【作者】 吴劲松；

【导师】 种康；

【作者基本信息】 中国科学院研究生院（植物研究所） ， 植物学， 2003， 硕士

【摘要】 茉莉酸(JA)以及茉莉酸甲酯(MeJA)统称为茉莉素(jasmonates)，是由亚麻酸起始合成的一类具环戊酮基的广泛存在于植物界的类激素，它们对于植物的发育和抗逆性等都起着重要的作用。为了进一步的了解茉莉酸的生物合成以及功能，我们对冬小麦中的茉莉酸生物合成、低温环境中的作用及对拟南芥开花时间的影响等方面进行了研究。为了方便分离茉莉酸诱导的基因，我们构建了一个高质量的小麦茉莉酸诱导文库。未扩增时滴度为3-4×106pfu／ml，平均插入的长度为1． 2 kb。TaJIP是一个JA诱导的基因，进一步的Northern分析发现它亦可以被低温诱导表达，这给了我们一个提示，JA信号系统可能参与了植物对低温反应的过程。当外源施加JA于拟南芥时，无论是春化处理或者没有春化处理，无论是C24还是Col生态型，开花时间都有所增加，而且进一步的Nortbern实验证明，这种外源的JA的处理延迟开花的现象是与开花抑制基因FLC表达水平的增加相平行，与长日促进途径中的主效基因CO的表达水平无关。这种JA处理延迟开花的现象与FLC表达水平增加相平行的现象，表明了JA有可能是通过作用于FLC，使它的表达水平增加来延迟丌花。AOS(Allene oxide synthase)是茉莉酸合成的脂氧合酶途径中的第一个关键酶。我们克隆了小麦中的该基因并作了表达分析。它的开放阅读框(ORF)约1410 bp，编码的多肽长约470个氨基酸，推测其蛋白分子量为51． 9 kDa，pI为9． 39。Southern分析表明其在基因组中的拷贝数为3个。其mRNA表达可被外源的JA强烈的诱导。处理10小时达到高峰。RNA原位杂交表明，该基因在幼苗中组织特异表达，主要集中在幼叶，特别是在维管束区域，与大麦中的AOS不同的是，它还在胚芽鞘和茎尖的维管束区域有强烈的表达信号。原位杂交还显示La3+并不能阻断JA对它的诱导表达。更多还原

【Abstract】 Jasmonic acid (JA) and its methyl ester (MeJA) collectively named jasmonates, are linoleic acid-derived cyclopeantanone-based compounds of wide distribution in the plant kingdom. They play important roles in plant growth and development as well as in plant defense. To further understand the biosynthesis and function of JA, a gene encoding a key enzyme involved in JA biosynthesis, effect of JA on response to low temperature in wheat and flowering time in Arabidopsis were focused on the thesis.A JA-induced cDNA library was constructed. The titer of the primary library was about 3-4 x 10 pfu/ml, and an average length of the insert was about 1.2 kb. TaJIP was a JA induced gene in wheat. The northern analysis indicated that it could also response to low temperature. It suggested that JA signal pathway was involved in the process of plant resistance to low temperature.When Arabidopsis was treated with exogenous JA, the flowering time was delayed not only in C24 ecotype but also in Col ecotype under the conditions of vernalization or non-vernalization. Delayed flowering was correlated to increasing expression of FLC, while CO was stable expression, It suggested that JA may play a role on delaying flowering through FLC in Arabidopsis.Allene oxide synthase (AOS) is the first enzyme in the lipoxygenase pathway which leads to the formation of JA. A full-length cDNA of TaAOS was cloned from winter wheat (Triticum aestivum L. cv. Jinghua NO.3) seedling. The open reading frame (ORF) consists of 1,410 bp encoding a polypeptide of 470 amino acids withcalculated molecular mass of 51.9 kDa and pI 9.39. Southern blot analysis suggested the gene exists with three copies in wheat genome. The TaAOS mRNA could be strongly induced by exogenous JA, and the highest level induced by JA was observed under treatment often hours. RNA in situ hybridization of seedling indicated the gene preferential expressed in young leaves, especially in the parenchyma cells around the vascular bundles, and in cells around vascular bundles in coleoptile and shoot apex. The hybridization also showed that exogenous La3+ could not reduce the expression of TaAOS induced by JA.更多还原