1. Defective mitochondrial function by mutation in THICK ALEURONE 1 encoding a mitochondrion-targeted single-stranded DNA-binding protein leads to increased aleurone cell layers and improved nutrition in rice.
- Author
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Li, Dong-Qi, Wu, Xiao-Ba, Wang, Hai-Feng, Feng, Xue, Yan, Shi-Juan, Wu, Sheng-Yang, Liu, Jin-Xin, Yao, Xue-Feng, Bai, Ai-Ning, Zhao, Heng, Song, Xiu-Fen, Guo, Lin, Zhang, Shi-Yong, and Liu, Chun-Ming
- Abstract
Cereal endosperm comprises an outer aleurone and an inner starchy endosperm. Although these two tissues have the same developmental origin, they differ in morphology, cell fate, and storage product accumulation, with the mechanism largely unknown. Here, we report the identification and characterization of rice thick aleurone 1 (ta1) mutant that shows an increased number of aleurone cell layers and increased contents of nutritional factors including proteins, lipids, vitamins, dietary fibers, and micronutrients. We identified that the TA1 gene, which is expressed in embryo, aleurone, and subaleurone in caryopses, encodes a mitochondrion-targeted protein with single-stranded DNA-binding activity named OsmtSSB1. Cytological analyses revealed that the increased aleurone cell layers in ta1 originate from a developmental switch of subaleurone toward aleurone instead of starchy endosperm in the wild type. We found that TA1/OsmtSSB1 interacts with mitochondrial DNA recombinase RECA3 and DNA helicase TWINKLE, and downregulation of RECA3 or TWINKLE also leads to ta1 -like phenotypes. We further showed that mutation in TA1/OsmtSSB1 causes elevated illegitimate recombinations in the mitochondrial genome, altered mitochondrial morphology, and compromised energy supply, suggesting that the OsmtSSB1-mediated mitochondrial function plays a critical role in subaleurone cell-fate determination in rice. Aleurone in rice is the endosperm tissue in which major nutrients are accumulated. Subaleurone, as the intermediate tissue, switches its cell fate from starchy endosperm to aleurone when TA1 , which encodes a single-stranded DNA-binding protein, is mutated. The ta1 mutant with thick aleurone phenotype identified in this study was used to develop a nutrient-rich black rice variety. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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