Abstract
The F4, Fs and F, lines of eggplant derived from the crosses of Dohazari G x BAU Begun-1 and
Laffa S x BAU Begun-1 were evaluated for resistance to phomopsis blight and fruit rot. The three
parents and seven lines were inoculated with Phomopsis vexans under field conditions in winter
seasons of 2006-07, 2007-08 and 2008-09. The inoculated plants exhibited differential disease
reactions. Among the parents, BAU Begun-1 was resistant whereas Dohazari G and Laffa S were
susceptible to P. vexans. All the lines of three generations showed resistant reaction to the
disease. Significant differences were observed among the phenotypes in all the yield components.
High genotypic and phenotypic coefficient of variation, heritability and per cent genetic advance
were recorded for number of fruits per plant, number of secondary branch per plant, fruit length
and fruit breadth in all the generations. Significant positive correlation was observed between
yield contributing characters. Random amplified polymorphic DNA (RAPD) technique was used
for assessing genetic variation and relationship among three parent cultivars and their F4, Fs and
Fo progenies of eggplant. Amplification with five decamer primers generated 69.0, 66.1 and
65.2% polymorphic bands for F4, Fs and F6 lines respectively. The dendogram constructed from
Nei's genetic distance produced parent cultivars merged into one subgroup with resistant cultivar
BAU Begun-1 and formed a separate sub-group in all the generations studied. The lines through
F4 to Fo grouped into sub-cluster together, that indicates some common trait was being shared by
all of these advanced lines of both the crosses. This might be the resistance trait inherited from
BAU Begun-1 as supported by other characters like fruit colour and fruit shape also inherited
from the parents. A PCR-based molecular cloning technique was used to identify Nucleotide
binding site-Leucine rich repeat (NBS-LRR) type resistance gene sequence in eggplant. Primers
were designed based on previously used in sugar beet and the resultant amplicons were cloned.
Nine clones were sequenced and found to be about 243 nucleotides in length. Most of the
sequences have similarity with TIR and non-TIR types of NBS-LRR gene of Solanaceous crops.
These sequences also have similarity with 12 gene sequence which is a non-TIR type resistance
gene in tomato- that confers resistances to the tomato wilt pathogen. Another experiment was
conducted to determine if an osmotin gene in eggplants correlates with phomopsis resistance.
Primers were designed against homologous regions in osmotins, and made to be most similar to
sequences in Solanaceous crops. These primers were used to PCR amplify and clone~700 bp
sequence from both the resistant BAU Begun-1 and the susceptible Laffa S eggplant cultivars.
Analysis of the sequences revealed six different types osmotin like sequence (Genes or alleles) for
the phomopsis susceptible eggplant cultivar Laffa S and resistant cultivar BAU Begun-1 which
encodes some conserved osmotin amino acids including 16 of the characteristic Cysteine residues
and five acidic cleft amino acid residue. This means that there were at least 3 different osmotinlike genes in eggplants. Four types of sequences were amplified from both the cultivars. One type
of sequence (C) was found only in BAU Begun-1 and another (E) only in Laffa. PCR products
were successfully digested with restriction enzymes in presence of PCR buffer without any
purification and addition of any reagents to find out the allele or gene responsible for resistance in
eggplant. Further analysis of the C and E type sequence uncommon in the resistant and
susceptible eggplant cultivars would reveal the presence or absence of any other resistance trait in
BAU Begun-1.