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Abstract Detail

Bryological and Lichenological Section/ABLS

Merced, Amelia [1], Renzaglia, Karen [2].

Cell wall composition during stomata development in moss.

Flexibility of guard cell walls is necessary for stomata to properly open and close, this flexibility is imparted by the pectins in the cell walls. In vascular plants, removal of arabinan pectins (rhamnogalacturonans I -RG1) from the cell walls of stomata set them in a lock position; removal of unesterified homogalacturonan (HG) pectins makes them flexible again. Knowledge of the structure and composition of guard cell wall is critical to understand its function and evolution but this has been scantly documented. Mosses are essential to study stomata evolution because they were the fist plants to evolve stomata. Stomata of different developmental stages were examined for cell wall composition in the model moss Funaria hygrometrica. Plants were collected from the field and grown in the lab at room temperature to obtain different developmental stages; plant tissues were prepared for immunolocalization of pectin epitopes and examined in the transmission electron microscopy (TEM). Monoclonal antibodies used were LM19 (unesterified HG), LM20 (esterified HG), LM5 (galactan RG1), LM6 (arabinan RG1). Cell walls of stomata before pore formation are thinner than epidermal cells and contain abundant unesterified HG and few esterified HG. Minimal galactan RG1 epitopes localize in walls and cytoplasm near walls. In contrast, arabinan RG1 are abundant in guard cell walls but not as abundant as unesterified HG. Walls of mature stomata before sporogenesis are thick with defined ledges, and at least two distinct layers. The outer electron dense layer strongly label for unesterified HG and some esterified HG, while the electron light layer does not localized uniquely for any of the pectins tested. The arabinan RG1 are homogeneously localized in both layers of outer and inner walls but are absent in the ledges, and more abundant in the electron dense layer of the ventral wall. These findings suggest that ventral walls of mature guard cells have the flexibility to allow the pore to close. This is the first study that shows changes in wall composition during development of stomata in moss.

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1 - Southern Illinois University, Plant Biology, 1125 Lincoln Dr, Life Science II 477, Carbondale, IL, 62901, USA
2 - Southern Illinois University, PLANT BIOLOGY DEPARTMENT, MAILCODE 6509, Carbondale, IL, 62901, USA

cell wall

Presentation Type: Oral Paper:Papers for Sections
Session: 29
Location: Ascot/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 1:45 PM
Number: 29004
Abstract ID:786
Candidate for Awards:A. J. Sharp Award

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