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Plant Biotechnol J ; 20(3): 437-453, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34655511


Starch accounts for over 80% of the total dry weight in cereal endosperm and determines the kernel texture and nutritional quality. Amyloplasts, terminally differentiated plastids, are responsible for starch biosynthesis and storage. We screened a series of rice mutants with floury endosperm to clarify the mechanism underlying amyloplast development and starch synthesis. We identified the floury endosperm19 (flo19) mutant which shows opaque of the interior endosperm. Abnormal compound starch grains (SGs) were present in the endosperm cells of the mutant. Molecular cloning revealed that the FLO19 allele encodes a plastid-localized pyruvate dehydrogenase complex E1 component subunit α1 (ptPDC-E1-α1) that is expressed in all rice tissues. In vivo enzyme assays demonstrated that the flo19 mutant showed decreased activity of the plastidic pyruvate dehydrogenase complex. In addition, the amounts of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) were much lower in the developing flo19 mutant endosperm, suggesting that FLO19 participates in fatty acid supply for galactolipid biosynthesis in amyloplasts. FLO19 overexpression significantly increased seed size and weight, but did not affect other important agronomic traits, such as panicle length, tiller number and seed setting rate. An analysis of single nucleotide polymorphism data from a panel of rice accessions identified that the pFLO19L haplotype was positively associated with grain length, implying a potential application in rice breeding. In summary, our study demonstrates that FLO19 is involved in galactolipid biosynthesis which is essential for amyloplast development and starch biosynthesis in rice.

Oryza , Grão Comestível , Endosperma/metabolismo , Galactolipídeos , Regulação da Expressão Gênica de Plantas , Mutação/genética , Melhoramento Vegetal , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plastídeos/metabolismo , Complexo Piruvato Desidrogenase , Amido/metabolismo
Rice (N Y) ; 14(1): 29, 2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33689034


BACKGROUND: The sequences of several important mitochondrion-encoded genes involved in respiration in higher plants are interrupted by introns. Many nuclear-encoded factors are involved in splicing these introns, but the mechanisms underlying this splicing remain unknown. RESULTS: We isolated and characterized a rice mutant named floury shrunken endosperm 5 (fse5). In addition to having floury shrunken endosperm, the fse5 seeds either failed to germinate or produced seedlings which grew slowly and died ultimately. Fse5 encodes a putative plant organelle RNA recognition (PORR) protein targeted to mitochondria. Mutation of Fse5 hindered the splicing of the first intron of nad4, which encodes an essential subunit of mitochondrial NADH dehydrogenase complex I. The assembly and NADH dehydrogenase activity of complex I were subsequently disrupted by this mutation, and the structure of the mitochondria was abnormal in the fse5 mutant. The FSE5 protein was shown to interact with mitochondrial intron splicing factor 68 (MISF68), which is also a splicing factor for nad4 intron 1 identified previously via yeast two-hybrid (Y2H) assays. CONCLUSION: Fse5 which encodes a PORR domain-containing protein, is essential for the splicing of nad4 intron 1, and loss of Fse5 function affects seed development and seedling growth.