Tissue shrinkage/growth analyses.
To investigate the distribution of water between vegetative and
reproductive tissues as plants dehydrated, we used cameras to
simultaneously monitored the shrinkage dynamics of reproductive and
vegetative organs, petioles, peduncles, and fruit within individual
plants. 5 different plants were measured and exposed to the same
dehydration and water potential monitoring as above. Intact proximal
regions of S. lycopersicum petioles and peduncles were secured in
cavicams as described above. Images were acquired using transmitted
light to produce a silhouette every 10 minutes until the plant was fully
desiccated (approximately 8 days). Cameras were refocussed every day as
the tissue dried. Intact tomato fruit approximately 1cm diameter (older
than 7 days) were photographed using a Leica DFC450 digital camera.
Single fruit were secured to the stage of a Leica M205A stereomicroscope
(Leica Microsystems, Wetzlar, Germany) or a custom-built gantry holding
a Nikon lens attached to a Raspberry PI camera and Images taken at
intervals of 10 minutes until the plant was fully desiccated.
Images were processed in IMAGEJ (NIH). Image sequences were thresholded
to isolate plant tissue from the background. The total thresholded area
and fruit diameter were recorded every 50 images and this decrease in
size, expressed as a percentage if the original area, was plotted
against water potential.
To confirm that a vascular connection was required for fruit growth the
growth of tomato fruit was also assessed once fruit were removed from
the plant’s vascular supply. A tomato fruit of ~1cm
diameter was monitored as above, however once the plant water potential
had reached -1MPa, after demonstrating initial positive expansion, the
fruit was excised from the plant at the peduncle using a razor blade.
Images were captured every 2 minutes until the rest of the plant was
fully desiccated.