Test of the hybrid origin of <i>Broussonetia</i> × <i>kazinoki</i> (Moraceae) in Korea using molecular markers

Abstract

Broussonetia × kazinoki Siebold has long been utilized as a major component in the manufacturing of Korean traditional paper, hanji, and has been suggested as a hybrid species of B. papyrifera and B. monoica. By applying three molecular markers, chloroplast (cp) ndhF-rpl32 IGS, a nuclear ribosomal internal transcribed spacer, and the TOPO6 gene, the hybrid origin of B. × kazinoki is tested. As a result, B. × kazinoki in Korea is demonstrated to be a hybrid of B. monoica × B. papyrifera, most likely formed naturally in Korea. The cp haplotypes detected provided information about the origins and genetic diversity of the maternal lineage B. monoica and paternal lineage B. papyrifera. The two nuclear markers were supplemented to each other, leading to the discovery of introgression in Broussonetia.

The chloroplast genome comparative characteristic of artificial breeding tree, a case about Broussonetia kazinoki �Broussonetia papyrifera

“…Cp genome, as an independent genetic unit, is mostly unisexual, although multiple inheritance patterns had been found in the cpDNA of Actinidia (Li et al, 2013). The selection pressure during the evolution of the cp genome is small, which can directly reflect the genetic variation accumulated in the long-term evolution of plants, and can be used to trace the origin and migration of species as well as study genetic diversity (Nadachowska-Brzyska et al, 2015;Timmis et al, 2004;Won, 2019). The cp genome contains a large number of functional genes, which can be divided into three categories: genes related to photosynthesis (Photosystem I: psa; Subunits of Photosystem I: ycf3 and ycf4; Photosystem II: psb), genes related to gene expression (ribosomal RNA genes and transfer RNA genes, etc.…”

The Chloroplast Genome Comparative Characteristic of Artificial Breeding Tree, a Case About Broussonetia Kazinoki × Broussonetia Papyifera

“…It has undergone many cross-breeding and space mutation to form excellent plants with stable inheritance. And its maternal B. kazinoki has experienced controversy [15,54], therefore, it is necessary to compare ZJGS and its hybrid parent systematically. Unlike the previous study [36], the cp genome of ZJGS was analyzed in detail.…”

“…Chloroplast is a uniparentally inherited and stable organelle in green plants, who is often considered to be an informative resource for genetic diversity of plant [13][14][15]. The cp genome always consists of four conserved regions: a pair of inverted repeats (IRs), a small single-copy region (SSC) and a large single-copy region (LSC) [16][17][18].…”

“…Paper mulberry, Broussonetia papyifera, B. kazinoki × B. papyifera are all used to called the tree, while it may not the same tree [36]. In recent year, a hybrid variety for paper mulberry was bred [15,37]. The breeding process is showed in Fig.…”

“…The mutant materials were optimized and cultivated after the spacecraft returned to the ground, and nally hybrid plants with excellent traits were obtained. However, in recent years, B. kazinoki was found to be probably a naturally occurring hybrid, with B. monoica as the female parent and B. papyifera as the male parent [15]. The complicated hybridization process has blurred the genetic background of paper mulberry and hindered the determination of the classi cation status of the tree and its utilization.…”