different PA concentrations and compositions under different nutrient and water
treatments, so it seemed that PA expression was affect by genotype by environment
interactions [15].
4
Leaf-Surface PA Variations of the Jacobaea and Jacobaea
Hybrid Plants
4.1
Total Concentration of the Leaf-Surface PAs
Vrieling and Derridj [41] have investigated the leaf-surface PA content of eight
genotypes from the wild J. vulgaris plants grown in a greenhouse and found that low
concentrations (10–76 ng cm
À2 ) of leaf-surface PAs, corresponding to 0.10–0.89%
of the total amount PA present in the leaf tissue in of natural grown J. vulgaris plants.
The average total PA amount present on the surface of the leaves of hybrid plants
from a crossing between J. vulgaris and J. aquatica was 8.0 ng (range 0.5–57.3 ng).
Corrected for the leaf-surface area, the average total PA concentration was
349 pg cm
À2 , with a range from 12.2 to 2835 pg cm
À2 (Table 1). Expressed per
leaf, the total amount of leaf-surface PAs was 8 ng (range: 0.5–57 ng), corresponding
to 0.0064% (range: 0.0004–0.060%) of the total PA amount in the leaf tissue.
Evidently, only a minute proportion of the PAs is deposited on the outside of the
leaves [44].
4.2
Composition of the Leaf-Surface PAs
On average 77% of the total PA content present on the leaf surface of hybrid plants
from a crossing between J. vulgaris and J. aquatica was in the N-oxide form,
although a wide range (27–98%) was observed. The five major PAs found on
the leaf surface were free base of jacobine and the N-oxides of four PAs
(seneciphylline, senecionine, jacobine, and erucifoline, Table 1). Together these
major PAs accounted for 83% (290 pg cm
À2 ) of the total PA concentration. Jaconine,
jaconine N-oxide, dehydrojaconine, dehydrojacoline, and usaramine N-oxide were
detected in most of the leaf-tissue samples at somewhat higher concentrations, but
nevertheless were absent or virtually absent in the leaf-surface samples (Table 2).
The results for jaconine and jaconine N-oxide are in agreement with the study
of [41], which was unable to detect jaconine on the leaf surface.
5
Correlation Between Leaf-Surface and Leaf-Tissue PAs
Compared to the concentrations of individual PAs on the leaf surface with those
in leaf tissue of hybrid plants from a crossing between J. vulgaris and J. aquatica,
it was found that several otosenine-like PA (otosenine, onetine, florosenine,
and floridanine) and jacobine-like PAs (jacobine, jacobine N-oxide, jacoline,
256
D. Cheng
treatments, so it seemed that PA expression was affect by genotype by environment
interactions [15].
4
Leaf-Surface PA Variations of the Jacobaea and Jacobaea
Hybrid Plants
4.1
Total Concentration of the Leaf-Surface PAs
Vrieling and Derridj [41] have investigated the leaf-surface PA content of eight
genotypes from the wild J. vulgaris plants grown in a greenhouse and found that low
concentrations (10–76 ng cm
À2 ) of leaf-surface PAs, corresponding to 0.10–0.89%
of the total amount PA present in the leaf tissue in of natural grown J. vulgaris plants.
The average total PA amount present on the surface of the leaves of hybrid plants
from a crossing between J. vulgaris and J. aquatica was 8.0 ng (range 0.5–57.3 ng).
Corrected for the leaf-surface area, the average total PA concentration was
349 pg cm
À2 , with a range from 12.2 to 2835 pg cm
À2 (Table 1). Expressed per
leaf, the total amount of leaf-surface PAs was 8 ng (range: 0.5–57 ng), corresponding
to 0.0064% (range: 0.0004–0.060%) of the total PA amount in the leaf tissue.
Evidently, only a minute proportion of the PAs is deposited on the outside of the
leaves [44].
4.2
Composition of the Leaf-Surface PAs
On average 77% of the total PA content present on the leaf surface of hybrid plants
from a crossing between J. vulgaris and J. aquatica was in the N-oxide form,
although a wide range (27–98%) was observed. The five major PAs found on
the leaf surface were free base of jacobine and the N-oxides of four PAs
(seneciphylline, senecionine, jacobine, and erucifoline, Table 1). Together these
major PAs accounted for 83% (290 pg cm
À2 ) of the total PA concentration. Jaconine,
jaconine N-oxide, dehydrojaconine, dehydrojacoline, and usaramine N-oxide were
detected in most of the leaf-tissue samples at somewhat higher concentrations, but
nevertheless were absent or virtually absent in the leaf-surface samples (Table 2).
The results for jaconine and jaconine N-oxide are in agreement with the study
of [41], which was unable to detect jaconine on the leaf surface.
5
Correlation Between Leaf-Surface and Leaf-Tissue PAs
Compared to the concentrations of individual PAs on the leaf surface with those
in leaf tissue of hybrid plants from a crossing between J. vulgaris and J. aquatica,
it was found that several otosenine-like PA (otosenine, onetine, florosenine,
and floridanine) and jacobine-like PAs (jacobine, jacobine N-oxide, jacoline,
256
D. Cheng