VERIFICATION OF THE PARTHENOGENETIC CAPABILITY OF UNREDUCED EGGS IN AN ALFALFA MUTANT BY A PROGENY TEST BASED ON MORPHOLOGICAL AND MOLECULAR MARKERS

Apomixis involves the parthenogenetic development of apomeiotic eggs. It has the potential of cloning plants through seed, and thus furnishe s a unique opportunity in breeding of allogamous sexual species, such as alfalfa, for developing superior cultivars with permanently fixed h eterosis. Apomixis as a whole has not been detected in the genus Medic ago, but components of apomixis have been reported. The formation of u nreduced eggs through diplosporic meiosis was documented in a diploid mutant of M. saliva ssp. falcata (L.) Arcang., named PG-F9. Since in f acultative apomictic species non-reductional meiosis and parthenogenes is could be tightly associated processes, a progeny test based on morp hological trait and molecular marker evaluation was carried out to ver ify the occurrence of parthenogenesis in PG-F9. Morphological traits s uch as leaf shape, stipule form, stem pigmentation and flower colour w ere shown to be effective in the preliminary screening of progenies an d most of the plants were classified as non-maternal (i.e. from sexual reproduction). Molecular investigations by means of random amplified polymorphic DNA (RAPD) fingerprint and heterozygous restriction fragme nt length polymorphism (RFLP) loci detection conducted on the progenie s classified morphologically as maternal allowed two plants, molecular ly similar but not identical to PG-F9, to be discovered. Owing to the high number of molecular markers conserved as in the mother plant, and because of the great discriminating efficiency of the primers and pro bes used, these progeny plants could most likely be generated through parthenogenesis of diplosporic eggs. In fact, the extraordinary preser vation of maternal morphological traits and genomic loci over one gene ration may be explained only if apomictic reproductive events rarely t ook place in PG-F9.