sci.bio.paleontology dropped.

In article , wrote...
24 Oct 2002 03:35:16 GMT mel turner wrote:
In article , wrote...
[previous snipped]

Thanks for that well-informed response.

No problem, it's a fun group of plants to look up info on.

Question: how far away are we from getting a entire genome project on
the *wild potato* and *wild tomato* plus all the other Solanum species?
Are we 50 years away from getting that data?

All Solanums? It unlikely we're that close. It seems there are lots
[over a hundred?] of different wild potato species [Solanum
subgenus Potatoe section Petota], and IIRC well over a thousand
different species in the rest of the genus.

However, there is ongoing genetic research looking into improving
the cultivated potato, including using crosses with different wild
potato species, and no doubt the potato and its closest wild
relatives would be a very likely candidate for a major genome
project of somewhat narrower scope.

My hypothesis is that once the data is available that the wild potato and wild
tomato genomes are the closest-matching genomes of all the Solanum species.

You're probably right, with the clarification that it's the whole
group of several tomato species [both wild and cultivated] that
together are the closest relative of the large group of many
potato species [wild and cultivated].

We do have genetic data on all the primates and the Human genetics closest-
match is the chimpanzee.

So my theory is that as close as Human genetics matches chimpanzees of all the
primates, that the wild-potato matches the closest with the wild-tomato of all
of
the Solanum species.

And yes, that seems to be the case [again with the clarification
that there are several species of wild tomatoes and many species
of wild potatoes. Together the two groups reportedly make
up the subgenus Potatoe of the genus Solanum, which also
contains many other much more distant subgroups.

Some references and abstracts [from a BioAbstracts search]
illustrating recent research that you may find of interest:

TI: Molecular evolution of 5S rDNA of Solanum species (sect. Petota):
Application for molecular phylogeny and breeding.
AU: Volkov-R-A; Zanke-C; Panchuk-I-I; Hemleben-V {a}
SO: Theoretical-and-Applied-Genetics. [print] December, 2001; 103
(8): 1273-1282..
AB: Nucleotide sequences of 5S rRNA genes (5S rDNA) of 26 wild
species of the genus Solanum (sect. Petota) originating from Middle
or South America, four Solanum tuberosum breeding lines and one
European species, Solanum dulcamara (sect. Dulcamara) were compared
with each other and with the 5S rDNA of Lycopersicon esculentum. The
length of the repeat ranges from 285 bp to 349 bp. The complete 5S
repeat unit consists of the 120-bp long conserved coding region and
of a intergenic spacer with a high variability in the central portion
as result of deletions/duplications of short motifs demonstrating
sequence similarity to box C in the 5S rRNA coding region. Numerous
structural rearrangements found in the spacer region can be applied
to design species-specific molecular markers for Solanum species
involved in breeding programs. Characteristic insertions/deletions
(indels) were used to reconstruct phylogenetic relationships among
the species studied. S. dulcamara forms a separate clade; L.
esculentum is more related to Solanum species of sect. Petota.
Conservation of ancestral 5S spacer organization was demonstrated
for the representatives of several series of sect. Petota, both
Stellata and Rotata. Further rearrangements of the spacer
organization occurred in at least four independent lineages:
(1) L. esculentum, (2) ser. Polyadenia, (3) other Stellata species
from Middle America (ser. Pinnatisecta and Bulbocastana),
(4) superser. Rotata. In this last group, series Megistacroloba and
Conocibaccata show a common origin, and separation from ser.
Tuberosa. Solanum chacoense and Solanum maglia demonstrate a close
relatedness to species of ser. Tuberosa and should be included
into this group, whereas Solanum bukasovii should be excluded due
to conservation of ancestral spacer organization. Three major
subgroups may be distinguished for species from ser. Tuberosa,
although a high sequence similarity was found here. Several wild
species (diploids Solanum phureja and Solanum spegazzinii) probably
participated in the natural origin of tetraploid S. tuberosum;
others were later used for crossing in breeding programs (e.g.
Solanum demissum). Clear separation of Middle-American Stellata
species from South-American Stellata and from Middle-American Rotata
polyploids is shown.

TI: Molecular systematics of Solanum section Lycopersicum
(Lycopersicon) using the nuclear ITS rDNA region.
AU: Marshall-J-A; Knapp-S; Davey-M-R {a}; Power-J-B; Cocking-E-C;
Bennett-M-D; Cox-A-V
SO: Theoretical-and-Applied-Genetics. [print] December, 2001; 103
(8): 1216-1222..
AB: The phylogenetic relationships of all nine known tomato species
of Solanum section Lycopersicum, together with other Solanum sections
and species from several related genera, were investigated using
parsimony analysis of the internal transcribed spacer (ITS) region of
nuclear ribosomal DNA (rDNA). Most parsimonious reconstructions
divided the section Lycopersicum into three clades, reflecting their
mating behaviour and fruit colour. Data from sequencing studies were
congruent with those from morphological and other molecular
investigations, and provided detailed information concerning species
relationships.

