Auxin biosynthesis by the YUCCA genes in rice.
Although indole-3-acetic acid (IAA), the predominant auxin in plants, plays a critical role in various plant growth and developmental processes, its biosynthesis and regulation have not been clearly elucidated. To investigate the molecular mechanisms of IAA synthesis in rice (Oryza sativa), we identified seven YUCCA-like genes (named OsYUCCA1-7) in the rice genome. Plants overexpressing OsYUCCA1 exhibited increased IAA levels and characteristic auxin overproduction phenotypes, whereas plants expressing antisense OsYUCCA1 cDNA displayed defects that are similar to those of rice auxin-insensitive mutants. OsYUCCA1 was expressed in almost all of the organs tested, but its expression was restricted to discrete areas, including the tips of leaves, roots, and vascular tissues, where it overlapped with expression of a beta-glucuronidase reporter gene controlled by the auxin-responsive DR5 promoter. These observations are consistent with an important role for the rice enzyme OsYUCCA1 in IAA biosynthesis via the tryptophan-dependent pathway.
Yamamoto
Yuko
Y
Bioscience and Biotechnology Center, Nagoya University Chikusa, Nagoya Aichi, 464-8601, Japan.
Kamiya
Noriko
N
Morinaka
Yoichi
Y
Matsuoka
Makoto
M
Sazuka
Takashi
T
D003001:Cloning, Molecular; D016373:DNA, Antisense / Q000378:metabolism; D005966:Glucuronidase / Q000032:analysis; D007210:Indoleacetic Acids / Q000378:metabolism*; D008969:Molecular Sequence Data; D012275:Oryza / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D030821:Plants, Genetically Modified / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis
D016373:DNA, Antisense; D007210:Indoleacetic Acids; D010940:Plant Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C030737:indoleacetic acid; D005966:Glucuronidase