Osmotic stress and ion-specific effects on xylem abscisic acid and the relevance to salinity tolerance in poplar

We designed two experiments to investigate the osmotic stress and ion-specific effects on xylem abscisic acid (ABA) and the relevance to salinity tolerance in one-year-old seedlings of Populus euphratica Oliv. (a salt-resistant genotype) and one-year-old rooted cuttings of P. 'popularis 35-44&#...

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Bibliographic Details
Published in:Journal of plant growth regulation 2002-09, Vol.21 (3), p.224-233
Main Authors: SHAOLIANG CHEN, JINKE LI, TIANHUA WANG, SHASHENG WANG, POLLE, Andrea, HÜTTERMANN, Aloys
Format: Article
Language:English
Subjects:
Abiotic stress
Abscisic acid
Agronomy. Soil science and plant productions
Biological and medical sciences
Chloride transport
Dilution
Economic plant physiology
Fundamental and applied biological sciences. Psychology
Genotypes
Osmosis
Osmotic potential
Osmotic shock
Osmotic stress
Plant physiology and development
Pressurization
Saline water
Salinity
Salinity effects
Salinity tolerance
Salt
Salt effect
Salts
Seedlings
Sodium chloride
Solutes
Suction
Transpiration
Water and solutes. Absorption, translocation and permeability
Water flow
Water relations, transpiration, stomata
Xylem
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Summary:We designed two experiments to investigate the osmotic stress and ion-specific effects on xylem abscisic acid (ABA) and the relevance to salinity tolerance in one-year-old seedlings of Populus euphratica Oliv. (a salt-resistant genotype) and one-year-old rooted cuttings of P. 'popularis 35-44' (P. popularis) (a salt-sensitive genotype). Net photosynthetic rates (Pn) and unit transpiration rates (TRN) of the two genotypes were significantly decreased upon osmotic shock caused by PEG 6000 (osmotic potential = -0.24 MPa) or iso-NaCl (50 mM). Shoot xylem ABA concentrations in both genotypes increased rapidly after the onset of PEG stress, resulting from a decreased water flow. NaCl-treated trees of P. euphratica maintained considerably greater concentrations of ABA than PEG-treated plants in a longer term, whereas salinized P. popularis exhibited a transient accumulation of ABA in the shoot. TRN was greatly enhanced in both genotypes when pressure (0.24 MPa) was applied to counteract the osmotic suction of 50 mM NaCl. Pressurizing of root systems diluted solutes in the root xylem, but the dilution effect was more pronounced in P. popularis. Root xylem ABA concentrations in P. euphratica steadily increased with salt stress although pressurization lowered its levels. In contrast, there were no observed changes in ABA response to salinity in pressured P. popularis. Therefore, we concluded that the salt-tolerant P. euphratica had a greater capacity to synthesize ABA under saline conditions, which may partially result from specific salt effects. In addition, P. euphratica exhibited a higher capacity for salt (Na+ and Cl-) transport control under salt stress, compared with P. popularis. The possible association between ABA and salt transport limitation, and the relevance to salinity tolerance were discussed. [PUBLICATION ABSTRACT]
ISSN:0721-7595
1435-8107
DOI:10.1007/s00344-002-1001-4