Endophytes including fungal leaf endophytes (A), bacterial leaf endophytes (B), Rhizobia (C), and arbuscular mycorrhizal fungi (D), can infect all organs of a plant, which in their presence exhibits what we usually know as its normal phenotype (left panel). These endophytes contribute so strongly to vitally important traits of the plant that a completely endophyte-free plant would suffer from chlorosis and lowered photosynthetic rates due to nutritional shortcomings, lowered resistance to abiotic stress and lowered resistance to both pathogens and herbivores and, in consequence, lowered competitive abilities and lower survival rates in nature (right panel).