Plant Genome IV Conference Plant Genome IV Conference
Abscission is a universal process in the plant kingdom whereby plants shed their organs such as flowers, fruits and leaves and thus self-regulate their growth and development. This attribute is of significance for management of fruit crop production in agriculture. Abscission occurs at the abscission zone (AZ) called the "joint" of a flower, fruit or leaf. Two mutations completely suppressing the development of AZ were discovered in tomato, jointless (j) and jointless-2 (j-2). The two genes both control the development of AZs but they are non-allelic and mapped to different chromosomes of tomato [Wing et al., Mol. Gen. Genet., 224, 681-688 (1994) and Zhang et al., unpublished]. In previous studies, we isolated a set of overlapping tomato YAC clones containing the J locus [Zhang et al., Mol. Gen. Genet. 224, 513-521 (1994)]. Using one of these YACs (TY142, 285 kb) containing the J locus as a probe, we isolated 3 cDNA clones (C11, C13 and C34) consegregating with the J gene from a jointed tomato cDNA library constructed from floral meristems [Zhang et al., Plant Genome III Abstract #P277, (1995)]. To identify the Jointed gene, we are performing three experiments: 1) high resolution mapping of the J region with a large mapping population, 2) comparative sequence analysis of cDNA clones isolated with C11, C13 and C34 from the jointed and jointless tomato NIL (Fireball) cDNA libraries, and 3) genetic transformation of genomic DNA and cDNA constructs for genetic complementation and/or antisense suppression. The results of these experiments will be reported.