
TY  - JOUR
A1  - Dannel, Frank 
A1  - Pfeffer, Heidrun 
A1  - R&ouml;mheld, Volker 
T1  - Distribution within the plant or compartmentation does not contribute substantially to the detoxification of excess boron in sunflower (<emph type="2">Helianthus annuus</emph>)
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1999
VL  - 26
IS  - 2
SP  - 95
EP  - 99
KW  - boron, compartmentation, detoxification, Helianthus annuus L., toxicity.
UR  - https://doi.org/10.1071/PP98110 
N2  - Distribution and compartmentation of boron as possible mechanisms for the notable tolerance of sunflower (Helianthus annuus L.) to excess B supply have been studied. Following a short- term treatment (6 h) with 1000 &#181;&#x041C; B, the distribution of B between different shoot organs was preferentially directed to the readily transpiring ones. Thus, B distribution in sunflower plants seems to be mainly influenced by transpiration and does not act as a B tolerance mechanism in sunflower. As a second possible mechanism for B tolerance, the compartmentation of B between water insoluble residue (i.e. cell wall) and cell sap (i.e. symplasm) was determined. Additional binding of B in the cell wall in response to excess B supply for 6 h was very low in leaves and negligible in roots. Thus, a substantial contribution of the cell wall in detoxification of excess B can be ruled out. In an additional experiment with a B supply of 1 &#181;&#x041C; (marginal) to 1000 &#181;&#x041C; (moderately toxic), the compartmentation of B between the apoplasmic fluid and the cell sap was investigated. The B concentration in the apoplasmic fluid was always lower than that in the symplasm. Thus, B was not excluded from the symplasm, but accumulated within it. The apoplasmic fluid did not contribute substantially to the detoxification of excess B in the leaf. 
ER  -

