Unexpectedly low δ 13C in leaves, branches, stems, and roots of three acacia species growing in hyper-arid environments

Abstract Aims In plant eco-physiology, less negative (enriched) carbon 13 ( 13C) in the leaves indicates conditions of reducing leaf gas exchange through stomata, e.g. under drought. In addition, 13C is expected to be less negative in non-photosynthetic tissues as compared with leaves. However, these relationships in δ 13C from leaves (photosynthetic organs) to branches, stems and roots (non- photosynthetic organs) are rarely tested across multiple closely related tree species, multiple compartments, or in trees growing under extreme heat and drought. Methods We measured leaf-to-root 13C in three closely related desert acacia species (Acacia tortilis, A. raddiana, A. pachyceras). We measured δ 13C in leaf tissues from mature trees in Southern Israel. In parallel, a 7-year irrigation experiment with 0.5, 1.0, or 4.0 L plant -1 day -1 was conducted in an experimental orchard. At the end of the experiment, growth parameters and δ 13C were measured in leaves, branches, stems, and roots. Important findings The δ 13C in leaf tissues sampled from mature trees was ca. -27 ‰, far more depleted than expected from a desert tree growing in one of the Earth’s driest and hottest environments. Across acacia species and compartments, δ 13C was not enriched at all irrigation levels (-28‰ to ca. -27‰), confirming our measurements in the mature trees. Among compartments, leaf δ 13C was unexpectedly similar to branch and root δ 13C, and surprisingly, even less negative than stem δ 13C. The highly depleted leaf δ 13C suggests that these trees have high stomatal gas exchange, despite growing in extremely dry habitats. The lack of δ 13C enrichment in non-photosynthetic tissues might be related to the seasonal coupling of growth of leaves and heterotrophic tissues.

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The Lanata trichome mutation increases stomatal conductance and reduces leaf temperature in tomato

10.1101/2020.02.11.943761 ◽

2020 ◽

Author(s):

Karla Gasparini ◽

Ana Carolina R. Souto ◽

Mateus F. da Silva ◽

Lucas C. Costa ◽

Cássia Regina Fernandes Figueiredo ◽

...

Keyword(s):

Stomatal Conductance ◽

Gas Exchange ◽

Spectral Properties ◽

Growth Parameters ◽

Stomatal Density ◽

Leaf Gas Exchange ◽

Glandular Trichomes ◽

Glandular Trichome ◽

Leaf Temperature ◽

Trichome Density

ABSTRACTBackground and aimsTrichomes are epidermal structures with an enormous variety of ecological functions and economic applications. Glandular trichomes produce a rich repertoire of secondary metabolites, whereas non-glandular trichomes create a physical barrier against biotic and abiotic stressors. Intense research is underway to understand trichome development and function and enable breeding of more resilient crops. However, little is known on how enhanced trichome density would impinge on leaf photosynthesis, gas exchange and energy balance.MethodsPrevious work has compared multiple species differing in trichome density, instead here we analyzed monogenic trichome mutants in a single tomato genetic background (cv. Micro-Tom). We determined growth parameters, leaf spectral properties, gas exchange and leaf temperature in the hairs absent (h), Lanata (Ln) and Woolly (Wo) trichome mutants.Key resultsShoot dry mass, leaf area, leaf spectral properties and cuticular conductance were not affected by the mutations. However, the Ln mutant showed increased carbon assimilation (A) possibly associated with higher stomatal conductance (gs), since there were no differences in stomatal density or stomatal index between genotypes. Leaf temperature was furthermore reduced in Ln in the early hours of the afternoon.ConclusionsWe show that a single monogenic mutation can increase glandular trichome density, a desirable trait for crop breeding, whilst concomitantly improving leaf gas exchange and reducing leaf temperature.HIGHLIGHTA monogenic mutation in tomato increases trichome density and optimizes gas exchange and leaf temperature

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The influence of soil temperature and water content on belowground hydraulic conductance and leaf gas exchange in mature trees of three boreal species

Plant Cell & Environment ◽

10.1111/pce.13709 ◽

2020 ◽

Vol 43 (3) ◽

pp. 532-547 ◽

Cited By ~ 2

Author(s):

Anna Lintunen ◽

Teemu Paljakka ◽

Yann Salmon ◽

Roderick Dewar ◽

Anu Riikonen ◽

...

