Genetic diversity analysis of Bt cotton genotypes in Pakistan using simple sequence repeat markers

Area of Science:

• Agricultural Science
• Genetics
• Biotechnology

Background:

• Large-scale cultivation of insect-resistant (Bt) cotton has led to concerns about genetic homogeneity.
• Limited information exists regarding the genetic diversity within existing Bt cotton varieties.

Purpose of the Study:

• To evaluate the genetic divergence among 19 Bt cotton genotypes.
• To identify the level of genetic diversity in Bt cotton varieties, particularly those developed in Pakistan.

Main Methods:

• Employed simple sequence repeat (SSR) markers to assess genetic divergence.
• Utilized 104 SSR primers, with 37 found to be informative, and selected 52 based on intra-hirsutum polymorphism data.
• Amplified 177 loci, generating 38 markers ranging from 98 to 256 bp.

Main Results:

• A high average genetic similarity of 0.947 was observed among the 19 Bt cotton genotypes, indicating a lack of diversity.
• Genotypes from public sector organizations showed higher similarity than those from private companies.
• Cluster analysis revealed three major clusters and two independent entries, with Pakistani varieties demonstrating very high similarity.

Conclusions:

• There is a significant lack of genetic diversity among the studied Bt cotton varieties, especially Pakistani-bred ones.
• Incorporating genetically diverse recurrent parents is crucial for enhancing the genetic diversity of Bt cotton.
• Intra-hirsutum polymorphic SSRs are effective tools for molecular genetic diversity studies in cotton.