Chunlin Liu, Y. Ruan, C. Guan
Dec 1, 2004
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Influential Citations
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Journal
Chinese Science Bulletin
Abstract
β-ocimene, a kind of monoterpene, was found recently as a plant communication signal molecule. It has two isomeric forms in nature: cis-β-ocimene and trans-βocimene. According to recent reports, all investigated plants, such as corn, cotton, lima bean, potato, tobacco, arabidopsis, and Mediterranean pine, could release the chemical component β-ocimene after fed by arthropod herbivores, suggesting that β-ocimene is an important functioal component in the herbivore-induced volatile. Nowadays, we know that β-ocimene can induce the expression of defense genes relative to salicylic acid in detatched leaves. But many problems of β-ocimene, for example, whether β-ocimene can induce the defense gene expression in intact plants, what role it can play in the expression model of defense genes, are elusive. To investigate the two problems, we used intact arabidopsis plants as test materials, the fragment of PR1 gene (a symbol of salicylic acid (SA) signaling pathway) and the fragment of PDF1.2 gene (a symbol of jasmonic acid (JA) signaling pathway) as probes, and Northern blot and hybrid to detect the two-gene transcript. The Northern hybrid results show that: (i) βocimene could induce defense gene expression, which means that β-ocimene can induce defense gene expression in intact plants (Fig. 1). (ii) The two isomeric forms, cis-β-ocimene and trans-β-ocimene, have different models of inducing defense gene expression. For trans-β-ocimene, with its concentration increasing, at the beginning, the transcrip quantity of PR1 and PDF1.2 genes increased. When its concentration was 5 μmol/L, the transcript quantity reached the maximum. After the concentration of trans-β-ocimene was higher than 5 μmol/L, the transcript quantity of PR1 and PDF1.2 gene decreased (Fig. 1(a) and (b)). For cis-β-ocimene, with its concentration increasing, the transcrip quantity of PR1 and PDF1.2 increased continuously (Fig. 1(c) and (d)). In natural state, the β-ocimene in the volatile emitted from herbivore-fed