Figure 9.

Overexpression of Ma1β alone, both Ma1α and Ma1 or genomic Ma1 on transcripts of Ma1α and Ma1β and malic acid levels in “Royal Gala” fruit. A) The expression levels of Ma1β and Ma1α and malic acid concentration in mature fruit after rattle virus‐based gene‐overexpression of Ma1β in WT and cMa1‐OE lines (L14 and L16). The fruit was infiltrated with virus vector IL60‐Ma1β, with an empty vector (IL60) as control. B) The expression levels of Ma1β, Ma1,α and malic acid concentrations after rattle virus‐based gene‐overexpression of both Ma1α and Ma1β or genomic sequence of Ma1 (gMa1) in WT mature fruits. IL60‐Ma1α and IL60‐Ma1β were co‐infiltrated, or IL60‐gMa1 was infiltrated into fruits for overexpression of Ma1α and Ma1β. Fruit infiltrated with empty vector (IL60) was used as control. C) The expression levels of Ma1β, Ma1,α and malic acid concentrations after rattle virus‐based gene‐silencing of Ma1 in WT mature fruits. The fruit was infiltrated with A. tumefaciens containing TRV‐Ma1 for silencing Ma1 expression, with an empty vector (TRV) as control. Quantitative RT‐PCR was performed using gene‐specific primers (Table S3, Supporting Information), with actin as the internal reference gene, and the relative expression level of each gene was obtained using the ddCT method. Data are mean ± SE of five biological replicates with three fruits per replicate (three injection sites per fruit). * Represents significant differences using Student's t‐test at p < 0.05. Different letters (a, b, c) indicate significant differences between groups using Tukey's HSD test at p < 0.05 after ANOVA.