Plants use their epigenetic memories to adapt to climate change

"One day I thought how the living style and experience of a person can affect his or her gametes transmitting molecular marks of their life into their children," says Federico Martinelli, a plant geneticist at the University of Florence. "Immediately I thought that even more epigenetic marks must be transmitted in plants, being that plants are sessile organisms that are subjected to many more environmental stresses than animals during their life."

Plants are facing more environmental stressors than ever. For example, climate change is making winters shorter and less severe in many locations, and plants are responding. "Many plants require a minimum period of cold in order to set up their environmental clock to define their flowering time," says Martinelli. "As cold seasons shorten, plants have adapted to require less period of cold to delay flowering. These mechanisms allow plants to avoid flowering in periods where they have less chances to reproduce."

Because plants don't have neural networks, their memory is based entirely on cellular, molecular, and biochemical networks. These networks make up what the researchers term somatic memory. "These mechanisms allow plants to recognize the occurrence of a previous environmental condition and to react more promptly in presence of the same consequential condition," says Martinelli.

These somatic memories can then be passed to the plants' progeny via epigenetics. "We have highlighted key genes, proteins, and small oligonucleotides, which previous studies have shown play a key role in the memory of abiotic stresses such as drought, salinity, cold, heat, and heavy metals and pathogen attacks," says Martinelli. "In this peer-reviewed opinion piece, we provide several examples that demonstrate the existence of molecular mechanisms modulating plant memory to environmental stresses and affecting the adaptation of offspring to these stresses."

Going forward, Martinelli and his colleagues hope to understand even more about the genes that are being passed down. "We are particularly interested in decoding the epigenetic alphabet underlying all the modifications of the genetic material caused by the environment, without changes in DNA sequence," he says. "This is especially important when we consider the rapid climate change we observe today that every living organism, including plants, needs to quickly adapt to in order to survive."