High Temperature Inhibits the Expressions of Some Genes Involved in Anthocyanin Biosynthesis in Strawberry ‘Sachinoka' Fruit

We investigated the effect of high temperature on anthocyanin content of pot-grown strawberry plants. Recently, Japanese strawberry growers have problems about fruit quality because of global warming. We had reported that strawberry ‘Sachinoka’ fruit grown at high temperature conditions had decreased anthocyanin content, especially inside of the fruit (Ikeda et al. ASHS Conference 2011). In this research, we focused on the genes involved in anthocyanin biosynthesis in order to clarify the mechanisms to control it at high temperatures. To obtain the plant samples, the air temperature was set to either 30/15 °C (day/night, 14/10h) (high temperature regime) or 20/15 °C (control) in growth chamber. The mature fruits were divided into three parts [skin, flesh, and center (pith)]. Total RNA was extracted from divided fruits. After reverse transcription, target genes were amplified and analyzed using real-time PCR. We investigated three anthocyanin biosynthetic genes, MYB, anthocyanidin synthase (ANS), and UDP glucose-flavonoid 3-O-glucosyltransferase (UFGT). In skin, RNA levels of three genes were not different in both temperature regimes. Also, in center, RNA levels were not different. In flesh, RNA levels of MYB and UFGT in high temperature were lower than those in control—especially UFGT—decreased by 40%. But RNA levels of ANS were not different. As a result, Color degradation of flesh in high temperature may be caused by inhibition of the expressions of MYB and UFGT. We found that high temperature had negative effects on expressions of MYB and UFGT in flesh part of strawberry ‘Sachinoka’ fruit.