Plant Physiol. email content delivery
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Plant Physiology Preview
Published on May 23, 2008; 10.1104/pp.108.121418

OPEN ACCESS ARTICLE
This Article
Free via Open Access: OA
Right arrow Full Text (Plant Physiology Preview (PDF))
Right arrowOA All Versions of this Article:
147/3/1288    most recent
pp.108.121418v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Essmann, J.
Right arrow Articles by Scharte, J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Essmann, J.
Right arrow Articles by Scharte, J.
Agricola
Right arrow Articles by Essmann, J.
Right arrow Articles by Scharte, J.

Received April 17, 2008
Accepted May 19, 2008

RNAi-Mediated Repression of Cell Wall Invertase Impairs Defense in Source Leaves of Tobacco

Jutta Essmann , Ina Schmitz-Thom , Hardy Schon , Sophia Sonnewald , Engelbert Weis , and Judith Scharte *

Institut fur Botanik, Schlossgarten 3, 48149 Munster, Germany; Institut fur Biologie, Staudtstr. 5, 91058 Erlangen, Germany

* Corresponding author; email: jschart{at}uni-muenster.de.

The significance of cell wall invertase (cwINV) for plant defense was investigated by comparing wild type tobacco Nicotiana tabacum L. Samsun NN (SNN) with plants with RNAi-mediated repression of cwINV (SNN::cwINV). In source leaves of SNN::cwINV the activity of cwINV was repressed about 90%. Sucrose export and apoplastic carbohydrate levels were significantly reduced, while photosynthesis and dark-respiration exhibited little or no change. Activities of sucrose synthase and phosphofructokinase were depressed moderately, while ADP-glucose pyrophosphorylase was diminished greatly. Yet, the content of cytosolic/vacuolar carbohydrates was not significantly lower, which correlated with the absence of phenotypic effects in SNN::cwINV under normal growing conditions. By contrast, defense-related processes in primary metabolism and hypersensitive cell death were impaired and delayed in correlation with repression of cwINV. The increase in cwINV observed in source leaves of the resistant wild type following infection with Phytophthora nicotianae was absent in SNN::cwINV. Also, defense-related callose deposition at cell-to-cell interfaces, the related decline in sugar export, and accumulation of apoplastic carbohydrates were reduced and delayed. Expression of pathogenesis-related proteins and increase in phenylalanine ammonia-lyase and glucose-6-phosphate dehydrogenase activities were alleviated. Formation of hydrogen peroxide and development of hypersensitive lesions were weak and heterogeneous, and the pathogen was able to sporulate. We conclude that in photosynthetically active leaves of the apoplastic phloem loader tobacco cwINV plays an essential role for acquisition of carbohydrates during plant-pathogen interactions, and that the availability of these carbohydrates supports the onset of the hypersensitive reaction and ensures successful defense.




This article has been cited by other articles:


Home page
 Plant Physiol.Home page
N. Kocal, U. Sonnewald, and S. Sonnewald
Cell Wall-Bound Invertase Limits Sucrose Export and Is Involved in Symptom Development and Inhibition of Photosynthesis during Compatible Interaction between Tomato and Xanthomonas campestris pv vesicatoria
Plant Physiology, November 1, 2008; 148(3): 1523 - 1536.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
ASPB Publications PLANT PHYSIOLOGY THE PLANT CELL
Copyright © 2008 by the American Society of Plant Biologists