An official website of the United States government
Summary Grasses are exceptionally productive, yet their hydraulic adaptation is paradoxical. Among C3grasses, a high photosynthetic rate (Aarea) may depend on higher vein density (Dv) and hydraulic conductance (Kleaf). However, the higherDvof C4grasses suggests a hydraulic surplus, given their reduced need for highKleafresulting from lower stomatal conductance (gs).Combining hydraulic and photosynthetic physiological data for diverse common garden C3and C4species with data for 332 species from the published literature, and mechanistic modeling, we validated a framework for linkages of photosynthesis with hydraulic transport, anatomy, and adaptation to aridity.C3and C4grasses had similarKleafin our common garden, but C4grasses had higherKleafthan C3species in our meta‐analysis. Variation inKleafdepended on outside‐xylem pathways. C4grasses have highKleaf : gs, which modeling shows is essential to achieve their photosynthetic advantage.Across C3grasses, higherAareawas associated with higherKleaf, and adaptation to aridity, whereas for C4species, adaptation to aridity was associated with higherKleaf : gs. These associations are consistent with adaptation for stress avoidance.Hydraulic traits are a critical element of evolutionary and ecological success in C3and C4grasses and are crucial avenues for crop design and ecological forecasting.
more »
« less
This content will become publicly available on November 1, 2026
Environmental factors have a greater influence on photosynthetic capacity in C4 plants than biochemical subtypes or growth forms
Our understanding of how photosynthetic capacity varies among C4species and across growth and measurement conditions remains limited.We collated 1696 CO2response curves of net CO2assimilation rate (A/Cicurves) from C4species grown and measured at various environmental conditions and used these data to estimate the apparent maximum carboxylation activity of phosphoenolpyruvate carboxylase (VpmaxA) and CO2‐saturated net photosynthetic rate (Amax), two key parameters describing photosynthetic capacity. We examined howVpmaxAandAmaxvary with species‐specific traits, growth and measurement conditions.We found little systematic variation ofVpmaxAandAmaxacross the classical C4biochemical subtypes or growth forms, but showed that growth temperature and measurement conditions are major factors determining C4photosynthetic capacity. We found no evidence that common C4model species (e.g. maize, sorghum andSetaria viridis) differ in photosynthetic capacity from other C4species when grown in controlled environments. However, C4model species showed up to twice the photosynthetic capacity of other C4species when grown in the field.Our multivariate model accounts for 47–51% of the variation reported inVpmaxAandAmax, and we argue that environmental conditions have a greater influence on C4photosynthetic capacity than biochemical subtypes or growth forms.
more »
« less
- PAR ID:
- 10693155
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 248
- Issue:
- 3
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- 1205 to 1224
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Photosynthetic acclimation to both warming and elevated CO2of boreal trees remains a key uncertainty in modelling the response of photosynthesis to future climates. We investigated the impact of increased growth temperature and elevated CO2on photosynthetic capacity (VcmaxandJmax) in mature trees of two North American boreal conifers, tamarack and black spruce. We show thatVcmaxandJmaxat a standard temperature of 25°C did not change with warming, whileVcmaxandJmaxat their thermal optima (Topt) and growth temperature (Tg) increased. Moreover,VcmaxandJmaxat either 25°C,ToptorTgdecreased with elevated CO2. TheJmax/Vcmaxratio decreased with warming when assessed at bothToptandTgbut did not significantly vary at 25°C. TheJmax/Vcmaxincreased with elevated CO2at either reference temperature. We found no significant interaction between warming and elevated CO2on all traits. If this lack of interaction between warming and elevated CO2on theVcmax,JmaxandJmax/Vcmaxratio is a general trend, it would have significant implications for improving photosynthesis representation in vegetation models. However, future research is required to investigate the widespread nature of this response in a larger number of species and biomes.more » « less
-
