB15 showed >5-fold increased transcript expression in the presence of CdCl2 and NiCl2•6H2O. The constitutive overexpression of SbMYB15 conferred cadmium and nickel tolerance in transgenic tobacco, with improved growth and chlorophyll content. Further, the transgenics showed reduced generation of reactive oxygen species (H2O2 and O2•-) as compared with the wild-type (WT) with both Cd2+ and Ni2+ stress. Transgenics also showed low uptake of heavy metal ions, increased scavenging activity of the antioxidative enzymes (CAT and SOD) and higher transcript expression of antioxidative genes (CAT1 and MnSOD). Thus, the present study signifies that SbMYB15 can be deployed for developing heavy metal tolerance in crop plants via genetic engineering.