Better green than yellow
Zigmunds Orlovskis, John Innes Centre
Many plant pathogens induce organ yellowing in their host plants. Leaf yellowing can be observed in this image in leaves from the Madagascan Periwinkle Catharanthus roseus infected with phytoplasma bacterium (right) compared to leaves from healthy plants (left). Since phytoplasma are insect-transmitted pathogens, it has been hypothesised that the yellow colour helps to attract the insects to the infected plants thus facilitating phytoplasma dispersal. This hypothesis has never been rigorously tested and is under investigation by scientists at the John Innes Centre on the Norwich Research Park.