棉花离体不定根系的发生对色素腺体密度和棉酚含量的影响

为探明根系对色素腺体密度和棉酚含量的影响，以离体条件下的无根幼苗、不同生根状态幼苗以及无菌种子苗作为研究对象，对其茎叶色素腺体密度、棉酚含量以及棉酚生物合成关键基因表达量进行分析。结果表明，不同生根状态幼苗中，色素腺体密度和棉酚含量与一定范围内生根数呈显著正相关，随后趋于平稳。荧光定量PCR显示，棉酚生物合成关键基因GhCDN1和GhWRKY1表达量在生根数多的无菌苗中显著增高，而对棉酚合成具有反馈调节作用的 GhCYP706B1表达量呈现相反趋势；无根幼苗茎叶腺体密度和棉酚含量均显著低于有根幼苗，棉酚生物合成关键基因GhCDN1、GhWRKY1和 GhCYP706B1表达量反而高于有根幼苗。有根幼苗中根的棉酚含量显著高于茎和叶，无菌种子苗根系中棉酚生物合成关键基因表达量显著高于茎和叶。说明棉花根系能对棉酚含量产生直接影响，同时影响腺体密度。本研究进一步验证了根系是棉酚主要合成部位，地上部分也存在少量的棉酚合成，只是不能引起棉酚发生显著变化。

Effect of Isolated Adventitious Root on Density of Pigment Glands and Content of Gossypol in Gossypium spp

In order to investigate the effect of root system on density of pigment glands and content of gossypol, we used rootless seedlings, seedlings with different rooting states and sterile seedlings as materials in this study to analyze the density of pigment glands in the stem and leaves and the content of gossypol and relative expression level of the key genes for gossypol biosynthesis. The results showed that the density of pigment glands and content of gossypol in seedlings with different rooting states had significantly positive relation with the number of roots within a certain range, and then it tended to be stable. The qRT-PCR showed that the relative expression level of the key genes of GhCDN1 and GhWRKY1 for gossypol biosynthesis, significantly increased in aseptic seedlings with a large number of roots, while the relative expression level of the GhCYP706B1 gene having a feedback regulatory effect on gossypol synthesis showed the opposite trend; the content of gossypol in rootless seedlings and the density of pigment glands in stem and leaves were significantly lower than those in rooted seedlings, but the relative expression level of the gossypol biosynthesis genes of GhCDN1, GhWRKY1 and GhCYP706B1 were higher than those in rooted seedlings. In rooted seedlings, the content of gossypol in the roots was significantly higher than that in stems and leaves, and the relative expression level of the key genes for gossypol biosynthesis in the roots of sterile seedlings was significantly higher than that in stems and leaves, the results showed that cotton roots could directly affect the content of gossypol, and then affect the density of pigment glands.It was further approved that the root system was the main part for gossypol synthesis, a small amount of gossypol synthesis also was found in the aerial part, but it could not significant change in the content of gossypol.