Abstract
Plant natriuretic peptides (PNPs) are signalling molecules that are secreted into the apoplast particularly under conditions of biotic and abiotic stress. At the local level, PNPs modulate their own expression via feed forward and feedback loops to enable tuning of the response at the transcript and protein level and to prevent over-expression. PNPs also employ a systemic signal, possibly electrical, to rapidly alter photosynthesis and respiration not only in treated leaves but also in upper and lower leaves thereby modulating and integrating physiological responses at the level of the whole plant.