Relationships between several genes that influence blossom-end morphology in tomato and their usefulness in breeding efforts towards smooth blossom-end scars

Barten, J.H.M., Scott, J.W., Gardner, R.C., Kedar, N., and Elkind, J.

A successful approach to breeding for smooth blossom-end scars has been the use of genes influencing blossom-end morphology. The nipple tip (n) gene codes for a pointed blossom-end, especially in young fruits, and is used most frequently in spite of occasional problems with beakiness in mature fruit and an adaxial leaf curl which is linked to n and can increase foliar disease problems. Several breeding lines (NC140, Fla890559-24, Fla90E317S), that had nippled fruit without the associated leaf curl, were tested for allelism with all previously described blossom-end morphology influencing genes (n in LA2353, bk in LA986, Bk-2 in LA1787 and pst in LA2-5) and each other. The percentage nippled fruit was scored on 20 fruits per plant (10 young and 10 old) for 10 plants of parental and F1 generations and for 30 plants in F2 generations. The results showed that bk in LA986 and pst in LA2-5 were allelic. Furthermore, Bk-2 in LA1787 was almost completely recessive. The nippling in LA2353, LA986, LA1787 and LA2-5 was too pronounced for practical use. NC140 contains a gene, different from all previously described genes. More research is needed to investigate the relationship between LA1787, Fla890559-24 and Fla90E317S, but each of these is different from all other described genes. NC140, Fla890559-24 and Fla90E317S are feasible alternatives to achieve smooth blossom-end scars. Segregations in F2's between mutants and wild types did not deviate significantly from 3:1, except for pst in LA2-5, where pst was under represented probably due to association with deleterious genes. Thus all mutants were recessive for nippling. When looking at the shape of the ovary and stylar base at anthesis, plants with pst, bk and n could be identified before fruit set. Pubescence at the stylar base seemed to be inherited quantitatively and could not be used as a marker.