GENETIC DIVERSITY, POPULATION STRUCTURE AND ASSOCIATION ANALYSIS FOR FIBER QUALITY TRAITS IN COTTON (Gossypium hirsutum L.) USING SIMPLE SEQUENCE REPEAT MARKERS
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Date
2024-05-01
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Acharya N G Ranga Agricultural University
Abstract
The present investigation entitled “Genetic diversity, population structure and
association analysis for fiber quality traits in cotton (Gossypium hirsutum L.) using
simple sequence repeat markers” was carried out at the Regional Agricultural Research
Station (RARS), Lam, Guntur, Andhra Pradesh during kharif 2021-22.
A total of 48 cotton genotypes (Gossypium hirsutum L.) including two checks
(NDLH1938 and LHDP-1) were studied for important fibre quality and yield attributing
traits. The diversity among 48 genotypes were studied at the molecular level, using SSR
markers. Sigle marker analysis was conducted to identify the markers that are
significantly associated with the fibre quality traits. The observations were recorded for
48 genotypes on different plant morphological and yield attributing traits such as, plant
height (cm), number of monopodia per plant, number of sympodia per plant, number of
bolls per plant, boll weight (g), ginning outturn (%), seed index (g), lint index (g) and
fibre quality traits i.e., upper half mean length (mm), micronaire value (μg/inch), fibre
strength (g/tex), fibre uniformity (%) and fibre elongation (%).
Among all the genotypes studied, five genotypes performed better for the yield
and fibre quality traits. Among them, GP144 (number of sympodia per plant, seed index,
fibre strength and fibre elongation) , GP55 (boll weight, ginning outturn (GOT),
micronaire and fibre elongation), GP73 (boll weight, lint index, upper half mean length
(UHML) and fibre uniformity), GP66 (lint index, upper half mean length (UHML) and
elongation) and GP5 (number of sympodia per plant, boll weight, fibre strength and fibre
elongation) exhibited good phenotypic performance.
Correlation studies among the yield and fibre quality traits revealed that the
number of sympodia per plant exhibited significant and positive correlation with number
of bolls, lint index and ginning outturn (GOT). The upper half mean length (UHML)
exhibited significant positive correlation with fibre uniformity. The fibre strength and
fibre uniformity recorded significant positive correlation with fibre elongation.
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Among the 26 SSR markers studied, only six were found to be polymorphic. The
six polymorphic SSR markers amplified a total of 12 alleles. Polymorphic information
content (PIC) ranged from 0.40 to 0.50 with an average of 0.46. The highest PIC value
was exhibited by the markers, JESPR204 (0.50), DPL0068 (0.50) and NAU2443 (0.49).
The number of effective alleles ranged from 1.60 (NAU3467) to 2.00 (JESPR204) with
a mean value of 1.83. The highest number of effective alleles were recorded by JESPR204
(2.00), DPL0068 (1.98) and NAU2443 (1.96). The shannon's information index varied
between 0.56 (NAU3467) to JESPR204 (0.69) with a mean of 0.64.
The cluster analysis based on UPGMA method revealed that the 48 genotypes
were grouped into three major clusters. The cluster I comprised of 32 genotypes, cluster
II comprised of 12 genotypes and cluster III comprised of 4 genotypes. The dissimilarity
values obtained between the genotypes GP131 and GP138 was found to be 0.07, which
indicated that these two genotypes having least dissimilarity, where as dissimilarity value
of 0.11 was observed between GP101 and GP105, 0.125 was observed between the
genotypes GP88 and GP109 and GP90 and GP92.
The population structure analysis revealed that the entire 48 genotypes were
divided into two subgroups based on the ΔK value (ΔK = 2). The marker trait association
study conducted using single marker analysis revealed that the marker DPL0041 on
chromosome 9 was significantly found to be associated with the trait boll weight with a
phenotypic variance of 17.22%. Hence the marker can be utilized for the selection of
genotypes with high boll weight using marker assisted selection. Among all the genotypes
studied, five genotypes namely, GP144, GP55, GP73, GP66 and GP5 performed better
for both yield and fibre quality traits. Hence, the above genotypes may be considered as
the best donors for the breeding programme when aiming for development of high
yielding hybrids coupled with good fibre quality