Laboratory of Biochemistry, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya 464-01, Japan.
Plant Physiol. 1992 Jun;99(2):422-7. doi: 10.1104/pp.99.2.422.
Sporamin and beta-amylase are two major proteins of tuberous storage root of sweet potato (Ipomoea batatas) and their accumulation can be induced concomitantly with the accumulation of starch in leaves and petioles by sucrose (K Nakamura, M Ohto, N Yoshida, K Nakamura [1991] Plant Physiol 96: 902-909). Although mechanical wounding of leaves of sweet potato only occasionally induced the expression of sporamin and beta-amylase genes, their expression could be reproducibly induced in leaf-petiole cuttings when these explants were dipped in a solution of polygalacturonic acid or chitosan at their cut edges. Polygalacturonic acid seemed to induce expression of the same genes coding for sporamin and beta-amylase that are induced by sucrose. Because polygalacturonic acid and chitosan are known to mediate the induction of wound-inducible defense reactions, these results raise an interesting possibility that beta-amylase, in addition to sporamin, may have some role in the defense reaction. Expression of sporamin and beta-amylase genes could also be induced by abscisic acid, and this induction by abscisic acid, as well as induction by polygalacturonic acid or sucrose, was repressed by gibberellic acid. By contrast, methyl jasmonate did not cause the significant induction of either sporamin or beta-amylase mRNAs. Induction of expression of sporamin and beta-amylase genes by polygalacturonic acid or sucrose was inhibited by cycloheximide, suggesting that de novo synthesis of proteins is required for both of the induction processes.
旋花蛋白和β-淀粉酶是甘薯（Ipomoea batatas）块根中两种主要的蛋白，它们的积累可以与叶片和叶柄中淀粉的积累同时被蔗糖诱导（K. Nakamura、M. Ohto、N. Yoshida、K. Nakamura[1991]，《植物生理学》96:902-909）。尽管叶片的机械损伤偶尔会诱导旋花蛋白和β-淀粉酶基因的表达，但当这些外植体的切口处浸泡在果胶酸或壳聚糖溶液中时，叶片-叶柄切段可以重复地诱导它们的表达。果胶酸似乎诱导了与蔗糖诱导的相同的编码旋花蛋白和β-淀粉酶的基因表达。因为果胶酸和壳聚糖已知可以介导诱导性防御反应，这些结果提出了一个有趣的可能性，即除了旋花蛋白外，β-淀粉酶可能在防御反应中具有某种作用。脱落酸也可以诱导旋花蛋白和β-淀粉酶基因的表达，这种脱落酸的诱导，以及果胶酸或蔗糖的诱导，都被赤霉素抑制。相比之下，茉莉酸甲酯不会导致旋花蛋白或β-淀粉酶 mRNA 的显著诱导。果胶酸或蔗糖诱导旋花蛋白和β-淀粉酶基因的表达被环己酰亚胺抑制，这表明这两种诱导过程都需要新合成蛋白质。
