PART I
RESEARCH NOTES
Achkova-Valkova, Z., and P. Stoeva Bilate-
The utilization of L. peruvianum as a female
ral hybridization of Lycopersicon eru-
parent with self-compatible species from the
vianum Mill. with some self-compatible
genus Lycopersicon will give the opportunity
species. (Submitted by C. Daskaloff)
to study the interaction of its cytoplasm with
the genomes of these species. When the hy-
bridization is done at a diploid level, L. peruvianum manifests considerable or full reproductive
isolation. That's why hybridization at heteroploid level with three self-compatible species
manifesting certain instability in their interspecific reproductive relations - L. hirsutum f.
glabratum, L. minitum and S. pennellii (Atico) - has been applied.
The hybridization has been carried out in the greenhouse in two directions so that each
parent takes part as an autotetraploid and a diploid. An indispensable condition for successful
hybridization is the use of unemasculated buds. In order to preclude self pollination, about 24 h after the
pollination the bared stigma has been covered with a layer of dextrine glue. The hybrid character
of the plants has been determined by the chromosome number (2n=36) and some marked characteristics.
Hybrid seeds have been obtained from the two directions of crossing on condition that L.
peruvianum takes part as a diploid and its partner as a tetraploid. While the hybridization with L.
minutum and S. pennellii is relatively easy (18.9 - 25.7 hybrid plants per 100 pollinated buds)
hybridization with L. hirsutum f. glabratum is very difficult (2.1 - 2.4 hybrid plants per 100 pollinated
buds). Phenotypically the sesquidiploids are diverted strongly towards the tetraploid parent. The
fertility reaches up to 58%.
The sesquidiploid L. peruvianum (2n) X L. hirsutum f. glabratum (4n) was the first to be used for a
bridge between L. peruvianum and other species because the work with it began earlier. The
obtaining of F2 and BC1 was difficult. From 230 crosses with L. hirsutum f. glabratum 2 aneuploid
plants with 25 and 26 chromosomes were obtained. The second backcross was easily obtained.
The plants from BC1 with L. hirsutum f. glabratum failed to cross with L. esculentum but in
hybridization with L. pimpinellifolium from 147 pollinated buds 75 plants were obtained. Their hybrid
character was determined by the orange color of the fruits. F1 of this complex hybrid was crossed
easily with L. esculentum (from 213 pollinated buds - 157 hybrid plants). The fruits of the new
hybrid were red- or orange-colored with intermediate inheritance of fruit size.
Via the sesquidiploid L. peruvianum (2n) X L. hirsutum f. glabratum (4n) have been obtained BC with
L. esculentum. With the progress of the backcrosses in the first two cases an increasing of pollen
fertility has been observed. These data suggest that the appearance of cytoplasmic male sterility
can hardly be expected. It is too early to speak about certain phenotypic manifestations of the
combination between the cytoplasm of L. peruvianum and the genomes of L. esculentum.
The work for hybridization of L. peruvianum with L. esculentum was done in the period from
the end of 1974 'til the middle of 1977. This characterizes the method as relatively quick and
efficient in investigation of the interrelations of the cytoplasm of L. peruvianum and the genomes of
the self-compatible species from the genus Lycopersicon.
Allavena, A., and G. P. Soressi Tetraploid
Tetraploid seeds from hand-pollination of
parthenocarpic fruitful tomatoes.
polyploid shoots following colchicine treat-
ment (0.5% emulsion) of pat/pat F3 seedlings
have been obtained. These self-fertilized seeds produced 4N parthenocarpic plants as fruitful as the
corresponding diploids. On the contrary the 4N homozygous pat+ plants were almost completely
sterile. Besides the 4N parthenocarpic fruits were larger and heavier (30%) than the corresponding
2N. In addition their soluble solids and pH did not significantly differ from the diploid pat/pat, while the
ascorbic acid content was higher (20%). As the tetraploid tomatoes have not so far proved to be of
economic importance mainly because of their reduced fertility, our data put in evidence the
potential of the polyploidy coupled with the parthenocarpy in tomato breeding.
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