IDENTIFICATION OF ZYGOTIC AND NUCELLAR SEEDLINGS FROM CITRUS ROOTSTOCK CANDIDATES USING RAPD

Abstract

The preliminary approach in citrus breeding is to eliminate undesirable genotypes by distinguishing between zygotic and nucellar seedlings. The identification of true nucellar seedlings with the desired genotype is a daunting process as many citrus varieties produce both nucellar and zygotic embryos. We have carried out a series of crosses aimed at introgression of mandarin (Citrus reticulata) and pummelo (C. grandis) germplasm to develop alternative rootstocks to sour orange (C. (C. grandis), and it is necessary to identify those hybrids that yield nucellar seeds for rootstock propagation. Randomly Amplified Polymorphic DNA (RAPD) marker characterization was used to select hybrids that produce primarily nucellar seedlings. Five random primers were screened to classify various citrus seedlings from a total of 276 individual progeny obtained from 46 hybrid parental plants. The degrees of genetic similarity (nucellar) among progeny seedlings for each primer and among all primers were determined and compared with that of the parents. The usefulness and efficiency of RAPD-PCR method as a quick screening technique for citrus hybrids are discussed.