Identification of zygotic and nucellar seedlings in Citrus interploid crosses by means of isozymes, flow cytometry and ISSR-PCR

'Milam' (a purported hybrid of Citrus jambhiri Lush) + 'Femminello' lemon (Citrus limon L. Burm. f.) allotetraploid somatic hybrids were used as pollen parents in interploid crosses with diploid 'Femminello' lemon to achieve mal secco tolerance in different populations of seedless triploid lemon types with good fruit quality. A total of 137 plantlets were obtained and subjected to screening experiments, in order to distinguish zygotic embryos from nucellars. Here we report on and discuss the results obtained with three techniques: flow cytometry, isozyme analysis and ISSR-PCR (the inter-simple sequence repeats-polymerase chain reaction). ISSR-PCR resulted to be a very efficient and reliable technique for the identification of zygotic plantlets.