Biology Reference
In-Depth Information
Table 4.
Proteins identified in various plant nectars.
Protein/enzyme
Species
Function
Reference
Invertase
Tilia
sp.
Acacia
spp.
Hydrolysis of sucrose
Beutler, 1935
Heil et al., 2005
Transglucosidase
Robinia pseudacacia
Polymerization of glucose
molecules
Zimmerman,
1953
Transfructosidase
Impatiens holstii
Polymerization of fruc-
tose molecules
Zimmerman,
1954
Phosphatase
several
Breakdown of phosphate-
rich molecules—possibly
defence
Cotti, 1962
Tyrosinase
Lathraea clandestina
Production of melanin
Lüttge, 1961
Mannose-binding lectin
Allium porrum
Possibly defence
Peumans et al.,
1997
Alliinase
Allium porrum
Possibly allelochemical
defence
Peumans et al.,
1997
Nectarin I—Superoxide
dismutase
Nicotiana
sp.
Generates hydrogen per-
oxide
Carter & Thorn-
burg, 2000
Nectarin II—Breakdown
product of
Nec3
Nicotiana
sp.
Probably non-functional
Carter & Thorn-
burg, 2004b
Nectarin III—
Bifunctional carbonic
anhydrase and MDH
reductase
Nicotiana
sp.
pH-balanced nectar and
recycles ascorbate to
protect from hydroxyl
free radicals
Nectarin IV—
Xyloglucan-specific
Endoglucanase Inhibitor
Protein (XEGIP)
Nicotiana
sp.
Prevents fungal invasion
of the gynoecium
Naqvi et al., 2005
Nectarin V—Glucose
oxidase and possible
dehydroascorbate reduc-
tase
Nicotiana
sp.
Generates hydrogen per-
oxide; may recycle
ascorbate to protect from
hydroxyl free radicals
Carter & Thornburg,
2004c; unpublished
results
ascorbate oxidase. Scogin (1979) identified the presence of esterase and malate
dehydrogenase in the nectar of
Fremontia californica
and
F. mexicana
. These
two species differed in their protein profiles, and hybrid plants showed a
composite nectar protein profile. In addition to esterase and malate dehydro-
genase, other proteins were also observed, but were not fully characterized.
These proteins accumulated to 87 µg/ml of nectar.
6.1
Proteins in leek nectar
Subsequently there is a rather lengthy gap in the literature until the next
identification of nectar proteins. In examining the nectar of
Allium porrum
,
