GENETIC DIVERSITY OF MEXICAN GUAVA GERMPLASM EVALUATED USING AFLP AND SSR MARKERS

Abstract

In Mexico, guava (Psidium guajava) is grown on more than 20,000 ha. Significant morphological and biochemical variation among and between guava orchards of Mexico have been previously observed. The goal of this work was to evaluate the diversity of Mexican guava maintained on the ex situ germplasm bank of INIFAP using 9 AFLP primer combinations and 6 SSR loci. In this analysis, 68 accessions from 12 different regions of Mexico were analyzed, with six accessions from Venezuela and two from Cuba included as references. In the AFLP profiling, a total of 335 bands were identified, of which 71.9% were polymorphic. Specific region-bands were not observed. The similarity index varied from 0.46 to 0.90, with accessions from Aguascalientes and Guanajuato showing the greatest similarity. The SSR marker analysis revealed a total of 101 alleles. The number of alleles per locus ranged from 12 to 25 and averaged 17. The microsatellite mPgCIR161 revealed the highest number of alleles. The AFLP- and SSR-based dendrogram grouped guava accessions into four groups, with other diverse accessions failing to cluster. Most Mexican accessions were in groups B and C, while Venezuelan cultivars were placed in group E. The results show that Mexican guava germplasm is diverse and that a more detailed analysis is needed in order to determine the level of genetic variability for conservation, management, and development of new varieties.