Читать книгу Biotechnology of Fruit and Nut Crops - Группа авторов - Страница 172

DNA-based markers have been used to study phylogenetic and genetic relationships in Ananas, and only recently have they been developed for pineapple breeding where marker-assisted selection (MAS) can accelerate the selection process and reduce the progeny size and associated costs of raising individuals to maturity in the field.

The use of DNA molecular markers for pineapple germplasm management has been recently reviewed (Zhang et al., 2014). Early studies used randomly amplified polymorphic DNA (RAPD) markers to distinguish four cultivars, ‘Perola’, ‘Smooth Cayenne’, ‘Primavera’ and ‘Perolera’ (Ruas et al., 1995). Noyer et al. (1996) used restriction fragment length polymorphism (RFLP) on ribosomal RNA and found the genus Ananas to be very homogenous. Duval et al. (2001), also using RFLP markers, evaluated 294 accessions with 25 polymorphic probes and failed to reveal clear species boundaries, even though some species appeared to be reasonably well grouped.

Kato et al. (2004) evaluated 162 accessions, including 148 of A. comosus, using amplified fragment length polymorphism (AFLP) markers and found little congruence between phenotype and molecular markers-based classification. Shoda et al. (2012) analysed 31 pineapple accessions using simple sequence repeat (SSR) markers, and they too showed disagreement between the horticultural phenotype and the results of the SSR analysis. Rodriguez et al. (2013) used SSR markers developed for A. bracteatus to characterize six commercial pineapple cultivars and were able to amplify polymorphic DNA fragments from the A. comosus genome. More recently, Lin et al. (2015) used 16 SSR markers to establish genetic relationships among 27 Taiwanese pineapple genotypes and successfully identified different cultivars, but they found no correlation with their morphological characters. Zhou et al. (2015) developed SNPs through data mining of expressed sequence tags (ESTs) and transcriptome data, a high-quality genotyping tool, and while ‘Cayenne’ cultivars have a distinguishable genetic identity, accessions in other horticultural phenotypes did not cluster well. This study with 64 accessions showed that the phenotypes lack consistency in terms of their genetic makeup and some revision is needed.

Few DNA markers have been reported for use in pineapple breeding to date. Urasaki et al. (2015), studying leaf margin phenotypes, used a restriction-site-associated DNA sequencing (RAD-seq) analysis to study three bulked DNAs of the F₁ progeny from a cross between a piping-leaf type (‘Yugafu’) and a spiny-tip-leaf type (‘Yonekura’). They successfully converted five RAD-seq tags specific to the piping gene and two RAD-seq tags specific to the spiny gene into SSR markers that could be used for MAS in pineapple breeding.

The application of Diversity Arrays Technology (DArT) was reported for pineapple improvement by Kilian et al. (2016) as a powerful tool to detect linkages between particular traits and the gene(s) responsible for those traits, as it can discover hundreds of polymorphic markers at thousands of loci in a single experiment. This technology is currently being used to identify molecular markers that are associated with resistance to Phytophthora cinnamomi, a root-rot pathogen of economic importance, as genetic resistance is known to exist within the Ananas gene pool (Sanewski et al., 2016).