IDENTIFICATION, TRANSMISSION, AND CYTOLOGICAL BEHAVIOR OF SOLANUM LYCOPERSICOIDES DUN. MONOSOMIC ALIEN ADDITION LINES IN TOMATO (LYCOPERSICON-ESCULENTUM MILL.)

The wild nightshade Solanum lycopersicoides possesses a number of dise ase-and arthropod-resistance and environmental stress tolerance traits of potential value for the cultivated tomato, Lycopersicon esculentum . F-1 hybrids are readily obtained by sexual crosses, but backcrosses to tomato are hindered by sterility and incompatibility barriers. In t he present studies, intergeneric sesquidiploid hybrids (2 genomes of L . esculentum and 1 of S. lycopersicoides) were pollinated with Lycoper sicon pennellii derived bridging lines, yielding diploid aneuploid (up to 2n + 6), and polyploid (3x,4x) progeny. After diploids (58% of tot al progeny), the group most frequently obtained was 2n + 1 (31%), whic h included all 12 possible monosomic alien addition lines (MAALs) cont aining a single extra chromosome from S. lycopersicoides in a tomato b ackground. MAAL groups were identified with a combination of allozyme, RFLP, and monogenic visual markers. Transmission rates of the extra c hromosomes in MAALs varied from 0%, for chromosome 6, to 24%, for chro mosome 10. At diakinesis and metaphase I of meiosis, the alien chromos ome was usually unpaired (in an average of 90% of PMCs), but associati on of homoeologous chromosomes was observed in each of the 12 MAAL gro ups (in an average of 5.7% of PMCs). The MAALs showed a striking hemor heological resemblance to the corresponding tomato primary trisomic. I n addition, each MAAL expressed S. lycopersicoides specific leaf, flow er, and (or) fruit characters. This set of MAALs, the first of its kin d in Lycopersicon, is expected to be useful for a variety of gene-mapp ing and introgression studies.