Cytokinins (CKs) are a chemically diverse class of plant growth regulators, exhibiting wide-ranging actions on plant growth and development, hence their exploitation in agriculture for crop improvement and management. Their coordinated regulatory effects and cross-talk interactions with other phytohormones and signaling networks are highly sophisticated, eliciting and controlling varied biological processes at the cellular to organismal levels. In this review, we briefly introduce the mode of action and general molecular biological effects of naturally occurring CKs before highlighting the great variability in the response of fruit crops to CK-based innovations. We present a comprehensive compilation of research linked to the application of CKs in non-model crop species in different phases of fruit production and management. By doing so, it is clear that the effects of CKs on fruit set, development, maturation, and ripening are not necessarily generic, even for cultivars within the same species, illustrating the magnitude of yet unknown intricate biochemical and genetic mechanisms regulating these processes in different fruit crops. Current approaches using genomic-to-metabolomic analysis are providing new insights into the in planta mechanisms of CKs, pinpointing the underlying CK-derived actions that may serve as potential targets for improving crop-specific traits and the development of new solutions for the preharvest and postharvest management of fruit crops. Where information is available, CK molecular biology is discussed in the context of its present and future implications in the applications of CKs to fruits of horticultural significance.

Cleome gynandra (Syn. Gynandropsis gynandra) is fast emerging as one of the most widely consumed leafy vegetables due to its nutrition and health-promoting properties. In addition to its high nutritional content, the plant has a rich pool of diverse antioxidant phytochemicals. The current review provides a critical appraisal on the increasing nutritional significance of Cleome gynandra due to its rich pool of natural bioactive compounds and beneficial health-promoting qualities. The rich nutritional content especially the high levels of macro- and micronutrients is an indication of its potential to mitigate malnutrition and the increasing incidence of diet-related obesity and non-communicable diseases. The presence of health-promoting natural compounds, notably polyphenols, glucosinates and terpernoids has been confirmed in Cleome gynandra using different analytical methods. Cleome gynandra possesses high levels of α-tocopherol, β-tocopherol and γ-tocopherol, ascorbic acid, α-carotene, β-carotene, lutein, violaxanthin, and β-cryptoxanthin. These nutritional compounds could be useful in food applications as supplements, colorants and extending shelf-life of food products. Cleome gynandra extracts have demonstrated promising effects in several biological assays using in vitro and in vivo systems. Clearly, diversified diets that include a regular intake of dark green leafy vegetables including Cleome gynandra, holds great promise in ensuring food and nutrition security. GRAPHICAL ABSTRACT

The efficacy of phytoextracts is equally affected by the extraction solvent and the extraction method. Details of the solvent type, concentration, density, and other characteristics are associated with the quality of the resultant extract. Some solvents have been found to be effective only on specific parts of plants. Industry has shown a growing interest in eco-friendly plant extracts for the formulation of medication, food additives, cosmetics, and agricultural products. This interest is aligned with the proven necessity of sustainability, marketability, and regulation of manufactured products in value chains. In this review, the literature on antioxidant compounds and activity of extracts from African medicinal plants is reviewed. Findings indicate that the use of ethanol, methanol, water, and to a lesser extent, acetone as solvents for the extraction of antioxidant compounds is common. The use of these solvents is supported by decisive selection of procedure, ideal temperature, duration, solvent pH, and the extracted plant parts. Fermentation enhances the antioxidant activity of aqueous extracts but reduces that of alcohol extracts. This is particularly essential in continents such as Africa, where water is available but alcohol is scarce. “Green” extraction technologies are not as successful as solvent extractions for use with African medicinal plants. There is a financial hurdle that results in a mismatch between academic research innovations and societal transmission to new technologies, as most communities are dominated by small-to-medium enterprises. Further studies on the extraction of antioxidants from African medicinal plants are recommended to guide the research and link it to ordinary African societies.