Dwarf and deformed flower 1, encoding an F‐box protein, is critical for vegetative and floral development in rice (Oryza sativa L.)

Abstract

SUMMARYRecent studies have shown that F-box proteins constitute a large family in eukaryotes, and play pivotal roles in regulating various developmental processes in plants. However, their functions in monocots are still obscure. In this study, we characterized a recessive mutant dwarf and deformed flower 1-1 (ddf1-1) in Oryza sativa (rice). The mutant is abnormal in both vegetative and reproductive development, with significant size reduction in all organs except the spikelet. DDF1 controls organ size by regulating both cell division and cell expansion. In the ddf1-1 spikelet, the specification of floral organs in whorls 2 and 3 is altered, with most lodicules and stamens being transformed into glume-like organs and pistil-like organs, respectively, but the specification of lemma/ palea and pistil in whorls 1 and 4 is not affected. DDF1 encodes an F-box protein anchored in the nucleolus, and is expressed in almost all vegetative and reproductive tissues. Consistent with the mutant floral phenotype, DDF1 positively regulates B-class genes OsMADS4 and OsMADS16, and negatively regulates pistil specification gene DL. In addition, DDF1 also negatively regulates the Arabidopsis LFY ortholog APO2, implying a functional connection between DDF1 and APO2. Collectively, these results revealed that DDF1, as a newly identified F-box gene, is a crucial genetic factor with pleiotropic functions for both vegetative growth and floral organ specification in rice. These findings provide additional insights into the molecular mechanism controlling monocot vegetative and reproductive development.

A Rice PECTATE LYASE-LIKE Gene Is Required for Plant Growth and Leaf Senescence

“…The orderly development process involves many genes and pathways that affect plant organ size by altering cell number, cell size, or both (Krizek, 2009). Although recent studies have uncovered some key regulators and genes that affect plant organ size, the intrinsic mechanisms responsible for organ size variation are yet to be fully understood (Krizek, 2009;Duan et al, 2012). In this study, we identified a PLL gene, DEL1, that appeared to play an important role in the control of organ size in rice.…”

“…Cell division/expansion is a fundamental, dynamic cellular process driving plant growth and development, and it enables the plant and various organs to develop to suitable sizes (Duan et al, 2012). The orderly development process involves many genes and pathways that affect plant organ size by altering cell number, cell size, or both (Krizek, 2009).…”

Fine Mapping of a Novel defective glume 1 (dg1) Mutant, Which Affects Vegetative and Spikelet Development in Rice

“…Many rice mutants associated with the vegetative development and floral organ identity have been obtained such as apo1, sad1, opb, afd1 , and ddf1 (Ikeda et al, 2007; Horigome et al, 2009; Duan et al, 2012; Ikeda-Kawakatsu et al, 2012; Li et al, 2015; Ren et al, 2016b). However, our understanding of vegetative and reproductive development in rice remains limited, and the discovery of more rice mutants will further our knowledge of the regulatory mechanism behind these processes.…”

“…Additionally, lateral growth of the lemma and palea was suppressed and the resulting structure was unable to enclose the inner floral organs (Horigome et al, 2009). Dwarfism occurred in the afd1 and ddf1 mutants due to defects in cell proliferation and expansion and the lodicules and stamens were transformed into glume-like organs (Duan et al, 2012; Ren et al, 2016b). The genes responsible for these phenotypes are expressed in all tissues and organs, suggesting that these genes are not tissue-specific and play important roles in the regulation of whole-plant development.…”

“…The apo1 mutant produces more leaves, smaller inflorescences, lodicule-like stamens, and extra carpels, suggesting that the mutant affects the identity of floral organs and floral meristem determinacy. Super Apical Dormant1 ( SAD1 ) encodes a Mediator-interacting protein that binds to OsMED4 and controls various aspects of plant development (Duan et al, 2012). The sad1 mutant exhibited a low number of tillers, severe dwarfism, slender and short leaves, and abnormal floral organs.…”