Palisade cell geometry in relation to leaf optical and photosynthetic properties in Viburnum.

The optical properties of lobed palisade mesophyll cells remain poorly understood despite their presence in diverse taxa and the critical role of the palisade layer in leaf-light interactions and carbon assimilation. Using micro-computed tomography, 3D ray tracing simulations, and physiological experiments, we tested the interactions between palisade cell geometry, chloroplast localization, light directional quality, and leaf optical and photosynthetic performance in the model taxon Viburnum. Simulations showed that lobed cells shifted between absorptance- or transmittance-dominated states depending on chloroplast localization, irrespective of light directional quality.

Tree drought physiology: critical research questions and strategies for mitigating climate change effects on forests.

Droughts of increasing severity and frequency are a primary cause of forest mortality associated with climate change. Yet, fundamental knowledge gaps regarding the complex physiology of trees limit the development of more effective management strategies to mitigate drought effects on forests. Here, we highlight some of the basic research needed to better understand tree drought physiology and how new technologies and interdisciplinary approaches can be used to address them.

Into the spongy-verse: structural differences between leaf and flower mesophyll.

As the site of almost all terrestrial carbon fixation, the mesophyll tissue is critical to leaf function. However, mesophyll tissue is not restricted only to leaves but also occurs in the laminar, heterotrophic organs of the floral perianth, providing a powerful test of how metabolic differences are linked to differences in tissue structure. Here, we compared mesophyll tissues of leaves and flower perianths of six species using high-resolution X-ray computed microtomography (microCT) imaging.

Sensitive Hydraulic and Stomatal Decline in Extreme Drought Tolerant Species of California Ceanothus.

Identifying the physiological mechanisms by which plants are adapted to drought is critical to predict species responses to climate change. We measured the responses of leaf hydraulic and stomatal conductances (K and g, respectively) to dehydration, and their association with anatomy, in seven species of California Ceanothus grown in a common garden, including some of the most drought-tolerant species in the semi-arid flora. We tested for matching of maximum hydraulic supply and demand and quantified the role of decline of K in driving stomatal closure.

Stomatal closure as a driver of minimum leaf conductance declines at high temperature and vapor pressure deficit in Quercus.

Rising global temperatures and vapor pressure deficits (VPDs) are increasing plant water demand and becoming major drivers of large-scale plant mortality. Controlling transient leaf water loss after stomatal closure (minimum stomatal conductance [gmin]) is recognized as a key trait determining how long plants survive during soil drought. Yet, substantial uncertainty remains regarding how gmin responds to elevated temperatures and VPD and the underlying mechanisms.