Xing Junchao, Li Min, Li Jinxin, Shen Wanna, Li Ping, Zhao Jiaping, Zhang Yinan
Institute of Ecological Conservation and Restoration, Chinese Academy of Forestry, Beijing, China.
Front Plant Sci. 2022 Sep 20;13:1008834. doi: 10.3389/fpls.2022.1008834. eCollection 2022.
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 (. ) on () 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 . using an epidermal scraping method. In the early stage of . 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 . inhibiting photosynthesis. Compared with the control groups, . noteworthily inhibited the net photosynthetic rate ( ), stomatal conductance ( ), intercellular CO concentration ( ), transpiration rate ( ), and other photosynthetic parameters of poplar leaves, but stomatal limit value ( ) increased. Consistent with the above results, . also reduced stomatal aperture and stomatal opening rate. In addition, . not only remarkably reduced the content of photosynthetic pigments, but also decreased the maximum photochemical efficiency ( / ), actual photochemical efficiency ( ), electron transfer efficiency (ETR), and photochemical quenching coefficient ( ). Furthermore, both chlorophyll and were positively correlated with . In summary, the main reason for the abated under stem canker pathogen was that . 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 CO and 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 . inoculation in phloem, hindering downward transport of these products.
真菌病原体可在许多树种中诱发溃疡病斑、枯萎甚至枯死。树木会因茎干溃疡而遭受严重的生理影响。在本研究中，我们调查了在茎干接种病原体时，（.）对（.）叶片光合作用和气孔反应的影响。为杨树溃疡病的早期预防提供实验和理论依据。采用表皮刮擦法对一年生杨树茎干接种（.）。在接种（.）的早期阶段（接种后2 - 14天，dpi），评估气体交换、气孔动态、激素含量、光合色素含量、叶绿素荧光参数和非结构性碳水化合物（NSC），以阐明（.）抑制光合作用的病理生理机制。与对照组相比，（.）显著抑制了杨树叶片的净光合速率（）、气孔导度（）、胞间CO浓度（）、蒸腾速率（）和其他光合参数，但气孔限制值（）增加。与上述结果一致，（.）还降低了气孔孔径和气孔开放率。此外，（.）不仅显著降低了光合色素的含量，还降低了最大光化学效率（/）、实际光化学效率（）、电子传递效率（ETR）和光化学猝灭系数（）。此外，叶绿素和（.）均与（.）呈正相关。综上所述，茎干溃疡病原菌侵染下（.）降低的主要原因是（.）不仅抑制了气孔开放，还阻碍了杨树叶片光能的转换、电子传递和光能利用。总体而言，减少的CO和（.）会降低光合产物的合成。然而，蔗糖和淀粉在杨树叶片中积累，这可能是由于（.）接种对韧皮部造成的局部损伤，阻碍了这些产物的向下运输。
