The endo-1,3-.beta.-glucanase gene family encodes isozymes that catalyze the hydrolysis of 1,3-.beta.-D-glycosidic bonds in cell wall polymers of plants and fungi. The substrates for these glucanases include 1,3-.beta.-glucans and 1,3;1,6-.beta.-glucans. An N-terminal signal peptide directs all glucanase isozymes into the endoplasmic reticulum. Most glucanase isozymes are then secreted into the apoplast, but C-terminal peptides direct certain glucanase isozymes into the vacuole (Simmons, 1994).
This diversity of functions is matched by a multiplicity of 1,3-.beta.-glucanase genes and isozymes. In the more exhaustively studied plant species, the number of genes or isozymes ranges from 5 to 14 (Simmons, 1994). The first .beta.-glucanase gene characterized in rice was Gns1;1, which was predicted to encode a 1,3;1,4-.beta.-glucanase based on homology to the EI gene of barley (Simmons, et al., 1992). Akiyama, et al. have recently characterized a glucanase isozyme from rice which has 1,3;1,4-.beta.-glucanase activity and an acidic pI (Akiyama, et al., 1996a, 1996b); this isozyme may be encoded by the Gns1;1 gene. Akiyama, et al. have also recently characterized two 1,3-.beta.-glucanase isozymes from rice (Akiyama, et al., 1996a, 1996b; Akiyama, et al., 1997).
Eight genes which encode novel rice .beta.-glucanase isozymes Gns2-9 are discosed herein. The genes, the gene promoters, and nucleic acids encoding signal peptides, full-length proteins, and mature proteins, are useful in a variety of transgenic monocot plants, for example, in achieving increased plant resistance to fungal infection, improved growth characteristics, and high levels of expression of heterologous proteins in various tissues obtained from the plants.