In the plant pathogenic bacterium, Pseudomonas syringae, the exopolysaccharide levan is synthesized by extracellular levansucrase (Lsc), which is encoded by two conserved 1,296-bp genes termed lscB and lscC in P. syringae strain PG4180. A third gene, lscA, is homologous to the 1,248-bp lsc gene of the bacterium Erwinia amylovora, causing fire blight. However, lscA is not expressed in P. syringae strain PG4180. Herein, PG4180 lscA was shown to be expressed from its native promoter in the Lsc-deficient E. amylovora mutant, Ea7/74-LS6, suggesting that lscA might be closely related to the E. amylovora lsc gene. Nucleotide sequence analysis revealed that lscB and lscC homologs in several P. syringae strains are part of a highly conserved 1.8-kb region containing the ORF, flanked by 450-452-bp and 49-51-bp up- and downstream sequences, respectively. Interestingly, the 450-452-bp upstream sequence, along with the initial 48-bp ORF sequence encoding for the N-terminal 16 amino acid residues of Lsc, were found to be highly similar to the respective sequence of a putatively prophage-borne glycosyl hydrolase-encoding gene in several P. syringae genomes. Minimal promoter regions of lscB and lscC were mapped in PG4180 by deletion analysis and were found to be located in similar positions upstream of lsc genes in three P. syringae genomes. Thus, a putative 498-500-bp promoter element was identified, which possesses the prophage-associated com gene and DNA encoding common N-terminal sequences of all 1,296-bp Lsc and two glycosyl hydrolases. Since the gene product of the non-expressed 1,248-bp lscA is lacking this conserved N-terminal region but is otherwise highly homologous to those of lscB and lscC, it was concluded that lscA might have been the ancestral lsc gene in E. amylovora and P. syringae. Our data indicated that its highly expressed paralogs in P. syringae are probably derived from subsequent recombination events initiated by insertion of the 498-500-bp promoter element, described herein, containing a translational start site.
The systematic Agroforestry practice is being popular day by day in Monirampur Upazilla of Jessore district of Bangladesh. Considering this situation, the present research work was conducted with a view to know agroforestry practice and to find out the potentialities of agroforestry based on sustainability. Multistage sampling technique method by using semi-structured questionnaires was followed in the field survey to collect data and information in the year of 2014-2016 from 140 respondents in Monirampur Upazilla of Jessore district in Bangladesh to fulfill the purpose of the research. The results showed that most of the respondents are middle aged (45%), education level is primary (32%) with medium size family (54%) and 74% of the respondents are involved in agriculture. Communication exposure is very low (70%) with low organizational participation (55%). The results illustrated that the respondents preferred homestead agroforestry (55%) as their major land use practice followed by livestock under tree cover (16%), tree crop association (13%), boundary plantation (9%) and woodlot agroforestry (7%) in the research area. Besides, 80% respondents get all benefits (environmental, social, economic, and biological) followed by economic benefit directly (10%), social benefit directly (5%), environmental benefit directly (3%), and biological benefit directly (2%). Most of them (90%) get security, employment generation and household income which accelerate their livelihood pattern. Majority respondents (64%) showed more favorable attitudes, 29% respondents showed favorable attitudes, only 7% showed neutral attitudes and no one shows negative attitudes towards agroforestry. Housing condition, proper sanitation, and asset possessions before practicing agroforestry were 40%, 77% and 35% respectively and after practicing agroforestry that changed condition are 75%,100% and 60% which revealed that peoples are benefitted due to practice of agroforestry. The result also revealed that majority primary educated respondents are involved in agriculture with medium size family mostly practiced mixed agroforestry around homestead along with livestock under tree cover, tree crop association, boundary plantation, woodlot agroforestry through possessing more favorable attitudes which ensures environmental, social, economical, biological benefits, enhance livelihood pattern, security, employment, household income etc. But communication exposure and organizational participation should be increased to adopt more technique and technology. Thus, agroforestry improve the proper utilization of resources; enhance environmentally friendly, socio-economic sustainable production system and livelihood which is socially reasonable and economically feasible through diversification of input and output which reflects that agroforestry is a sustainable system in Bangladesh.
This study mainly focused on exploring perception of farmers' towards agroforestry practices and identifying the demographic factors influencing agroforestry adoption in Faridpur district. Field survey was conducted during November-December, 2016 using semistructured questionnaire. Multi-stage random sampling was used to select upazillas, unions and villages. Snowball purposive sampling was applied to select 84 respondents in total for the questionnaire survey. Chi-square was used to test variables at 5% level of significance. Homestead agroforestry was found to be the most common agroforestry practice (39.28%), followed by fruit-based agroforestry (21.42%), woodlot plantation (13.09%) and so on. Agroforestry was perceived to increase farm productivity by 82.14% of the respondents, 73.8% opined that agroforestry increase household income, while 30.95% perceived it as a means to food security. On the contrary, 34.52% opined that agroforestry practices decrease cash crops production, 17.85% of the respondents stated agroforestry as a difficult practice. Chi-square test showed no significant association between the adoption of agroforestry practices and respondent's age (P > 0.05) or income range (P > 0.05) of the respondents. On the other hand, there is a posit ive significant association between the adoption of agroforestry practices and educational level (p< 0.05) as well as the farm size (p< 0.05) of the respondents. The study suggests raising awareness regarding the benefits of agroforestry practices as well as providing technical assistance.
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