Drought and heat stress interactions modify photorespiration and hydrogen peroxide content in Silver fir.

IF 3.5 2区 农林科学 Q1 FORESTRY
Franklin Alongi, Peter Petrík, Nadine K Ruehr
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引用次数: 0

Abstract

Photorespiration (PR) greatly reduces net carbon assimilation in trees (by c. 25%), but has received recent attention particular for its potential role in stress-signaling through the accumulation of hydrogen peroxide (H2O2), a stress signaling agent. Despite an increasing frequency of drought and heat events affecting forests worldwide, little is known about how concurrent abiotic stressors may interact to affect PR and subsequent H2O2 accumulation in trees. Here, we sought to identify how drought and a compounded one-day heat treatment individually and interactively affect PR (determined under variable O2) in Abies alba Mill. seedlings. Additionally, we quantified foliar H2O2 accumulation and enzymatic scavenging via peroxidase in relation to PR rates. We found drought stress to slightly increase PR (+5.2%) during mild-drought (12 days, Ψmd = -0.85 MPa), but ultimately to decrease PR (-13.6%) during severe-drought (26 days, Ψmd = -1.70 MPa) compared to the control, corresponding to increasing non-stomatal limitations of photosynthesis (i.e., decreased electron transport rate). The response of PR to heat stress was dependent on soil water availability as heat stress increased PR in control seedlings (+37.8%), but not in drought-stressed seedlings. Decreased PR during severe-drought corresponded to ~2x lower foliar H2O2 compared to the control. Despite increased PR under heat stress in control seedlings, foliar H2O2 decreased to near-zero likely due to enhanced scavenging as observed in ~2x greater peroxidase activity. Our results demonstrate that carbon loss to PR during drought stress can be highly dynamic, depending on the severity of soil dehydration. Additionally, increased PR under abiotic stress does not necessarily lead to accumulated H2O2, as tight regulation by scavenging enzymes instead minimize oxidative stress, reducing stress-signaling potential.

干旱和热胁迫相互作用改变银杉的光呼吸和过氧化氢含量
光呼吸(PR)大大降低了树木的净碳同化(约减少 25%),但最近因其通过积累过氧化氢(H2O2)(一种应激信号物质)在应激信号传递中的潜在作用而受到特别关注。尽管影响全球森林的干旱和高温事件日益频繁,但人们对同时发生的非生物胁迫如何相互作用以影响树木的 PR 和随后的 H2O2 积累知之甚少。在这里,我们试图确定干旱和为期一天的复合热处理如何单独和相互作用地影响白叶松苗的 PR(在可变氧气条件下测定)。此外,我们还量化了叶片 H2O2 积累和过氧化物酶清除与 PR 率的关系。我们发现,在轻度干旱(12 天,Ψmd = -0.85 MPa)期间,干旱胁迫会使 PR 略有增加(+5.2%),但与对照相比,在严重干旱(26 天,Ψmd = -1.70 MPa)期间,PR 最终会降低(-13.6%),这与光合作用的非气孔限制增加(即电子传输速率降低)相对应。PR对热胁迫的反应取决于土壤水分的供应情况,因为热胁迫会提高对照幼苗的PR(+37.8%),但不会提高干旱胁迫幼苗的PR。与对照组相比,严重干旱时 PR 的降低与叶片 H2O2 降低约 2 倍相对应。尽管对照组幼苗在热胁迫下 PR 增加,但叶片 H2O2 降低到接近零,这可能是由于过氧化物酶活性提高了约 2 倍,从而增强了清除作用。我们的研究结果表明,干旱胁迫期间 PR 的碳损失是高度动态的,这取决于土壤脱水的严重程度。此外,非生物胁迫下 PR 的增加并不一定会导致 H2O2 的积累,因为清除酶的严格调节反而会将氧化胁迫降到最低,从而降低胁迫信号转导的潜力。
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来源期刊
Tree physiology
Tree physiology 农林科学-林学
CiteScore
7.10
自引率
7.50%
发文量
133
审稿时长
1 months
期刊介绍: Tree Physiology promotes research in a framework of hierarchically organized systems, measuring insight by the ability to link adjacent layers: thus, investigated tree physiology phenomenon should seek mechanistic explanation in finer-scale phenomena as well as seek significance in larger scale phenomena (Passioura 1979). A phenomenon not linked downscale is merely descriptive; an observation not linked upscale, might be trivial. Physiologists often refer qualitatively to processes at finer or coarser scale than the scale of their observation, and studies formally directed at three, or even two adjacent scales are rare. To emphasize the importance of relating mechanisms to coarser scale function, Tree Physiology will highlight papers doing so particularly well as feature papers.
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