title: Does chloroplast size influence photosynthetic nitrogen use efficiency?
abstract: High nitrogen (N) supply frequently results in a decreased photosynthetic N-use efficiency (PNUE), which indicates a less efficient use of accumulated Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Chloroplasts are the location of Rubisco and the endpoint of CO2 diffusion, and they play a vital important role in photosynthesis. However, the effects of chloroplast development on photosynthesis are poorly explored. In the present study, rice seedlings (Oryza sativa L., cv. 'Shanyou 63', and 'Yangdao 6') were grown hydroponically with three different N levels, morphological characteristics, photosynthetic variables and chloroplast size were measured. In Shanyou 63, a negative relationship between chloroplast size and PNUE was observed across three different N levels. Here, plants with larger chloroplasts had a decreased ratio of mesophyll conductance (gm) to Rubisco content (gm/Rubisco) and a lower Rubisco specific activity. In Yangdao 6, there was no change in chloroplast size and no decline in PNUE or gm/Rubisco ratio under high N supply. It is suggested that large chloroplasts under high N supply is correlated with the decreased Rubisco specific activity and PNUE.
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Binbin
authors.initials: B
authors.lastname: Ren
authors.forename: Lei
authors.initials: L
authors.lastname: Ding
authors.forename: Qirong
authors.initials: Q
authors.lastname: Shen
authors.forename: Shaobing
authors.initials: S
authors.lastname: Peng
authors.forename: Shiwei
authors.initials: S
authors.lastname: Guo
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009584:Nitrogen / Q000378:metabolism* / Q000494:pharmacology; D053141:Organelle Size; D012275:Oryza / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development
chemical_list: D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen