Crossing paths in plants

On Monday 31 March ecologists will meet with molecular biologists at the University of Southampton for the most novel and broad-ranging scientific session of its kind. They will present findings in Session C5/P3 which show that the biochemical pathways which influence a plant’s response to stimuli such as attack, disease or other stresses are not mutually exclusive as previously thought. For example, up until recently the two separate signalling pathways in plants which respond independently to disease (caused by microorganisms and pathogens) and to wounding (by herbivores) were believed to be completely separate. Now biologists know that these pathways talk to each other in a process known as ‘signalling cross-talk’.

These findings, which are being investigated at the molecular level, show that the stimuli which switch on the genes for the salicylic acid pathway (for disease) can also switch on the genes of the jasmonate pathway (for wounding). This has important implications for plant physiologists and ecologists who, up till now, have been breeding plants and applying external chemicals such as pesticides and stimulants on the basis that each pathway is distinct. Now they are investigating whether there are detrimental effects on a plant’s health or productivity if all factors are not considered; for example, plants bred or engineered for salt tolerance or drought resistance may be less able to resist disease or herbivorous attack.

Dr Jian-Kang Zhu (Arizona), who will be speaking at the meeting, has identified cross-talk between pathways for salt, drought and cold tolerance. The FIERY1 gene regulates all three pathways, and mutations in FIERY1 simultaneously affect gene induction by salt, drought and cold stresses. The cross-talk in the gene induction implies that by manipulating one stress tolerance pathway you can affect or even confer tolerance to salt, drought and cold stresses.