Abstract Improved understanding of bacterial community responses to multiple environmental filters over long time periods is a fundamental step to develop mechanistic explanations of plant–bacterial interactions as environmental change progresses.This is the first study to examine responses of grassland root‐associated bacterial communities to 15 years of experimental manipulations of plant species richness, functional group and factorial enrichment of atmospheric CO2(eCO2) and soil nitrogen (+N).Across the experiment, plant species richness was the strongest predictor of rhizobacterial community composition, followed by +N, with no observed effect of eCO2. Monocultures of C3and C4grasses and legumes all exhibited dissimilar rhizobacterial communities within and among those groups. Functional responses were also dependent on plant functional group, where N2‐fixation genes, NO3−‐reducing genes and P‐solubilizing predicted gene abundances increased under resource‐enriched conditions for grasses, but generally declined for legumes. In diverse plots with 16 plant species, the interaction of eCO2+N altered rhizobacterial composition, while +N increased the predicted abundance of nitrogenase‐encoding genes, and eCO2+N increased the predicted abundance of bacterial P‐solubilizing genes.Synthesis: Our findings suggest that rhizobacterial community structure and function will be affected by important global environmental change factors such as eCO2, but these responses are primarily contingent on plant species richness and the selective influence of different plant functional groups.more » « less
-
Societal Impact StatementThe invasive speciesS. alternifloraandP. australisare fast growing coastal wetland plants sequestering large amounts of carbon in the soil and protect coastlines against erosion and storm surges. In this global analysis, we found thatSpartinaandPhragmitesincrease methane but not nitrous oxide emissions, withPhragmiteshaving a lesser effect. The impact of the invasive species on emissions differed greatly among different types of native plant groups, providing valuable information to managers and policymakers during coastal wetland planning and restoration efforts. Further, our estimated net emissions per wetland plant group facilitate regional and national blue carbon estimates. SummaryGlobally,Spartina alternifloraandPhragmites australisare among the most pervasive invasive plants in coastal wetland ecosystems. Both species sequester large amounts of atmospheric carbon dioxide (CO2) and biogenic carbon in soils but also support production and emission of methane (CH4). In this study, we investigated the magnitude of their net greenhouse gas (GHG) release from invaded and non‐invaded habitats.We conducted a meta‐analysis of GHG fluxes associated with these two species and related soil carbon content and plant biomass in invaded coastal wetlands.Our results show that both invasive species increase CH4fluxes compared to uninvaded coastal wetlands, but they do not significantly affect CO2and N2O fluxes. The magnitude of emissions fromSpartinaandPhragmitesdiffers among native habitats. GHG fluxes, soil carbon and plant biomass ofSpartina‐invaded habitats were highest compared to uninvaded mudflats and succulent forb‐dominated wetlands, while being lower compared to uninvaded mangroves (except for CH4).This meta‐analysis highlights the important role of individual plant traits as drivers of change by invasive species on plant‐mediated carbon cycles.more » « less
-
Summary The mesophyll provides a critical signal for stomatal responses to red light (RL) and CO2in angiosperms. By contrast, the stomatal response to blue light (BL) is largely guard cell‐specific. It is not known whether substomatal or mesophyll anatomy influences the effectiveness of the mesophyll signal driving stomatal responses to RL and CO2.Here we utilize the diverse substomatal anatomy in Restionaceae to investigate whether mesophyll anatomy has an influence on stomatal responses to light and CO2. Restionaceae from the subfamily Restionoideae have distinctive nonphotosynthetic, cuticle‐covered protective cells that line a large substomatal cavity, while most species from the subfamily Leptocarpoideae have a small substomatal cavity surrounded by mesophyll cells.We found that representative Restionoideae species do not have a stomatal response to RL or CO2, with only BL driving stomatal responses to light. By contrast, representative Leptocarpoideae species have a stomatal response to RL, BL and CO2.The absence of stomatal responses to RL and CO2in species with protective cells lining the substomatal cavity demonstrates the importance of mesophyll anatomy in stomatal control and suggests that the mesophyll signal that drives stomatal responses to RL and CO2requires close proximity of photosynthetic cells to the guard cells.more » « less
