Fruit characters among apomicts and sexual progeny of a cross of the Texas native Opuntia lindheimerii (1250) with a commercial fruit type Opuntia ficus–indica (1281)
Keywords:Cactus, genetics, seeds, soluble solids, DNA.
A wide interspecific cross between two wild, spiny Texas native Opuntia lindheimerii Texas A&M University Kingsville (TAMUK) accession 1250 male parents and a spineless commercial Opuntia ficus–indica fruit type TAMUK accession 1281 was made to serve as the mapping population for a genetic map. Seedlings (127) resulting from this cross were grown in Santiago del Estero, Argentina and evaluated at four years of age when they were 3 to 5 m tall. At this age, the female parent was spineless, 4 m tall, with greenish pads and large fruits (ca 150 gram) while the male was spiny with bluish pads, and about 1 m tall with small (ca 35 gram fruits). Due to the presence of apomixis (asexual reproduction of seeds without fertilization) in Opuntia, we used Random Amplification of Polymorphic DNA (RAPD) markers to test for apomixis. RAPD bands were obtained that distinguished the two males and the female. The lack of “male” RAPD bands in “female looking progeny” confirmed the presence of apomixis in some of the progeny. However, 46% of the progeny had at least one morphological character (spines, small cladodes, bluish cladodes) of the male parent indicating that these were not apomicts. Spine, and disease ratings were measured for all of the 127 “progeny” and fruit characters were measured for 109 progeny. Ten fruits were analyzed for the male and female parents and four fruits were analyzed for the progeny. The fruits ranged from 6 to 15.5% soluble solids, 22 to 197 g fruit weight, 24.4 to 59.2% edible pulp portion, 2 to 22,100 g fruit per plant, 0.63 to 2.86 kg pulp firmness, 3.3 to 10.4 g of seed per 100 g pulp, 4.35 to 6.95 in pH and there were 78 days difference in maturity of the fruits. Several of the progeny had many characteristics of the male parent (short habit and small, bluish cladodes but without spines) and may have potential as cold hardy forage types.