A novel short-root gene that affects specifically early root development in rice ( Oryza sativa L.)

• Published in: Plant science (Limerick) 2002-08, Vol.163 (2), p.207-215
• Main Authors: Yao, Shan-Guo, Taketa, Shin, Ichii, Masahiko
• Format: Article
• Language: English
• Subjects: ABA; Agronomy. Soil science and plant productions; Biological and medical sciences; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Growth and development; Hormone response; Morphogenesis, differentiation, rhizogenesis, tuberization. Senescence; Morphology; Mutant; Plant growth. Development of the storage organs; Plant physiology and development; Rice; Root; Vegetative apparatus, growth and morphogenesis. Senescence
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/S0168-9452(02)00084-5

We have isolated a novel short-root mutant, srt5, from an M 2 population of rice ( Oryza sativa L. cv. Oochikara) treated with NaN 3, and mapped its causal gene to chromosome 2. The mutant showed extreme inhibition of seminal root, crown root and lateral root elongation, and altered root hair formation at the seedling stage. Histological observation of seminal root tips indicated that the short-root phenotype was due to the reduced cell size and cell number. At later stages of plant development, roots of the mutant elongated acceleratingly and recovered normal morphology 45 days after transplantation, and adult plants of the mutant resembled the wild type except for reduced pollen and seed fertilities. Seminal root growth of the mutant was partially rescued by exogenously applied ABA, suggesting that ABA biosynthesis might be affected in srt5 plants. Moreover, the mutant also showed high resistance to 2,4-D, GA 3 and KIN based on seminal root growth assays, but the resistance to these hormones disappeared when ABA was concomitantly applied. Thus, the wild type allele of srt5 seems to be of great importance for early root development by altering plant hormone homeostasis, in which ABA plays a critical role.