title: Genome duplication improves rice root resistance to salt stress.
abstract: BACKGROUND
  Salinity is a stressful environmental factor that limits the productivity of crop plants, and roots form the major interface between plants and various abiotic stresses. Rice is a salt-sensitive crop and its polyploid shows advantages in terms of stress resistance. The objective of this study was to investigate the effects of genome duplication on rice root resistance to salt stress.
  
  
  RESULTS
  Both diploid rice (HN2026-2x and Nipponbare-2x) and their corresponding tetraploid rice (HN2026-4x and Nipponbare-4x) were cultured in half-strength Murashige and Skoog medium with 150 mM NaCl for 3 and 5 days. Accumulations of proline, soluble sugar, malondialdehyde (MDA), Na(+) content, H(+) (proton) flux at root tips, and the microstructure and ultrastructure in rice roots were examined. We found that tetraploid rice showed less root growth inhibition, accumulated higher proline content and lower MDA content, and exhibited a higher frequency of normal epidermal cells than diploid rice. In addition, a protective gap appeared between the cortex and pericycle cells in tetraploid rice. Next, ultrastructural analysis showed that genome duplication improved membrane, organelle, and nuclei stability. Furthermore, Na(+) in tetraploid rice roots significantly decreased while root tip H(+) efflux in tetraploid rice significantly increased.
  
  
  CONCLUSIONS
  Our results suggest that genome duplication improves root resistance to salt stress, and that enhanced proton transport to the root surface may play a role in reducing Na(+) entrance into the roots.
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Tu
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China ; Faculty of Biochemistry and Environmental Engineering, Yunyang Teachers' College, Shiyan 442000, P.R. China.
authors.forename: Aiming
authors.initials: A
authors.lastname: Jiang
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China ; Faculty of Biochemistry and Environmental Engineering, Yunyang Teachers' College, Shiyan 442000, P.R. China.
authors.forename: Lu
authors.initials: L
authors.lastname: Gan
authors.affiliation: School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Mokter
authors.initials: M
authors.lastname: Hossain
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China.
authors.forename: Jinming
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Peng
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China.
authors.forename: Yuguo
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China.
authors.forename: Zhaojian
authors.initials: Z
authors.lastname: Song
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China.
authors.forename: Detian
authors.initials: D
authors.lastname: Cai
authors.affiliation: School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China ; State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Xu
authors.affiliation: School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China ; School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Yuchi
authors.initials: Y
authors.lastname: He
keywords: Genome duplication; Proton transport; Root; Salt stress; Tetraploid rice