Enzymatic activities on the phenylpropanoid metabolism and their relationships with an accumulation of lignin in brown-midrib-6 (bmr-6) mutant of sorghum (Sorghum bicolor L. Moench)
2003
Tsuruta, S. (National Inst. of Livestock and Grassland Science, Tsukuba, Ibaraki (Japan)) | Sakatani, Y. | Kawabe, T. | Kawano, T. | Ebina, M. | Akashi, R. | Kawamura, O.
Synopsis Shin-ichi TSURUTA, Yoichiro SAKATANI, Toshio KAWABE, Tomoe KAWANO, Masumi EBINA, Ryo AKASHI and Osamu KAWAMURA (2003) Enzymatic Activities on the Phenylpropanoid Metabolism and their Relationships with an Accumulation of Lignin in brown-midrib-6 (bmr-6) Mutant of Sorghum (Sorghum bicolor L. Moench). Grassland Science 49, 379-383. Brown-midrib mutants (bm or bmr) existed in maize (Zea mays L), sorghum (Sorghum bicolor (L) Moench) and pearl millet (Pennisetum americanum (L.) Leeke), which have been reported to have signiflcantly, lower lignin contents than their normal plants, and they have inherently high digestibility. In this study, we conducted to investigate for accumulation of lignin according to developmental stages in brown-midrib-6 (bmr-6) mutant comparing with its original normal-6 (N-6) line of sorghum. Lignin content determined by the acetyl bromide method was lower in bmr-6 than in N-6 during the developmental stages. In contrast, lignin content determined by the phloroglucinol-HCI assay. which detects aldehyde groups, was higher in bmr-6 than in N-6. Enzyme activities of PAL (phenylalanin ammonialyase), CAD (cinnamyl alcohol dehydrogenase) and POD (peroxidase), involved in phenylpropanoid pathway, were measured in N-6 and bmr-6 during the developmental stages. Bmr-6 had severely deficient in PAL activity at 50-day-old after seeding, with only 40% of the activity found in N-6. CAD activity of bmr-6 was also depressed during 50 to 90-days-old. POD activity was increased equally in N-6 and bmr-6 until 70-days-old, but the activity in bmr-6 was significantly low after 80-days-old comparing with N-6. These results suggested that bmr-6 mutant of sorghum was caused by a number of enzymes denficiency in the phenylpropanoid pathway.
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