LOCALIZATION OF BORON IN CELL-WALLS OF SQUASH AND TOBACCO AND ITS ASSOCIATION WITH PECTIN - EVIDENCE FOR A STRUCTURAL ROLE OF BORON IN THE CELL-WALL

被引:280
作者
HU, HI [1 ]
BROWN, PH [1 ]
机构
[1] LAWRENCE LIVERMORE NATL LAB,DEPT POMOL,DAVIS,CA 95616
关键词
D O I
10.1104/pp.105.2.681
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
B deficiency results in a rapid inhibition of plant growth, and yet the form and function of B in plants remains unclear. In this paper we provide evidence that B is chemically localized and structurally important in the cell wall of plants. The localization and chemical fractionation of B was followed in squash plants (Curcurbita pepo L.) and cultured tobacco cells (Nicotiana tabacum) grown in B-replete or B-deficient medium. As squash plants and cultured tobacco cells became deficient, an increasingly large proportion of cellular B was found to be localized in the cell wall. Cytoplasmic B concentrations were reduced to essentially zero as plants became deficient, whereas cell wall B concentration remained at or above 10 mu g B/g cell wall dry weight in all experiments. Chemical and enzymic fractionation studies suggest that the majority of cell B is associated with pectins within the cell wall. Physical analysis of B-deficient tissue indicates that cell wall plastic extensibility is greatly reduced under B deficiency, and anatomical observations indicate that B deficiency impairs normal cell elongation in growing plant tissue. In plants in which B deficiency had inhibited all plant growth, tissues remained green and did not show any additional visible symptoms for at least 1 week with no additional B. This occurred even though cytoplasmic B had been reduced to extremely low levels (<0.2 mu g/g). This suggests that B in these species is largely associated with the cell wall and that any cytoplasmic role for B is satisfied by very low concentrations of B. The localization of B in the cell wall, its association with cell wall pectins, and the contingent effects of B on cell wall extensibility suggest that B plays a critical, although poorly defined, role in the cell wall structure of higher plants.
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页码:681 / 689
页数:9
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