The Role of Chromosome 2 in the Genetics of Maturation Time in the Tomato

Abstract

Currence (1938) reported that the number of days to ripe fruit in the tomato was under the genetic control of chromosome 2. Using Lindstrom's (1932) and MacArthur's (1936) original linkage group of d p o s genes Currence showed that at least two distinct regions of the marlted chromosome were associated with time to maturity. One region was marlted by the genes d and p, the other by s.he ilumber o f davs between seeding and the first r i~e fruit was reearded 2 U 1 U as enlbodying the entire time process of maturation. Powers, Loclte, and Garrett (1950) divided this total time interval into three components as delimited b y certain morphological stages during the growth of the plant. These components were: 1) the number of days between seeding and first bloom, 2) days between first bloom and first fruit set, and 3) days between first fruit set and first ripe fruit. T h e y showed that such a division was valid and further r e~o r t e d that the c o m~o h e n t s were eeneticallv controlled and that a 1 0 simpler scheme of inheritance 'could be postulated t h k when one considered the entire interval. T h e analysis of components therefore has a greater chance of revealing the genetic mechanisms involved than has an analysis which is based on the whole interval between seeding and fruit ripening. Materials and MethodsT w o lines of tomatoes developed at the Univcrsity of Toronto appeared promising for this investigation. Line T2003 contained the genes 772 d p nw o and had a total time t o maturity of 133.7 t 1.66 days. Line T2006 contained the genes nz d p o s and a time to maturity of 126.1 -+ 1.64 days. T h e two comrnercial varieties, Yellow Cherry and Fireball, were selected for their earliness in time of maturity, i.e. 93.2 t 0.68 days and 101.1 0.97 days, respectively. I t should be noted that both the two early varieties and the two late varieties are 8 days apart in time of maturity.