Salicylic acid, an ambimobile molecule exhibiting a high ability to accumulate in the phloem.
نویسندگان
چکیده
The ability of exogenous salicylic acid (SA) to accumulate in castor bean (Ricinus communis) phloem was evaluated by HPLC and liquid scintillation spectrometry analyses of phloem sap collected from the severed apical part of seedlings. Time-course experiments indicated that SA was transported to the root system via the phloem and redistributed upward in small amounts via the xylem. This helps to explain the peculiarities of SA distribution within the plant in response to biotic stress and exogenous SA application. Phloem loading of SA at 1, 10, or 100 microm was dependent on the pH of the cotyledon incubating solution, and accumulation in the phloem sap was the highest (about 10-fold) at the most acidic pH values tested (pH 4.6 and 5.0). As in animal cells, SA uptake still occurred at pH values close to neutrality (i.e. when SA is only in its dissociated form according to the calculations made by ACD LogD suite software). The analog 3,5-dichlorosalicylic acid, which is predicted to be nonmobile according to the models of Bromilow and Kleier, also moved in the sieve tubes. These discrepancies and other data may give rise to the hypothesis of a possible involvement of a pH-dependent carrier system translocating aromatic monocarboxylic acids in addition to the ion-trap mechanism.
منابع مشابه
Heavy Metals Effects on Brassica Oleracea and Elements Accumulation by Salicylic Acid
Background & Aims of the Study: The objective of this study was to investigate the seed pre-treatment with salicylic acid (SA) on tolerance and remediation ability of Brassica oleracea var. acephala under lead and zinc stresses. Materials and Methods: Present study was conducted to evaluate phyto-accumulative ability of Brassica oleracea var. acephala in heavy metal concentrat...
متن کاملSalicylic Acid 1s a Systemic Signal and an lnducer of Pathogenesis-Related Proteins in Virus-lnfected TÕbacco
Systemic induction of pathogenesis-related (PR) proteins in tobacco, which occurs during the hypersensitive response to tobacco mosaic virus (TMV), may be caused by a minimum 10-fold systemic increase in endogenous levels of salicylic acid (SA). This rise in SA parallels PR-1 protein induction and occurs in TMV-resistant Xanthi-nc tobacco carrying the N gene, but not in TMV-susceptible (nn) tob...
متن کاملEffect of Salicylic Acid on Somatic Embryogenesis and Chlorogenic Acid Levels of Carrot (Daucus carota cv. Nantes) Explants
Many factors may influence the efficiency of somatic embryogenesis. This capability may be differ with regard to media compositions, genotype, tissue, organ ontology and the stage of differentiation. The effects of five salicylic acid concentrations (0, 25, 50, 75 and 100 mM) on different stages of carrot somatic embryogenesis were studied using petiole and root secondary phloem explants as sta...
متن کاملTobacco mosaic virus-directed reprogramming of auxin/indole acetic acid protein transcriptional responses enhances virus phloem loading.
Vascular phloem loading has long been recognized as an essential step in the establishment of a systemic virus infection. In this study, an interaction between the replication protein of tobacco mosaic virus (TMV) and phloem-specific auxin/indole acetic acid (Aux/IAA) transcriptional regulators was found to modulate virus phloem loading in an age-dependent manner. Promoter expression studies sh...
متن کاملAccumulation of salicylic acid and 4-hydroxybenzoic acid in phloem fluids of cucumber during systemic acquired resistance is preceded by a transient increase in phenylalanine ammonia-lyase activity in petioles and stems.
Cucumber (Cucumis sativa) leaves infiltrated with Pseudomonas syringae pv. syringae cells produced a mobile signal for systemic acquired resistance between 3 and 6 h after inoculation. The production of a mobile signal by inoculated leaves was followed by a transient increase in phenylalanine ammonia-lyase (PAL) activity in the petioles of inoculated leaves and in stems above inoculated leaves;...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Plant physiology
دوره 141 4 شماره
صفحات -
تاریخ انتشار 2006