Umemoto Naoyuki, Nakayasu Masaru, Ohyama Kiyoshi, Yotsu-Yamashita Mari, Mizutani Masaharu, Seki Hikaru, Saito Kazuki, Muranaka Toshiya
Central Laboratories for Key Technologies, Kirin Co., Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan (N.U.); RIKEN Center for Sustainable Resource Science, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan (N.U., K.O., K.S.); Graduate School of Agricultural Science, Kobe University, Nada-ku, Kobe, Hyogo 657-8501, Japan (M.N., M.M.); Department of Chemistry and Materials Science, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan (K.O.); Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 981-8555, Japan (M.Y.-Y.); Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan (H.S., T.M.); and Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 260-8675, Japan (K.S.)
Central Laboratories for Key Technologies, Kirin Co., Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan (N.U.); RIKEN Center for Sustainable Resource Science, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan (N.U., K.O., K.S.); Graduate School of Agricultural Science, Kobe University, Nada-ku, Kobe, Hyogo 657-8501, Japan (M.N., M.M.); Department of Chemistry and Materials Science, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan (K.O.); Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 981-8555, Japan (M.Y.-Y.); Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan (H.S., T.M.); and Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 260-8675, Japan (K.S.).
Plant Physiol. 2016 Aug;171(4):2458-67. doi: 10.1104/pp.16.00137. Epub 2016 Jun 15.
α-Solanine and α-chaconine, steroidal glycoalkaloids (SGAs) found in potato (Solanum tuberosum), are among the best-known secondary metabolites in food crops. At low concentrations in potato tubers, SGAs are distasteful; however, at high concentrations, SGAs are harmful to humans and animals. Here, we show that POTATO GLYCOALKALOID BIOSYNTHESIS1 (PGA1) and PGA2, two genes that encode cytochrome P450 monooxygenases (CYP72A208 and CYP72A188), are involved in the SGA biosynthetic pathway, respectively. The knockdown plants of either PGA1 or PGA2 contained very little SGA, yet vegetative growth and tuber production were not affected. Analyzing metabolites that accumulated in the plants and produced by in vitro enzyme assays revealed that PGA1 and PGA2 catalyzed the 26- and 22-hydroxylation steps, respectively, in the SGA biosynthetic pathway. The PGA-knockdown plants had two unique phenotypic characteristics: The plants were sterile and tubers of these knockdown plants did not sprout during storage. Functional analyses of PGA1 and PGA2 have provided clues for controlling both potato glycoalkaloid biosynthesis and tuber sprouting, two traits that can significantly impact potato breeding and the industry.
α-茄碱和α-查茄碱是马铃薯（茄属）中发现的甾体糖苷生物碱（SGAs），是粮食作物中最知名的次生代谢产物之一。在马铃薯块茎中含量较低时，SGAs味道不佳；然而，含量高时，SGAs对人和动物有害。在此，我们表明，马铃薯糖苷生物碱生物合成1（PGA1）和PGA2这两个编码细胞色素P450单加氧酶（CYP72A208和CYP72A188）的基因分别参与SGA生物合成途径。PGA1或PGA2的基因敲除植株含有极少的SGA，但营养生长和块茎产量未受影响。对植株中积累的代谢产物以及体外酶促试验产生的代谢产物进行分析表明，PGA1和PGA2分别催化SGA生物合成途径中的26-羟基化和22-羟基化步骤。PGA基因敲除植株有两个独特的表型特征：植株不育，且这些敲除植株的块茎在储存期间不发芽。对PGA1和PGA2的功能分析为控制马铃薯糖苷生物碱生物合成和块茎发芽提供了线索，这两个性状会对马铃薯育种和产业产生重大影响。
