Читать книгу Biotechnology of Fruit and Nut Crops - Группа авторов - Страница 92

Thanks to next-generation DNA sequencing methods and the decreasing price of these technologies, new molecular markers are developing rapidly. Those include simple nucleotide polymorphisms (SNPs), which are variations of single nucleotides, which do not change the overall length of the DNA sequence in the region and occur throughout the genome. A massive pyrosequencing of transcriptome from early stages of fruit development in A. squamosa enabled the development of new SSRs and SNPs (Gupta et al., 2015). In this study, two genotypes which differed significantly in the number of seeds were analysed allowing the identification of candidate genes related to seed development. Liu et al. (2017) developed cDNA libraries from normal and abnormal flowers and reported >700 flower-development-related genes and selected 15 genes involved in the observed differences. Genotyping by sequencing technologies are currently being used with cherimoya to link molecular markers to traits of interest in the Spanish cherimoya germplasm collection. Although only plastid genomes have been sequenced (Blazier et al., 2016; Hoekstra et al., 2017), draft genomes of A. cherimola and A. triloba are being developed combining different sequencing technologies (Talavera et al., unpublished data). Transcriptome analysis has also been reported from early fruit developmental stages in A. triloba (Lee et al., 2016). A. cherimola has an estimated genome size of 1.17 Gb, and 1.05% of heterozygosity (Talavera et al., unpublished data) with a haploid chromosome number of 7 (Martín et al., 2019) in line with the basic chromosome number of the family (Walker, 1972). A. triloba has a genome size of c.1 Gb (Talavera et al., unpublished data).