Drought tolerance mechanisms and aquaporin expression of wild vs. cultivated pear tree species in the field

Paudel, Indira; Gerbi, Hadas; Zisovich, Annat; Sapir, Gal; Ben‐Dor, Shifra; Brumfeld, Vlad; Klein, Tamir

doi:10.1016/j.envexpbot.2019.103832

Cited by 22 publications

(11 citation statements)

References 49 publications

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“…In A. thaliana, drought stress upregulated AtPIP1;4 in both the roots and aerial parts of the plants [ 60 ]. Similar results are observed for PIP1;4 expression in three Pyrus species [ 61 ]. Specifically, drought stress during the summer up-regulated PIP1;4 across the three species and explained as help the plant to cope with water stress, potentially by channeling water to target cells.…”

Section: Discussionsupporting

confidence: 87%

Molecular Characterization and Expression of Four Aquaporin Genes in Impatiens walleriana during Drought Stress and Recovery

Đurić

Subotić

Prokić

et al. 2021

Plants

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Aquaporins comprise a large group of transmembrane proteins responsible for water transport, which is crucial for plant survival under stress conditions. Despite the vital role of aquaporins, nothing is known about this protein family in Impatiens walleriana, a commercially important horticultural plant, which is sensitive to drought stress. In the present study, attention is given to the molecular characterization of aquaporins in I. walleriana and their expression during drought stress and recovery. We identified four I. walleriana aquaporins: IwPIP1;4, IwPIP2;2, IwPIP2;7 and IwTIP4;1. All of them had conserved NPA motifs (Asparagine-Proline-Alanine), transmembrane helices (TMh), pore characteristics, stereochemical properties and tetrameric structure of holoprotein. Drought stress and recovery treatment affected the aquaporins expression in I. walleriana leaves, which was up- or downregulated depending on stress intensity. Expression of IwPIP2;7 was the most affected of all analyzed I. walleriana aquaporins. At 15% and 5% soil moisture and recovery from 15% and 5% soil moisture, IwPIP2;7 expression significantly decreased and increased, respectively. Aquaporins IwPIP1;4 and IwTIP4;1 had lower expression in comparison to IwPIP2;7, with moderate expression changes in response to drought and recovery, while IwPIP2;2 expression was of significance only in recovered plants. Insight into the molecular structure of I. walleriana aquaporins expanded knowledge about plant aquaporins, while its expression during drought and recovery contributed to I. walleriana drought tolerance mechanisms and re-acclimation.

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Section: Discussionsupporting

confidence: 87%

Molecular Characterization and Expression of Four Aquaporin Genes in Impatiens walleriana during Drought Stress and Recovery

Đurić

Subotić

Prokić

et al. 2021

Plants

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“…For instance, only PIP2;4 in the roots of 7307 was transcriptionally downregulated when that of the other two cultivars was upregulated, which could probably lead to decreased water absorption from the soil. The mRNA level of PIP1;2 in the wood was inhibited in Yu711 but stimulated in Wubu and 7307, which partly corresponded to the findings in wood of pear trees ( Paudel et al., 2019 ). PIP1;3 abundance in the root and bark was depressed in Wubu but increased in Yu711 and 7307.…”

Section: Discussionsupporting

confidence: 79%

Physiological and PIP Transcriptional Responses to Progressive Soil Water Deficit in Three Mulberry Cultivars

Cao

Shen

et al. 2020

Front. Plant Sci.

