Disruption of a Rice Chloroplast-Targeted Gene OsHMBPP Causes a Seedling-Lethal Albino Phenotype

Abstract

Background Chloroplast development is coordinately regulated by plastid- and nuclear-encoding genes. Although many regulators have been reported to be involved in chloroplast development, new factors remain to be identified, given the complexity of this process. Results In this study, we characterized a rice mutant lethal albinic seedling 1 ( las1 )form of a 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (OsHMBPP) that was targeted to the chloroplasts. The LAS1 mutation caused the albino lethal phenotype in seedlings. Transmission electron microscopy indicated that las1 were defective in early chloroplast development. LAS1 is preferentially expressed in leaves, implying its role in controlling chloroplast development. The expression levels of many chloroplast-encoded genes were altered significantly in las1 . The expression levels of nuclear-encoded gene involved in Chl biosynthesis were also decreased in las1 . We further investigated plastidic RNA editing in las1 and found that the edit efficiency of four chloroplast genes were markly altered. Compared with WT, las1 exhibited defective in biogenesis of chloroplast ribosomes. Conclusions Our results show that LAS1/OsHMBPP plays an essential role in the early chloroplast development in rice.

Genome-Wide Association Mapping of Seedling Vigor and Regrowth Vigor in Winter Wheat

“…Similarly, on chromosome 4B, significant SNP IWB31302 for shoot length features a 97% sequence similarity with a candidate gene, aminopeptidase M1-B, which plays a role in embryonic, vegetative and reproductive development in Arabidopsis (Arabidopsis thaliana) [53]. In addition, the significant SNP IWB8217 for shoot length on chromosome 4B features a 94% sequence similarity with 4-hydroxy-3-methylbut-2-enyl diphosphate reductase, which regulates the early development of chloroplast in rice [54]. Chloroplast is one of the compartments in a plant cell that contains chlorophyll, which positively correlates with shoot length in rice [55].…”

Plastid caseinolytic protease OsClpR1 regulates chloroplast development and chloroplast RNA editing in rice

“…Approximately 200 mg of powdered leaves were soaked in 20 mL of 95% ethanol for 48 h in the dark. Chl contents for each sample were measured in triplicate as previously described (Liu et al 2020 ).…”

“…For TEM, leaves from wild-type and al3 plants were collected and fixed in 2.5% (v/v) glutaraldehyde. The sample preparation was performed as previously described (Liu et al 2020 ). The chloroplast structure of leaf cells was observed under a JEOL 1200EX transmission electron microscope.…”

“…First-strand cDNA was generated from 1 μg of total RNA using the PrimeScript 1st Strand cDNA Synthesis Kit (TaKaRa). Quantitative RT-PCR was performed as previously described and the primers used to measure the expression level of chlorophyll biosynthesis and chloroplast-associated genes were obtained from the study by Liu et al 2020 . The primers used for the expression level of OsClpR1 are listed in Additional file 1 : Table S2.…”

Differential Regulation of an OsIspH1, the Functional 4-Hydroxy-3-Methylbut-2-Enyl Diphosphate Reductase, for Photosynthetic Pigment Biosynthesis in Rice Leaves and Seeds

“…At present, several IspH genes have been characterized in diverse species, including cyanobacteria ( Synechocystis strain PCC 6803, Cunningham et al, 2000 ), E. coli ( Altincicek et al, 2002 ), Aquifex ( Aquifex aeolicus , Wang et al, 2010 ), green microalgae ( Botryococcus braunii , Uchida et al, 2018 ), ginkgo ( Ginkgo biloba , Kim et al, 2008 ), red pine ( Pinus densiflora , Kim et al, 2009 ), tobacco ( Nicotiana benthamiana , Page et al, 2004 ), tomato ( Lycopersicon esculentum , Botella-Pavia et al, 2004 ), Arabidopsis ( Arabidopsis thaliana , Hsieh and Goodman, 2005 ), corn ( Zea mays , Lu et al, 2012 ), danshen ( Salvia miltiorrhiza , Hao et al, 2013 ), melon ( Cucumis melo , Saladie et al, 2014 ), sweet wormwood ( Artemisia annua , Ma et al, 2017 ), and rice ( Oryza sativa , Liu et al, 2020 ). Among them, the protein structures were first examined in bacterial systems, such as A. aeolicus and E. coli , to discover IspH inhibitors that have potential for novel cancer immunotherapy because the substrate of IspH , HMBPP, has been known as a potent phosphoantigen that activates γδ T cells to kill tumor cells ( Hintz et al, 2001 ; Grawert et al, 2004 ; Rao and Oldfield, 2016 ).…”