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Isolation and characterisation of a dwarf rice mutant exhibiting defective gibberellins biosynthesis
Author(s) -
Ji S. H.,
Gururani M. A.,
Lee J. W.,
Ahn B.O.,
Chun S.C.
Publication year - 2014
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/plb.12069
Subject(s) - biology , mutant , dwarfism , gene , genetics , gibberellin , phenotype , wild type , oryza sativa , microbiology and biotechnology
We have isolated a severe dwarf mutant derived from a D s ( D issociation) insertion mutant rice ( O ryza sativa var. japonica c.v. D ongjin). This severe dwarf phenotype, has short and dark green leaves, reduced shoot growth early in the seedling stage, and later severe dwarfism with failure to initiate flowering. When treated with bioactive GA 3 , mutants are restored to the normal wild‐type phenotype. Reverse transcription PCR analyses of 22 candidate genes related to the gibberellin ( GA ) biosynthesis pathway revealed that among 22 candidate genes tested, a dwarf mutant transcript was not expressed only in one O s KS 2 gene. Genetic analysis revealed that the severe dwarf phenotype was controlled by recessive mutation of a single nuclear gene. The putative O s KS 2 gene was a chromosome 4‐located ent ‐kaurene synthase ( KS ), encoding the enzyme that catalyses an early step of the GA biosynthesis pathway. Sequence analysis revealed that osks2 carried a 1‐bp deletion in the ORF region of O s KS 2 , which led to a loss‐of‐function mutation. The expression pattern of O s KS 2 in wild‐type cv D ongjin, showed that it is expressed in all organs, most prominently in the stem and floral organs. Morphological characteristics of the dwarf mutant showed dramatic modifications in internal structure and external morphology. We propose that dwarfism in this mutant is caused by a point mutation in O s KS 2 , which plays a significant role in growth and development of higher plants. Further investigation on O s KS 2 and other O s KS ‐like proteins is underway and may yield better understanding of the putative role of O s KS in severe dwarf mutants.