Bajguz Andrzej, Asami Tadao
Institute of Biology, University of Bialystok, Swierkowa 20 B, 15-950, Bialystok, Poland.
Planta. 2004 Mar;218(5):869-77. doi: 10.1007/s00425-003-1170-9. Epub 2003 Dec 4.
Treatment of cultured Chlorella vulgaris Beijerinck cells with 0.1-10 microM brassinazole (Brz2001), an inhibitor of brassinosteroid (BR) biosynthesis, inhibits their growth during the first 48 h of cultivation in the light. This inhibition is prevented by the co-application of BR. This result suggests that the presence of endogenous BRs during the initial steps of the C. vulgaris cell cycle is indispensable for their normal growth in the light. In darkness, a treatment with 10 nM brassinolide (BL) promotes growth through the first 24 h of culture, but during the following 24 h the cells undergo complete stagnation. Treatment of dark-grown cells with either Brz2001 alone, or a mixture of 10 nM BL and 0.1/10 microM Brz2001, also stimulates their growth. The effects of treatment with 10 nM BL mixed with 0.1-10 microM of a mevalonate-pathway inhibitor (mevinolin), or a non-mevalonate-pathway inhibitor (clomazone), were also investigated. Mevinolin at these concentrations did not inhibit growth of C. vulgaris; however, clomazone did. Addition of BL overcame the inhibition. These results suggest that the mevalonate pathway does not function in C. vulgaris, and that the non-mevalonate pathway for isopentenyl diphosphate biosynthesis is responsible for the synthesis of one of the primary precursors in BR biosynthesis.
用0.1 - 10微摩尔的油菜素唑（Brz2001，一种油菜素甾醇（BR）生物合成抑制剂）处理培养的普通小球藻（Chlorella vulgaris Beijerinck）细胞，在光照培养的最初48小时内会抑制其生长。BR的共同施用可防止这种抑制作用。这一结果表明，在普通小球藻细胞周期的初始阶段，内源性BR的存在对于其在光照下的正常生长是不可或缺的。在黑暗中，用10纳摩尔油菜素内酯（BL）处理可促进培养最初24小时的生长，但在接下来的24小时细胞会完全停滞。单独用Brz2001或10纳摩尔BL与0.1/10微摩尔Brz2001的混合物处理黑暗培养的细胞，也会刺激其生长。还研究了将10纳摩尔BL与0.1 - 10微摩尔甲羟戊酸途径抑制剂（美伐他汀）或非甲羟戊酸途径抑制剂（异恶草酮）混合处理的效果。这些浓度的美伐他汀不会抑制普通小球藻的生长；然而，异恶草酮会。添加BL可克服这种抑制作用。这些结果表明甲羟戊酸途径在普通小球藻中不起作用，并且异戊烯基二磷酸生物合成的非甲羟戊酸途径负责BR生物合成中一种主要前体的合成。
