Studies on sexual compatibility and or incompatibility among Psidium species and their hybridity confirmation through ssr markers

The present investigation was carried out with an aim to determine the cross compatibility between Psidium species (P. chinensis, P. guineense, P. cattleianum and P. molle) and commercial guava cultivars (Arka Kiran, Arka Rashmi, Arka Mridula and Allahabad Safed). The results revealed that, P. chinensis and P. guineense were found to be good cross compatible male parents whereas, Allahabad Safeda and Arka Kiran were found to be good cross compatible female parents. However, no fruit set and seed set were obtained when P. cattleianum and P. molle were used as male parent indicating the cross incompatibility of these species with commercial guava cultivars which is reconfirmed using florescence microscopy technique to understand the pollen-pistil interaction between incompatible P. cattleianum and P. molle species with P. guajava cv. Allahabad Safeda. Result indicated that low fluorescence intensity along with poor pollen germination and improper pollen-tube growth could be the reason for incompatibility. In order to break this incompatibility, a modified pollination technique called stigma maceration technique was followed wherein stigma of the male parent macerated with different chemicals viz., carbohydrate source (2% sucrose), growth regulators (50 ppm GA3 and iaa) and micronutrients (50 ppm of each Boric acid, MgSO4, CaNO3 and KNO3) and pollinated twice i.e., on the day of flower opening and the same time of next day resulted in cross compatibility of P. cattleianum and P. molle with commercial guava cultivars. Further hybridity confirmation of interspecific hybrids using ssr markers revealed that, 8 markers were found to be co-dominant and confirmed the hybridity of interspecific hybrid combinations.