Assessing the robustness of IRAP and RAPD marker systems to study intra-group diversity among Cavendish (AAA) clones of banana

Abstract

SummaryBananas belonging to the Cavendish sub-group (AAA) are cultivated commercially for their high yield, short cropping cycle, and high economic returns. The field performance of exotic Cavendish cultivars such as ‘Grand Naine’, ‘Williams’, and ‘Dwarf Cavendish’ is superior due to their sturdy stature, high yield potential, and better bunch quality. However, morphological similarities among the dwarf, medium, tall, and giant types of Cavendish clones make identification difficult under field conditions. Multiplication by tissue culture further aggravates this problem by inducing somaclonal variants. In the present study, ten IRAP (Inter-Retrotransposon Amplified Polymorphism) primer pairs and 30 decamer RAPD (Randomly Amplified Polymorphic DNA) primers were tested to examine intra-group diversity in Cavendish bananas. The average level of polymorphism exhibited by RAPD markers was 67.8%, and by IRAP markers the level was 81.3%, indicating that there was substantial variation at the DNA level among the 19 accessions tested. All dwarf Cavendish-type cultivars such as ‘Williams’, ‘Dwarf Cavendish’, ‘Singapuri’, ‘Jahaji’, and ‘Manjahaji’ clustered together using IRAP markers. Similarly, all medium-tall types of Cavendish such as ‘Harichal’, ‘Robusta’, ‘Shrimanti’, and ‘Pedda Pacha’, and giant Cavendish types such as ‘Gandevi Selection’, ‘Grand Naine’, and ‘Madhukar’ grouped separately. These results suggest that IRAP markers are more robust than RAPD markers for studying intra-group diversity in the Cavendish sub-group. Furthermore, the use of appropriate primer combinations could enable the development of DNA fingerprints for genetic fidelity testing within Cavendish clones.