Mutation of the Light-Induced Yellow Leaf 1 Gene, Which Encodes a Geranylgeranyl Reductase, Affects Chlorophyll Biosynthesis and Light Sensitivity in Rice

Abstract

Chlorophylls (Chls) are crucial for capturing light energy for photosynthesis. Although several genes responsible for Chl biosynthesis were characterized in rice (Oryza sativa), the genetic properties of the hydrogenating enzyme involved in the final step of Chl synthesis remain unknown. In this study, we characterized a rice light-induced yellow leaf 1-1 (lyl1-1) mutant that is hypersensitive to high-light and defective in the Chl synthesis. Light-shading experiment suggested that the yellowing of lyl1-1 is light-induced. Map-based cloning of LYL1 revealed that it encodes a geranylgeranyl reductase. The mutation of LYL1 led to the majority of Chl molecules are conjugated with an unsaturated geranylgeraniol side chain. LYL1 is the firstly defined gene involved in the reduction step from Chl-geranylgeranylated (ChlGG) and geranylgeranyl pyrophosphate (GGPP) to Chl-phytol (ChlPhy) and phytyl pyrophosphate (PPP) in rice. LYL1 can be induced by light and suppressed by darkness which is consistent with its potential biological functions. Additionally, the lyl1-1 mutant suffered from severe photooxidative damage and displayed a drastic reduction in the levels of α-tocopherol and photosynthetic proteins. We concluded that LYL1 also plays an important role in response to high-light in rice.

Identification of a Geranylgeranyl reductase gene for chlorophyll synthesis in rice

“…The result showed that the majority of Chl molecules in the mutant were conjugated with an unsaturated geranylgeraniol side chain, in addition to small amount of normal Chl Phy (Figure 5;Tanaka et al 2010;Zhou et al 2013), indicated that the mutant has a defective OsCHL P. Therefore, we concluded the candidate gene underlying the 502ys mutant phenotype is OsChl P .

Figure 5 HPLC analysis of Chls. The elution profiles of wild type (a) , 502ys mutant (b) and 502ys/OsCHL P transgenic line (c) were detected at 660 nm.

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A kiwifruit (Actinidia deliciosa) R2R3‐MYB transcription factor modulates chlorophyll and carotenoid accumulation

“…Downregulation of GGR transcripts in transgenic tobacco using antisense RNA resulted in plants with less Chl and accumulating geranylgeranylated Chl, an intermediate compound suggesting GGR is required to increase Chl levels in plants (Tanaka et al, 1999). The rice yellow green leaf mutant, which has a single base mutation in the rice GGR (OsCHl P), exhibited reduced Chl levels and arrested chloroplast development (Zhou et al, 2013;Wang et al, 2014). By contrast, the significant decrease in pigment concentration observed in some of the lines showing high expression of the AdMYB7 transgene was intriguing.…”

A recruiting protein of geranylgeranyl diphosphate synthase controls metabolic flux toward chlorophyll biosynthesis in rice

“…S9). Of the analyzed potential partners, only OsGGR (Os02g51080), an enzyme that reduces GGPP into phytyl diphosphate for chlorophyll biosynthesis in thylakoid membranes (16,17), interacted with OsGGPPS1 ( Fig. 4A and SI Appendix, Fig.…”