Keyword(s):

Gas Exchange ◽

Soil Temperature ◽

Water Content ◽

Leaf Gas Exchange ◽

Hydraulic Conductance ◽

Mature Trees ◽

Boreal Species

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Photosynthesis in a desert tree is driven by the highest light and temperature

10.5194/egusphere-egu2020-3868 ◽

2020 ◽

Author(s):

Daphna Uni ◽

Efrat Sheffer ◽

Gidon Winters ◽

Tamir Klein

Keyword(s):

Gas Exchange ◽

Maximum Rate ◽

Leaf Gas Exchange ◽

Natural Habitat ◽

Carbon Assimilation ◽

Soil Parameters ◽

Arid Ecosystem ◽

Acacia Tortilis ◽

Living Tree ◽

Physiological Processes

Among living tree species, Acacia raddiana (Savi) and Acacia tortilis (Forssk), species of the legume family, populate some of the hottest and driest places on earth. Our research investigates the physiological processes underlying the unique survival of these trees in their extreme environmental conditions. We measured Acacia trees in their natural habitat once a month for two years to unravel the photosynthesis dynamics and water relations. Leaf gas exchange and leaf water potential were measured, as well as atmospheric and soil parameters. Daily and annual gas-exchange curves showed higher carbon assimilation during noon and in summer, when temperature and radiation were maximal (44&#176;C, 2000 &#181;mol m-2 s-1), and the air was dry (21% RH). Additionally, we found that the maximum rate of carbon assimilation was at PAR (photosynthetic active radiation) of 3000 &#181;mol m-2 s-1. Our results suggest that water did not drive net carbon assimilation but rather light and temperature, which are already close to their maximum in our hyper-arid ecosystem.

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Diel patterns of leaf carbohydrate concentrations differ between seedlings and mature trees of two sympatric oak species

Botany ◽

10.1139/cjb-2014-0032 ◽

2014 ◽

Vol 92 (7) ◽

pp. 535-540 ◽

Cited By ~ 13

Author(s):

Ori Baber ◽

Martijn Slot ◽

Gerardo Celis ◽

Kaoru Kitajima

Keyword(s):

Gas Exchange ◽

Carbon Balance ◽

Leaf Gas Exchange ◽

Sun Exposure ◽

Fundamental Aspect ◽

Sink Strength ◽

Mature Trees ◽

Leaf Mass ◽

Diel Patterns ◽

Unit Leaf

A fundamental aspect of the carbon cycle is the exchange of carbon between plants and the atmosphere. It is, therefore, important to understand factors that affect differences in gas exchange and carbon balance within and among species. Concentrations of nonstructural carbohydrates are often used as a proxy for carbon balance. We determined diel patterns of leaf carbohydrate concentrations in relation to irradiance (sun vs. shade) in seedlings and mature trees of two sympatric oak species (Quercus virginiana Mill. and Quercus hemisphaerica Bartram ex Willd.). For seedlings, we also measured leaf gas exchange. Higher sun exposure significantly increased photosynthesis and carbohydrate concentrations in both species. Carbohydrate concentrations of seedling leaves showed strong diel fluctuations, whereas concentrations in mature tree leaves did not. This contrast might be attributed to faster carbohydrate export from leaves of mature trees. The difference in sink strength between seedlings and adults may be related to the decreasing ratio of leaf mass to plant mass with ontogeny, increasing the demand for carbohydrates per unit leaf mass. Seedlings and mature trees are clearly functionally different and care must be taken when extrapolating results from seedling experiments to mature trees.

