Assessment of genetic diversity of guava (Psidium guajava L.) using SSR marker for application in guava breeding program

Abstract

The genetic variation of germplasm and accurate selection are important factors in the success of a breeding program. The objectives of this study were to identify Simple Sequence Repeat (SSR) markers for studying the genetic diversity of 68 Psidium guajava (P. guajava) varieties in germplasm and to study association of SSR marker with the leaf, peel, and pulp color of guava including used to verify hybrid guava varieties. The results indicated that fifty SSR markers showed DNA amplification. The Polymorphic Information Content (PIC) was found to have an average value of 0.31. Notably, six SSR markers exhibited a high level of PIC (>0.5), namely mPgCIR32, mPgCIR132, mPgCIR139, mPgCIR150, mPgCIR383, and mPgCIR446. These markers proved effective in distinguishing different guava varieties. The result revealed genetic divergence between P. guajava and Psidium cattleianum. Within the 68 varieties of P. guajava, a similarity index ranging from 0.30 to 0.99 was observed, leading to the identification of two clusters and six clades within a subgroup. Moreover, this work demonstrated the association of SSR markers with pulp colors such as pink, red, and purple. The marker mPgCIR153 was linked to pink pulp, while the marker mPgCIR446 was associated with both red and purple pulp. Additionally, the study confirmed the detection of five guava hybrids using these SSR markers. Therefore, utilization of SSR markers and understanding of the genetic diversity in guava will prove to be essential tools. This knowledge can be harnessed to improve the breeding and cultivation of guava varieties with specific pulp colors.