Assessing genetic variability in male sterile and low fertile citrus cultivars utilizing simple sequence repeat markers (SSRs)

Abstract

Understanding phylogenetic relationships and genetic diversity in citrus are important in clarifying genetic relationships, characterizing germplasm and the registration of new cultivars. In this study, the genetic diversity of 28 accessions of citrus including male sterile, sterile, low fertile and fertile cultivars were investigated using eight pairs of simple sequence repeat markers (SSR) markers, which in total, 54 polymorphic alleles with an average of 4.2 alleles per primer were detected. The lowest number of alleles was observed in TAA27, CTT01, CCSM18 and ATC09 loci with only three alleles and the highest number of alleles was observed in TAA15 locus with eight alleles. Polymorphic information content (PIC) values changed from 0.34 (AG14) to 0.90 (CCSM18). Genetic similarities among accessions were calculated according to Jaccard similarity index and used to construct a dendrogram based on the unweighted pair group method using arithmetic averages (UPGMA) which put the 28 samples into four major groups (A, B, C and D). The cultivars of male sterile satsuma mandarin were clustered into group A; those of orange, grapefruit and Page (a complex hybrid) into group B; mandarin cultivars into group C; and lemon Lisbon into group D. Genetic analysis of sterile and low fertile citrus, provide useful information for further breeding programs, collection, preservation and utilization.

Key words: Male sterility, genetic diversity, SSR markers, citrus.