Biogenic amines—polyamines (PAs), particularly putrescine, spermidine and spermine are ubiquitous in all living cells. Their indispensable roles in many biochemical and physiological processes are becoming commonly known, including promoters of plant life and differential roles in human health and disease. PAs positively impact cellular functions in plants—exemplified by increasing longevity, reviving physiological memory, enhancing carbon and nitrogen resource allocation/signaling, as well as in plant development and responses to extreme environments. Thus, one or more PAs are commonly found in genomic and metabolomics studies using plants, particulary during different abiotic stresses. In humans, a general decline in PA levels with aging occurs parallel with some human health disorders. Also, high PA dose is detrimental to patients suffering from cancer, aging, innate immunity and cognitive impairment during Alzheimer and Parkinson diseases. A dichotomy exists in that while PAs may increase longevity and reduce some age-associated cardiovascular diseases, in disease conditions involving higher cellular proliferation, their intake has negative consequences. Thus, it is essential that PA levels be rigorously quantified in edible plant sources as well as in dietary meats. Such a database can be a guide for medical experts in order to recommend which foods/meats a patient may consume and which ones to avoid. Accordingly, designing both high and low polyamine diets for human consumption are in vogue, particularly in medical conditions where PA intake may be detrimental, for instance, cancer patients. In this review, literature data has been collated for the levels of the three main PAs, putrescine, spermidine and spermine, in different edible sources—vegetables, fruits, cereals, nuts, meat, sea food, cheese, milk, and eggs. Based on our analysis of vast literature, the effects of PAs in human/animal health fall into two broad, Yang and Yin, categories: beneficial for the physiological processes in healthy cells and detrimental under pathological conditions.

Feeding nutrition-dense food to future world populations presents agriculture with enormous challenges as estimates indicate that crop production must as much as double. Crop production cannot be increased to meet this challenge simply by increasing land acreage or using past agricultural intensification methods. Food production doubled in the past through substantial use of synthetic fertilizer, pesticides, and irrigation, all at significant environmental cost. Future production of nutrition-dense food will require next-generation crop production systems with decreased reliance on synthetic fertilizer and pesticide. Here, we present three case studies detailing the development of cover crops and plant-beneficial microbes for sustainable, next-generation small grain, tomato, and oilseed rape production systems. Cover crops imparted weed and pathogen control and decreased soil erosion and loss of soil nitrogen, phosphorus and carbon, while plant-beneficial microbes provided disease control and phosphorus fertility. However, yield in these next-generation crop production systems at best approximated that associated with current production systems. We argue here that to substantially increase agricultural productivity, new crop germplasm needs to be developed with enhanced nutritional content and enhanced tolerance to abiotic and biotic stress. This will require using all available technologies, including intensified genetic engineering tools, in the next-generation cropping systems.