LINKAGE IN LYCOPERSICUM 

 DONALD F. JONES 

 New Havek, Conn. 



The known cases of linkage of hereditary factors in 

 plants are not as yet so numerous but that it seems de- 

 sirable to place on record all instances of this condition. 

 With that end in view I wish to call attention to some 

 scattered data obtained several years ago, before much 

 was known about linkage, and presented in publications 

 which are probably not widely circulated. 



Part of the data to be considered resulted from an in- 

 vestigation, started by Hedrick and Booth, shortly after 

 the beginning of the awakened interest in Mendelism, 

 which was designed to test the inheritance of Mendelian 

 characters in the garden tomato (Lycopersicum esculen- 

 tum Mill.). The results were published in the Proceed- 

 ings of the Society for Horticultural Science in 1907. 

 Two different crosses were studied. One cross was made 

 between two varieties which differed in one character 

 only, viz., standard and dwarf habit of vine. The other 

 cross was between two varieties which differed in three 

 characters, habit of vine, shape of fruit and color of fruit. 

 It is this second cross which gives evidence that there is a 

 genetic linkage between the factors for habit of vine and 

 shape of fruit. 



In this latter cross the varieties used are known under 

 the varietal names of Quarter Century and Yellow Pear. 

 The Quarter Century variety is described as having a 

 dwarf type of vine, red-colored fruit which is shaped like 

 that of the common garden varieties, i. e., more or less 

 spherical. The Yellow Pear variety has a standard or 

 spreading vine, fruit yellow in color and pear-shaped. 



The first generation plants grown from this cross were 

 standard in habit of vine, with red-colored fruit which 

 differed in shape from either parent, being oval rather 

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