转Bt基因玉米叶片次生代谢物DIMBOA和酚酸类物质含量的变化

Change in concentration of secondary metabolites- DIMBOA and phenolic acids in leaves of Bt corn

异羟肟酸和酚酸类物质是玉米植株中重要的次生代谢物,可以帮助抵御多种病原菌、害虫、线虫和其它植物的危害。采用HPL C法研究了Bt玉米34B2 4、G30、农大6 1(Nongda6 1)和14 2 6×14 82以及部分相应的非转基因玉米叶片DIMBOA和酚酸类物质含量的变化。试验结果表明,不同玉米品种之间DIMBOA含量的差异很大;各Bt玉米品种叶片的DIMBOA含量普遍低于相对应的非转基因近等基因系。从不同部位的叶片看,玉米幼嫩叶片中的DIMBOA含量普遍较高;不同品种叶片DIMBOA含量的差异主要表现在幼叶之间,而老叶间的差异普遍较小。无论是Bt玉米还是非转基因玉米,随着生长时间的增加,各品种玉米幼苗全株叶片的DIMBOA含量急剧减少;各品种倒1叶的DIMBOA含量也都随着生长期的增加而减少,倒3叶却没有这样的规律。Bt玉米叶片的DIMBOA含量在单一的干旱胁迫或缺氮胁迫下的变化规律与非转基因玉米相似,即单一的干旱胁迫或缺氮胁迫下玉米各部位叶片的DIMBOA含量均显著升高;然而,在干旱和缺氮双重胁迫下,Bt玉米14 2 6×14 82在生长的中后期各部位叶片的DIMBOA含量却低于正常生长条件,明显不同于非转基因玉米的变化规律。与相应的非转基因近等基因系相比,虽然Bt玉米中香草酸和丁香酸的含量没有显著减少,但阿魏酸的含量显著降低。

Cyclic hydroxamic acids and phenolic acids are among important secondary metabolites of corn plant. These materials and their derivatives have implications for the resistance of the plants to herbivores, pests and pathogens. The content of leaf DIMBOA (2,4-dihydroxy-7-methoxy y-2H-1,4-benzoxazin-3-one) and phenolic acids in Bt corns 34B24, G30, Nongda 61, and 1426×1482 were quantified by HPLC. The content of leaf DIMBOA in Bt corns of 34B24 and G30 were significantly lower than that in their corresponding near isogenic lines 34B23 and G26, indicating that the introduction of Bt gene had inhibited the biosynthesis and accumulation of DIMBOA. The concentration of DIMBOA in the younger leaves at different plant ages were generally higher than that in the older leaves. The difference of DIMBOA concentration among different varieties was mainly existed in their younger leaves. The difference of DIMBOA concentration among the older leaves of different varieties was relatively smaller. No matter Bt corn and non-Bt corn, the concentration of DIMBOA in the mixed sample of the whole plant leaves decreased rapidly as the corn seedlings grew. The DIMBOA concentration in the first leaf of Bt corn or non-Bt corn from the top also decreased rapidly when the plant stages added while the third leaf from the top had not similar phenomenon. Under the single stress of drought or nitrogen, DIMBOA concentration in corn leaves was significantly higher than that of normal condition, which was similar in Bt corn and non-Bt corn. The result indicated that single stress of drought or nitrogen promoted the biosynthesis and accumulation of DIMBOA in corn leaves. But when compared with the normal condition, Bt corn leaves had lower DIMBOA concentration in medium and late stages under the coordinated stress of drought and nitrogen, which was significantly different from non-Bt corn. The content of leaf vanillic acid and syringic acid had no significant difference between Bt corns and their corresponding near isogenic lines, while the content of leaf ferulic acid in Bt corns were significantly lower than their corresponding near isogenic lines. This suggested that some phenolic acids in corn leaves could also be affected greatly by the introduction of Bt gene.