References Nettancourt, D. de, M. Devreux, U. Laneri, M. Cresti, E. Pacini, and G. Sarfatti. 1974. Genetical and ultrastructural aspects of self- and cross-incompatibility in interspecific hybrids between self-compatible Lycopersicum esculentum and self-incompatible L. peruvianum. Theoret. Appl. Genet. 44:278-288. Nettancourt, D. de. 1977. Incompatibility in angiosperms. Edited by Springer-Verlag, Berlin, Heidelberg, New York. 230 pp. Atanassova, B. Comparative studies on the morphogenesis of longistylic and normal tomato cultivars and lines. The studies were carried out on the following tomato cultivars and lines divided in accordance with the anther/pistil ratio into three groups: I, with longistylic flowers -  GCR-66, GCR-115 and Hera; II, with styles almost on the level of the pollen tube - BC-2, line 7/3; III, with styles 1.5 to 2 times shorter than the stamens of line XXIV-13. Observations focused mainly on the following stages of tomato morphogenesis (after Poloumordvinova, 1962, and Kuperman, 1972): VI stage - buds with a size of 1.0 to 2.0 mm; VII stage - buds with a size up to 3.0 mm; VIII stage - buds just before anthesis; IX stage - flowers in bloom. At the VI stage the style of both longistylic and normal tomato flowers is 1.5 to 2 times shorter than the stamens, i.e. no differences are evident in the development of the three groups. At the VII stage a strict individuality of morphogenesis is observed in the various cultivars and lines. The styles of GCR-66 and GCR-115 suddenly grow very fast and by the end of that stage are at the level of or above the pollen tubes. In BC-2 at the same stage the style reaches about 2/3 of the stamen length, while during the IX stage in the blooming flowers it is almost equal with the top of the pollen tube. In line XXIV-13 until the end of the IX stage the style grows more slowly than the stamens and at the time of anthesis it reaches 1/2 to 2/3 of their length. At the end of stage VI the style of line 7/3 is about 1.5 to 2.0 times shorter than the stamens, during the VII stage its length equals the length of the pollen tube and the situation does not change until full bloom. It can be assumed, therefore, that at the end of stage VI and the beginning of stage VII in the longistylic cultivars and lines some enzyme or growth substance is activated which stimulates the fast growth of the style. Such an enzyme or growth substance either does not exist or is not activated in cultivars and lines with normal flowers. Avdeyev, Y. I. Inheritance of resistance to concentric fruit cracking. Resistance to concentric cracking was studied in hybrids of the susceptible line G-A-8and the resistant variety Mashinny. The plantswere grown in the glasshouse, where temperature was about 23° C. The plants were watered when the partial loss of foliage turgor was visible. The soil medium was a mix of 24% light loam and 76% sand; sulphate- chloride type solination was used. Resistance to concentric cracking in F1 and F2 is incompletely dominant (see table below). If monogenic determination of inheritance of resistance to concentric cracking is assumed, the expected number of heterozygotes in the F2 should be 50% of the total number or 42.5. Account must be taken of the background performance of the heterozygotes, as indicated by the fact that 43.8% of the F1 plants had cracked fruits. Accordingly, 18.6 F2 heterozygotes (43.8% of 42.5) are expected to have cracked fruit. The number of crack- susceptible F2 homozygotes expected is 25% of the total, or 21.2. But since penetrance to susceptibility is not complete in the susceptible parent but approximates 95%, the expected number of cracked susceptible homozygotes must be corrected to 20.1. Thus, under the actual growing conditions, if the monogenic hypothesis is accepted, 16.8 + 20.1. = 36.9 plants with cracked fruit are expected, and the ratio of plants with cracked fruit to those without cracked fruit should be 46.3 : 38.7. The actual ratio observed was 49 : 36, which fits expectation well (X2 = 0.345; 0.75 > p > 0.50). The hypothesis is confirmed and action of a single incompletely dominant gene is indicated. The symbol Rc is proposed for resistance to concentric fruit cracking of this type.

No navigation control above? Click here!