Is desiccation tolerance and avoidance reflected in xylem and phloem anatomy of two coexisting arid‐zone coniferous trees?

Sevanto, Sanna; Ryan, Max; Dickman, L. Turin; Derome, Dominique; Patera, Alessandra; Defraeye, Thijs; Pangle, Robert E.; Hudson, Patrick J.; Pockman, William T.

doi:10.1111/pce.13198

Cited by 23 publications

(17 citation statements)

References 70 publications

(138 reference statements)

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“…Small sieve cells in tall Douglas-fir trees that were related to a height reduction in shoot midday water potential were the main factor accounting for low phloem conductivity in tall compared to small trees (Woodruff 2014). Interestingly, an increase in phloem conduit diameter under drought in piñon pine, and no change in one-seed juniper with ambient and 50% precipitation removal was found (Sevanto et al 2018), suggesting that species adapted to drought may be affected less or differently than species from moist environments. However, we lack experimental data showing whether water in the phloem comes directly from the xylem or through the phloem parenchyma cells and therefore cannot directly asses the influence of declining xylem water potential on phloem growth.…”

Section: How Does Drought Affect Phloem Transport?mentioning

confidence: 97%

“…This model suggests that plants are susceptible to turgor loss, which hinders the phloem flow at low xylem water potentials or during prolonged drought when carbohydrate reserves decline below the limit needed for effective osmoregulation (Sevanto 2014;Sevanto et al 2014). For trees, the model used might vary between the 'semi-permeable phloem' and models in which conduit walls are non-permeable with loading and unloading zones where material exchange occurs, as well as the degree to which the model can be modified (Sevanto et al 2018). However most of the conclusions about trees seem to be speculative or hypothetical because of a lack of empirical evidence (Sevanto 2014;Malone et al 2016;Sevanto et al 2018).…”

Section: Is the Phloem Involved In Drought-induced Mortality?mentioning

confidence: 99%

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Drought impacts on tree phloem: from cell-level responses to ecological significance

et al. 2019

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On-going climate change is increasing the risk of drought stress across large areas worldwide. Such drought events decrease ecosystem productivity and have been increasingly linked to tree mortality. Understanding how trees respond to water shortage is key to predicting the future of ecosystem functions. Phloem is at the core of the tree functions, moving resources such as non-structural carbohydrates, nutrients, and defence and information molecules across the whole plant. Phloem function and ability to transport resources is tightly controlled by the balance of carbon and water fluxes within the tree. As such, drought is expected to impact phloem function by decreasing the amount of available water and new photoassimilates. Yet, the effect of drought on the phloem has received surprisingly little attention in the last decades. Here we review existing knowledge on drought impacts on phloem transport from loading and unloading processes at cellular level to possible effects on long-distance transport and consequences to ecosystems via ecophysiological feedbacks. We also point to new research frontiers that need to be explored to improve our understanding of phloem function under drought. In particular, we show how phloem transport is affected differently by increasing drought intensity, from no response to a slowdown, and explore how severe drought might actually disrupt the phloem transport enough to threaten tree survival. Because transport of resources affects other organisms interacting with the tree, we also review the ecological consequences of phloem response to drought and especially predatory, mutualistic and competitive relations. Finally, as phloem is the main path for carbon from sources to sink, we show how drought can affect biogeochemical cycles through changes in phloem transport. Overall, existing knowledge is consistent with the hypotheses that phloem response to drought matters for understanding tree and ecosystem function. However, future research on a large range of species and ecosystems is urgently needed to gain a comprehensive understanding of the question.

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Section: How Does Drought Affect Phloem Transport?mentioning

confidence: 97%

Section: Is the Phloem Involved In Drought-induced Mortality?mentioning

confidence: 99%

Drought impacts on tree phloem: from cell-level responses to ecological significance

et al. 2019

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“…Changes in the diameter and number of xylem vessels indicate the adaptation level of plants grown under adverse environmental conditions (CASTANHEIRA et al, 2016;HACKE;SPICER;SCHREIBER, 2017). Smaller diameter and higher number of xylem vessels indicate high plants efficiency for sap conduction since they decrease chances for air embolism in plants grown, for example, under water stress (SEVANTO et al, 2018). However, the decrease in number of xylem vessels found in treatments containing agricultural gypsum and the control treatment in this study may be the result of damages caused by water restriction to plants grown at 40% irrigation.…”

Section: Resultsmentioning

confidence: 99%

“…The higher spacing of the phloem observed in plants grown under water stress is also an indicating of plants adaptation form developed to address adverse growing conditions, to allow greater translocation of photoassimilates and favor plants growth (SEVANTO et al, 2018).…”

Section: Resultsmentioning

confidence: 99%

Agronomic Techniques for Mitigating the Effects of Water Restriction on Coffee Crops

Castanheira

Resende

Guimarães

et al. 2019

C.Sci.

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Water restriction significantly affects coffee (<em>Coffea arabica</em> L.) production. The study of a few agronomic techniques that optimizes water use can generate technologies for mitigating the effects of climatic variations on coffee crops. The aim of this study was to indicate agronomic techniques that mitigate the effects of water restriction on coffee crops. For this end, we analyzed the morphophysiological changes in coffee plants cultivated in a greenhouse with different types of fertilizers and soil conditioners and under two levels of irrigation. The evaluations were conducted 130 days after planting, assessing the morphological and physiological characteristics of the plants. We also quantified soil moisture in the different treatments. The water restriction expressively hindered plant growth. The use of controlled release fertilizers and soil conditioners, especially coffee husk, is indicated for mitigating water restriction in coffee crops.

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“…Sevanto et al. ). In a study of C. endlicheri it was considered their strong drought tolerance (Lunt et al.…”

Section: Discussionmentioning

confidence: 99%

The foliar characters in Callitris (Callitroideae, Cupressaceae s. str.) and their evolutionary and ecological significance

2019

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The foliar shift from juvenile needle leaves to the mature scale leaves was investigated in five Callitris species. Their habitats range from rainforest to the semi‐arid. In C. macleayana from the most mesic environment the change from needle to scale leaves is variable and juvenile leave are even retained on mature trees. In the other four species there is a rapid change in size and structure to scale leaves. Anatomically the photosynthetic tissue is condensed and stomatal area is limited compared to species with conventional leaves. A hypodermis is most prominent on the abaxial side of the leaves and may play a role in protection from high solar radiation as most species grow in high light areas. While stomata in the four taxa from wet or moderate rainfall areas are freely exposed, those of C. gracilis from semi‐arid habitats are well protected in longitudinal furrows between the decurrent leaves. The reduced leaf area of all species allows close association between the water‐conducting xylem and the stomata that will facilitate rapid leaf conductance. This links with the anisohydric physiology of the genus and the shallow rooting that can take advantage of brief rainfall events for species in arid climates.

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Is desiccation tolerance and avoidance reflected in xylem and phloem anatomy of two coexisting arid‐zone coniferous trees?

Cited by 23 publications

References 70 publications

Drought impacts on tree phloem: from cell-level responses to ecological significance

Drought impacts on tree phloem: from cell-level responses to ecological significance

Agronomic Techniques for Mitigating the Effects of Water Restriction on Coffee Crops

The foliar characters in Callitris (Callitroideae, Cupressaceae s. str.) and their evolutionary and ecological significance

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