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Abstract Within the North American boreal forest, a widespread outbreak of the epidermal leaf miner Phyllocnistis populiella has damaged quaking aspen (Populus tremuloides) for nearly 20 years. In a series of experiments, we tested the effects of feeding damage by P. populiella on leaf water relations and gas exchange. Relative to insecticide-treated trees, the leaves of naturally-mined trees had lower photosynthesis, stomatal conductance to water vapor, transpiration, water use efficiency, predawn water potential, and water content, as well as more enriched foliar δ13C. The magnitude of the difference between naturally-mined and insecticide-treated trees did not change significantly throughout the growing season, suggesting the effect is not caused by accumulation of incidental damage to mined portions of the epidermis over time. The contributions of mining-related stomatal malfunction and cuticular transpiration to these overall effects were investigated by restricting mining damage to stomatous abaxial and astomatous adaxial leaf surfaces. Mining of the abaxial epidermis decreased photosynthesis and enriched leaf δ13C, while increasing leaf water potential and water content relative to unmined leaves; effects consistent with stomatal closure due to disfunction of mined guard cells. Mining of the adaxial epidermis also reduced photosynthesis but had different effects on water relations, reducing midday leaf water potential and water content relative to unmined leaves, and did not affect δ13C. In the laboratory, extent of mining damage to the adaxial surface was positively related to the rate of water loss by leaves treated to prevent water loss through stomata. We conclude that overall, despite water savings due to closure of mined stomata, natural levels of damage by P. populiella negatively impact water relations due to increased cuticular permeability to water vapor across the mined portions of the epidermis. Leaf mining by P. populiella could exacerbate the negative effects of climate warming and water deficit in interior Alaska.
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Tracking the paths of residual conductance during leaf expansion in Tilia americana and Fagus grandifolia
Abstract The rate of residual water loss is a major determinant of plant survival during drought, yet how the major paths of residual water flow develop as leaves expand is poorly understood. Here, we tracked the rate of residual water loss, the compositional development of cuticular wax, stomatal differentiation, pore formation, and xylem development as leaves expand in two co-occurring, deciduous tree species Tilia americana and Fagus grandifolia. As leaves expanded, residual conductance declined rapidly, primarily driven by decreases in cuticular conductance, which was the main pathway for residual water loss from branches with young leaves. Very little water was lost through stomatal pores as leaves expanded, because the outer cuticular ledge only formed above the majority of stomata once leaves approached complete expansion. Similar development of residual conductance was observed between the two species despite differences in cuticle composition and stomatal development timing as leaves expanded. Our work suggests that the cuticle is the primary pathway through which water is lost from the youngest expanding leaves, and residual conductance is minimized only when cuticular wax deposition is complete, stomata have formed, and leaves have fully expanded.
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- Award ID(s):
- 2140119
- PAR ID:
- 10683186
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Plant Physiology
- Volume:
- 199
- Issue:
- 1
- ISSN:
- 0032-0889
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/plphys/kiaf150
