The photosynthetic and structural differences between leaves and siliques of Brassica napus exposed to potassium deficiency

BMC Plant Biology

Research Article

Rihuan Cong¹  Yonghui Pan¹  Wenshi Hu¹  Tao Ren¹  Jianwei Lu¹  Zhifeng Lu²  Shiwei Guo³ 

[1] Collge of Resources and Environment, Huazhong Agricultural University, Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Shizishan Street 1, 430070, Wuhan, People’s Republic of China;Collge of Resources and Environment, Huazhong Agricultural University, Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Shizishan Street 1, 430070, Wuhan, People’s Republic of China;Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, 210095, Nanjing, People’s Republic of China;Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, 210095, Nanjing, People’s Republic of China;

关键词: Brassica napus;    Leaf photosynthesis;    Potassium deficiency;    Silique photosynthesis;    Structural properties;   

DOI  :  10.1186/s12870-017-1201-5

 received in 2017-08-14, accepted in 2017-12-01,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundMost studies of photosynthesis in chlorenchymas under potassium (K) deficiency focus exclusively on leaves; however, little information is available on the physiological role of K on reproductive structures, which play a critical role in plant carbon gain. Brassica napus L., a natural organ-succession species, was used to compare the morphological, anatomical and photo-physiological differences between leaves and siliques exposed to K-deficiency.ResultsCompared to leaves, siliques displayed considerably lower CO2 assimilation rates (A) under K-deficient (−K) or sufficient conditions (+K), limited by decreased stomatal conductance (gs), apparent quantum yield (α) and carboxylation efficiency (CE), as well as the ratio of the maximum rate of electron transport (Jmax) and the maximum rate of ribulose 1,5-bisphosphate (RuBP) carboxylation (Vcmax). The estimated Jmax, Vcmax and α of siliques were considerably lower than the theoretical value calculated on the basis of a similar ratio between these parameters and chlorophyll concentration (i.e. Jmax/Chl, Vcmax/Chl and α/Chl) to leaves, of which the gaps between estimated- and theoretical-Jmax was the largest. In addition, the average ratio of Jmax to Vcmax was 16.1% lower than that of leaves, indicating that the weakened electron transport was insufficient to meet the requirements for carbon assimilation. Siliques contained larger but fewer stoma, tightly packed cross-section with larger cells and fewer intercellular air spaces, fewer and smaller chloroplasts and thin grana lamellae, which might be linked to the reduction in light capture and CO2 diffusion. K-deficiency significantly decreased leaf and silique A under the combination of down-regulated stomatal size and gs, chloroplast number, α, Vcmax and Jmax, while the CO2 diffusion distance between chloroplast and cell wall (Dchl-cw) was enhanced. Siliques were more sensitive than leaves to K-starvation, exhibiting smaller reductions in tissue K and parameters such as gs, Vcmax, Jmax and Dchl-cw.ConclusionSiliques had substantially smaller A than leaves, which was attributed to less efficient functioning of the photosynthetic apparatus, especially the integrated limitations of biochemical processes (Jmax and Vcmax) and α; however, siliques were slightly less sensitive to K deficiency.

【 授权许可】

CC BY   
© The Author(s). 2017