EFFICIENCY OF NONPARAMETRIC STATISTICS IN EVALUATING PHENOTYPIC VARIABILITY AND OF RAPD ANALYSIS IN EVALUATING VARIABILITY AT THE MOLECULAR LEVEL, OF THE MAIN APPLE VARIETIES GROWN IN TRANSYLVANIA

  • M. Ardelean University of Agricultural Sciences and Veterinary Medicine
  • V. Mitre University of Agricultural Sciences and Veterinary Medicine
  • L. Lukács University of Agricultural Sciences and Veterinary Medicine
  • Rodica Pop University of Agricultural Sciences and Veterinary Medicine
  • Ioana Mitre University of Agricultural Sciences and Veterinary Medicine
  • Mirela Cordea University of Agricultural Sciences and Veterinary Medicine
Keywords: apple cultivars, nonparametric statistics, phenotypic/genotypic variability, RAPD analysis

Abstract

Five apple cultivars (Florina, Golden Delicious, Idared, Jonathan and Starkrimson), were tested in 2004 and 2005 in five commercial orchards located in different counties of Transylvania with quite nonsimilar environments. Fruit yield was registered, the resulting data being evaluated by means of HUHN (1990a and 1990b) nonparametric stability indices: Si(1) = mean of the absolute rank differences of a genotype over environments and Si(2) = variance among the ranks over environments. For a genotype with maximum stability Si(1) = 0 and Si(2) = 0. In June 2004, young shoots were harvested from each cultivar and taken to the laboratory by means of a refrigerating bag. Young leaves were harvested from the shoots and preserved in refrigerator at –70oC until the DNA extraction was performed. 12 decamer primers were used for DNA amplification out of which ten produced polymorphic bands in each variety/location . Six dendrograms were constructed based on DNA migration in agarose gel and analysis of formed bands and genetic distances, one for revealing the intervarietal polymorphism in all five locations and five for evaluating the polymorphism within each cultivar depending on its location of origin. The highest stability of fruit yield (or the lowest variability), in both experimental years, was found in Florina (Si(1) = 1.60 and Si(2) = 2.0) which is the only domestic variety tested in this experiment and, quite expectedly, best adapted to the studied environments. The dendrograms exhibited the existence of obvious differences, at the molecular level, both among cultivars across all the environments and within the same cultivar, depending on location. The last type of differences should be attributed mainly to the lack of uniformity of initial mother plants used in the process of planting material production for the five cultivars. It is concluded that RAPD analysis could successfully be used in checking the authenticity of planting material for apple trees produced in different nurseries, provided there are available standard forms of the interested cultivars from which DNA could be analyzed and used as control.