Gibberellin regulates pollen viability and pollen tube growth in rice.
Gibberellins (GAs) play many biological roles in higher plants. We collected and performed genetic analysis on rice (Oryza sativa) GA-related mutants, including GA-deficient and GA-insensitive mutants. Genetic analysis of the mutants revealed that rice GA-deficient mutations are not transmitted as Mendelian traits to the next generation following self-pollination of F1 heterozygous plants, although GA-insensitive mutations are transmitted normally. To understand these differences in transmission, we examined the effect of GA on microsporogenesis and pollen tube elongation in rice using new GA-deficient and GA-insensitive mutants that produce semifertile flowers. Phenotypic analysis revealed that the GA-deficient mutant reduced pollen elongation1 is defective in pollen tube elongation, resulting in a low fertilization frequency, whereas the GA-insensitive semidominant mutant Slr1-d3 is mainly defective in viable pollen production. Quantitative RT-PCR revealed that GA biosynthesis genes tested whose mutations are transmitted to the next generation at a lower frequency are preferentially expressed after meiosis during pollen development, but expression is absent or very low before the meiosis stage, whereas GA signal-related genes are actively expressed before meiosis. Based on these observations, we predict that the transmission of GA-signaling genes occurs in a sporophytic manner, since the protein products and/or mRNA transcripts of these genes may be introduced into pollen-carrying mutant alleles, whereas GA synthesis genes are transmitted in a gametophytic manner, since these genes are preferentially expressed after meiosis.
Chhun
Tory
T
Bioscience and Biotechnology Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
Aya
Koichiro
K
Asano
Kenji
K
Yamamoto
Eiji
E
Morinaka
Yoichi
Y
Watanabe
Masao
M
Kitano
Hidemi
H
Ashikari
Motoyuki
M
Matsuoka
Makoto
M
Ueguchi-Tanaka
Miyako
M
D035264:Flowers / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D005875:Gibberellins / Q000378:metabolism / Q000494:pharmacology* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D030821:Plants, Genetically Modified; D011058:Pollen / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
D005875:Gibberellins; D010940:Plant Proteins