Comparison of <i>Vigna vexillata</i> linkage group with those of <i>V</i>. <i>radiata</i> and <i>V</i>. <i>unguculata</i>, and some characteristics of the constructed <i>V</i>. <i>vexillata</i> SSR linkage map.

<p>Unlinked markers: CEDG074a and VES0660</p><p>Comparison of <i>Vigna vexillata</i> linkage group with those of <i>V</i>. <i>radiata</i> and <i>V</i>. <i>unguculata</i>, and some characteristics of the constructed <i>V</i>. <i>vexillata</i> SSR linkage map.</p

Construction of an SSR and RAD-Marker Based Molecular Linkage Map of <i>Vigna vexillata</i> (L.) A. Rich

<div><p><i>Vigna vexillata</i> (L.) A. Rich. (tuber cowpea) is an underutilized crop for consuming its tuber and mature seeds. Wild form of <i>V</i>. <i>vexillata</i> is a pan-tropical perennial herbaceous plant which has been used by local people as a food. Wild <i>V</i>. <i>vexillata</i> has also been considered as useful gene(s) source for <i>V</i>. <i>unguiculata</i> (cowpea), since it was reported to have various resistance gene(s) for insects and diseases of cowpea. To exploit the potential of <i>V</i>. <i>vexillata</i>, an SSR-based linkage map of <i>V</i>. <i>vexillata</i> was developed. A total of 874 SSR markers successfully amplified single DNA fragment in <i>V</i>. <i>vexillata</i> among 1,336 SSR markers developed from <i>Vigna angularis</i> (azuki bean), <i>V</i>. <i>unguiculata</i> and <i>Phaseolus vulgaris</i> (common bean). An F₂ population of 300 plants derived from a cross between salt resistant (V1) and susceptible (V5) accessions was used for mapping. A genetic linkage map was constructed using 82 polymorphic SSR markers loci, which could be assigned to 11 linkage groups spanning 511.5 cM in length with a mean distance of 7.2 cM between adjacent markers. To develop higher density molecular linkage map and to confirm SSR markers position in a linkage map, RAD markers were developed and a combined SSR and RAD markers linkage map of <i>V</i>. <i>vexillata</i> was constructed. A total of 559 (84 SSR and 475 RAD) markers loci could be assigned to 11 linkage groups spanning 973.9 cM in length with a mean distance of 1.8 cM between adjacent markers. Linkage and genetic position of all SSR markers in an SSR linkage map were confirmed. When an SSR genetic linkage map of <i>V</i>. <i>vexillata</i> was compared with those of <i>V</i>. <i>radiata</i> and <i>V</i>. <i>unguiculata</i>, it was suggested that the structure of <i>V</i>. <i>vexillata</i> chromosome was considerably differentiated. This map is the first SSR and RAD marker-based <i>V</i>. <i>vexillata</i> linkage map which can be used for the mapping of useful traits.</p></div

RAD-seq results in parents and F₂ populations using HiSeq2000 platform.

<p>RAD-seq results in parents and F₂ populations using HiSeq2000 platform.</p

A genetic linkage map of <i>V</i>. <i>vexillata</i> constructed from 300 F₂ individuals of intraspecific cross between accessions V1 and V5.

<p>Map distances and marker names are shown on the left and right side of the linkage groups, respectively. Marker names in italics indicate dominant loci. Markers showing significant deviation from the expected segregation ratio at 0.05 are indicated with*. SSR markers with prefixes CED are derived from azuki bean. Markers with prefixes cp and VM are derived from cowpea. BM157 (LG6) is derived from common bean. Markers with prefixes VES are EST-SSR markers derived from azuki bean.</p

Characteristics of a <i>V</i>. <i>vexillata</i> linkage map based on the SSR and RAD markers.

<p>Characteristics of a <i>V</i>. <i>vexillata</i> linkage map based on the SSR and RAD markers.</p

Comparative linkage maps among <i>Vigna radiata</i> (left: rad), <i>V</i>. <i>unguiculata</i> (middle: ung), and <i>V</i>. <i>vexillata</i> (right: vex) based on common SSR markers.

<p>Linkage group 4 (LG 4) of <i>V</i>. <i>vexillata</i> (vex 4) was placed to the left and LG 7 of <i>V</i>. <i>vexillata</i> (vex 7) was placed to the right of LG4 of <i>V</i>. <i>radiata</i> (rad 4) to show the relationships of common markers. The positions of common markers were connected by dotted lines. Markers which were mapped on different LGs among 3 <i>Vigna</i> species were written in red text. Major translocations were indicated by red arrows. The species abbreviation name and number in parentheses below red text marker names, e.g., (vex 5) indicate that the species and linkage group number on which corresponding marker was mapped.</p

The SSR and RAD markers linkage map of <i>V</i>. <i>vexillata</i> constructed from 286 F₂ individuals of intraspecific cross between accessions V1 and V5.

<p>Map distances and marker names are shown on the left and right side of the linkage groups, respectively. Marker names in italics indicate dominant loci. Markers showing significant deviation from the expected segregation ratio at 0.05 and at 0.01 are indicated with* and **, respectively. SSR markers with prefixes CED are derived from azuki bean (red text). Markers with prefixes cp and VM are derived from cowpea (blue text). BM157 (LG6) is derived from common bean (green text). Markers with prefixes VES are EST-SSR markers derived from azuki bean (purple text). Markers without prefixes are RAD-markers derived from <i>V</i>. <i>vexillata</i> (black text).</p