Pg. 5-7 The use of Isozyme Analysis for Differentiation Between Litchi Cultivars

Polymorphic isozyme banding patterns of phospho-glucose isomerase (PGI), triosephosphate isomerase (TPI) and alcohol dehydrogenase (ADH) were obtained from leaf extracts of 19 litchi cultivars and six vegetative selections. Differences were sufficient to distinguish between most cultivars. The six vegetative selections could, however, not be distinguished from the mother plant.

Summary:

• The study analyzed polymorphic isozyme banding patterns of three enzymes—phospho-glucose isomerase (PGI), triose-phosphate isomerase (TPI), and alcohol dehydrogenase (ADH)—from leaf extracts of 19 litchi cultivars and six vegetative selections.
• Differences in isozyme patterns were sufficient to distinguish most litchi cultivars, but the six vegetative selections could not be distinguished from their mother plant.
• Isozymes are multiple molecular forms of enzymes with catalytic activity, useful as genetic markers for differentiating cultivars or species and for breeding program applications.
• The study used horizontal starch gel electrophoresis to separate PGI, TPI, and ADH isozymes from leaf tissues.
• Nine different PGI banding patterns (zymotypes) were identified, suggesting possible control by at least three alleles at a single locus.
• Only three TPI banding patterns were observed among cultivars, with further work needed for genetic interpretation.
• ADH analysis showed three banding patterns, with most cultivars displaying a triple-band pattern indicating a single ADH locus.
• Isozyme polymorphisms allowed differentiation between most cultivars; however, clones and vegetative selections of the HLH Mauritius cultivar showed identical isozyme patterns.
• Litchi cultivar nomenclature is inconsistent globally, often leading to confusion, addressable with isozyme analysis for reliable identification.
• Morphological traits for identification are limited due to environmental interaction, making isozyme analysis a convenient and reliable alternative for cultivar differentiation.
• The work builds on previous literature that demonstrated isozyme analysis effectiveness for cultivar identification in various fruit tree species.
• This study highlights the practicality and cost-effectiveness of isozyme analysis for genetic differentiation and identification of litchi cultivars in germplasm management and breeding programs.