Male sterile plants of lettuce (Lactuca sativa L.) cv. 'Lake Nyah' wer
e produced using a genotype-independent transformation method employin
g Agrobacterium tumefaciens with a binary vector. The latter carried t
he neomycin phosphotransferase II gene controlled by the nopaline synt
hase promoter and terminator sequences, enabling transformed shoots to
be selected on medium containing kanamycin sulphate. In addition, exp
ression of a pathogenesis-related glucanase gene linked to a tapetum-s
pecific promoter, caused the dissolution of the callose wall of develo
ping microspores in transgenic plants. All transformed plants were mal
e sterile. Plants regenerated from uninoculated, excised cotyledons of
'Lake Nyah' exhibited normal microspore development and were fertile.
These results suggest that callose degradation may cause male sterili
ty and provides the opportunity for producing F1 hybrid seed in lettuc
e.