The Geography of Phytochemical Races

2.6 South America 73
Fig. 2.45 Map of coastal
Peru showing Lycopersicon
pennellii sites
have been identifi ed as 2-methylpropanoate (syn. = isobutyrate), 2- methylbutanoate,
3-methylbutanoate, 8-methylnonanoate, n-decanoate, 9-methyldecanoate, 10-methylundecanoate,
and n-dodecanoate (Burke et al., 1987). A generalized structure of a
tetra-acylated sugar is shown as [170] (see Fig. 2.43).
Shapiro et al. (1994) observed several signifi cant differences in the biosynthetic
capacities of the varieties and, in particular, members of var. pennellii. The most
obvious difference reported by those workers is the apparent inability of some individuals
of var. puberulum to make any acylsugar derivatives at all. In those cases
where individuals do accumulate acylsugars, their capacity to do so appear limited
to derivatives based on glucose. While individuals belonging to var. pennellii do
possess the capacity to make acyl derivatives of both sugars, the total amount of
acylated glucose present always exceeds the amount of acylated sucrose present.
Signifi cantly different ester chemistries distinguish northern and southern populations
of var. pennellii. Table 2.14 lists occurrence data for the 2-methylpropionate
and 3-methylbutanoate esters, along with percent acylglucoside in the acylsugar
fraction, along with collection number and latitude of population. As can be seen,
the 2-methylpropionate derivative predominates in the southern populations (positive
correlation with latitude, r = 0.54, p = 0.02) while the 2-methylbutanoate derivative
is the major compound in the northern populations (negative correlation with
latitude, r = −0.70, p = 0.001). There also appears to be a signifi cant break in the
values between samples taken at Rio Chillón, Sisicaya at 12°0′S, and Rio Cañete,