A Plant, A Fungus, A Virus: What It Takes To Take the Heat

Crop plants are generally grown under conditions where microbes are reduced, or eliminated if possible.  They are also susceptible to biotic stress (diseases) and abiotic stress (heat, cold, drought, salinity).  Wild plants are always found with multiple microbial symbionts, including viruses, bacteria and fungi.  Wild plants can also be found adapted to extreme environmental stress.  In Yellowstone National Park plants can grow in geothermal soils with temperatures up to 50 °C, and in volcanic areas of Costa Rica we have found plants growing in soils with temperatures as high as 65 °C.  These plants are colonized by endophytic fungi that have been shown, in some cases, to confer tolerance to the heat stress, but not without the help of a fungal virus.  Hence in plant adaptation to extreme conditions, multiple symbiotic partners are required, and viruses are likely the source of very novel genetic information that allows these adaptations to occur.