Leaf hydraulics coordinated with leaf economics and leaf size in mangrove species along a salinity gradient

Novel leaf-root coordination driven by leaf water storage tissues in mangroves

“…10 Here, we used mangroves under high salinity as an example to understand the role of leaf water storage tissues in shaping the decoupling relationship between leaf hydraulics and economics. Under such salinity stress, mangrove leaf hydraulic traits, such as, leaf minor vein diameter, are faced with two competing selection pressures: (1) reducing leaf minor vein diameter due to inadequate water supply from thinner root vessels 5,11,40 ; and (2) increasing the size of leaf water storage tissues 35 entails a thick leaf minor vein diameter to meet the water requirement of the increased leaf water storage tissues (Fig. 4).…”

“…Under high soil salinity, plant leaves usually suffer greatly from water deficiency in transpiration due to insufficient water supply from the roots 5,11 . For example, in the mangrove species Ceriops tagal , the vessel diameter of absorptive roots under high salinity is only two-thirds of that under low salinity.…”

“…Leaf and root anatomical structures were determined using a common method for paraffin sectioning. Briefly, several leaves and the first-order roots were taken from the FAA solutions and were then processed in a suite of procedures, including dehydration, embeding in paraffin, cutting into sections (8 μm thickness), staineding and then photographing 5,26 . First-order root and leaf anatomical structures were determined using IMAGE J software (NIH Image, Bethesda, MD, USA).…”

“…During this process, atmospheric CO 2 enters the leaf mesophyll, mainly the palisade cells, and is fixed as carbohydrates through a series of biochemical reactions 1 . Researchers coined a term, “leaf economics spectrum”, to describe a tradeoff in this process across species worldwide; that is, leaves with higher leaf CO 2 fixation rates have a shorter leaf lifespan, and vice versa 2,3,4,5 .…”

“…Given that WUPM is negligible compared to WUT , it is likely that WUPM and hence leaf economics could have little impact on leaf hydraulics. Therefore, the contrasting amount and functioning of WUPM and WUT constitute a novel mechanism that essentially drives leaf economics-hydraulics decoupling 5,7,9 .…”