Fruit skin coloration is a unique phase in the life cycle of fruiting plants and is mainly attributed to anthocyanin pigments. Anthocyanins are the largest and most diverse group of plant pigments derived from the phenyl propanoid pathway. They are water-soluble phenolic compounds that form part of a large and common group of plant flavonoids. Coloration encompasses several physiological and biochemical changes that happen through differential expression of various developmentally regulated genes. Due to research importance and economic value, Arabidopsis thaliana (chromosome no. = 5) and Vitis vinifera (chromosome no. = 19) have been used for investigations of the structural genes involved in anthocyanin biosynthesis. Thus for this review, V. vinifera is used as a model crop. In anthocyanin biosynthesis, a wide range of constructive genes including phenylalanine ammonia lyase, chalcone synthase and anthocyanidin synthase that are regulated by MYB transcription factors are involved. These genes are coordinately expressed and their levels of expression are positively related to the anthocyanin concentrations. Expression or suppression of the constructive genes contributes to a variety of changes that make fruits visually attractive and edible. Transgenic approaches also have discovered a strong relationship between phenyl propanoid/flavonoid gene expressions for fruit skin coloration. In this study, various developments that have taken place in the last decade with respect to identifying and altering the function of color-related genes are described.

ABSTRACT. Among different classes of molecular markers, expressed sequence tags (ESTs) are a new resource for developing simple sequence repeat (SSR) functional markers for genotyping and genetic mapping in F 1 hybrid populations of Vitis vinifera L. Recently, because of the availability of an enormous amount of data for ESTs in the public domain, the emphasis has shifted from genomic SSRs to EST-SSRs, which belong to transcribed regions of the genome and may have a role in gene expression or function. The objective of this study was to assess the polymorphisms among 94 F 1 hybrids from "Early Rose" and "Red Globe" using 25 EST-derived and 25 non-EST SSR markers. A total collection of 362,375 grape ESTs that were retrieved from the National Center for Biotechnology Information (NCBI) and 2522 EST-SSR sequences were identified. From them, 205 primer pairs were randomly selected, including 176 pairs that were EST-derived and 29 non-EST SSR primer pairs, for polymerase chain reaction amplification. A total Characterization of EST and non-EST SSRs in grapevine of 131 alleles were amplified using 50 pairs of primers; 78 alleles were amplified using EST-derived SSR primers and 53 were from non-EST SSR primers. At most, 6 and 5 alleles were amplified by EST-derived and non-EST SSR primers, respectively. The EST-derived SSR markers showed a maximum polymorphic information content (PIC) value of 1 and a minimum of 0.33 while non-EST SSR markers had maximum and minimum PIC values of 1 and 0.25, respectively. The average PIC value was 0.56 for EST-derived SSR markers and 0.45 for non-EST SSR markers.

ABSTRACT. The objectives of this investigation were to develop and validate the expressed sequence tag (EST)-simple sequence repeat (SSR) markers from large EST sequences, and to study the segregation and distribution of SSRs within two grapevine parental lines. In total, 94 F 1 lines crossed between "Early Rose" and "Red Globe" were studied. Approximately 2100 EST-SSR sequences of Vitis vinifera L. were searched for SSRs and analyzed for the design of polymerase chain reaction (PCR) primers amplifying the SSR-rich regions. Trinucleotide repeats were found to be the most abundant, followed by other nucleotide repeats. A total of 182 SSR primer pairs were first developed for the study on the parental polymorphism. Among the 182 SSR primers, 142 primer pairs (78%) could amplify the anticipated PCR products, among which only 52 primer pairs (36.62%) showed polymorphism between the two parents. These polymorphic bands were further surveyed among the 94 F 1 lines, and the results showed that a total of 162 bands were amplified, and 98 of them were polymorphic in both parents (60.86% polymorphism), with an average of 1.88 polymorphic DNA bands for each primer pair. After testing with the chi-square test, 33 of the clearly amplified polymorphic bands followed a 3:1 ratio, and 37 followed a 1:1 ratio. The rest showed distorted segregation ratios.