Composite Attribute Based Ad-hoc On Demand Multipath Distance Vector Routing Protocol (CAB-AOMDV)

281-284In this paper composite attribute-based ad-hoc on demand multipath distance vector (CAB-AOMDV) routing protocol has been proposed. Composite attributes are used to select the optimized multiple path for transmitting data and determined what percentage of total data can be share by the specific path. Composite factor is the combination of two factors, one is drop and another is queue factor. The performance analysis is evaluated under various node densities. Using control-overhead (CO), normalized-routing-overhead and throughput performance of proposed CAB-AOMDV is compared with Risk factor-based Ad-hoc on demand multipath (RF-AOMDV) routing protocol, from where it is observed that performance of proposed CAB-AOMDV is outperform RF-AOMDV in respect of all scenario taken into considerations

In vitro cultivation and regeneration of Solanum melongena (L.) using stem, root and leaf explants

The treatment combinations was BAP (0, 2.0, 3.0 and 4.0 mg/L) and NAA (0, 0.1, 0.5, and 1.0 mg/L). The rate of callus formation varied in different treatments. The highest amount of callus (48.66%) was produced on MS medium containing 2.0 mg/l BAP and 0.5 mg/l NAA from stem and 8.2 days required for callus induction. The number of shoot regenerated through callus from stem containing 2.0 mg/l BAP and 0.5 mg/l NAA was 3.4 (23.287%) and days required for 38.8 days. Key words: Regeneration; BAP; NAA. Nepal Journal of Biotechnology. Jan. 2011, Vol. 1, No. 1 : 49-5

Biochemical changes of rice genotypes against blast (Magnaporthe oryzae) disease and SSR marker validation for resistance genes

Rice blast caused by Magnoporthe oryzae is a major devastating fungal disease and represents a potential threat to world rice productions. However, information about the genetic and biochemical basis of disease tolerance is still limited. In this study, we tested the presence and diversity of resistant R genes using SSR markers, and the antioxidant enzymes catalase (CAT), ascorbate peroxidise (APX) and guaicol peroxidise (POD), activity and also the concentration of hydrogen peroxide (H2O2) and malondialdehyde (MDA) in resistant (BAUdhan 3) and susceptible (BRRIdhan 28) genotype. Molecular marker analysis reveals the presence of all ten studied resistant genes in BAUdhan 3. Among the markers studied, three markers namely RM224, RM72 and RM206 produce distinct band only in resistant genotype BAUdhan 3, which might be used to screen resistant genotypes. The enzymatic activity of APX, CAT and POD increased in the inoculated plant for both cultivars but the increase was more prominent for BAUdhan 3. The M. oryzae infections significantly increased the H2O2 content in BRRIdhan 28 and not much changed in BAUdhan 3. The MDA concentration was higher in the leaves of inoculated plants of BRRIdhan 28. The higher activities of APX and POD in the leaves of the inoculated plants of BAUdhan 3 resulted in lower H2O2 accumulation which can minimize the cellular damages possibly caused by reactive oxygen species. The result shows that the presence of more resistance genes and an effective antioxidative system in BAUdhan 3, which limits the damage caused due to fungal infection and thus contributes to greater resistance

Composite Attribute Based Ad-hoc On Demand Multipath Distance Vector Routing Protocol (CAB-AOMDV)

In this paper composite attribute-based ad-hoc on demand multipath distance vector (CAB-AOMDV) routing protocol has been proposed. Composite attributes are used to select the optimized multiple path for transmitting data and determined what percentage of total data can be share by the specific path. Composite factor is the combination of two factors, one is drop and another is queue factor. The performance analysis is evaluated under various node densities. Using control-overhead (CO), normalized-routing-overhead and throughput performance of proposed CAB-AOMDV is compared with Risk factor-based Ad-hoc on demand multipath (RF-AOMDV) routing protocol, from where it is observed that performance of proposed CAB-AOMDV is outperform RF-AOMDV in respect of all scenario taken into considerations

Response of morphological and biochemical traits of maize genotypes under waterlogging stress

Maize (Zea mays L.) is one of the most important cereal crops cultivated around the world. Waterlogging stress is a major production constraint of maize production in rain-fed agricultural systems. The main objective of this experiment was to investigate the effect of continuous waterlogging on morphological and biochemical traits of maize genotypes at the vegetative stage. Ten maize genotypes were treated under no waterlogging (control) and continuous waterlogging of five centimeters depth for 10 days. The treatments were applied to the plants at their 45 days of age. Visual leaf injury scores from Leaf 4 (youngest leaf is the reference point) to Leaf 7 separated tolerant and susceptible genotypes. Waterlogging stress significantly reduced the total number of live leaves and chlorophyll content in leaf tissues in susceptible genotypes. The anatomical study revealed that tolerant maize genotypes produce a large number of aerenchyma cells under waterlogging stress compared to susceptible genotypes. The enzymatic activities of ascorbate peroxidase (APX) and peroxidase (POD) exhibited a greater increase in tolerant genotypes than susceptible genotypes whereas the contents of reactive oxygen species (H2O2) greatly increased in susceptible genotypes than tolerant genotypes under waterlogging stress compared to control. Principal component 2 (PC2) indicated that increasing plant height in the genotypes BHM-14, BHM-13 and BHM-9 was associated with waterlogging tolerance. The findings of this experiment will add value to maize breeding to screen out maize genotypes for waterlogging stress tolerance

Molecular and pathological identification of maize genotypes having Wsm gene governing resistance against MDMV and MCDV

