Construction of a genetic linkage map in Pyropia yezoensis (Bangiales, Rhodophyta) and QTL analysis of several economic traits of blades

Abstract

17 Pyropia yezoensis is an important economic seaweed, to construct a genetic linkage map 18 and analyze the quantitative trait loci (QTLs) of blades, a doubled haploid (DH) 19 population containing 148 DH strains established from the intraspecific hybridization 20 between two strains with different colors was used in the present study and genotyped 21 using 79 pairs of polymorphic sequence-related amplified polymorphism (SRAP) 22 markers labeled with 5'-HEX and capillary electrophoresis. A chi-square test for 23 significance of deviations from the expected ratio (1:1) on the loci which were 24 polymorphic between parents and segregated in mapping population identified 301 loci 25 with normal segregation (P ≥ 0.01) and 96 loci (24.18%) with low-level skewed 26 segregation (0.001 ≤ P < 0.01). The map was constructed using JoinMap software after a 27 total of 92 loci were assembled into three linkage groups. The map spanned 557.36 cM 28 covering 93.71% of the estimated genome, with a mean interlocus space of 6.23 cM.29 Kolmogorov-Smirnov test (α=5%) of the marker positions along each LG showed a 30 uniform distribution. After that, 10 QTLs associated with five economic traits of blades 31 were detected, among which one QTL was for length, one for width, two for fresh 32 weight, two for specific growth rate of length and four for specific growth rate of fresh 33 weight. These QTLs could explain 2.29-7.87% of the trait variations, indicating that 34 their effects were all minor. The results will serve as a framework for future marker-35 assisted breeding in P. yezoensis. 36 37 Keywords: Economic trait; genetic linkage map; Pyropia yezoensis; quantitative trait 38 locus; SRAP 39 40 Introduction 41 Pyropia yezoensis is a marine red alga with high nutritional values and is one of the 42 most important maricultural crops across the world, mainly in Japan, Korea and China 43 [1]. During the cultivation of P. yezoensis, hundreds of tons of nutrients (nitrogen and 44 phosphorus) are removed by blade harvest from the eutrophic seawaters every year [2]. 45 However, some problems such as germplasm degeneration, frequent diseases and bad 46 harvests [3-5] have arisen under the influence of global warming [6]. Therefore, new 47 varieties with higher yield, stronger resistant to abiotic stress and greater ecological 48 adaptability were urgently needed for the stable development of Pyropia industry. 49 50 The traditional breeding methods of P. yezoensis are based on either observed variations 51 by selecting blades with induced variants [3, 7, 8], or controlled crosses by selecting 52 blades presenting recombination of desirable genes from different parents [9-11]. 53 However, traditional breeding is usually time-consuming and less efficient [12], and has 54 a limited ability to breed complex characters [13]. Fortunately, progress in molecular 55 genetics has enabled plant breeders the direct selection of genotypes, thereby accelerates 56 crop improvement [14]. Molecular marker-assisted selection (MAS) has become the 57 main d...

Development of simple sequence repeat markers in Pyropia yezoensis (Bangiales, Rhodophyta) by high‐throughput sequencing technology

“…A red‐type pigmentation mutant HT was used with LS to screen polymorphic SSRs for the further saturation of the medium‐density genetic linkage map of P . yezoensis (Huang & Yan, ). HT and LS were the cross parents of the doubled haploid population used for the linkage mapping, and were preserved in laboratory as free‐living conchocelis according to the method described by Kato and Aruga ().…”

“…The first genetic linkage map of P . yezoensis has been constructed with 92 SRAP markers, and the map spanned 557.36 cM with a mean interlocus space of 6.23 cM (Huang & Yan, ). Nevertheless, the level of marker saturation is medium‐density and is still low in the context of QTL fine mapping.…”

Assessment of genetic diversity within eucheumatoid cultivars in east Sabah, Malaysia

“…These qualities may include high carrageenan yield, fast growth, disease resistance, and heat tolerance among others. This can ultimately be achieved via marker-assisted selection (MAS), in which certain genetic markers correlate to traits of interest such as recent progresses seen in Saccharina japonica (Wang et al 2018) and Pyropia yezoensis (Huang and Yan 2019;Yu et al 2020).…”

The Inheritable Characteristics of Monoecy and Parthenogenesis Provide A Means for Establishing A Doubled Haploid Population in the Economically Important Brown Alga Undariapinnatifida (Laminariales, Alariaceae)

“…2010, Xu et al. 2015, Huang and Yan 2017, 2019). However, no DH mapping population has been established in kelps.…”