caa a22 4500 605481121 CHVBK 20210128100419.0 cr unu---uuuuu 210128e20150601xx s 000 0 eng 10.1007/s11099-015-0110-9 doi (NATIONALLICENCE)springer-10.1007/s11099-015-0110-9 Identification of obligate C3 photosynthesis in Dendrobium [Elektronische Daten] [S. Qiu, S. Sultana, Z. Liu, L. Yin, C. Wang] Dendrobium is one of the three largest genera in the Orchidaceae and is distributed throughout various habitats. We investigated photosynthesis in seven Dendrobium species and cultivars by comparing their leaf δ13C values, titratable acidity, and CO2 exchange in well-watered and drought-stressed conditions. In addition, the leaf thickness and mesophyll succulence index (Sm) were measured in well-watered conditions. Our results indicate that Dendrobium loddigesii is a typical obligate (or constitutive) CAM plant because the leaf δ13C values were −14.47 and −14.66‰ in both conditions, respectively. Others showed the leaf thickness of 0.31-0.89 mm and their δ13C values ranged from −25.68 to −28.37‰. These are not the CAM plants but they could not be classified as obligate C3 or C3/CAM intermediate plants. Dendrobium crepidatum and Dendrobium fimbriatum were further identified as the obligate C3 plants because the net CO2 uptake was positive during daytime and negative during nighttime in both conditions. In contrast, Dendrobium chrysotoxum, Dendrobium nobile, and D. nobile ‘V1' and ‘V4', showed no positive net CO2 uptake and low ΔH+ values during nighttime under well-watered conditions, indicating C3 photosynthesis. However, they showed the positive net CO2 uptake and large ΔH+ values during nighttime after drought-stress (21 or 28 days without H2O), indicating CAM photosynthesis. Therefore, these four species and cultivars were identified as C3/CAM intermediate (inducible or facultative) plants. In brief, obligate CAM, C3/CAM intermediate, and obligate C3 plant types all exist in the section of Dendrobium. To the best of our knowledge, this is the first report of the obligate C3 plants in Dendrobium, and these diverse photosynthetic pathways may explain their varied environmental adaptations. The Institute of Experimental Botany, 2015 C3/CAM intermediate plant nationallicence CO2 exchange nationallicence crassulacean acid metabolism nationallicence titratable acidity nationallicence δ13C value nationallicence CAM : crassulacean acid metabolism nationallicence Chl : chlorophyll nationallicence DM : dry mass nationallicence DS : drought-stressed nationallicence FM : fresh mass nationallicence ΔH+ : titratable acidity accumulated during nighttime nationallicence LWC : leaf water content nationallicence Sm : mesophyll succulence index nationallicence WW : well-watered nationallicence δ13C : carbone isotope ratio 13C/12C nationallicence Qiu S. Key Laboratory for Biology of Horticultural Plants, Ministry of Education, Huazhong Agricultural University, 430070, Wuhan, China aut Sultana S. Key Laboratory for Biology of Horticultural Plants, Ministry of Education, Huazhong Agricultural University, 430070, Wuhan, China aut Liu Z. Key Laboratory for Biology of Horticultural Plants, Ministry of Education, Huazhong Agricultural University, 430070, Wuhan, China aut Yin L. Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Hainan University, 570228, HaiKou, China aut Wang C. Key Laboratory for Biology of Horticultural Plants, Ministry of Education, Huazhong Agricultural University, 430070, Wuhan, China aut Photosynthetica The Institute of Experimental Biology of the Czech Academy of Sciences 53/2(2015-06-01), 168-176 0300-3604 53:2<168 2015 53 11099 https://doi.org/10.1007/s11099-015-0110-9 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s11099-015-0110-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Qiu S. Key Laboratory for Biology of Horticultural Plants, Ministry of Education, Huazhong Agricultural University, 430070, Wuhan, China aut NATIONALLICENCE 700 1- Sultana S. Key Laboratory for Biology of Horticultural Plants, Ministry of Education, Huazhong Agricultural University, 430070, Wuhan, China aut NATIONALLICENCE 700 1- Liu Z. Key Laboratory for Biology of Horticultural Plants, Ministry of Education, Huazhong Agricultural University, 430070, Wuhan, China aut NATIONALLICENCE 700 1- Yin L. Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Hainan University, 570228, HaiKou, China aut NATIONALLICENCE 700 1- Wang C. Key Laboratory for Biology of Horticultural Plants, Ministry of Education, Huazhong Agricultural University, 430070, Wuhan, China aut NATIONALLICENCE 773 0- Photosynthetica The Institute of Experimental Biology of the Czech Academy of Sciences 53/2(2015-06-01), 168-176 0300-3604 53:2<168 2015 53 11099