Study On The Effects Of The MdMYB10Locus On Fruit Quality In Apple

Apple is one of the most important fresh and processed fruits in China and even in the world.Fruit quality is composed of many components such as fruit color, aroma, hardness, friability,taste and so on. As one of the most important appearance quality, fruit color has drawn greatconcern not only from consumers but also from apple breeders. However, it is largely unkonwabout how the flesh color affects the other aspects of fruit quality. Exploring the relationshipbetween flesh color and other quality of fruit will be helpful for the cultivation of high qualityfruits and for the breeding program of new red-fleshed apple cultivars. The red color of applefruits come from the accumulation of anthocyanin, which is regulated by lots of number ofhighly conserved transcription factors. In Apple, the MdMYB10gene regulates flesh and leafcolor, while MdMYB1gene modulates peel color. The Effects of the MdMYB10lucus on fruitquality and its molecular mechanis were investigated using ‘red-fleshed’ and ‘white-fleshed’apple individuals, which were hybrids from a cross between ‘Malus sieversii f.neidzwetzkyana’ and ‘Fuji’. The main results ware shown as follows:1. The semi-quantitative RT-PCR results showed that, during the apple development,MdMYB10gene expression was higher in the red-fleshed apples than white-fleshed ones.Western blot results also proved that the abundancy of MdMYB10protein was higher in thered-fleshed apples than in the white-fleshed ones.2. The fruits of red-and white-flesh apples showed similar hardness and friability, while theformer produced smaller fruits than the latter. In addition, they exhibited a similar patternwith ethylene release, however, in the mature period, red-fleshed apples generated lessethylene than the white-flesh ones, and the release time of high ethylene is later in red-fleshfruits than white-fleshed ones.3. We detected the contents of malic acid and solute sugars were detected with HPLC methodin the red-fleshed and white-fleshed apples. The results showed that the red-fleshed apple hadincreased contents of malic acid and fructose, compared with the white-fleshed apple.Meanwhile, the red-fleshed apple produced lessglucose and sucrose, but more fructose, thanthe white-fleshed apples. As a result, the red-fleshed fruits are more sweet than thewhite-fleshed ones.4. The results of the detection MdMYB10transgenic apple callus and wild-type apple callusshowed that the malic acid content and expression levels of the malic acid-related genes werehigher in transgenic apple callus than in the wild-type control.5. To investigate the molecular mechanism of how the MdMYB10gene affects fruit quality, RNA-seq was conducted. The results showed that MdMYB10affected fruit quality byregulating genes associted with photosynthesis and other metabolic pathways.