Expression Of Genes Related To Anthocyanin Biosynthesis In Strawberry Fruits Under Light And Dark Conditions

Two cultivars of strawberry (Fragaria Xananassa 'Nyoho' and FragariaXananassa 'Toyonoka') were used as materials and gene expression related to anthocyanin biosynthesis was analyzed under light and dark conditions. The content of anthocyanidins and sugars such as fructose, glucose and sucrose in the light-exposed and light-interrupted fruits of the two strawberry cultivars were analyzed by using a spectrophotometer and a high pressure liquid chromatography. The expression of CHS, DFR and ANS related to anthocyanin biosynthesis in the light-exposed and light-interrupted fruits and developing fruits of the two strawberry cultivars was analyzed by northern hybridization. The content of anthocyanidin in developing fruits of the two strawberry cultivars was analyzed and a key gene CHS was cloned as well by RACE (Rapid amplification cDNA ends). The main results are as follows.1. There were two major anthocyanidins, i.e., pelargonidin and cyanidin, in strawberry fruits. The content of anthocyanidins in mature fruit was different between 'Nyoho' and 'Toyonoka' and the content in 'Nyoho' was higher than that in 'Toyonoka'. The pigment content of 'Nyoho' was not or little affected by light environment and regarded as a non-sensitive type as for light response, but 'Toyonoka' was affected to some extent and regarded as a partial-sensitive type.2. When 'Nyoho' or 'Toyonoka' fruits were shaded with aluminum foil, the content of fructose, glucose and sucrose was not obviously different from that of control fruits. This suggested that light was not a main factor affecting the content of sugars in fruits of strawberry.3. In both 'Nyoho' and 'Toyonoka' fruits, the expression of anthocyanin biosynthesis genes, CHS, DFR and ANS, was strong when fruits were young and green and then passed a transient low period after fruits developed about 3 week. When fruits began to turn red, the expression of CHS* DFR and ANS was increased dramatically. This change in gene expression was consistent with the change in pigment content. Northern blotting indicated that the expression of CHS* DFR and ANS was not obviously different between a light irradiated part and a shade part of 'Nyoho', but in 'Toyonoka' the expression was weaker in shade part than light part.4. CHS gene was cloned from cDNA and CHS open reading frame sequence was obtained.