Genetic Resources of Guava (Psidium guajava']java) in Cuba: Germplasm Characterization and Breeding

In the first half part of the last century, guava (Psidium guajava) was not cultured in Cuban, and breeding programs were not formally developed. In 1965, with the foundation of the Germplasm Bank of Tropical and Subtropical Fruit Trees (Havana Province), the principal Cuban guava collection was established. This gene bank was formed from three different sources: (i) foreign cultivars, (ii) plants prospected in different localities throughout the country, and (iii) selected genotypes segregating from open-pollinated seeds. During this period, an incipient breeding program was started, which resulted in the identification of nine cultivars with 'E.E.A. 1-23', 'E.E.A. 18-40', 'Belic L-207', 'Belic L-215', 'Belic L-97' and 'E.E.A. 28-44' showed the highest yields. The two formers are also dwarf genotypes and nowadays constitute the main cultivars for commercial production in Cuba. In 2001, a breeding program by controlled crosses produced a total of 354 hybrid plants from which 25 dwarf genotypes were finally selected on the basis of quantitative and qualitative traits for the establishment of new commercial cultivars. The three populations from these crosses were further employed to develop guava genetic linkage maps and to map QTLs using morph-agronomic characters and molecular markers. The combination of molecular marker methods and phenotypic description was greatly facilitated cultivar identification, diversity estimation, and elite genotypes recommendation in guava germplasm. Other modern biotechnology techniques such as in vitro culture and the detection of candidate genes for resistance and plant development can be potential tools to assist guava breeding program.