Coordinated expression of functionally diverse fructosyltransferase genes is associated with fructan accumulation in response to low temperature in perennial ryegrass
Coordinated expression of functionally diverse fructosyltransferase genes is associated with fructan accumulation in response to low temperature in perennial ryegrass
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DOI：
10.1111/j.1469-8137.2008.02409.x
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发表时间：
2008-01-01
期刊：
影响因子：
9.4
通讯作者：
Yamada, Toshihiko
中科院分区：
文献类型：
--
作者：
Hisano, Hiroshi;Kanazawa, Akira;Yamada, Toshihiko
果聚糖是温带禾本科植物主要的非结构性碳水化合物储备。为了解果聚糖合成的调控机制和对低温环境的适应性，对多年生黑麦草（Lolium perenne）果糖基转移酶（fructosyltransferase，FT）基因的分离、功能鉴定和遗传定位进行了研究。在毕赤酵母中产生重组蛋白并表征酶活性。同时分析了低温处理过程中碳水化合物水平和FT基因mRNA水平的变化，其中1个基因编码蔗糖-蔗糖1-果糖基转移酶（1-SST），2个基因编码果聚糖-果聚糖6 G-果糖基转移酶（6 G-FFT）。其他基因（prfts 1、2和6）的蛋白质序列与蔗糖-果聚糖6-果糖基转移酶（6-SFT）相似。1-SST和prft 1基因在黑麦草连锁图谱上与转化酶基因共定位。在低温处理过程中，prft 1和prft 2的mRNA水平逐渐升高，而1-SST和6 G-FFT基因的mRNA水平先升高后降低，在低温处理过程中又逐渐升高，因此，在功能多样的FT基因进化过程中，至少出现了两种不同的基因表达模式，它们与低温环境中果聚糖的合成密切相关。
Fructan is the major nonstructural carbohydrate reserve in temperate grasses. To understand regulatory mechanisms in fructan synthesis and adaptation to cold environments, the isolation, functional characterization and genetic mapping of fructosyltransferase (FT) genes in perennial ryegrass (Lolium perenne) are described.Six cDNAs (prft1-prft6) encoding FTs were isolated from cold-treated ryegrass plants, and three were positioned on a perennial ryegrass linkage map. Recombinant proteins were produced in Pichia pastoris and enzymatic activity was characterized. Changes in carbohydrate levels and mRNA levels of FT genes during cold treatment were also analysed.One gene encodes sucrose-sucrose 1-fructosyltransferase (1-SST), and two gene encode fructan-fructan 6G-fructosyltransferase (6G-FFT). Protein sequences for the other genes (prfts 1, 2 and 6) were similar to sucrose-fructan 6-fructosyltransferase (6-SFT). The 1-SST and prft1 genes were colocalized with an invertase gene on the ryegrass linkage map. The mRNA levels of prft1 and prft2 increased gradually during cold treatment, while those of the 1-SST and 6G-FFT genes first increased, but then decreased before increasing again during a longer period of cold treatment.Thus at least two different patterns of gene expression have developed during the evolution of functionally diverse FT genes, which are associated in a coordinated way with fructan synthesis in a cold environment.