Molecular fingerprinting exploits the variation between individuals at the genome level. It is generally performed for clear identification of various accessions, verifying ambiguous nomenclature, i.e., if similar cultivars are known by different names and different cultivars are called by similar names; to address Intellectual Property Rights related issues in the case of developed hybrids. The objective of the present study was to genotype and deoxyribonucleic acid (DNA) fingerprint 79 guava (Psidium guajava) accessions. Statistical analysis was performed by CERVUS 3.0 software. DNA fingerprint of the guava genotypes was developed by using 13 microsatellite loci that showed high polymorphic information content (PIC), allelic number per loci, and heterozygosity values. A total of 86 different alleles were amplified; number of alleles per locus ranged from five to nine, with a mean of 6.5. Allelic sizes ranged from 86 to 256 bp and the observed heterozygosity values ranged from 0.00 to 0.364. The expected heterozygosity varied from 0.689 to 0.821. The PIC varied from 0.630 to 0.789. Probability of identity varied from 0.05 to 0.12. The DNA barcode developed is very discriminative. So, it can be used for efficient and unambiguous identification of guava accessions, thereby increasing the accuracy in maintenance of genetic resources. Apart from the DNA fingerprint, interpretation of the results clearly indicated that each accession had a unique allelic combination at the 13 nuclear microsatellite loci, indirectly reflecting the fact that none of accessions were similar.

The bark-eating caterpillar (Indarbela tetraonis Moore) is one of the two species of insect pests known to infest guava (Psidium guajava). Severe infestation with this pest causes drying up of shoots, which ultimately results in substantial losses in fruit yield and quality. Genetic options are considered most eco-friendly and cost effective to mitigate such losses. DNA marker-assisted breeding of guava for improved resistance to bark-eating caterpillar is expected to increase the efficiency of developing resistant cultivars. As a prelude to this, an investigation was carried out to identify pairs of genotypes contrasting for responses to infestation by bark-eating caterpillar and for a large number of simple sequence repeat (SSR) markers, for use as putative parents to develop mapping populations for chromosomal localization of genomic regions controlling resistance to bark-eating caterpillar in guava. Dendrogram generated by 135 polymorphic SSR markers could separate five morphologically resistant and three morphologically highly susceptible genotypes into two different clusters, barring two exceptions (Bangalore Local and 7-12EC 147036). Four pairs of accessions, viz., Superior Sour Lucidum and Seedless, Portugal and Seedless, Lalit and Seedless, Spear Acid and Seedless, had contrasting response to bark-eating caterpillar and were polymorphic at 111, 103, 101, and 101, SSR loci, respectively. These contrasting pairs of accessions are suggested for use as parents to develop mapping populations to identify DNA markers linked to genomic regions controlling resistance to bark-eating caterpillar, which could help in implementing SSR marker-assisted breeding of guava for resistance to bark-eating caterpillar. ARTICLE HISTORY