Data from: Inheritance of somatic mutations can affect fitness in monkeyflowers

Plants have the ability to transmit mutations to progeny that arise
through both meiotic and mitotic (somatic) cell divisions. This is because
the same meristem cells responsible for vegetative growth will also
generate gametes for sexual reproduction. Despite the potential for
somatic mutations to contribute to genetic variation and adaptation, their
role in plant evolution remains largely unexplored. We conducted
experiments with the bush monkeyflower (Mimulus aurantiacus) to assess the
phenotypic effects of somatic mutations inherited across generations. By
generating self-pollinations within a flower (autogamy) or between flowers
on different stems of the same plant (geitonogamy), we tracked the effects
of somatic mutations transmitted to progeny. Autogamy and geitonogamy lead
to different segregation patterns of somatic mutations among stems, with
only autogamy resulting in offspring that are homozygous for somatic
mutations specific to that stem. This allowed us to compare average
phenotypic differences between pollination treatments that could be
attributed to the inheritance of somatic variants. While most experimental
units showed no impacts on fitness, in some cases, we detected increased
seed production, as well as significant increases in drought tolerance,
even though M. aurantiacus is already well adapted to drought conditions.
We also found increased variance in drought tolerance following autogamy,
consistent with the hypothesis that somatic mutations transmitted between
generations can impact fitness. These results highlight the potential role
of inherited somatic mutations as a relevant source of genetic variation
in plant evolution.