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DNA fingerprinting and genetic diversity analysis helps direct selective breeding and conservation of plant species. Since simple sequence repeats (SSR) markers are co-dominant, they can predict level of genetic diversity and thereby protect plant genetic resources of a region. Keeping the aforesaid rationale in mind, we worked on molecular characterization of eight cotton varieties in Bangladesh using simple sequence repeat (SSR) or microsatellite DNA markers. All the three microsatellite DNA markers were found to be polymorphic, extracting a total of eight alleles with an average of 2.67 alleles per locus in the present study. Allele sizes were as 149-155 bp, 178-198 bp and 140-202 bp for the loci BNL1551, BNL1721 and BNL2960, respectively. Polymorphism Information Content (PIC) values were ranged from 0.469 to 0.531. UPGMA dendrogram separated 8 varieties of cotton into two clusters. One cluster contained six varieties CB-1, CB-2, CB-3, CB-7, CB-9 and CB-10 while other two varieties CB-5 and HC 1 formed another cluster. The findings of this study would provide a useful guide for selecting specific germplasm with distinct genetic background for diversifying cotton breeding program in Bangladesh.

An experiment was conducted to study the in vitro culture of pointed gourd. Cotyledon rescued from physiologically matured seeds (PMS) and immatured seeds (IMS) of pointed gourd were used as explants. Cotyledon excised from PMS responded very well in all culture conditions. Plant regenerated from cotyledon of PMS ranged from 38 to 96% in different hormonal formulations of culture media. Highest percentage of shoot regeneration was observed in MS + 1.0 mg/l BAP and lowest in MS + 2.5 mg/l BAP. No plant regeneration was observed in cotyledon from immatured seeds. The highest percentage of root induction (99%) was achieved in half MS medium supplemented with 0.5 mg/l NAA. The regenerated plantlets were successfully established in earthen pot. Keywords: Cotyledon; in vitro; pointed gourd. DOI: 10.3329/bjar.v35i1.5874Bangladesh J. Agril. Res. 35(1) : 135-142, March 2010

An efficient protocol was developed for in vitro plant regeneration and multiplication through callus culture in pointed gourd. Among the explants, highest percentage of cotyledon explants (92.00%) produced callus when this explant cultured in MS medium supplemented with NAA (0.1, 0.5, 1.0, 1.5, and 2.0 mg/l) and 2, 4-D (0.1, 0.5, 1.0, 1.5, and 2.0 mg/l). The highest number of shoots per explant was observed in MS + 0.5 mg/l BAP + 0.5 mg/l NAA followed by 1.0 mg/l BAP + 0.5 mg/l NAA when inter-node derived callus cultured in MS medium. Among the explants derived calli from leaf, inter-node and cotyledon in in vitro regeneration study, inter-node appeared as the most suitable explant for callusing and plant regeneration. The best response towards root induction was achieved on half MS medium supplemented with 0.5 mg/l NAA. The regenerated plantlets were successfully established in prepared earthen soil pot.

The cucumber (Cucumis sativus L.) is one of the most important vegetables in Bangladesh as well as across the globe. However, many of the important cucumber landraces have disappeared in Bangladesh due to climate change, particularly erratic rainfall, extreme temperature, salinity, and drought. Therefore, to protect against the extinction of the cucumber landraces, we collected 103 landraces in different geographical regions of Bangladesh, including drought and saline-prone areas, and studied their divergence for the future breeding programme for the development of cultivars suitable for the climate-changing situations. Data on morphological features, yield, and its components, which include 17 qualitative and quantitative traits, were recorded during the observation. Among the cucumber landraces, the Shannon–Weaver diversity index analysis revealed the presence of genetic diversity in these landraces. The biggest diversity appeared in the fruit-related characteristics, i.e., stem end fruit shape, bottom end fruit shape, fruit shape, and fruit skin colour at the table and harvest maturity. The descriptive statistics and analysis of variance expressed a wide range of variability for quantitative traits. A broad phenotypic variation was also observed for traits such as yield plant−1 [CV (%) 31.88, ranges 0.96 to 3.11 kg] and fruits plant−1 (CV (%), 28.71, ranges, 2.58 to 9.75). High heritability (broad sense) coupled with a high genetic gain was observed for yield and yield-contributing characteristics, indicating that these characteristics are controlled by additive gene effects, and they are more reliable for effective selection. The phenotypic correlation studies showed that fruit yield plant−1 exhibited a positive and significant correlation with fruits plant−1, fruit length, fruit weight, fruit width, branches plant−1, and plant height. All landraces were grouped into six clusters, and the maximum number of landraces were accommodated in cluster VI (30), followed by cluster V (22), cluster III (22), cluster IV (14), cluster I (13), and cluster II (2). Comparing cluster means with studied traits revealed that cluster III with landraces AC-14, AC-97, AC-471, AC-451, and RAI-209 were more divergent for improving average fruit weight, fruit length, and fruit width. On the other hand, cluster IV with landraces AC-201, TT-161, RAI- 217, RAI-215, and TRMR-103 were more divergent for improving average vine length, internode length, and the number of primary branches plant−1, the number of fruits plant−1, and yield plant−1. According to the MGIDI index, AC-14 (G1), AC-201 (G7), AC-471 (G24), AC-97 (G30), RAI-215 (G68) and TT-161 (G 94) may be considered to be the best parents based on their qualitative and quantitative characteristics for the future breeding programme. Moreover, crossing between the landraces, which were collected from saline and drought areas, in clusters I, V, and VI with those in other clusters could produce suitable cucumber varieties for the climatic changing situation.

Lentil is an important pulse crop with high nutritional value and high market price worldwide. Molecular markers have emerged as useful tools to assess the genetic diversity across crops. The study was conducted to explore genetic diversity of twenty lentil genotypes considering yield and yield attributing traits. Among all genotypes, BARI Masur-6, BARI Masur-7 followed by genotypes BD-3806 and BD-4090 showed the highest value of yield attributing traits therefore, these genotypes are considered as best performer. The results of cluster analysis based on the Ward’s method grouped the genotypes into three clusters and the genotypes of cluster III revealed the maximum value for yield per plants which indicated their importance in the selection for yield improvement program of lentil. Afterwards, 20 genotypes were evaluated through 7 sets of SSR primers to assess genetic diversity among the genotypes. Among them, four sets of primers viz., SSR 19, SSR 33, SSR 90 and SSR 213 showed high polymorphism which suggesting the greater genetic diversity in the genotypes. The unweighted pair group method of arithmetic mean (UPGMA) dendrogram based on Nei’s (1973) genetic distance led the genotypes into four major clusters which showed a bit deviation with the morphological cluster. The findings of this study will be very useful for selection of appropriate parents and the genetic understanding for the set up for future systematic lentil breeding programs.

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