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Temporal and spatial changes in phyllosphere microbiome of acacia trees growing in arid environments

10.21203/rs.3.rs-15477/v2 ◽

2021 ◽

Author(s):

Ashraf Al-Ashhab ◽

Shiri Meshner ◽

Rivka Alexander-Shani ◽

Hana Dimerets ◽

Michael Brandwein ◽

...

Keyword(s):

Microbial Communities ◽

Bacterial Diversity ◽

Air Temperature ◽

Bacterial Communities ◽

Abiotic Factors ◽

Keystone Species ◽

Tree Canopy ◽

Arid Environments ◽

Acacia Tortilis ◽

Acacia Species

Abstract Background: The evolutionary relationships and interactions between plants and their microbiomes are of high importance to the survival of plants in extreme conditions. Changes in the plant’s microbiome can affect plant development, growth and health. Along the arid Arava, southern Israel, acacia trees (Acacia raddiana and Acacia tortilis) are considered keystone species. In this study, we investigated the ecological effects of plant species, microclimate (different areas within the tree canopy) and seasonality on the epiphytic and endophytic microbiomes associated with these two tree species. One hundred and thirty nine leaf samples were collected throughout the year and their microbial communities were assessed using 16S rDNA gene amplified with five different primers (targeting different gene regions) and sequenced (150 bp paired-end) on an Illumina MiSeq sequencing platform.Results: Epiphytic bacterial diversity estimates (Shannon-Wiener, Chao1, Simpson and observed number of OTUs), were found to be nearly double compared to endophyte counterparts, in addition epi- and endophyte communities were significantly different from each other. Interestingly, the epiphytic bacterial diversity was similar in the two acacia species but the canopy sides and sample months exhibited different diversity, while the endophytic bacterial communities were different in the two acacia species but similar throughout the year. Abiotic factors, such as air temperature and precipitation, were shown to significantly affect both epi- and endophytes communities. Bacterial community compositions showed that Firmicutes dominate Acacia raddiana and Proteobacteria dominate Acacia tortilis; these bacterial communities only consisted of a small number of bacterial families mainly Bacillaceae and Comamonadaceae in the endophyte for A. raddiana and A. tortilis, respectively, and Geodematophilaceae and Micrococcaceae for epiphyte bacterial communities. Interestingly, about 60% of the obtained bacterial classification were unclassified below family level. Conclusions: These results shed light on the unique desert phyllosphere microbiome highlighting the importance of multiple genotypic and abiotic factors in shaping the epiphytic and endophytic microbial communities. This study also shows that only a few bacterial families dominate both epi- and endophytes, highlighting the importance of climate change (precipitation, air temperature and humidity) in affecting arid land ecosystems where acacia trees are considered keystone species.

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Optimizing the Electrical Conductivity of a Nutrient Solution for Plant Growth and Bioactive Compounds of Agastache rugosa in a Plant Factory

Agronomy ◽

10.3390/agronomy10010076 ◽

2020 ◽

Vol 10 (1) ◽

pp. 76 ◽

Cited By ~ 3

Author(s):

Vu Phong Lam ◽

Sung Jin Kim ◽

Jong Seok Park

Keyword(s):

