A paper on the transition of Hygrophila difformis from emersed to submersed

dw1305

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Hi all,
A paper has come my way that I thought might be of interest. : <"Photosynthetic acclimation of terrestrial and submerged leaves in the amphibious plant Hygrophila difformis">.

It is "Open Access", so should be available to every-one.

It is quite interesting, it suggests that ethylene is the substance that regulates the production of the dissected submerged leaf, and that all submerged leaves (including morphologically terrestrial ones) have the ability to utilise bicarbonate (HCO3-) as a carbon source.
Hygrophila difformis, a heterophyllous amphibious plant, develops serrated or dissected leaves when grown in terrestrial or submerged conditions, respectively.

In this study, we tested whether submerged leaves and ethylene-induced leaves of .....H. difformis have improved photosynthetic ability under submerged conditions. ........Submerged leaves and submerged terrestrial leaves were able to use bicarbonate but submerged terrestrial leaves had an intermediate ability to use HCO3−
cheers Darrel
 

dw1305

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Hi all,
Isn''t ethylene also mentioned as a factor in internodal length?
It is, plants produce it naturally, but if they are stressed they can over-produce it and it causes a shortening in internode length. They use ethylene commercially in fruit ripening for Bananas etc.

A lot of the research on ethylene has been on plant response to flooding and low oxygen levels in the root zone. Hypoxia in the root zone leads to the ethylene production, which is presumably the is the cue for H. difformis to start to making submerged leaves. I don't know about the natural habitat of H. difformis, but my guess would be that it grows in monsoon areas where there is a regular seasonal rhythm of rising and falling water. This was <"all I could find">.

cheers Darrel
 

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