DNA barcoding of <i>Actinidia</i> (Actinidiaceae) using internal transcribed spacer, <i>matK</i>, <i>rbcL</i> and <i>trnH</i>-<i>psbA</i>, and its taxonomic implication

<p><i>Actinidia</i> is taxonomically difficult and economically important. Four traditional barcoding markers, internal transcribed spacer (ITS), <i>rbcL</i>, <i>matK</i> and <i>trnH</i>-<i>psbA</i>, were used to identify the 29 <i>Actinidia</i> species sampled. High-quality sequences could be obtained easily for <i>rbcL</i>, <i>matK</i> and <i>trnH</i>-<i>psbA</i>, and <i>matK</i> performed best at resolving species among these three markers. ITS had a moderate sequencing success of 72% and the species resolution proportion was 60.7%. Sequencing success rate for <i>matK </i>+ <i>rbcL</i> was 97.4% and it discriminated 48.3% of the species analysed. The barcode <i>trnH</i>-<i>psbA</i> could only identify <i>Actinidia eriantha. MatK </i>+ <i>rbcL</i> and ITS are useful markers to barcode <i>Actinidia</i>; the utility of ITS in barcoding needs further investigation using high-throughput sequencing technology. Phylogenetic analyses based on ITS, <i>matK</i>, <i>matK </i>+ <i>rbcL</i> and <i>matK </i>+ <i>rbcL </i>+ <i>trnH</i>-<i>psbA</i> indicated Sect. <i>Leiocarpae</i> to be paraphyletic, while Sect. <i>Maculatae</i> and Sect. <i>Strigosae</i> together with Sect. <i>Stellatae</i> formed a monophyletic group. We recommended the subdivision of <i>Actinidia</i> into two groups: one consisting of Sect. <i>Leiocarpae</i> (ovaries glabrous, fruits spotless), and the other comprising sections <i>Maculatae</i>, <i>Strigosae</i> and <i>Stellatae</i> (ovaries hairy, fruits spotted). This study supported the separation of <i>Actinidia chinensis</i> var. <i>chinensis</i> and var. <i>deliciosa</i> at the infraspecific level, and the separation of <i>Actinidia tetramera</i> and <i>Actinidia kolomikta</i> at the specific level. The treatment of <i>Actinidia maloides</i> as a synonym of <i>A</i>. <i>kolomikta</i> and <i>Actinidia cinerascen</i>s as a variety of <i>Actinidia fulvicoma</i> was also warranted.