Estimating genetic diversity among selected cotton genotypes and the identificationof DNA markers associated with resistance to cotton leaf curl disease

Abstract

To the extent of our knowledge, applications of DNA markers in marker-assisted breeding of cotton are handicapped due to low genetic diversity in cotton germplasm. Cotton leaf curl disease, a disease of viral origin, has substantially depressed cotton production in Pakistan, and this disease is also an emerging threat to the neighboring cotton-growing countries like China and India. The present study was designed to identify DNA markers, predominately simple sequence repeats (SSRs), associated with tolerance and/or resistance to the disease. Based upon 2 years of disease-screening field experiments, a total of 10 cotton genotypes (five highly tolerant, four highly susceptible, and one immune) of diverse origin were selected from the available cotton germplasm (~1200 accessions) of the National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan. In total, 322 SSRs derived from bacterial artificial chromosome end sequences of Gossypium raimondii (one of the progenitor species of cultivated tetraploid cotton) were screened. Out of these, 65 primer pairs were found polymorphic, and the extent of genetic similarity was in the range of 81.7% to 98.7%. A similarity matrix was used for studying their phylogenetic relationship using unweighted pair-group method with arithmetic means (UPGMA) analysis. The dendrogram showed the grouping of the genotypes into two distinct clusters comprising tolerant and susceptible genotypes, respectively. Out of the polymorphic markers, two SSR markers, PR-91 and CM-43, that were amplified only in tolerant genotypes showed significant association with resistance to the disease. These preliminary results set the stage for initiating indepth marker-trait association studies, which will be instrumental for initiating marker-assisted breeding in cotton.

Identification of Marker-Trait Associations for Lint Traits in Cotton

“…Multivariate analysis for studying a number of phenotypic triats in multiple crop species including cotton (Abbas et al, 2015 ; Shakeel et al, 2015 ), wheat (Janmohammadi et al, 2014 ), and maize (Mustafa et al, 2015 ) have been applied. In the present study, two clusters were developed using the first two principal components (El-Lawendey et al, 2008 ).…”

Molecular Screening of Cotton Germplasm for Cotton Leaf Curl Disease Caused by Viral Strains

“…Cotton leaf curl disease is a major biotic constraint for cotton production in Pakistan since the last two decades. After the occurrence of first epidemic in Pakistan, plant breeders are working for permanent and long lasting solution to develop resistance in high yielding varieties (Abbas et al, 2015;Iqbal et al, 2016).…”

Cotton germplasm improvement and progress in Pakistan

“…Of the total, 65 primer pairs were identified as polymorphic, and the genetic similarity was found in the range of 81.7%∼98.7%. Among the polymorphic markers, only two SSR markers, PR-91 and CM-43 were amplified in the CLCuV-tolerant genotypes which showed significant association with tolerance to the disease (Abbas et al 2015).…”

“…Additionally, the National Institute of Biotechnology and Genetic Engineering (NIBGE) screened 322 SSR markers derived from bacterial artificial chromosome end sequences of G. raimondii. When PR-91 and CM-43 were amplified, they showed an association of resistance against CLCuV (Abbas et al 2015). Using RAPD markers, two QTLs for relative water content were detected with the nearest markers NAU2954 and NAU2715, respectively, each on chromosome 23 and 12 at Department of Plant Breeding and Genetics BZU-Multan (Saleem et al 2015).…”