Department of Agriculture, Food and Environment, University of Pisa, Via Del Borghetto 80, I-56124, Pisa, Italy.
Department of Agriculture, Food and Environment, University of Pisa, Via Del Borghetto 80, I-56124, Pisa, Italy; CIRSEC, Centre for Climate Change Impact, University of Pisa, Via Del Borghetto 80, I-56124, Pisa, Italy.
Environ Res. 2021 Oct;201:111581. doi: 10.1016/j.envres.2021.111581. Epub 2021 Jun 24.
Ozone (O)-induced metabolic changes in leaves are relevant and may have several ecological significances. Here, variations in foliar chemistry of two poplar clones (Populus deltoides × maximowiczii, Eridano, and P. × euramericana, I-214) under a chronic O treatment (80 ppb, 5 h d for 10 consecutive days) were investigated. The aim was to elucidate if leaf age and/or O-sensitivity (considering Eridano and I-214 as O-sensitive and O-resistant, respectively) can affect suitability of poplar foliage for Chrysomela populi L. (Coleoptera Chrysomelidae), in terms of palatability. Comparing controls, only low amino acid (AA) contents were reported in Eridano [about 3- and 4-fold in mature and young leaves (ML and YL, respectively)], and all the investigated primary metabolites [i.e. water soluble carbohydrates (WSC), proteins (Prot) and AA] were higher in YL than in ML of I-214 (+23, +54 and + 20%, respectively). Ozone increased WSC only in YL of Eridano (+24%, i.e. highest values among samples; O effects are always reported comparing O-treated plants with the related controls). A concomitant decrease of Prot was observed in both ML and YL of Eridano, while only in YL of I-214 (-41, -45 and -51%, respectively). In addition, O decreased AA in YL of Eridano and in ML of I-214 (-40 and -14%, respectively). Comparing plants maintained under charcoal-filtered air, total ascorbate (Asc) was lower in Eridano in both ML and YL (around -22%), and abscisic acid (ABA) was similar between clones; furthermore, higher levels of Asc were reported in YL than in ML of Eridano (+19%). Ozone increased Asc and ABA (about 2- and 3-fold, respectively) in both ML and YL of Eridano, as well as ABA in YL of I-214 (about 2-fold). Comparing leaves maintained under charcoal-filtered air, the choice feeding test showed that the 2nd instar larvae preferred YL, and the quantity of YL consumed was 9 and 4-fold higher than ML in Eridano and I-214, respectively. Comparing leaves exposed to O-treatment, a significant feeding preference for YL disks was also observed, regardless of the clone. The no-choice feeding test showed that larval growth was slightly higher on untreated YL than on untreated ML (+19 and + 10% in Eridano and I-214, respectively). The body mass of larvae fed with O-treated YL was also significantly higher than that of larvae fed with untreated YL (3- and 2-fold in Eridano and I-214). This study highlights that realistic O concentrations can significantly impact the host/insect interactions, a phenomenon dependent on leaf age and O-sensitivity of the host.
臭氧（O）诱导叶片代谢变化具有相关性，可能具有多种生态意义。本研究以两种杨树无性系（Populus deltoides × maximowiczii，Eridano 和 P. × euramericana，I-214）为材料，在慢性臭氧处理（80 ppb，5 h/d，连续 10 天）下，研究了叶片化学物质的变化。目的是阐明叶片年龄和/或臭氧敏感性（分别将 Eridano 和 I-214 视为臭氧敏感和臭氧抗性）是否会影响杨树叶片对 Chrysomela populi L.（鞘翅目叶甲科）的适口性。与对照相比，仅在 Eridano 中报道了较低的氨基酸（AA）含量（成熟叶和幼叶分别约为 3-和 4 倍），并且所有研究的初级代谢物[即水溶性碳水化合物（WSC）、蛋白质（Prot）和 AA]在 I-214 的幼叶中均高于成熟叶（分别增加 23%、54%和 20%）。臭氧仅增加了 Eridano 幼叶中的 WSC（增加 24%，即所有样本中最高值；臭氧处理植物与相关对照相比，始终报告臭氧效应）。同时，Eridano 的成熟叶和幼叶中的 Prot 均减少，而 I-214 仅在幼叶中减少（分别减少 41%、45%和 51%）。此外，臭氧降低了 Eridano 幼叶和 I-214 成熟叶中的 AA（分别减少 40%和 14%）。与在活性炭过滤空气中培养的植物相比，Eridano 的成熟叶和幼叶中的总抗坏血酸（Asc）均较低（约 22%），两个无性系之间的脱落酸（ABA）相似；此外，Eridano 的幼叶中的 Asc 水平高于成熟叶（增加 19%）。臭氧增加了 Eridano 的成熟叶和幼叶中的 Asc 和 ABA（分别约增加 2 倍和 3 倍），以及 I-214 幼叶中的 ABA（约增加 2 倍）。与在活性炭过滤空气中培养的叶片相比，2 龄幼虫更喜欢幼叶，在 Eridano 和 I-214 中，幼叶的消耗量分别是成熟叶的 9 倍和 4 倍。与暴露于臭氧处理的叶片相比，无论无性系如何，幼虫对幼叶盘的摄食偏好也显著增加。非选择性摄食试验表明，未经处理的幼叶上幼虫的生长速度略高于未经处理的成熟叶（Eridano 和 I-214 分别增加 19%和 10%）。用臭氧处理的幼叶喂养的幼虫的体重也明显高于用未经处理的幼叶喂养的幼虫（Eridano 和 I-214 分别增加 3 倍和 2 倍）。本研究表明，实际的臭氧浓度会显著影响宿主/昆虫的相互作用，这一现象取决于叶片年龄和宿主的臭氧敏感性。
