Introduction: Microbial diseases are increasing year by year and they are becoming a big threat to public health. There are more than 200 known diseases transmitted by bacteria, fungi, viruses, prions, rickettsia and other microbes to humans. The emergence of drug resistance to chemical drugs is the biggest threat in controlling human pathogens. Hence novel antimicrobial agents from actinomycetes are timely needed for the control of several human pathogens. Aim: The aim was to find some actinomycetes with antimicrobial metabolites. Methods: Soil samples were collected from Nilgiris district in Western Ghats of Tamil Nadu, India. Actinomycetes were isolated using serial dilution and plating techniques on actinomycetes isolation agar. Streptomycin and ketoconazole (25 lg/disc) were used as reference controls. The active strains were identified by 16S rRNA and phylogenetic tree was constructed; the sequences were submitted in the GenBank. Results: Totally 106 actinomycete strains were isolated and cross streaked against various human microbial pathogens. Only 44 (41.50%) exhibited good antimicrobial activity against different pathogenic microbes. Five isolates (FMS-20, TGH-30, TGH-31, TGH-31-1 and IS-4) were chosen for secondary screening using filtrate. Among them FMS-20 filtrate showed good inhibition on the 16th day against all tested microbial pathogens. Further the intracellular methanol extract of FMS-20 showed maximum zone of inhibition against A. brasiliensis (22 mm) at 5 mg/disc. Similarly the extracellular ethyl acetate extract of FMS-20 showed maximum zone of inhibition against B. subtilis (25 mm).
Agricultural production is severely affected by various abiotic stresses including drought. Development of crop plants tolerant to drought is an urgent need to increase crop productivity to feed the growing population. It is imperative to understand the adaptive mechanism of plants to drought especially the type and expression levels of drought responsive genes. Several genes upregulated during abiotic stress have been exploited to develop drought tolerant plants. Genetic engineering of crop plants with stress responsive genes has been an effective method of generating drought tolerant plants. But expressions of these stress responsive genes are regulated by several transcription factors (TFs). TFs are DNA binding proteins that bind to the specific sequence motif and modulate the levels of gene expression. They may function as an activator, or repressor for the expression of specific genes. Transgenic plants expressing drought responsive TFs have been shown to improve drought tolerance in many crop plants. In this review, we have discussed the details on TFs used for developing various transgenic plants and also analyzed the potential of TFs for further transgenic studies. The future direction to exploit TFs for sustainable crop production under drought is also highlighted.
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