Abstract Detail

Development and Structure

Sun, Qiang [1].

Structural Variation of Intervessel Pit Membranes in Grapevine.

Intervessel pit membrane (PM) is an important cell wall structure in the vessel system that may impact a plant’s safety/efficiency in water transport and its susceptibility to vascular diseases. The functional roles of intervessel PM largely depend on its structures, which are mostly unknown or lack accurate information. This study uses grapevine as a model plant and a scanning electron microscopy technique to analyze intervessel PM structures in relation to its functions. The results have indicated that intervessel PMs in secondary xylem displayed significant surface structural variations and were accordingly classified into four types (Types I-IV). The four types corresponded to progressive stages in the integrity loss of an intervessel PM derived from the removal of its cell wall material. Type I intervessel PMs had a homogeneously smooth surface over the whole PM region. Microfibrils and pores were not distinguishable from the PMs even at a magnification of up to 30,000, indicating the presence of amorphous wall material covering microfibrils on the PM surface PMs. This intervessel PM type represents no or the least damage on the structural integrity of intervessel PMs. Type II intervessel PMs had a large, relatively smooth surface region and some small, less smooth regions. The smooth region was present in a PM’s wide central strip region, while the less smooth regions mostly occurred in its narrow peripheral region. Microfibrils became largely distinguishable as dense randomly oriented threads and were filled with amorphous material in between. Type III intervessel PMs showed significantly increased non-uniformity in their surface features. The PMs’ central strip region was reduced in area and became rough in the surface, while their peripheral region appeared to be a more porous structure. In the reduced central region, microfibrils were still distinguishable in a dense network with some associated amorphous material. But in the peripheral region, amorphous material associated with the microfibril network was further reduced in quantity. Type IV intervessel PMs lost their integrity with some regions losing PM. Few PM patches still in place were different in size and shape and appeared to be much looser networks. Microfibrils remaining in each network were distinguishable with little amorphous structure associated and pores in the network were irregular in shape and usually over 100 nm in size. Frequencies of the four types of intervessel PMs in secondary xylem were different, with Types I and II having a majority of presence (53.9 % and 36.8 %, respectively) and Type III an occurrence of 5.8 %. Type IV intervessel PMs were present at a very low frequency of 3.6 %. These results differ from a long-standing viewpoint on the structure of intervessel PMs and are crucial to understand intervessel PM’s roles in the safety and regulation of water transport as well as a plant’s susceptibility mechanisms to vascular diseases.

1 - University Of Wisconsin-Stevens Point, Department Of Biology, 348 Chemistry Biology Building, 2101 Fourth Avenue, Stevens Point, WI, 54481, United States

Grapevine (Vitis vinifera)
Intervessel pit membrane (PM)
PM structural integrity
Primary cell wall
Scanning electron microscopy (SEM)
Vessel system.

Presentation Type: Poster
Number: PDS001
Abstract ID:186
Candidate for Awards:None

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