title: Anatomical variation of mesophyll conductance under potassium deficiency has a vital role in determining leaf photosynthesis.
abstract: Leaves exposed to potassium (K) deficiency usually present decreased mesophyll conductance (gm) and photosynthesis (A). The relative contributions of leaf anatomical traits in determining gmhave been quantified; however, anatomical variabilities related to low gmunder K starvation remain imperfectly known. A one-dimensional model was used to quantify anatomical controls of the entire CO2diffusion pathway resistance within a leaf on two Brassica napus L. cultivars in response to K deficiency. Leaf photosynthesis of both cultivars was significantly decreased under K deficiency in parallel with down-regulated gm. The mesophyll conductance limitation contributed to more than one-half of A decline. The decreased internal air space in K-starved leaves was associated with the increase of gas-phase resistance. Potassium deficiency reduced liquid-phase conductance by decreasing the exposed surface area of chloroplasts per unit leaf area (Sc/S), and enlarging the resistance of the cytoplasm that can be interpreted by the increasing distance of chloroplast from cell wall, and between adjacent chloroplasts. Additionally, the discrepancies of A between two cultivars were in part because of gmvariations, ascribing to an altered Sc/S. These results emphasize the important role of K on the regulation of gmby enhancing Sc/S and reducing cytoplasm resistance.
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, 430070, China.|Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, 430070, China.|Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Lu
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, 430070, China.|Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, 430070, China.|Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Piaopiao
authors.initials: P
authors.lastname: Lu
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, 430070, China.|Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Xiaokun
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, 430070, China.|Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Rihuan
authors.initials: R
authors.lastname: Cong
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan, 430070, China. rentao@mail.hzau.edu.cn.|Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China. rentao@mail.hzau.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Ren
mesh_terms: D029688:Brassica napus / Q000033:anatomy & histology / Q000378:metabolism* / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D058503:Mesophyll Cells / Q000378:metabolism / Q000502:physiology; D010788:Photosynthesis; D018515:Plant Leaves / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology; D011188:Potassium / Q000378:metabolism*
chemical_list: D002245:Carbon Dioxide; D011188:Potassium
keywords: Anatomical model; Brassica napus L; leaf anatomy; photosynthetic limitations