Positional Cloning, Gene Expression, and Molecular Evolution of the Gene Conferring Purple Leaf Sheath in Rice
Date Issued
2011
Date
2011
Author(s)
Chin, Han-Shiuan
Abstract
Anthocyanin can accumulate in several tissues in rice, leading to purple red or purple phenotypes for resistance to biotic and abiotic stresses. Purple and green leaf sheath with and without anthocyanin accumulation, respectively, can be found not only wild rice but also in cultivated rice. Japonica TNG 72 has purple leaf sheath, while indica TCS 17 has green leaf sheath. Based on the positional cloning approach, we used the F2 progenies of TNG 72 × TCS 17 to isolate the gene conferring purple leaf sheath in this segregating population, which was OsC1. Sequencing the OsC1 of 3 cultivars with green leaf sheath was found nonsynonymous SNP and deletion in the regulation region R2R3 Myb domain.. Thus, variation in OsC1 sequence changes the colors of the rice leaf sheath. In addition,, we used 36 accesions include cultivars, landraces and wild rice to study molecular evolution of OsC1, and neutrality tests, such as Tajama’s D, Fu and Li’s D, and Fu and Li’s F, revealed OsC1 alleles might be impacted by natural selection or artificial selection during rice evolution or domestication.
To determine the correlation between OsC1 and the anthocyanin accumulation of leaf sheath, we used four culativars, TNG 67, TNG 72, Shang-Chi-Tsao-Tao and Kun-Shan-Wu-Siang-Keng with different levels of anthocyanin content to detect gene expression of OsC1, OsB2, OsDfr, and OsAns by real-time PCR. The results showed that gene expression of OsC1 only but not the other threewas positively correlated with anthocyanin content. Gene expression of OsC1 was high in varieties with purple leaf sheath and increased along development stages. By the GUS promoter assay, OsC1 did not express in the leaf sheath during the 3-leaf stage but did express until the vegetative stage. Thus, gene function and expression of OsC1 really affect the colors of rice leaf sheath in different development stages.
Subjects
Anthocyanin
Molecular evolution
Positional cloning
Promoter assay
Type
thesis
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