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Photosynthate transport in stems of Phaseolus vulgaris L. treated with gibberellic acid, indole-3-acetic acid or kinetin. : Effects at the site of hormone application.

Abstract：

:Gibberellic acid (GA3), indole-3-acetic acid (IAA) or kinetin ((6)N-furfurylaminopurine) applied to the apical regions of decapitated stems of derooted Phaseolus vulgaris plants, promoted (14)C-photosynthate transport to the site of hormone application. Hormonal promotion of acropetal photosynthate transport was associated with significant increases in the pool size of free-space sugars at the hormone-treated region of the stem. The hormone-induced increases in the free-space pool size depended on continued phloem transport in the stem stumps while photosynthate leakage from the sink tissues of the stems was unaffected by the hormone treatments. On the basis of these observations, it is concluded that the increases in the pool size of sugars in the stem free-space results from hormonal action on processes that determine rates of sugar unloading from the sieve element-companion cell (se-cc) complexes. Furthermore, since loading of the se-cc complexes in the stem stumps was stimulated by GA3 and IAA and unaffected by kinetin applied at the loading site, hormonal effects on net unloading from the se-cc complexes must be caused by alterations in the efflux component. For winter-grown plants, it was found that predicted increases in sugar transfer through the stem free-space from the se-cc complexes to the sink tissues could account for the observed hormonal stimulation of photosynthate transport. In contrast, for summer-grown plants the higher sugar concentrations in the stem free-space of control plants approached saturation for the sugar-accumulation process. This caused an attenuation of the responsiveness of sugar accumulation by the stem sink tissues to hormone-induced increases in the pool size of sugars in the stem free-space. On this basis it is proposed that the bulk of photosynthates may move radially from the se-cc complexes through the stem symplast of summer-grown plants.

journal_name

Planta

journal_title

Planta

authors

Hayes PM,Patrick JW

doi

10.1007/BF00401175

subject

Has Abstract

pub_date

1985-11-01 00:00:00

pages

371-9

issue

eissn

0032-0935

issn

1432-2048

journal_volume

166

pub_type

杂志文章

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Photosynthate transport in stems of Phaseolus vulgaris L. treated with gibberellic acid, indole-3-acetic acid or kinetin. : Effects at the site of hormone application.