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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
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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.