Abstract Detail

Developmental and Structural Section

Sun, Qiang [1], He, Mimo [2], Sun, Yuliang [3], Juzenas, Kevin [2], Labavitch, John [4].

Immunogold-Scanning Electron Microscopy for Detection of Pectic and Hemicellulosic Polysaccharides in Pit Membranes.

The thin wall region separating two adjacent cells at a pit pair is called pit membrane (PM). A PM is structurally made up of two primary cell walls and one middle lamella and functionally serves to help intercellular communications. The current study deals with the PMs between a vessel and a parenchyma cell (vessel-parenchyma PMs) and between adjacent vessels (intervessel PMs) with regard to their potential role in host plant resistance to vascular system-localized pathogens.  The general belief is that vessel-parenchyma PMs are modified in the formation of vascular occlusions that may limit both pathogen and water movement in infected plants, while intervessel PMs are the barriers that a xylem-limited pathogen must pass by using its cell wall degrading enzymes to enhance its systemic spread through the vessel network.  Therefore, clarification of the polysaccharide compositions and distribution in these two types of PMs is crucial to a better understanding of the disease resistance/symptom development of host plants.  In this poster, we used grapevine stems to investigate pectic and hemicelluosic polysaccharides in the two PM types. Described here is our recently developed method for detecting the presence, relative concentration, and distribution of some major groups of pectic and hemicellulosic polysaccharides in grapevine PMs. This method combines scanning electron microscopy and immunohistochemical techniques and is effective in visualizing pectic and hemicellulosic polysaccharides in intervessel and vessel-parenchyma PMs. This method enables the high resolution visualization of PM structure while revealing the PMs’ polysaccharide compositions.  Our technique has the potential to identify cell wall polysaccharides exposed at the PM surface and changes in the PM polysaccharide components and quantities during the PM modifications/degradation. Also described here are some major differences in the polysaccharide compositions found between the two types of PMs. These should provide some essential information for a better understanding the balance of events that affect the success of vascular disease resistance mechanisms of host plants.

1 - University Of Wisconsin-Stevens Point, Department Of Biology, 237 TNR Building, 800 Reserve Street, Stevens Point, WI, 54481, USA
2 - University of Wisconsin-Stevens Point, Department of Biology, Stevens Point, WI, 54481, USA
3 - University of Wisconsin-Madison, Department of Biochemistry, 433 Babcock Drive , Madison, WI , 53706, USA
4 - University of California-Davis, Department of Plant Sciences, Davis, CA, 95616, USA

Keywords:
Pit membrane
Cell wall polysaccharide
Grapevine
Immunogold-SEM
Pectin
Hemicellulose
Disease resistance.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PDS002
Abstract ID:767
Candidate for Awards:None