Development of an SSR marker-based genetic linkage map and identification of a QTL associated with flowering time in <i>Eustoma</i>

Abstract

Lisianthus (Eustoma grandiflorum) is an important floricultural crop cultivated worldwide. Despite its commercial importance, few DNA markers are available for molecular genetic research. In this study, we constructed a genetic linkage map and to detect quantitative trait loci (QTLs) for important agronomic traits of lisianthus. To develop simple sequence repeat (SSR) markers, we used 454-pyrosequencing technology to obtain genomic shotgun sequences and subsequently identified 8263 putative SSRs. A total of 3990 primer pairs were designed in silico and 1189 unique primer pairs were extracted through a BLAST search. Amplification was successful for more than 1000 primer pairs, and ultimately 278 SSR markers exhibited polymorphism between the two lisianthus accessions evaluated. Based on these markers, a genetic linkage map was constructed using a breeding population derived from crosses between the two accessions, for which flowering time differed (>140 days when grown under 20°C). We detected one QTL associated with flowering time (phenotypic variance, 27%; LOD value, 3.7). The SSR marker located at this QTL may account for variation in flowering time among accessions (i.e., three accessions whose nodes of the first flower were over 30 had late-flowering alleles of this QTL).

Chromosome-scale genome assembly of Eustoma grandiflorum, the first complete genome sequence in the genus Eustoma

“… Griesbach and Bhat (1990) reported that E. grandiflorum had 18 basic chromosomes according to a chromosome observation in meiotic metaphase I of diploid E. grandiflorum . Later, Kawakatsu et al (2021) suggested that E. grandiflorum had 2n = 2x = 72 chromosomes based on the result of SSR linkage map construction. E. exaltatum was also considered to have 2n = 2x = 72 chromosomes ( Barba-Gonzalez et al 2015 ).…”

“…russellianum (Taxonomy ID: 52518). E. grandiflorum was previously considered an octoploid ( Rork 1949 ), but a recent study suggested that E. grandiflorum is a diploid, with a chromosome number of 2n = 2X = 72 ( Kawakatsu et al 2021 ).…”