An Ancient Duplication of Apple MYB Transcription Factors Is Responsible for Novel Red Fruit-Flesh Phenotypes    

Abstract

Anthocyanin accumulation is coordinated in plants by a number of conserved transcription factors. In apple (Malus 3 domestica), an R2R3 MYB transcription factor has been shown to control fruit flesh and foliage anthocyanin pigmentation (MYB10) and fruit skin color (MYB1). However, the pattern of expression and allelic variation at these loci does not explain all anthocyanin-related apple phenotypes. One such example is an open-pollinated seedling of cv Sangrado that has green foliage and develops red flesh in the fruit cortex late in maturity. We used methods that combine plant breeding, molecular biology, and genomics to identify duplicated MYB transcription factors that could control this phenotype. We then demonstrated that the red-flesh cortex phenotype is associated with enhanced expression of MYB110a, a paralog of MYB10. Functional characterization of MYB110a showed that it was able to up-regulate anthocyanin biosynthesis in tobacco (Nicotiana tabacum). The chromosomal location of MYB110a is consistent with a whole-genome duplication event that occurred during the evolution of apple within the Maloideae family. Both MYB10 and MYB110a have conserved function in some cultivars, but they differ in their expression pattern and response to fruit maturity.

Molecular genetics of blood‐fleshed peach reveals activation of anthocyanin biosynthesis by NAC transcription factors

“…MYB genes that are homologs of Arabidopsis MYB75 have been demonstrated to be responsible for the accumulation of anthocyanins in several fruit crops, including grape (Kobayashi et al, 2004), apple (Espley et al, 2009;Chagn e et al, 2013), pear (Feng et al, 2010), bayberry (Niu et al, 2010), and citrus fruits (Butelli et al, 2012). SQUAMOSA and SEPALLATA MADS box TFs have also been reported to be associated with the accumulation of anthocyanin in bilberry (Jaakola et al, 2010) and pear (Wu et al, 2013), respectively.…”

Identification of warm day and cool night conditions induced flowering-related genes in a Phalaenopsis orchid hybrid by suppression subtractive hybridization

“…In warm day-and cool night-induced spikes, specific transcription factors encoding NAC, MYB and ARF proteins were obtained. These proteins also participated in flower organ development (Sablowski and Meyerowitz, 1998), amino acid metabolism (ElKereamy et al, 2012), flavonoid biosynthesis (Nakatsuka et al, 2012), and red fruit-flesh phenotypes (Chagné et al, 2013), as well as response to different biotic and abiotic stresses (El-Kereamy et al, 2012;Li et al, 2012b). Compared with the expression levels in juvenile apical leaves, the accumulated transcripts of NAC (FS449) and R2R3-like MYB (FS789) were higher in all spikes tested, while the accumulated transcripts of ARF (FS899) were lower in early and later stages of spikes (Figure 1).…”

Apple Pollination Biology for Stable and Novel Fruit Production: Search System for Apple Cultivar Combination Showing Incompatibility, Semicompatibility, and Full-Compatibility Based on theS-RNaseAllele Database

“…Using this tight linkage, we found suitable cultivar combinations for efficient production of various red-fleshed apples (Table 2). Recently, new MYB-transcription factors named MdMYB110a and MdMYB110a JP responsible for red-fleshed trait in the type 2 were isolated from fruits from a cross between cv "Sciros" and a red-freshed cv "Sangrado" open pollinated (OP) seedling and JPP35 ("Jonathan" × "Pink Pearl"), respectively [43,45].…”