Xing Deke, Wu Yanyou
Research center for Environmental Bio-Science and Technology, State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, China.
Graduate School of Chinese Academy of Sciences, Beijing, 100049, China.
Bot Stud. 2014 Dec;55(1):60. doi: 10.1186/s40529-014-0060-8. Epub 2014 Aug 1.
P deficiency in karst areas significantly influenced leaf photosynthesis and carbon metabolisms in plants which were bad for plant growth. Meanwhile, fertilizer application would cause lots of environmental problems. Therefore planning and developing P deficiency-resistant plants in karst areas are important to prevent shortage of P resources and reduce the environmental impacts of P supplementation.
This study examined the photosynthetic response of three climber plant species, namely, Pharbitis nil (Linn.) Choisy, Lonicera pampaninii Levl, and Parthenocissus tricuspidata (Sieb.et Zucc.) Planch to phosphorus (P) deficiency stress. The plants were exposed to P deficiency stress at three treatments of 0.125 mM, 0.031 mM, and 0 mM for 30 d; 0.250 mM P was used as the control. Photosynthetic responses were determined by measurement of leaf photosynthesis, chlorophyll fluorescence, carbonic anhydrase activity, and stable carbon isotope ratios. Pharbitis nil showed high CA activity, more negative δC values and could maintain long-term stable photosynthetic capacity. Lonicera pampaninii also showed high CA activity but positive δC values compared to Pharbitis nil, and its photosynthetic capacity decreased as P deficiency stress increased. Parthenocissus tricuspidata had a low photosynthesis and positive δC values compared to Pharbitis nil, it could grow normally even under 0 mM P.
Pharbitis nil was tolerant to long-term, severe P deficiency stress, a finding that is attributed to its stable PSII and regulation of carbonic anhydrase. Lonicera pampaninii showed a poor adaptability to short-term P deficiency, but exhibited long-term tolerance under 0.125 mM P concentration. Parthenocissus tricuspidata was tolerant to long-term P deficiency stress, may exhibit a stomatal limitation. Besides, P deficiency stress had little effect on the way of inorganic carbon utilization of the three climber plants. Different adaptation mechanisms to P deficiency stress should be considered for the selection of species when developing P deficiency-resistant plants.
喀斯特地区的磷缺乏显著影响植物叶片光合作用和碳代谢，不利于植物生长。同时，施肥会引发诸多环境问题。因此，规划和培育喀斯特地区耐缺磷植物对于防止磷资源短缺以及减少补磷对环境的影响具有重要意义。
本研究考察了三种攀援植物，即裂叶牵牛（Pharbitis nil (Linn.) Choisy）、盘叶忍冬（Lonicera pampaninii Levl）和爬山虎（Parthenocissus tricuspidata (Sieb.et Zucc.) Planch）对磷缺乏胁迫的光合响应。将植株分别置于0.125 mM、0.031 mM和0 mM三种缺磷胁迫处理下30天；以0.250 mM磷作为对照。通过测定叶片光合作用、叶绿素荧光、碳酸酐酶活性和稳定碳同位素比值来确定光合响应。裂叶牵牛表现出高碳酸酐酶活性、更负的δC值，并且能够维持长期稳定的光合能力。与裂叶牵牛相比，盘叶忍冬也表现出高碳酸酐酶活性，但δC值为正，其光合能力随着缺磷胁迫加剧而下降。与裂叶牵牛相比，爬山虎光合作用较低且δC值为正，即使在0 mM磷条件下也能正常生长。
裂叶牵牛对长期、严重的磷缺乏胁迫具有耐受性，这一发现归因于其稳定的光系统II和碳酸酐酶调节。盘叶忍冬对短期缺磷适应性较差，但在0.125 mM磷浓度下表现出长期耐受性。爬山虎对长期磷缺乏胁迫具有耐受性，可能表现出气孔限制。此外，缺磷胁迫对这三种攀援植物无机碳利用方式影响较小。在培育耐缺磷植物时，选择物种时应考虑对缺磷胁迫的不同适应机制。
