title: Reduction of gibberellin by low temperature disrupts pollen development in rice.
abstract: Microsporogenesis in rice (Oryza sativa) plants is susceptible to moderate low temperature (LT; approximately 19°C) that disrupts pollen development and causes severe reductions in grain yields. Although considerable research has been invested in the study of cool-temperature injury, a full understanding of the molecular mechanism has not been achieved. Here, we show that endogenous levels of the bioactive gibberellins (GAs) GA4 and GA7, and expression levels of the GA biosynthesis genes GA20ox3 and GA3ox1, decrease in the developing anthers by exposure to LT. By contrast, the levels of precursor GA12 were higher in response to LT. In addition, the expression of the dehydration-responsive element-binding protein DREB2B and SLENDER RICE1 (SLR1)/DELLA was up-regulated in response to LT. Mutants involved in GA biosynthetic and response pathways were hypersensitive to LT stress, including the semidwarf mutants sd1 and d35, the gain-of-function mutant slr1-d, and gibberellin insensitive dwarf1. The reduction in the number of sporogenous cells and the abnormal enlargement of tapetal cells occurred most severely in the GA-insensitive mutant. Application of exogenous GA significantly reversed the male sterility caused by LT, and simultaneous application of exogenous GA with sucrose substantially improved the extent of normal pollen development. Modern rice varieties carrying the sd1 mutation are widely cultivated, and the sd1 mutation is considered one of the greatest achievements of the Green Revolution. The protective strategy achieved by our work may help sustain steady yields of rice under global climate change.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Sakata
authors.forename: Susumu
authors.initials: S
authors.lastname: Oda
authors.forename: Yuta
authors.initials: Y
authors.lastname: Tsunaga
authors.forename: Hikaru
authors.initials: H
authors.lastname: Shomura
authors.forename: Makiko
authors.initials: M
authors.lastname: Kawagishi-Kobayashi
authors.forename: Koichiro
authors.initials: K
authors.lastname: Aya
authors.forename: Kenichi
authors.initials: K
authors.lastname: Saeki
authors.forename: Takashi
authors.initials: T
authors.lastname: Endo
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Nagano
authors.forename: Mikiko
authors.initials: M
authors.lastname: Kojima
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakakibara
authors.forename: Masao
authors.initials: M
authors.lastname: Watanabe
authors.forename: Makoto
authors.initials: M
authors.lastname: Matsuoka
authors.forename: Atsushi
authors.initials: A
authors.lastname: Higashitani
mesh_terms: D018533:Biomass; D002851:Chromatography, High Pressure Liquid; D003080:Cold Temperature; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D051479:Plant Infertility / Q000187:drug effects / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011058:Pollen / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D013395:Sucrose / Q000494:pharmacology; D053719:Tandem Mass Spectrometry; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D005875:Gibberellins; D010940:Plant Proteins; D013395:Sucrose