Noiraud N, Delrot S, Lemoine R
Laboratoire de Physiologie et Biochimie Végétales, Centre National de la Recherche Scientifique Equipe Supérieure Associée 6161, 40, Avenue du Recteur Pineau, F-86022 Poitiers cedex, France.
Plant Physiol. 2000 Apr;122(4):1447-55. doi: 10.1104/pp.122.4.1447.
In celery (Apium graveolens L.), long-distance transport of reduced carbon occurs both in the form of sucrose (Suc) and mannitol. The presence of mannitol has been related to the resistance of celery to salt stress. To investigate the transport events occurring during salt stress, we have cloned the H(+)/Suc transporter of celery AgSUT1 (A. graveolens Suc uptake transport 1) from a mature leaf cDNA library. The function of the encoded protein was confirmed by expression in yeast. AgSUT1 is a H(+)/Suc transporter with a high affinity for Suc (K(m) of 139 microM). Another closely related cDNA (AgSUT2) was also identified. AgSUT1 is mainly expressed in mature leaves and phloem of petioles, but also in sink organs such as roots. When celery plants were subjected to salt stress conditions (30 d watering with 300 mM NaCl) favoring mannitol accumulation (J.D. Everard, R. Gucci, S.C. Kann, J.A. Flore, W.H. Loescher [1994] Plant Physiol 106: 281-292), AgSUT1 expression was decreased in all organs, but markedly in roots. The results are discussed in relation to the physiology of celery.
在芹菜（Apium graveolens L.）中，还原态碳的长距离运输以蔗糖（Suc）和甘露醇两种形式进行。甘露醇的存在与芹菜对盐胁迫的抗性有关。为了研究盐胁迫期间发生的运输事件，我们从成熟叶cDNA文库中克隆了芹菜的H(+)/蔗糖转运蛋白AgSUT1（A. graveolens Suc uptake transport 1）。通过在酵母中的表达证实了编码蛋白的功能。AgSUT1是一种对蔗糖具有高亲和力（K(m)为139 microM）的H(+)/蔗糖转运蛋白。还鉴定出了另一个密切相关的cDNA（AgSUT2）。AgSUT1主要在成熟叶和叶柄韧皮部中表达，但在根等库器官中也有表达。当芹菜植株在有利于甘露醇积累的盐胁迫条件下（用300 mM NaCl浇灌30天）（J.D. Everard、R. Gucci、S.C. Kann、J.A. Flore、W.H. Loescher [1994] Plant Physiol 106: 281 - 292），AgSUT1在所有器官中的表达均下降，但在根中下降明显。结合芹菜的生理学对结果进行了讨论。