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Although mulberry cultivars Wubu, Yu711, and 7307 display distinct anatomical, morphological, and agronomic characteristics under natural conditions, it remains unclear if they differ in drought tolerance. To address this question and elucidate the underlying regulatory mechanisms at the whole-plant level, 2-month old saplings of the three mulberry cultivars were exposed to progressive soil water deficit for 5 days. The physiological responses and transcriptional changes of PIPs in different plant tissues were analyzed. Drought stress led to reduced leaf relative water content (RWC) and tissue water contents, differentially expressed PIPs , decreased chlorophyll and starch, increased soluble sugars and free proline, and enhanced activities of antioxidant enzymes in all plant parts of the three cultivars. Concentrations of hydrogen peroxide (H 2 O 2 ), superoxide anion (O 2 •− ), and malonaldehyde (MDA) were significantly declined in roots, stimulated in leaves but unaltered in wood and bark. In contrast, except the roots of 7307, soluble proteins were repressed in roots and leaves but induced in wood and bark of the three cultivars in response to progressive water deficit. These results revealed tissue-specific drought stress responses in mulberry. Comparing to cultivar Yu711 and 7307, Wubu showed generally slighter changes in leaf RWC and tissue water contents at day 2, corresponding well to the steady PIP transcript levels, foliar concentrations of chlorophyll, O 2 •− , MDA, and free proline. At day 5, Wubu sustained higher tissue water contents in green tissues, displayed stronger responsiveness of PIP transcription, lower concentrations of soluble sugars and starch, lower foliar MDA, higher proline and soluble proteins, higher ROS accumulation and enhanced activities of several antioxidant enzymes. Our results indicate that whole-plant level responses of PIP transcription, osmoregulation through proline and soluble proteins and antioxidative protection are important mechanisms for mulberry to cope with drought stress. These traits play significant roles in conferring the relatively higher drought tolerance of cultivar Wubu and could be potentially useful for future mulberry improvement programmes.

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“…We acknowledge that simulating NSL as a decline in apparent V cmax and J max summarizes the effects from a multiplicity of interacting plant physiological responses to drought, which might be better considered separately. For example, water and carbon transport in the mesophyll might be described as a function of aquaporin expression in dependence on cell water potential (Flexas et al, 2012;Paudel et al, 2019), and the effects on photosynthesis could be separated into suppression of rubisco regeneration (Rizhsky et al, 2002;Pilon et al, 2018), and reduction in rubisco activity. Also, reduced sink strength of tissue experiencing drought limitations (Hsiao et al, 1976;Fatichi et al, 2014) could eventually be used to describe the down-regulation of photosynthesis explicitly, e.g., via higher leaf sugar concentration due to reduced phloem load (Riesmeier et al, 1994;Sevanto, 2014).…”

Section: Non-stomatal Limitations Of Photosynthesis As a Hydraulic Safety Mechanismmentioning

confidence: 99%

Leaf Shedding and Non-Stomatal Limitations of Photosynthesis Mitigate Hydraulic Conductance Losses in Scots Pine Saplings During Severe Drought Stress

et al. 2021

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During drought, trees reduce water loss and hydraulic failure by closing their stomata, which also limits photosynthesis. Under severe drought stress, other acclimation mechanisms are trigged to further reduce transpiration to prevent irreversible conductance loss. Here, we investigate two of them: the reversible impacts on the photosynthetic apparatus, lumped as non-stomatal limitations (NSL) of photosynthesis, and the irreversible effect of premature leaf shedding. We integrate NSL and leaf shedding with a state-of-the-art tree hydraulic simulation model (SOX+) and parameterize them with example field measurements to demonstrate the stress-mitigating impact of these processes. We measured xylem vulnerability, transpiration, and leaf litter fall dynamics in Pinus sylvestris (L.) saplings grown for 54 days under severe dry-down. The observations showed that, once transpiration stopped, the rate of leaf shedding strongly increased until about 30% of leaf area was lost on average. We trained the SOX+ model with the observations and simulated changes in root-to-canopy conductance with and without including NSL and leaf shedding. Accounting for NSL improved model representation of transpiration, while model projections about root-to-canopy conductance loss were reduced by an overall 6%. Together, NSL and observed leaf shedding reduced projected losses in conductance by about 13%. In summary, the results highlight the importance of other than purely stomatal conductance-driven adjustments of drought resistance in Scots pine. Accounting for acclimation responses to drought, such as morphological (leaf shedding) and physiological (NSL) adjustments, has the potential to improve tree hydraulic simulation models, particularly when applied in predicting drought-induced tree mortality.

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Drought tolerance mechanisms and aquaporin expression of wild vs. cultivated pear tree species in the field

Cited by 22 publications

References 49 publications

Molecular Characterization and Expression of Four Aquaporin Genes in Impatiens walleriana during Drought Stress and Recovery

Molecular Characterization and Expression of Four Aquaporin Genes in Impatiens walleriana during Drought Stress and Recovery

Physiological and PIP Transcriptional Responses to Progressive Soil Water Deficit in Three Mulberry Cultivars

Leaf Shedding and Non-Stomatal Limitations of Photosynthesis Mitigate Hydraulic Conductance Losses in Scots Pine Saplings During Severe Drought Stress

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