Electrical Conductivity ◽

Gas Exchange ◽

Plant Growth ◽

Bioactive Compounds ◽

Nutrient Solution ◽

Growth Parameters ◽

Leaf Gas Exchange ◽

Agastache Rugosa ◽

Gas Exchange Parameters ◽

Exchange Parameters

The objective of this study was to determine the proper electrical conductivity (EC) of a nutrient solution (NS) for accumulating bioactive compounds of Agastache rugosa without decreasing plant growth. Six-week-old seedlings were transplanted in a deep flow technique system with Hoagland NS with a 2.0 dS·m−1 EC for the initial week. From eight days after transplanting, the plants were treated with six EC treatments of 0.5, 1.0, 2.0, 4.0, 6.0, and 8.0 dS·m−1 for three weeks. Plant growth parameters, leaf gas exchange parameters, the relative chlorophyll value, and the ratio of variable to maximum fluorescence (Fv/Fm) were measured, and the rosmarinic acid (RA), tilianin, and acacetin concentrations were analyzed at 28 days after transplanting. The results showed that almost all plant growth parameters were maximized at 2.0 and 4.0 dS·m−1 and minimized at 8.0 dS·m−1 compared with the other EC treatments. The relative chlorophyll and Fv/Fm values were maximized at 2.0 and 4.0 dS·m−1. Similarly, leaf gas exchange parameters were increased at 2.0 and 4.0 dS·m−1. The RA content exhibited significantly higher values at 0.5, 1.0, 2.0, and 4.0 dS·m−1 compared with other treatments. The tilianin and acacetin contents exhibited the significantly highest values at 4.0 and 0.5 dS·m−1, respectively. These results suggest optimal EC treatment at 4.0 dS·m−1 for increasing bioactive compounds in A. rugosa plants without decreasing plant growth. Excessively high or low EC induced salinity stress or nutrient deficiency, respectively. Furthermore, among the plant organs, the roots of A. rugosa contained the highest RA concentration and the flowers contained the highest tilianin and acacetin concentrations, which revealed a higher utilization potential of the roots and flowers for bioactive compounds.

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Effects of atmospheric CO2 enrichment and root restriction on leaf gas exchange and growth of banana (Musa)

Physiologia Plantarum ◽

10.1034/j.1399-3054.1996.970408.x ◽

1996 ◽

Vol 97 (4) ◽

pp. 685-693

Author(s):

B. Schaffer ◽

C. Searle ◽

A. W. Whiley ◽

R. J. Nissen

Keyword(s):

Gas Exchange ◽

Leaf Gas Exchange ◽

Co2 Enrichment ◽

Atmospheric Co2 ◽

Root Restriction

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The Effects of Drought on Leaf Gas Exchange and Growth of Three Species of Herbaceous Perennials

HortScience ◽

10.21273/hortsci.33.3.540a ◽

1998 ◽

Vol 33 (3) ◽

pp. 540a-540

Author(s):

K.J. Prevete ◽

R.T. Fernandez

Keyword(s):

Drought Stress ◽

Stomatal Conductance ◽

Gas Exchange ◽

Drought Tolerance ◽

Transpiration Rate ◽

Leaf Gas Exchange ◽

Gas Analysis ◽

Herbaceous Perennials ◽

Effects Of Drought ◽

Analysis System

Three species of herbaceous perennials were tested on their ability to withstand and recover from drought stress periods of 2, 4, and 6 days. Eupatorium rugosum and Boltonia asteroides `Snowbank' were chosen because of their reported drought intolerance, while Rudbeckia triloba was chosen based on its reported drought tolerance. Drought stress began on 19 Sept. 1997. Plants were transplanted into the field the day following the end of each stress period. The effects of drought on transpiration rate, stomatal conductance, and net photosynthetic rate were measured during the stress and throughout recovery using an infrared gas analysis system. Leaf gas exchange measurements were taken through recovery until there were no differences between the stressed plants and the control plants. Transpiration, stomatal conductance, and photosynthesis of Rudbeckia and Boltonia were not affected until 4 days after the start of stress. Transpiration of Eupatorium decreased after 3 days of stress. After rewatering, leaf gas exchange of Boltonia and Rudbeckia returned to non-stressed levels quicker than Eupatorium. Growth measurements were taken every other day during stress, and then weekly following transplanting. Measurements were taken until a killing frost that occurred on 3 Nov. There were no differences in the growth between the stressed and non-stressed plants in any of the species. Plants will be monitored throughout the winter, spring, and summer to determine the effects of drought on overwintering capability and regrowth.

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