Carica papaya L. (family: Caricaceae), also known as ‘papaya,’ is a tropical American fruit tree. Due to the bioactive components (carpaines, BITC, benzyl glucosinolates, latex, papain, zeaxanthin, choline, etc.) in its seeds, leaves, and fruits, it is revered for its excellent antioxidant, digestive, and nutraceutical benefits. Papayas are high in vitamins A, B, C, E, and K, folate, pantothenic acid, zeaxanthin, lycopene, lutein, magnesium, copper, calcium, and potassium. Being rich in fiber, antioxidants, and vitamin C, it lowers the cholesterol in the arteries; prevents arthritis; reduces aging, cancer, macular degradation, risk of cardiovascular diseases, and stress; increases platelet count; controls dengue fever; facilitates digestion, and lowers body weight. Papaya leaf extract, with many in vitro and case studies in combination therapies with modern medicine, especially for cancers and many other viral diseases, has been found to be an efficient cure. Humans have cultivated papaya cultivars for millions of years because of their significant commercial, medicinal, and agronomic value. Several reports have been published on the genetic modification of papaya for resistance to abiotic (herbicide, Al toxicity, etc.) and biotic stressors (PRSV, mites, Phytophthora, etc.), delaying ripening, and improving shelf life. However, most of these traits have not been introduced globally to all commercial papaya varieties. Unraveling the genetics of papaya has shed light on various domestication impacts, evolutionary patterns, and sex determination in fruit tree crops. It also serves as a potential step toward developing new cultivars to fight climate-oriented stress. Furthermore, extensive research on the stability of the ‘transgene’ across generations, and the ‘yield-penalty’ caused by the transgene, is required. Thus, meticulous crop improvement research on commercial papaya cultivars is necessary for long-term food and health security. This review article encompasses information on the traditional and modern medicinal uses, nutritional properties, phytochemistry, diseases and etiology, post-harvest measures, genomics, biotechnological strategies (for papaya improvement), and value-added products of papaya for food and health security.

Native/endogenous promoters have several fundamental limitations in terms of their size, Cis-elements distribution/patterning, and mode of induction, which is ultimately reflected in their insufficient transcriptional activity. Several customized synthetic promoters were designed and tested in plants during the past decade to circumvent such constraints. Such synthetic promoters have a built-in capacity to drive the expression of the foreign genes at their maximum amplitude in plant orthologous systems. The basic structure and function of the promoter has been discussed in this review, with emphasis on the role of the Cis-element in regulating gene expression. In addition to this, the necessity of synthetic promoters in the arena of plant biology has been highlighted. This review also provides explicit information on the two major approaches for developing plant-based synthetic promoters: the conventional approach (by utilizing the basic knowledge of promoter structure and Cis-trans interaction) and the advancement in gene editing technology. The success of plant genetic manipulation relies on the promoter efficiency and the expression level of the transgene. Therefore, advancements in the field of synthetic promoters has enormous potential in genetic engineering-mediated crop improvement.

Daunorubicin (DNR) is an anthracycline antibiotic originating from soil-dwelling actinobacteria extensively used to treat malignant tumors. Over the decades, extensive attempts were made to enhance the production of anthracyclines by introducing genetic modifications and mutations in combination with media optimization, but the target production levels remain comparatively low. Developing an appropriate culture medium to maximize the yield of DNR and preventing autotoxicity for the producing organism remains a challenge. Our prospective review sheds light on a method involving perturbation that enhances the precursors to regulate the type II PKS pathway, enhancing cells’ capacity to increase secondary metabolite production. The suggested method also entails the preparation of culture media for the cultivation of Streptomyces sp. and enhanced yield of DNR, as well as making it inactive with iron or its reduced forms following efflux from the producer. The iron or iron–DNR complex is encapsulated by oleic acid or lipid micelle layers in the culture media, finally resulting in the generated inactive DNR and the DNR–iron–oil complex. This idea has the potential to protect the producer organism from autotoxicity and prevent the inhibition of metabolite production. The approach of substituting sugar with oil in culture media has a dual role wherein it promotes Streptomyces growth by utilizing lipids as an energy source and encapsulating the generated DNR–iron complex in the medium. In this review, we discussed aspects like anthracycline producers, biosynthesis pathways, and gene regulation; side effects of DNR; mechanisms for autotoxicity evasion; and culture media components for the enhancement of DNR production in Streptomyces sp. We anticipate that our work will help researchers working with secondary metabolites production and decipher a methodology that would enhance DNR yield and facilitate the extraction of the resulting DNR by lowering costs in large-scale fermentation.

Daunomycin is a chemotherapeutic agent widely used for the treatment of leukemia, but its toxicity toward healthy dividing cells limits its clinical use and its production by fermentation. Herein, we describe the development of a specialized cultivation medium for daunomycin production, including a shift to oil rather than sugar as the primary carbon source. This achieved an almost threefold increase in daunomycin yields, reaching 5.5–6.0 g/L. Daunomycin produced in the oil-based medium was predominantly found in the solid sediment, whereas that produced in the sugar-based medium was mostly soluble. The oil-based medium thus induces an autonomous daunomycin-resistance mechanism involving biogenic nanoparticle formation. The characterization of the nanoparticles confirmed the incorporation of iron and daunomycin, indicating that this approach has the potential to mitigate cytotoxicity while improving yields. The presence of proteins associated with iron homeostasis and oxidative stress responses revealed the ability of the production strain to adapt to high iron concentrations. Our findings provide insight into the mechanisms of biogenic nanoparticle formation and the optimization of cultivation processes. Further investigation will help to refine microbial production systems for daunomycin and also broaden the application of similar strategies for the synthesis of other therapeutically important compounds.