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|Title:||The Genetics, Breeding and Physiology of Parthenocarpy in Lycopersicon Esculentum Mill. (Tomato)|
|Author(s):||Lin, Steve Shih-Min|
|Department / Program:||Horticulture|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Agriculture, Plant Culture|
|Abstract:||'Severianin' is a tomato line which exhibits facultative parthenocarpy (functional seedless fruit) in some environments. It was found that the expression of parthenocarpy of this line was not due to male or female sterility or self-incompatibility. Environments which favor the expression of parthenocarpy act upon the sporophytic rather than the gametophytic tissue of the plant. Morphological studies showed that fertilization and seed formation do not occur during the development of parthenocarpic fruit of this mutant. Insufficient pollen shed plus rapid growth of the ovary are related to the expression of parthenocarpic fruit under glass-house environments.
The genetics of parthenocarpy of 'Severianin' was studied in crosses involving four seeded cultivars or lines ('Ohio M-R 13', 'Heinz 1350', 'Clld' and 'Positional Sterile'). Parthenocarpy was evaluated without emasculation of the flowers in parental, F(,1), F(,2) and backcross populations. The data indicated that the inheritance of the parthenocarpic trait of 'Severianin' was controlled by a single recessive gene, pat-2. No cytoplasmic inheritance of parthenocarpy was revealed based on reciprocal crosses.
The expression of parthenocarpy of this mutant is probably associated with a determination growth habit (sp) and/or earliness. No other linkages or associations between pat-2 and five other marker genes (u, c, ps, y and aw) were detected.
The general horticultural performance of 'Severianin' was evaluated under glasshouse and field conditions. 'Severianin' demonstrated better fruit-set without pollination than the control cultivars 'Ohio M-R 13' and 'Heinz 1350' under high temperature and glasshouse culture. The parthenocarpic trait from 'Severianin' accounted for most of the heat tolerance in the progenies of 'Severianin' and the seeded cultivars or lines. It appears possible to develop heat-tolerant cultivars or breed glasshouse cultivars which do not require pollination by using parthenocarpy governed by pat-2.
In a backcross program, parthenocarpy (pat-2) of 'Severianin' was transferred to four recurrent parents: (1) 'Ohio M-R 13', a commercial glasshouse cultivar; (2) 'Heinz 1350', a fresh market and processing field cultivar; (3) 'Clld', a heat-tolerant breeding line; and (4) 'Positional Sterile', a functional male sterile line. At present, BC-2 lines were obtained.
'Severianin' combined well with the four control cultivars and lines used in this study. Some of the F(,1)'s showed heterosis in fruit yield. No reciprocal differences were detected.
The inbred selection of the parthenocarpy-positional sterile-stigma exsertion line (Pat-Ex) can be used as a female line in F(,1) hybrid seed production without emasculation. Only 0.8 percent selfing contamination was found in the glasshouse studies. However, under field environments, this scheme may not be satisfactory due to the large percentage of seedless fruits which would reduce hybrid seed yield.
The F(,1) of the cross between 'Severianin' and the 'Pat-Ex' line (homozygous pat-2/pat-2) retained its ability to set parthenocarpic fruits. This indicates the possibility of using parthenocarpy to overcome yield reduction by stigma exsertion in a F(,1) hybrid seed production scheme.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.
|Date Available in IDEALS:||2014-12-16|