Plant-PET to investigate phloem vulnerability to drought in Populus tremula under changing climate regimes.

Phloem transport is of great importance in trees to distribute assimilated carbon across the entire tree. Nevertheless, knowledge of phloem is incomplete, because of the complexity of measuring its transport and characteristics. Only few studies have addressed how phloem transport might alter under climatic changes, with most data originating from theoretical studies.

Cambial pinning relates wood anatomy to ecophysiology in the African tropical tree Maesopsis eminii.

A better understanding and prediction of the impact of changing climate on tree stem growth could greatly benefit from the combination of anatomical and ecophysiological knowledge, yet the majority of studies focus on one research field only. We propose an approach that combines the method of pinning (cambial wounding) to timestamp anatomical X-ray computed microtomography images with continuous measurements of sap flow and stem diameter variations. By pinning the cambium of well-watered and drought-treated young African tropical trees of the species Maesopsis eminii Engl.

Plant-PET Scans: In Vivo Mapping of Xylem and Phloem Functioning.

Medical imaging techniques are rapidly expanding in the field of plant sciences. Positron emission tomography (PET) is advancing as a powerful functional imaging technique to decipher in vivo the function of xylem water flow (with (15)O or (18)F), phloem sugar flow (with (11)C or (18)F), and the importance of their strong coupling. However, much remains to be learned about how water flow and sugar distribution are coordinated in intact plants, both under present and future climate regimes.

Modelling reveals endogenous osmotic adaptation of storage tissue water potential as an important driver determining different stem diameter variation patterns in the mangrove species Avicennia marina and Rhizophora stylosa.

Background: Stem diameter variations are mainly determined by the radial water transport between xylem and storage tissues. This radial transport results from the water potential difference between these tissues, which is influenced by both hydraulic and carbon related processes. Measurements have shown that when subjected to the same environmental conditions, the co-occurring mangrove species Avicennia marina and Rhizophora stylosa unexpectedly show a totally different pattern in daily stem diameter variation.