hide
Free keywords:
-
Abstract:
Ranunculus trichophyllus is an amphibious plant that produces thin and cylindrical leaves if grown under water but thick and broad leaves if grown on land. We found that such heterophylly
is widely controlled by two plant hormones, abscisic acid (ABA) and ethylene,
which control terrestrial and aquatic leaf development respectively. Aquatic leaves produced
higher levels of ethylene but lower levels of ABA than terrestrial leaves. In aquatic leaves, its
distinct traits with narrow shape, lack of stomata, and reduced vessel development were
caused by EIN3-mediated overactivation of abaxial genes, RtKANADIs, and accompanying
with reductions of STOMAGEN and VASCULAR-RELATED NAC-DOMAIN7 (VDN7). In
contrast, in terrestrial leaves, ABI3-mediated activation of the adaxial genes, RtHD-ZIPIIIs,
and STOMAGEN and VDN7 established leaf polarity, and stomata and vessel developments.
Heterophylly of R.trichophyllus could be also induced by external cues such as cold
and hypoxia, which is accompanied with the changes in the expression of leaf polarity
genes similar to aquatic response. A closely-related land plant R. sceleratus did not show
such heterophyllic responses, suggesting that the changes in the ABA/ethylene signaling
and leaf polarity are one of key evolutionary steps for aquatic adaptation.
