Genetic diversity analysis of gladiolus genotypes (Gladiolus grandiflorus L.) using molecular markers

Abstract

Characterization of plant genotypes based on crop genetic diversity is important for effective usage and conservation. This is generally achieved by either morphological tools or molecular tools or by using both. This study entitled “Genetic diversity analysis of gladiolus genotypes (Gladiolus grandiflorus L.) using molecular markers” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, Thiruvananthapuram during 2020-2021 with an objective to analyse genetic diversity in the gladiolus genotypes using ISSR as well as morphological markers. Gladiolus (Gladiolus sp.) is a genus of perennial herbaceous cormous flowering plants in the family Iridaceae which is of high economic importance. Fifteen varieties of gladiolus including twelve varieties from IIHR, Bangalore and three varieties from NBRI, Lucknow were selected for this study. The study was divided into two parts- morphological characterization and molecular characterization. Morphological characterization was done by analysing both vegetative and floral characters. Different tools such as analysis of variance, co-variance, correlations, PCA and dendrogram were used for statistically analysing the recorded data. The dendrogram divided the genotypes into two principal clusters at a distance of 0.10. The major variables that contributed to the clustering of gladiolus genotypes were plant height, number of leaves per shoot, length of leaf, width of leaf, internode length, number of florets open at one time and number of florets per spike as revealed by PCA analysis. For molecular characterization using ISSR markers the genomic DNA was isolated using CTAB method of DNA isolation with little modifications. Ten ISSR primers were used for screening fifteen gladiolus genotypes. After the final PCR with selected primers, the amplicons were resolved in 2% agarose gel and polymorphic bands were obtained. Primers showed 94.56% polymorphism and the number of bands obtained ranged from 3(UBC 857) to 14 (UBC 890) with a mean value of 8.7 polymorphic bands per primer. A total of 87 polymorphic bands were obtained. The data analysed using NTSYS PC 2.02 program created a dendrogram, which grouped 113 the genotypes based on Jaccard’s similarity coefficient in which the fifteen genotypes were separated into two principal clusters. The first principal cluster consisted of most of the genotypes (12 genotypes). The second principal cluster comprised of ‘Arka Naveen’, ‘Archana’ and ‘Arka Gold’ with ‘Archana’ as an outlier. In molecular characterization, least similarity of 34% was observed between G3 (Arka Sapna) and G9 (Archana) whereas, maximum genetic similarity of 82% was observed between G6 (Arka Amar) and G10 (Arka Kumkum). The highest morphological similarity was also observed between G6 (Arka Amar) and G10 (Arka Kumkum) at a distance of 0.83 in UPGMA dendrogram based on Jaccard’s coefficient. Though some similarity in results existed between the morphological and molecular tools used for identifying the genetic relationships among selected gladiolus varieties in this study, it also revealed that the varieties were grouped as separate clusters based on morphological dendrogram. This may be due to the dependence of morphological expression on the physiological state of the individual plant along with environmental influence. Self-incompatibility, along with the outcrossing nature together might have contributed to the high variation observed among the gladiolus genotypes. Being a commercial cut flower crop, based on different floral parameters considered ‘Arka Sapna’, ‘Arka Nazrana’, Arka Darshan’, ‘Arka Amar’ and ‘Arka Poonam’ are recommended as the gladiolus genotypes that showed best performance in Kerala conditions. Tags from this library: No tags from this library for this title.