Distinguishing clonal apple rootstocks by isozymes banding patterns

Area of Science:

• Horticulture
• Plant genetics
• Biochemistry

Background:

• Clonal apple rootstocks are vital for orchard productivity and scion performance.
• Accurate identification of rootstock genotypes is crucial for maintaining varietal purity and breeding programs.
• Isozyme analysis offers a molecular approach for differentiating plant genotypes.

Purpose of the Study:

• To perform molecular characterization of seven clonal apple rootstocks using isozymes.
• To identify isozyme polymorphism within these rootstocks.
• To determine the most characteristic and stable enzyme markers for individual rootstock identification.

Main Methods:

• Studied five enzyme systems: polyphenol oxidase (PPO), malate dehydrogenase (MDH), acid phosphatase, peroxidase (PER), and esterase.
• Assessed isozyme polymorphism across seven clonal apple rootstock genotypes.
• Analyzed genetic variation using parameters such as percentage of polymorphic loci.

Main Results:

• Polyphenol oxidase, malate dehydrogenase, acid phosphatase, and peroxidase were effective in discriminating rootstocks.
• The peroxidase enzyme system exhibited the highest variation, while esterase showed the least.
• Three rootstocks (M.3, M.7, MM.111) were uniquely identified using single enzyme systems (MDH or PER).
• Seven out of sixteen studied loci were polymorphic, with variation ranging from 13.33% to 35.71%.

Conclusions:

• Isozyme analysis provides a reliable method for molecular identification of clonal apple rootstocks.
• Specific enzyme markers, particularly peroxidase and malate dehydrogenase, can be used for rapid and accurate rootstock differentiation.
• This molecular characterization aids in quality control and genetic resource management in apple breeding and horticulture.