Animals and plants produce regulatory signals at specific places of their bodies, in order to regulate developmental events which take place at a distance. Plants use this mechanism to adjust their development to the changing environment. Flowering and tuber formation are controlled by signals generated in the leaves that travel throughout the plant to reach their target tissues: the shoot apic...

What determines which plant species are susceptible to a given plant pathogen is poorly understood. Experimental inoculations with fungal pathogens of plant leaves in a tropical rain forest show that most fungal pathogens are polyphagous but that most plant species in a local community are resistant to any given pathogen. The likelihood that a pathogen can infect two plant species decreases con...