GRAFT-INDUCED GENETIC CHANGES AND THE INHERITANCE OF SEVERAL CHARACTERISTICS IN PEPPER (CAPSICUM-ANNUUM L.)

The general characteristics of several graft-induced changes in pepper were investigated in a cross experiment. F-1, F-2, and BC1 progenies derived from crosses of the original stock and scion cultivars 'Spanis h Paprika' and 'Yatsubusa', respectively, as well as their graft-induc ed variant strain G(5)S(25) were analyzed for inheritance of the most conspicuous graft-induced variant traits. As part of a research progra m with the aim of revealing the mechanism of graft induction, the pres ent study was carried out to examine the stability of the phenotypic c hanges and the characteristics of the graft-induced variants. For the fruit apex, a two-gene system was suggested, with other factors having a modifying influence. One of the two apex genes acted for pointed fr uits and the other for inverted-blunt fruits. The inverted-blunt gene, the apex gene of the stock, was unambiguously present in the graft-in duced variants, while the pointed gene that acted in the dominant mode in the original scion was inactive and expressed only under certain c onditions in a mosaic state. The stable inverted-blunt cultivar used f or the stock maintained certain factor(s) for pointed fruit, but the p resence of that factor(s) could not be detected in graft-induced varia nts. The results of pungency analysis suggested a gene for non-pungenc y that appeared to be introduced in the graft-induced variants. The fr uiting habit and fruiting direction that appeared in a mosaic state in graft-induced variants were found to combine factors of the stock wit h the appropriate characteristics of the scion asymmetrically. The bus hy plant type appeared in a transgressive state in the variants, showi ng a definitely higher number of branches on the main stem and more fr equent ramifications on the complete plant than on either the stock an d scion cultivars or the progency derived from sexual crosses. A chang e in mature fruit color from red to yellow occurred in an early genera tion of graft-induced variants. Our results demonstrate that some of t he characteristics of the stock were introduced into the progeny obtai ned from selfed seeds of the scion and that novel characteristics appe ared as a result of graft induction.