Abstract
The present study was conducted during the period from 2013 to 2017 for morphological and
molecular characterization and evaluation of 65 brinjal genotypes for identifying their levels
tolerance against brinjal shoot and fruit borer (BSFB) at the Biotechnology Laboratory and Field
Laboratory of Bangladesh Institute of Nuclear Agriculture and Insect Rearing Laboratory of the
Department of Entomology of Bangladesh Agricultural University. Morphological characterization,
performed as per the minimum descriptors as prescribed by IBPGR revealed wide and significant
variations for most of the traits investigated. The highest yield (58.34 t ha-1) was recorded from the
genotype S28 followed by S6 (56.95 t ha-¹). By contrast, the genotype S46 yielded the lowest (8.36 t ha1). In terms of individual fruit weight, the heaviest fruits were obtained from the genotype S17 (251.78
g fruit) followed by S6 (221.56 g), whereas the lightest fruits were found in genotype S58 (50.78 g). At
120 days of planting (DAP), the longest and shortest plants were recorded from the genotypes S44
(73.67 cm) and S24 (31.22 cm), respectively. Number of leaves plant¹ increased up to 70 DAP, at
which most of the genotypes attained the highest number of leaves plant¹ and decreased thereafter.
In terms of fruit colour, the collected genotypes were categorized into 5 major groups using Standard
Colour Chart. Fruit colour of the 65 genotypes were in the order of Green (29 genotypes), Violet (17
genotypes), Pink (11 genotypes), Brown (6 genotypes) and White (2 genotypes). Considering specific
colour, the predominant colour was Dark-violet with colour code 83A (11 genotypes) followed by
Green with colour code 137C (8 genotypes). Genetic diversity analysis based on selected phenotypic
traits revealed that the highest phenotypic and genotypic co-efficient of variations were obtained for
%shoot infestation by BSFB (95.43 and 94.31) followed by %fruit infestation (40.89 and 33.42),
peduncle length (39.09 and 35.03), fruit diameter (38.17 and 28.98) and yield (35.52 and 28.85), which
signify maximum contribution of these traits towards genetic variability, and eventually can
exploited in breeding programme for obtaining good transgressive segregants. The inter-cluster
be
distances werere higher than the intra-cluster distances suggesting wider genetic diversity among the
genotypes. The highest inter-cluster distance was present between Cluster VI and VII (5.07) followed
by Cluster II and VII (4.43). Principal component analysis (PCA) indicated that four components
accounted for 72.30% of the total variation among the selected traits. Results of PCA also suggested
that plant height, canopy spread, fruit length and breadth, individual fruit weight, 1000-seed weight,
yield, and levels of shoot and fruit infestation could be used to distinguish the genotypes. Molecular
characterization of the 65 genotypes was performed using six SSR markers. The selected primers,
namely EM107, EM114, EM133, EM139, EM140 and EM145 showed polymorphism. The values of
pair-wise comparison of Nei's (1973) genetic distance (D) between plants computed from combine
data for the 6 primers ranged from 0.17 to 1.00. The highest genetic dissimilarity (100%) was observed
among various combinations, such as Islampuri (S31), Thapara (S32), Mentar (S33), Iribegun (S35),
Eye-red (S36), Deembegun (S37), Comilla-L (S38) and Chega (S39) with Dohazari G (S10), Borka
(S11), Khatkhatia B (S12), Khatkhatia BAU (S13), ISD-006 (S2) and Laffa-M (S3). The UPGMA cluster
based on Nei's (1973) genetic distance analysis led to the grouping of the 65 genotypes into three
major clusters with nine sub-clusters. Most strikingly, 2 genotypes (S57: Marich Begun-S; and S58:
Marich Begun-E) were found to be tolerant against BSFB based on primary screening, artificial
release of pest in net house and subsequent field evaluation. These genotypes were similar in
morpho-molecular traits. They were located in sub-cluster II (S57) and sub-cluster-III (S58) under
Cluster-I based on molecular analysis. Similarly, both the genotypes were located in Cluster-VII as
per genetic diversity study based on phenotypic traits. Apart from that, 6 out of 65 genotypes tested
were identified as moderately tolerant against BSFB, and they were S13 (Khatkhatia-BAU), S17 (Jessore-L), S24 (China Oblong), S26 (Ishurdi-BS), S47 (BAU Begun-1) and S55 (Laffa-BAU). The
outputs of the present study would be utilized in the future for developing brinjal variety with BSFB tolerance attribute.