Maize is seriously affected by different viruses like Maize Dwarf Mosaic Virus (MDMV) and Maize Chlorotic Dwarf Virus (MCDV) throughout the world. In Bangladesh, no genotype has been identified yet as a source of resistant gene against MDMV and MCDV. The study was carried out with the objective to screen nine maize genotypes carrying Wsm gene using three sets of Single Sequence Repeat (SSR) marker. Maize plants were inoculated with viruses. Symptoms were scored at 7, 10 and 14 dpi (days post inoculation) to calculate infection percentage and Area Under Disease Progress Curve (AUDPC). The molecular result indicated that BHM-7, BHM-5, V-92, Uttaran and Duranta carried Wsm gene, but according to pathological test, functional resistance was observed for only BHM-7, V-92 and Uttaran on the basis of infection percentage and AUDPC score. BHM-7 (BARI Hybrid Maize 7) was noticed as the best one for showing resistance against MDMV and carrying Wsm gene. No genotype was found to govern resistance against MCDV

Evaluation of rice (Oryza sativa L.) genotypes grown under combined salinity and submergence stresses based on vegetative stage phenotyping

Sixteen rice genotypes were screened against combined salinity and submergence stresses to find out potential salt-submergence tolerant genotypes. Rice seedlings were subjected to submergence stress including two salinity levels viz., EC-6 dSm-1 and EC-8 dSm-1 for 10 days. Imposition of combined stress considerably decreased the growth parameters in rice seedlings, however ACM-18, ACM-35, and RC-251 demonstrated the maximum value for growth attributes such as leaf live (%), root and shoot length, plant fresh and dry biomass. The results of correlation and regression revealed a significant and negative association of leaf lives (%), root length, fresh weight of root and shoot, and root dry weight with mean tolerance score under combined stress indicating their importance as the useful descriptors for the selection. Euclidean clustering was categorized the rice genotypes into three major clusters, i.e., A-susceptible, B-tolerant and moderately tolerant, and C-highly tolerant. Results of cluster analysis showed that the highly tolerant genotypes namely ACM-18, ACM-35, and RC-251 were placed in the same cluster. Similar results were further confirmed by principal component analysis having the highly tolerant genotypes in the same group. Combining the morphological and multivariate analysis, ACM-18, ACM-35, and RC-251 were selected as promising genotypes for developing high-yielding salt-submergence tolerant rice

Epidemiology, Genetics and Resistance of <em>Alternaria</em> Blight in Oilseed <em>Brassica</em>

Alternaria blight is one of the most deadly diseases of oilseed Brassica. This recalcitrant disease causes up to 50% yield loss across the globe. The disease is mainly caused by Alternaria brassicae and Alternaria brassicicola. These pathogens lack sexual stages and survive as conidia or condiospores on the debris of previous crops and susceptible weeds. Developing resistant oilseed Brassica cultivars to this disease has become a prime concern for researchers over the years. In absence of resistant oilseed Brassica cultivar, identification and introgression of resistance related genes can be a potential source for Alternaria blight resistance. As resistance toward Alternaria blight is governed by polygenes, intercrossing between the tolerant genotypes and subsequent selection will be the most appropriate way to transfer the quantitative resistance. For that reason, future breeding goal should focus on screening of germplasms for selecting genotypes containing resistance genes and structural features that favors resistance, like thick epicuticular wax, biochemical components such as phenols, phytoalexins and lower soluble sugars, reducing sugars and soluble nitrogen. Selected genotypes should be brought under appropriate breeding programs for attaining Alternaria blight resistance

Adaptive Mechanisms of Root System of Rice for Withstanding Osmotic Stress

Being one of the major cereal crops, rice has a great effect on food security of the world population. But worldwide rice production faces severe threat due to a combination of factors like uncontrolled human rise, limited agricultural land and increasing environmental stresses. Coping with this situation is an urgent call for meeting the challenge. For overwhelming rice production by battling with this condition, scientists and researchers try their best to develop such rice varieties which can adapt to adverse climatic conditions. But, the majority of the research efforts are given on above ground parts of rice to make it stress tolerant. Root, one of the major parts of plant, remains unnoticed although it has immense possibility of adaptation under stress conditions. Fruitful and efficient utilization of limited resources are possible through healthier and competent root systems. Selection and breeding of rice genotypes with extensive root systems may contribute to more efficient use of soil nutrient resources and this ultimately influences the yield stability of rice

Drought Affected Wheat Production in Bangladesh and Breeding Strategies for Drought Tolerance

Wheat is one of the major cereal crops in Bangladesh. Over the last two decades, wheat consumption has passionately amplified in Bangladesh but its production has declined due to various stress environments. Recurrent drought event due to climate change that threatens the country’s food safety has become a serious concern. To safeguard the food security, adopting suitable breeding strategies can add momentum. Developing drought tolerant wheat varieties are the definitive means of protecting the crop against hostile effects of drought. Plant breeders are exploring various breeding strategies to breed for the varieties that can cope with water deficient conditions well. Besides, breeders are consistently looking for new prospects and strategies that can boost genetic gain in yield. To endorse drought tolerance in wheat, understanding the physiological and genetic adaptation mechanisms of wheat cultivars during drought stress would provide the estimated benchmarks to adjust for suitable breeding programs. The efforts of developing drought tolerant wheat genotypes could be supported by different breeding strategies including in vitro haploid and double haploid protocols, polyploidization, development of various types of hybrids and induced mutants by utilizing both classical and molecular breeding techniques. The proposed book chapter shall discuss the pattern of drought-stress in the wheat growing regions, effects of drought stress on wheat production and suitable breeding strategies for developing drought tolerant genotypes in Bangladesh