Effect of red light and blue light on the anthocyanin accumulation and expression of anthocyanin biosynthesis genes in red-leaf lettuce.

摘要

Since anthocyanin accumulation would become insufficient if protected culture of the red leaf lettuce is carried out, the method for improving the quality of lettuce is required. Our previous study showed that the combined irradiation of blue light and UV-B at night resulted in notable promotion of anthocyanin synthesis. In this research, we investigated whether the blue light intensity of a light period would influence anthocyanin accumulation. When the blue light intensity of the light period was increased, anthocyanin accumulation was promoted, but it was restricted to a temporary effect. To the next, we investigated the anthocyanin accumulation of the red leaf lettuce under low photosynthesis photon flux density condition using red and blue LED. As a result, anthocyanin content was the highest in 100 micro mol m-2 s-1 blue light or simultaneous irradiation with 20 micro mol m-2 s-1 red and 80 micro mol m-2 s-1 blue light. The second was simultaneous irradiation with 50 micro mol m-2 s-1 red and 50 micro mol m-2 s-1 blue light, the 3rd was simultaneous irradiation with 80 micro mol m-2 s-1 red and 20 micro mol m-2 s-1 blue light, and 100 micro mol m-2 s-1 red light was the lowest. To clarify the molecular regulation of the anthocyanin biosynthesis by light quality, we isolated five anthocyanin biosynthetic genes, CHS, F3H, DFR, ANS and UFGT from the red-leaf lettuce. Gene expression analysis from treatment to 48 hours was conducted by the real-time PCR method. The expression of the genes which involve in anthocyanin biosynthesis were not able to be observed in 100 micro mol m-2 s-1 red light. On the other hand, in the case of 100 micro mol m-2 s-1 blue light and simultaneous irradiation with 50 micro mol m-2 s-1 red and 50 micro mol m-2 s-1 blue light, up to 24 hours after the light quality treatments, the enhanced expression of CHS, F3H, DFR, ANS, and UFGT were observed. Moreover, although the expression of F3H, DFR, and ANS were high level in simultaneous irradiation with 80 micro mol m-2 s-1 red and 20 micro mol m-2 s-1 blue light, the expression of CHS and UFGT was not so high. Therefore, it became clear to the biosynthetic mechanism of anthocyanin of red leaf lettuce that the ratio of red light and blue light is closely related.