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Molecular markers, i.e. restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNAs (RAPDs) and amplified fragment length polymorphisms (AFLPs), are being used for genetic characterization (Palombi and Damiano, 2002; Oliveira and Fraser, 2005; Prado et al., 2006), somaclonal variation evaluation of in vitro regenerated plants (Palombi and Damiano, 2002; Prado et al., 2007), prediction of male plant flowering times (Novo et al., 2010) and the characterization of genetic and epigenetic diversity with respect to ploidy levels in A. chinensis (Liu et al., 2015). Genetic diversity was also analysed using short sequence repeats (microsatellites or SSRs) (Huang et al., 1998; Zhen et al., 2004; Fraser et al., 2005; Korkovelos et al., 2008; Man et al., 2011; Wang and Zhang, 2012; Kwon et al., 2013), and SSRs have been used for creating genetic maps (Testolin et al., 2001; Fraser et al., 2004; Liu et al., 2016). Single nucleotide polymorphisms (SNPs) are valuable for characterizing genetic variation in evolutionary and ecological studies of natural kiwifruit populations (Zhou et al., 2011). Recent studies provide new insights into the use of cpDNA markers in studies of phylogenetic, biogeography and introgression in Actinidia (Li et al., 2013b). The North American collection of cold-hardy kiwifruit has been deconvoluted through genotyping by sequencing (GBS) (Melo et al., 2017).

Some of these molecular markers can be used for marker assisted selection (MAS), especially for early sex identification. Gill et al. (1998) transformed two sex-linked RAPD markers into sequence-characterized amplified regions (SCAR) markers that are now routinely used to identify and discard male plants at the seedling stage in breeding programmes in New Zealand (Testolin and Cipriani, 2016). SSR markers have also been identified for discriminating between males and females in progenies (Scaglione et al., 2015; Zhang et al., 2015b) and for molecular studies of hermaphroditism and self-compatibility (Sakellariou et al., 2016).