Stem canker pathogen Botryosphaeria dothidea inhibits poplar leaf photosynthesis in the early stage of inoculation

Abstract

Fungal pathogens can induce canker lesions, wilting, and even dieback in many species. Trees can suffer serious physiological effects from stem cankers. In this study, we investigated the effects of Botryosphaeria dothidea (B. dothidea) on Populus bolleana (P. bolleana) leaves photosynthesis and stomatal responses, when stems were inoculated with the pathogen. To provide experimental and theoretical basis for preventing poplar canker early. One-year-old poplar stems were inoculated with B. dothidea using an epidermal scraping method. In the early stage of B. dothidea inoculation (2–14 days post inoculation, dpi), the gas exchange, stomatal dynamics, hormone content, photosynthetic pigments content, chlorophyll fluorescence parameters, and non-structural carbohydrate (NSC) were evaluated to elucidate the pathophysiological mechanism of B. dothidea inhibiting photosynthesis. Compared with the control groups, B. dothidea noteworthily inhibited the net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), and other photosynthetic parameters of poplar leaves, but stomatal limit value (Ls) increased. Consistent with the above results, B. dothidea also reduced stomatal aperture and stomatal opening rate. In addition, B. dothidea not only remarkably reduced the content of photosynthetic pigments, but also decreased the maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII), electron transfer efficiency (ETR), and photochemical quenching coefficient (qP). Furthermore, both chlorophyll and ΦPSII were positively correlated with Pn. In summary, the main reason for the abated Pn under stem canker pathogen was that B. dothidea not merely inhibited the stomatal opening, but hindered the conversion of light energy, electron transfer and light energy utilization of poplar leaves. In general, the lessened CO2 and Pn would reduce the synthesis of photosynthetic products. Whereas, sucrose and starch accumulated in poplar leaves, which may be due to the local damage caused by B. dothidea inoculation in phloem, hindering downward transport of these products.

Why the adventitious roots of poplar are so colorful: RNAseq and metabolomic analysis reveal flavonols, flavones, and anthocyanins accumulation in canker pathogens-induced adventitious roots in poplar

“…In this study, colorful and plenty of poplar ARs were observed in our experiments (Figure 1, Figure 2, and Figure 6), using the novel girdling-inoculation method (Li et al 2019;Li et al 2021;Xing et al 2020;Xing et al 2022) which only used in our physiological and pathological researches of poplar stem canker diseases. To our best knowledge, the formation of poplar ARs induced by fungal pathogens was a novel allometric phenomenon in woody species.…”

“…After 14-20 days, a novel allometric phenomenon, copious adventitious roots (ARs) with red color which sprouting from the inoculation sites of poplar stems, was observed in our research, aside from the common canker disease symptoms (such as bark lesions and canopy dieback), physiological and molecular performances (gas-exchange parameters, chlorophyll fluorescence parameters, carbohydrate contents, hydraulics, gene regulation, etc.) (Li et al 2021; Li et al 2019; Xing et al 2020; Xing et al 2022). To our best knowledge, there has been no report so far to find fungal pathogens-induced AR formation in plants.…”

Divergent effects of single and combined stress of drought and salinity on the physiological traits and soil properties of Platycladus orientalis saplings

“…Gibberellins have positive effects on plant growth and tolerance under drought and salt stress ( Moula et al., 2020 ; Gaion and Carvalho, 2021 ). JA and JA-Me are endogenous growth regulators, exhibit phytohormones crosstalk with ABA in the pathway for stomatal closure ( Xing et al., 2022 ), and can also improve plant tolerance to drought and salt ( Seo et al., 2005 ; Daszkowska-Golec and Szarejko, 2013 ). Under abiotic stresses such as drought and salinity, the JA signaling factor PeJAZ2 in Populus euphratica interacts with PeOST1 , which is involved in stomatal regulation.…”

Integrated transcriptome and microRNA sequencing analyses reveal gene responses in poplar leaves infected by the novel pathogen bean common mosaic virus (BCMV)

“…In this study, to reveal the effect of viral infection on poplar leaves, the gas-exchange characteristics, chlorophyll fluorescence parameters, and chlorophyll content were determined using a Li-6400XT portable photosynthesis system (LI-COR, Lincoln, USA) ( Xing et al., 2020 ; Xing et al., 2022 ). In the gas-exchange assays, the net photosynthesis rate (Pn), stomatal conductance (Gs), intercellular CO 2 concentration (Ci), transpiration rate (Tr), and vapor pressure deficit of leaves (VpdL) were determined.…”

“…Seven healthy mature leaves and seven leaves with mild mosaic symptoms were detected in the gas-exchange and chlorophyll fluorescence assays. In this study, approximately 0.2g leaf tissue collected from 6 mature leaves (Ctrl, SD, and LD samples) was used in the determination of chlorophyll content, chlorophyll a (Chl_a), chlorophyll b (Chl_b) and total chlorophyll (Chl) ( Xing et al., 2020 ; Xing et al., 2022 ).…”