Transition from the vegetative phase to reproductive phase is a crucial process in the life cycle of higher plants. Although the molecular mechanisms of flowering regulation have been extensively characterized in a number of plant species, little is known regarding how the transition process initiates. Here, we show that the Rice Indeterminate 1 (RID1) gene acts as the master switch for the transition from the vegetative to reproductive phase. RID1 encodes a Cys-2/His-2-type zinc finger transcription factor that does not have an ortholog in Arabidopsis spp. A RID1 knockout (rid1), mutated by T-DNA insertion, never headed after growing for >500 days under a range of growth conditions and is thus referred to as a never-flowering phenotype. This mutation-suppressed expression of the genes is known to be involved in flowering regulation, especially in the Ehd1/Hd3a pathway and a series of RFT homologs. RID1 seems to be independent of the circadian clock. A model was proposed to place RID1 in the molecular pathways of flowering regulation in rice, for which there are two indispensable elements. In the first, RID1 is controlling the phase transition and initiation of floral induction. In the other, the

Rice is one of the most important crops worldwide, both as a staple food and as a model system for genomic research. In order to systematically assign functions to all predicted genes in the rice genome, a large number of rice mutant lines, including those created by T-DNA insertion, Ds/dSpm tagging, Tos17 tagging, and chemical/irradiation mutagenesis, have been generated by groups around the world. In this study, we have reviewed the current status of mutant resources for functional analysis of the rice genome. A total of 246 566 flanking sequence tags from rice mutant libraries with T-DNA, Ds/dSpm, or Tos17 insertion have been collected and analyzed. The results show that, among 211 470 unique hits, inserts located in the genic region account for 68.16%, and 60.49% of nuclear genes contain at least one insertion. Currently, 57% of non-transposable-element-related genes in rice have insertional tags. In addition, chemical/irradiation-induced rice mutant libraries have contributed a lot to both gene identification and new technology for the identification of mutant sites. In this review, we summarize how these tools have been used to generate a large collection of mutants. In addition, we discuss the merits of classic mutation strategies. In order to achieve saturation of mutagenesis in rice, DNA targeting, and new resources like RiceFox for gene functional identification are reviewed from a perspective of the future generation of rice mutant resources.

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Plant male gametogenesis is a coordinated effort involving both reproductive tissues and sporophytic tissues, in which lipid metabolism plays an essential role. Although GDSL esterases/lipases have been well known as key enzymes for many plant developmental processes and stress responses, their functions in reproductive development remain unclear. Here, we report the identification of a rice male sterile 2 (rms2) mutant in rice (Oryza sativa), which is completely male sterile due to the defects in tapetum degradation, cuticle formation in sporophytic tissues, and impaired exine and central vacuole development in pollen grains. RMS2 was map-based cloned as an endoplasmic reticulum-localized GDSL lipase gene, which is predominantly transcribed during early anther development. In rms2, a three-nucleotides deletion and one base substitution (TTGT to A) occurred within the GDSL domain, which reduced the lipid hydrolase activity of the resulting protein and led to significant changes in the content of 16 lipid components and numerous other metabolites as revealed by a comparative metabolic analysis. Furthermore, RMS2 is directly targeted by male fertility regulators Undeveloped Tapetum 1 (UDT1) and Persistent Tapetal Cell 1 (PTC1) both in vitro and in vivo, suggesting that RMS2 may serve as a key node in the rice male fertility regulatory network. These findings shed light on the function of GDSLs in reproductive development and provide a promising gene resource for hybrid rice breeding.

Anthocyanins, carotenoids, and betalains are known as the three major pigments in the plant kingdom. Anthocyanins are flavonoids derived from the phenylpropanoid pathway. They undergo acylation and glycosylation in the cytoplasm to produce anthocyanin derivatives and deposits in the cytoplasm. Anthocyanin biosynthesis is regulated by the MBW (comprised by R2R3-MYB, basic helix-loop-helix (bHLH) and WD40) complex. Carotenoids are fat-soluble terpenoids whose synthetic genes also are regulated by the MBW complex. As precursors for the synthesis of hormones and nutrients, carotenoids are not only synthesized in plants, but also synthesized in some fungi and bacteria, and play an important role in photosynthesis. Betalains are special water-soluble pigments that exist only in Caryophyllaceae plants. Compared to anthocyanins and carotenoids, the synthesis and regulation mechanism of betalains is simpler, starting from tyrosine, and is only regulated by MYB (myeloblastosis). Recently, a considerable amount of novel information has been gathered on the regulation of plant pigment biosynthesis, specifically with respect to aspects. In this review, we summarize the knowledge and current gaps in our understanding with a view of highlighting opportunities for the development of pigment-rich plants.