Stress memory is the plants' ability to alter their physiological and
transcriptional responses to stresses when pre-exposed to a wide array of
abiotic stresses. In Arabidopsis thaliana, plants that have experienced
exposures to dehydration exhibit transcriptional behavior that suggests the
plants' memory of the earlier stress. Some genes respond to the first stress
by changing their transcription but provide a different response to
following stresses. These are the 'memory genes'. However, it is still
unknown whether these memory responses exist in other angiosperms.

The transcriptional responses of maize (Zea mays L.) plants with repeated
exposures to drought stress were compared with the responses of plants
exposed to the stress for the first time. Four separate transcription memory
response patterns similar to those displayed by A. thaliana were discovered.
There is also evidence that monocot and eudicot plants display similar
abilities to 'remember' a dehydration stress. Transcription patterns
indicate that the behavior of responding genes to repeated stresses is
different from the behavior during the initial stress, suggesting that
stress memory is a complex phenotype resulting from coordinated responses of
multiple-signaling pathways.

These results provide new insights into the knowledge of plants response to
multiple dehydration stresses compared to a single exposure. It may serve as
a reference for studies on memory genes.

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