A recent study has revealed that when plants are exposed to rain, hair-like structures on the leaf surface called trichomes recognize the rain as a risk factor for causing disease and activate their immune system to prevent infections. These findings could contribute to the development of methods to protect plants from infectious diseases caused by rain.
Although water is one of the key essentials for majority of plant life, there are also bacteria that come from these water sources which can harm the plants. Raindrops can contain pathogens, like bacteria, filamentous fungi, and viruses, which can cause disease in plants. Plants have their own immune systems, so when these plants detect pathogens, they express immune-related genes to prevent themselves from being infected.
A research team led by Professor Yasuomi Tada and assistant Professor Mika Nomoto of Nagoya University conducted a study using seedlings from Arabidopsis thaliana (common name: thale cress). They found that Ca2+ levels around the trichomes on leaf surfaces increase.
Professor Tada says that their findings may be able to artificially improve plants' defensive capabilities against diseases at any time and for any length of time.
Related Article: https://pubmed.ncbi.nlm.nih.gov/15085136/