Title: Characterization of pectin chemistry in unpollinated and pollinated pistils of Petunia hybrida
1Characterization of pectin chemistry in
unpollinated and pollinated pistils of Petunia
hybrida Faculty Mentors Gerry Prody
(Chemistry) Anu Singh-Cundy
(Biology) Undergraduate Research Team Iudita
Repta (Biology Cell emphasis) Peggy Leviton
(Chemistry Biochemistry) Justin Lamb
(Chemistry Biochemistry) Phil Moulton
(Biology Botany emphasis)
2Project goals for the summer ?To compare the
composition of pectic polysaccharides in the 3
different functional zones of the pistil the
stigma, the transition zone (TZ), and the
style ?To understand how pectic polysaccharides
are altered in response to the gaseous plant
hormone, ethylene.
3(No Transcript)
4(No Transcript)
5stigma
transition zone
style
6(No Transcript)
7(No Transcript)
8(No Transcript)
9Thursdays data
10(No Transcript)
11After reduction
12The Glycome Rules!
13(No Transcript)
14(No Transcript)
15Pollen Tube Growth
in vitro (culture medium)
In the pistil
16Background The Physiological Context Pistil
structure ?Pistils contain a tract of
cells--called the transmitting tissue--that
provides a specialized matrix for supporting the
growth of pollen tubes. ?The extracellular
matrix of the transmitting tissue is unusually
thick, and is presumed to be rich in pectic
polysaccharides. Pollen tubes grow (by tip
extension) in this extracellular matrix. ?The
pistil is composed of three structurally and
functionally distinct zones the stigma, the
transition zone (TZ), and the style. Pollen
tubes behave differently (for example, in terms
of growth rates) in each of these 3 zones.
17Background The Biochemical Context Extracellular
polysaccharides in plants and pistil cell wall
chemistry ?Plant cell walls contain three main
classes of extracellular polysaccharides
cellulose, hemicellulose, and pectins. ? In
living plant cells, the walls are frequently
re-modeled such that their physical, chemical,
and biological properties are altered. ? Pollen
tubes secrete pectinases, and pectinases such as
polygalacturonase are also constitutively
present in the stigma and TZ. It is assumed
that these pectinases hydrolyze the pectin matrix
in the transmitting tissue softened matrix may
offer less resistance to pollen tube growth,
released sugars may be used as energy source.
18Cell wall architecture
Common sugars found in plant polysaccharides
19Pectin structures
20Cross-bridging and esterification in pectins
21(No Transcript)
22Project Goals for This Summer 1. Are pistils
rich in pectins in all 3 zones? Early results
indicate Nope. Stigmas dont seem to have much
galacturoninc acid. So, we hope to
determine --the sugar composition of pectic
polysaccharides in the stigma, TZ, and style
--the degree, and type, of esterification on the
galacturonic acids found in each of these regions
2. Does ethylene promote pollen tube growth by
altering the pectic chemistry (leading
hypothesis)? We want to find if --ethylene
treatment increases hydrolysis of pectins
(increase in reducing sugars, release of low MW
pectic fragments) --ethylene treatment triggers
a change in the sugar composition, and degree of
esterification, of pectins extracted from the
stigma, TZ, and style (to detect differential
action of ethylene on the matrix in the 3
different zones)
23Research Methods To determine sugar composition
of pectic polysaccharides --dissect pistil into
stigma, TZ, and style freeze in liquid
nitrogen --extract pectic fractions analyze
for ? sugar content ? uronic acid
content ? reducing sugar content ? degree
and type of esterification --hydrolyze pectins,
derivatize the sugars --analyze by
GC-MS --compare ethylene vs. no ethylene
treatments --look for changes in any of the
above as well as for overall size changes in the
polysaccharides by size exclusion
chromatography --section tissues and stain with
pectin specific antibodies
24(No Transcript)
25(No Transcript)
26(No Transcript)