MOLECULAR MARKERS FOR SELF INCOMPATIBILITY PHENOMENA IN SOME MANGO CULTIVARS

Mango (Mangifera indica L.) is considered one of the oldest cultivated trees in the world. The genus Mangifera is one of 73 genera belonging to the family Anacardiaceae (Litz, 1997). Mango (2n=40), is an allopolyploid plant, most probably amphidiploids, out breeding species (Mukhejee, 1953). The mango crop, typically tropical fruit, is best adapted to a warm tropical monsoon climate, with a pronounced dry season followed by rains. It is cultivated in many countries of the world, although most of all the production comes from developing countries (Litz, 1997). In Egypt, the total cultivated area with mango reached 209040 Fed. in 2010 (Statistics' of 2011, Ministry of Agriculture, Egypt). The average yield per feddan is only 3.33 Ton. Low cropping of some mango cultivars is associate with low fruit set and or high fruit drop of immature fruits. The self and cross incompatibility was reported as one of the serious factor affecting low fruit set in many mango cultivars (Singh et al., 1962). Self incompatibility is a genetic mechanism used by hermaphroditic plants to prevent self-fertilization and to promote outbreeding gametophytic self incompatibility (GSI)) and sporophytic self incompatibility (SSI) are among the several types of self-incompatibility systems that exist. Self-incompatibility in mango was confirmed to be of the sporophytic type (Ram et al., 1976; c.f. Litz, 1997). It was reported in several commercial Indian mangos (Mangifera indica) such as the Langra and Dusheri cultivars (Singh, 1978). However, Floridian cultivars appear to be self-fertile (Dag et al., 1998). Cross pollination increased fruit set and retention in Alphonso, Goamankur and Kesar mango cultivars (Desai et al., 1985). Random Amplified Polymorphic DNA (RAPD) assay detects nucleotides sequence of polymorphisms in DNA using only a single primer pair of arbitrary nucleotide sequence (Welsh and McClelland, 1990; Williams et al., 1990). The protocol is quick, easy to perform and only nanograms of template DNA are required. The RAPD technique has been employed to develop sex-linked markers in Brassica oleracea (Camargo, et al., 1997), hazelnut (Corylus avellana) (Pomper et al., 1998), Medicago sativa (Campbell, 2000), Chinese cabbage (B. campestris subsp. chinensis var. communis [B. chinensis]) Shi Gong Jun and Hou XiLin (2004), A. comosus Tapia Campos et al. (2005), Mangifera indica (Damodaran et al., 2009). In this respect, five elite mango cultivars were investigated for their self- and cross-compatibility, and RAPD analysis was tried to assess the genetic variation in cross-compatibility between them.