Development of SRAP and SSR marker-based genetic linkage maps of guava (Psidium guajava L.).

Abstract

In the present study genotyping of guava full-sib population with 94 F1 progenies, derived from a two-way pseudo-testcross strategy differing in fruit quality traits such as seed strength (hardness/softness), fruit weight, and TSS, was carried out using simple sequence repeat (SSR) markers and sequence-related amplified polymorphic (SRAP) primer combinations. In the case of SSR's high-throughput genotyping, through a M13-Tailed PCR principle, using a set of 160 SSR primer pairs revealed 64.3% parental polymorphism that generated 321 alleles during the mapping population survey. Twenty percent of parental polymorphism was revealed with SRAPs that generated 126 scorable markers. Two linkage maps were constructed for parents using maternal-specific 143 testcross marker loci and paternal-specific 127 testcross markers along with 60 intercross marker loci. At a minimum logarithm of the odds (LOD) score of 4.0 and a maximum map distance of 40 cM the maternal Kamsari map covered 2551.3 cM with an average marker interval distance of 13.21 cM having a total of 193 framework marker loci being ordered into 11 linkage groups. The paternal Purple Local map covered 2113.0 cM with an average marker interval distance of 12.07 cM having 175 framework marker loci being ordered into 11 linkage groups. The estimated genome coverage was of 87.32% in Kamsari and 83.74% in Purple Local. These genetic maps will play a pivotal role in identification of complex quantitative trait loci (QTLs) related to fruit quality. This is the first report of linkage maps in guava based on the combination of SSR along with SRAP markers.