Abstract:

The long hull floral organ mutant in rice (Oryza sativa L.) was firstly discovered in the hybrid progeny of a wild rice (O. nivara Sharma et Shastry) and a cultivar rice (O. sativa subsp. indica Kato). The florets of the mutant plant show long, leafy paleas/lemmas that result in open hulls. A single floret consists of one to ten stamens, one to three pistils and one to five stigmas on the same ovary. Stamens/pistils-like structures and bulged tissues near ovaries were observed. Low seed setting rate was another obvious character of this mutant. According to statistical analysis, seed setting rate was 18.2%. The percentage of pollen fertility was 62.46%. The process of floral organ morphogenesis was also investigated using scanning electron microscopy (SEM), and genetic analysis indicated that mutant traits were controlled by single recessive gene (temporarily designated as lh). The possible relationships between this lh gene and other floral organ mutants reported earlier in rice are discussed. Furthermore, we deduced that this gene might represent an example of a gene required for generating proper floral organ number and also be similar to B-like genes in Arabidopsis and Antirrhinum.

Key words: Oryza sativa , long hull mutant, anatomical structure, floral organ morphogenesis, single recessive gene