Applied Microbiology and Biotechnology

, Volume 97, Issue 20, pp 9155–9164

Cytokinin-producing, plant growth-promoting rhizobacteria that confer resistance to drought stress in Platycladus orientalis container seedlings

  • Fangchun Liu
  • Shangjun Xing
  • Hailin Ma
  • Zhenyu Du
  • Bingyao Ma
Applied microbial and cell physiology

DOI: 10.1007/s00253-013-5193-2

Cite this article as:
Liu, F., Xing, S., Ma, H. et al. Appl Microbiol Biotechnol (2013) 97: 9155. doi:10.1007/s00253-013-5193-2

Abstract

One of the proposed mechanisms through which plant growth-promoting rhizobacteria (PGPR) enhance plant growth is the production of plant growth regulators, especially cytokinin. However, little information is available regarding cytokinin-producing PGPR inoculation on growth and water stress consistence of forest container seedlings under drought condition. This study determined the effects of Bacillus subtilis on hormone concentration, drought resistance, and plant growth under water-stressed conditions. Although no significant difference was observed under well-watered conditions, leaves of inoculated Platycladus orientalis (oriental thuja) seedlings under drought stress had higher relative water content and leaf water potential compared with those of noninoculated ones. Regardless of water supply levels, the root exudates, namely sugars, amino acids and organic acids, significantly increased because of B. subtilis inoculation. Water stress reduced shoot cytokinins by 39.14 %. However, inoculation decreased this deficit to only 10.22 %. The elevated levels of cytokinins in P. orientalis shoot were associated with higher concentration of abscisic acid (ABA). Stomatal conductance was significantly increased by B. subtilis inoculation in well-watered seedlings. However, the promoting effect of cytokinins on stomatal conductance was hampered, possibly by the combined action of elevated cytokinins and ABA. B. subtilis inoculation increased the shoot dry weight of well-watered and drought seedlings by 34.85 and 19.23 %, as well as the root by 15.445 and 13.99 %, respectively. Consequently, the root/shoot ratio significantly decreased, indicative of the greater benefits of PGPR on shoot growth than root. Thus, inoculation of cytokinin-producing PGPR in container seedlings can alleviate the drought stress and interfere with the suppression of shoot growth, showing a real potential to perform as a drought stress inhibitor in arid environments.

Keywords

Cytokinin Plant growth-promoting rhizobacteria Drought stress Container seedlings Platycladus orientalis 

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Fangchun Liu
    • 1
  • Shangjun Xing
    • 1
  • Hailin Ma
    • 1
  • Zhenyu Du
    • 1
  • Bingyao Ma
    • 1
  1. 1.Shandong Engineering Research Center for Ecological Restoration of Forest Vegetation, Institute of Resource and EnvironmentShandong Academy of ForestryJinanPeople’s Republic of China

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