TI: Use of microsatellites to evaluate genetic diversity and species
relationships in the genus Lycopersicon.
AU: Alvarez-A-E; van-de-Wiel-C-C-M {a}; Smulders-M-J-M; Vosman-B
SO: Theoretical-and-Applied-Genetics. [print] December, 2001; 103 (8):
1283-1292..
AB: In order to determine how informative a set of microsatellites
from tomato is across the genus Lycopersicon, 17 microsatellite loci,
derived from regions in and around genes, were tested on 31 accessions
comprising the nine species of the genus. The microsatellite
polymorphisms were used to estimate the distribution of diversity
throughout the genus and to evaluate the efficacy of microsatellites
for establishing species relationships in comparison with existing
phylogeny reconstructions. Gene diversity and genetic distances were
calculated. A high level of polymorphism was found, as well as a large
number of alleles unique for species. The level of polymorphism
detected with the microsatellite loci within and among species was
highly correlated with the respective mating systems, cross-pollinating
species having a significantly higher gene diversity compared to
self-pollinating species. In general, microsatellite-based trees were
consistent with a published RFLP-based dendrogram as well as with a
published classification based on morphology and the mating system. A
tree constructed with low-polymorphic loci (gene diversity 0.245)
was shown to represent a more-reliable topology than a tree constructed
with more-highly polymorphic loci.

TI: Granule-bound starch synthase (GBSSI) gene phylogeny of wild
tomatoes (Solanum L. section Lycopersicon (Mill.) Wettst. subsection
Lycopersicon).
AU: Peralta-Iris-E; Spooner-David-M {a}
SO: American-Journal-of-Botany. [print] October, 2001; 88 (10):
1888-1902..
AB: Eight wild tomato species are native to western South America and
one to the Galapagos Islands. Different classifications of tomatoes
have been based on morphological or biological criteria. Our primary
goal was to examine the phylogenetic relationships of all nine wild
tomato species and closely related outgroups, with a concentration on
the most widespread and variable tomato species Solanum peruvianum,
using DNA sequences of the structural gene granule-bound starch
synthase (GBSSI, or waxy). Results show some concordance with previous
morphology-based classifications and new relationships. The ingroup
comprised a basal polytomy composed of the self-incompatible
green-fruited species S. chilense and the central to southern Peruvian
populations of S. peruvianum, S. habrochaites, and S. pennellii. A
derived clade contains the northern Peruvian populations of S.
peruvianum (also self-incompatible, green-fruited), S. chmielewskii,
and S. neorickii (self-compatible, green-fruited), and the
self-compatible and red- to orange- to yellow-fruited species S.
cheesmaniae, S. lycopersicum, and S. pimpinellifolium. Outgroup
relationships are largely concordant with prior chloroplast DNA
restriction site phylogenies, support S. juglandifolium and S.
ochranthum as the closest outgroup to tomatoes with S. lycopersicoides
and S. sitiens as basal to these, and support allogamy,
self-incompatibility, and green fruits as primitive in the tomato
clade.

TI: Classification of wild tomatoes: A review.
AU: Peralta-Iris-Edith {a}; Spooner-David-M {a}
SO: Kurtziana-. [print] 2000; 28 (1): 45-54..
AB: Wild tomatoes are native to western South America. The generic
status of wild tomatoes within the Solanaceae has been controversial
since the eighteen century. Linnaeus in 1753 placed tomatoes in
Solanum while Miller, a contemporary of Linnaeus, classified tomatoes
in a new genus Lycopersicon. The majority of later botanists have
followed Miller. Differing numbers of species and conflicting
supraspecific classifications have been proposed, based on morphology
or crossing studies. Two major crossability groups have been
identified, one that includes mainly self-compatible species that
easily cross with the cultivated tomato, and another that comprises
self-incompatible species not easily cross with the cultivated tomato.
Recent molecular investigations using appropriate outgroups have shown
that tomatoes and potatoes are close related phylogenetically, and
support the inclusion of tomatoes within Solanum, the classification
advocated here. We discuss the conflicting goals of classifications
based on predictivity versus stability, a continuing controversy in
systematics.

TI: Phylogenetic relationships of wild potatoes, Solanum series
Conicibaccata (Sect. Petota).
AU: Castillo-Raul-O; Spooner-David-M {a}
SO: Systematic-Botany. 1997; 22 (1) 45-83..
AB: Solanum sect. Petota series Conicibaccata is a group of 40 wild
potato species, composed of diploids, tetraploids, and hexaploids,
distributed from central Mexico to central Bolivia. This study
examined their species boundaries and interrelationships by phenetic
analyses of morphological data and cladistic analyses of chloroplast
DNA restriction site data. Mitotic chromosome counts were obtained for
114 accessions; species whose first counts are reported here are S.
garcia-barrigae, S. orocense, and S. sucubunense. Most results were
concordant in showing three main groups of species: 1) tetraploids
and hexaploids from centra Mexico to southern Ecuador; 2) diploids
from northern Peru to Bolivia, included in a cpDNA clade of diploids
and hexaploids assigned to ser. Demissa and ser. Tuberosa, and 3)
diploids and tetraploids from southern Colombia to Peru, cladistically
related to members of ser. Piurana. Some species boundaries, and even
series boundaries of ser. Conicibaccata and ser. Piurana, are supported
morphologically only by a combination of widely overlapping character
states, none of which is constant for a species. Other species have
no support, and it is likely that too many species are recognized in
the group. The cladistic analysis of chloroplast DNA data suggested
that some species represent a combination of apospecies and
plesiospecies, and some populations are of possible hybrid origin.

