Plants may look passive, but beneath their still surfaces they are constantly sensing and responding to the world around them. A new study from Lund University reveals how a feather-light touch, a gust of wind, or the bite of an herbivore can trigger a molecular chain reaction inside a plant in less than a minute, reshaping its gene activity and even its growth.<\/p>\n
The knowledge of mechanical stimulation, wind, touch, and wound activation of MAP kinases \u2013 proteins that transduce signals within cells \u2013 has been known for many years. What was lacking was the understanding of how such activation leads to changes in plant development<\/a>.<\/p>\n By studying the model plant Arabidopsis thaliana<\/a>, researchers have now identified the pathway: a cascade involving MAPKKK3\/4\/5 \u2192 MKK4\/5 \u2192 MPK3\/6. Within 60 seconds of stimulation, this protein chain switches on, triggering the activity of around 800 genes, most of the early touch response.<\/p>\n In addition to being a protein waterfall in which one protein activates another, the fast-paced signaling from the cascade is similar to that controlled by CAMTA (calmodulin-binding transcription factor) genes, which indicates there is cooperation between MAPKs and CAMTAs in controlling the plant\u2019s reaction<\/a>.<\/p>\n Plants can sense when something touches them and stops<\/a><\/p>\n Interestingly, while the phosphorylation cascade described above is essential for the activation of protein activities regulated by touch, it does not directly influence the early activation of the jasmonic acid (JA) pathway, which is a common stress signaling route. Also, the absence of JA does not change the early phosphoproteome, indicating that there are multiple independent pathways.<\/p>\n The molecular pathways involved in this cascade are related to the plant response to physical stress, known as \u201cthigmomorphogenesis,\u201d which occurs when plants alter their development based upon past experiences of being subjected to physical forces (i.e., wind, rainfall, grazing).<\/p>\n These types of stresses can result in changes in plant morphology and increased levels of defense mechanisms. When MAPKKK3\/4\/5 or MKK4\/5 were lost from the system, it led to reduced capacity for adaptive growth, thereby indicating the significance of the molecular pathway.<\/p>\n \u201cRemarkably, a signal initiated within a minute can have such widespread effects,\u201d said Huy Cuong Tran, first author of the study.<\/p>\n How plants \u2018pay\u2019 their microbes?<\/a><\/p>\n \u201cPlants may appear still and passive, but they are constantly monitoring what happens around them,\u201d noted Viktor Johansson, PhD student at Lund University. \u201cBy understanding the molecular mechanisms behind these signals, we can better understand how plants adapt to their environment and cope with changing conditions such as climate change.\u201d<\/p>\n This study is still considered basic science; however, it may ultimately provide insight into agricultural practices. Controlled mechanical stimulation (such as rolling) of grain crops has shown potential in reducing the effects of lodging and drought on the crop.<\/p>\n This finding will bridge a 25-year-old knowledge gap in plant biology; namely, the upstream mechanism that connects physical stimulation to MAP kinase activation. Through the mapping of this pathway, researchers are now able to understand how plants convert physical contact into a form of molecular communication, which ultimately alters the plant\u2019s gene expression<\/a>, protein production, and development.<\/p>\n This reminds us that plants do not simply sit in one spot; they react to every movement in their environment (such as wind, rain, etc.) with a cascade of chemical and physical signals that help them live in a world where there is no way for them to leave.<\/p>\n Journal Reference:<\/p>\n