TI: Implications for the phylogeny, classification, and biogeography
of Solanum from cpDNA restriction site variation.
AU: Olmstead-Richard-G {a}; Palmer-Jeffrey-D
SO: Systematic-Botany. 1997; 22 (1) 19-29..
AB: A phylogenetic analysis of Solanum based on chloroplast DNA
restriction site variation confirms previous findings that
Lycopersicon and Cyphomandra are derived from within Solanum. Three
out of four Solanum subgenera with more than one representative in
this analysis (Minon, Potatoe, Solanum) are found to be polyphyletic,
suggesting that the subgeneric classification of the genus needs
revision. Subgenus Leptostemonum is monophyletic within the context
of our sampling. Three primary clades can be distinguished within
Solanum. Clade I includes representatives of sections Archaesolanum,
Dulcamara, Holophylla, Jasminosolanum, and Solanum. Clade II includes
members of subgenus Potatoe (sections Basarthrum, Lycopersicon, and
Petota). Clade III includes all representatives sampled from subg.
Leptostemonum, sects. Allophyllum, Brevantherum, Geminata,
Pseudocapsocum, and Cyphomandropsis, and species formerly assigned to
Cyphomandra. Solanum as a whole and each of the three primary
clades appear to be New World in origin. Within Leptostemonum, African
and Australian members are derived from New World ancestors.

TI: Phylogenetic relationships in Solanum (Solanaceae) based on ndhF
sequences.
AU: Bohs-Lynn {a}; Olmstead-Richard-G
SO: Systematic-Botany. 1997; 22 (1) 5-17..
AB: A phylogenetic analysis was conducted using sequence data from
the chloroplast gene ndhF. Sequences were obtained from 25 species of
Solanaceae, including 18 species of Solanum representing five of the
seven conventionally recognized subgenera. Trees were constructed
using parsimony and maximum likelihood methods. Results indicate that
Solanum lycopersicum (formerly in genus Lycopersicon) and Solanum
betaceum (formerly in genus Cyphomandra) are nested within the Solanum
clade. Each of the Solanum subgenera Leptostemonum, Minon, Potatoe,
and Solanum are not monophyletic as currently circumscribed. Four
major clades within Solanum are supported by high bootstrap values,
but the relationships among them are largely unresolved. The
problematical sections Aculeigerum (represented by S. wendlandii) and
Allophyllum (represented by S. allophyllum) emerge as sister taxa in
a larger clade composed of S. betaceum, S. luteoalbum, and members of
subgenera Leptostemonum, Minon, and Solanum. Several prominent
morphological characters such as spines, stellate hairs, and tapered
anthers apparently have evolved more than once in Solanum.

TI: Insect resistance in potatoes: Sources, evolutionary relationships,
morphological and chemical defenses, and ecogeographical associations.
AU: Flanders-Kathy-L; Hawkes-John-G; Radcliffe-Edward-B {a};
Lauer-Florian-I
SO: Euphytica-. 1992; 61 (2) 83-111..
AB: The past 25 years, 1986 potato accessions, representing 100
species in the genus Solanum L., subgenus Potatoe, section Petota,
were evaluated for field resistance to one or more of the following
insect pests: green peach aphid, Myzus persicae (Sulzer); potato
aphid, Macrosiphum euphorbiae (Thomas); Colorado potato beetle,
Leptinotarsa decemlineata (Say); potato flea beetle, Epitrix
cucumeris (Harris); and potato leafhopper, Empoasca fabae (Harris).
Accession highly resistant to green peach aphid were identified
within 36 species, to potato aphid within 24 species, to Colorado
potato beetle within 10 species, to potato flea beetle within 25
species, and to potato leafhopper within 39 species. Resistance
levels were characteristic within Solanum species. Insect resistance
appears to be a primitive trait in wild potatoes. Susceptibility was
most common in the primitive and cultivated Tuberosa. Insect
resistance was also characteristic of the most advanced species.
The glycoalkaloid tomatine was associated with field resistance to
Colorado potato beetle and potato leafhopper. Other glycoalkaloids
were not associated with field resistance at the species level. Dense
hairs were associated with resistance to green peach aphid, potato
flea beetle, and potato leafhopper. Glandular trichomes were
associated with field resistance to Colorado potato beetle, potato
flea beetle, and potato leafhopper. Significant correlation between
insect score and altitude of original collection were observed in six
of thirteen species. Species from hot and arid areas were associated
with resistance to Colorado potato beetle, potato flea beetle, and
potato leafhopper. Species from cool or moist areas tended to be
resistant to potato aphid.

cheers