Persicaria stagnina (Hamilt. ex Maisn.) Hassan (Polygonaceae) is a perennial herb growing mostly in marshy areas, on the edges of ponds, ditches and other watery bodies. The plant is well-known and widely distributed in Bangladesh. Extracts of this plant and some of other Persicaria species are used as folk medicine by the native people. The piscicidal and molluscicidal activities of this plant and its content have recently been reported by Balze et al. (1). As a part of our work on the chemical constituents and biological activities of different medicinal plants of Bangladesh, we investigated Persicaria stagnina and isolated a new drimane type sesquiterpene which is closely related to drimeninol (1) (2) and isodrimeninol (2) (3). The new sesquiterpene has been named stagninol (3). Many drimane-type sesquiterpenes -some of them having potent biological activities -were reported in earlier investigations from Porella vernicosa (2) and Polygonum hydropiper (3). The results of our chemical investigation of P. stagnina are presented in this communication. R3Ri H ii R2ç'The whole plant extract of Persicaria stagnina afforded in addition to tocopherol and 3-sitosterin, the new hemiacetal 3. The structure of 3 followed from the 1H-, 13CNMR spectral data (Table 1) and partial comparison of its spectral data with those of drimeninol (1) and isodrimeninol (2). The 1H-NMR spectrum showed that compound 3 is 2,3-ditigloyloxy derivative of isodrimeninol (2) and this fact is evident from the presence of the characteristic signals for two tiglates in the spectrum of 3 which are missing from the spectra of compounds I and 2. In addition to two tiglates, the 1H-NMR spectrum also showed the presence of three tertiary methyl groups, one olefinic proton, one hydroxy, and an isolated methylene group. The hydroxy group appearing at 5= 3.13 ppm as a broad singlet was confirmed by a clear band at 3420 cm1 in the IR spec-Downloaded by: Chinese University of Hong Kong. Copyrighted material.

Iron is a critical element for bacterial growth as most pathogenic bacteria relies on their host for iron supply. However, iron sources are bounded to the host iron binding protein and specific iron acquisition mechanism is required to chelate and transport the iron to the bacteria. Ferric hydroxamate uptake system or fhu is one of the transport systems that import iron in the form of ferric hydroxamate/ ferrichrome from the extracellular environment into the bacterial cytosol. In this present study, a detailed in silico structural analysis was conducted on an important component of fhu transport member from Erwinia mallotivora named as fhuB. This provide us the structural properties of the protein which includes the domain and 3D model, phylogenetic analysis and the membrane topology. For functional analysis, a knockout mutant of fhuB gene strain was generated to evaluate the effect of silencing this gene during E. mallotivora infection in papaya. When compared to the wild E. mallotivora strain, fhuB mutant strain of E. mallotivora loss its virulence in causing dieback disease symptom in papaya. The result of this study has revealed the significant role of iron acquisition and metabolism during E. mallotivora pathogenesis. This highlights fhuB role and importance as the target gene; to inhibit iron uptake in E. mallotivora for future study and as a part of future consideration for dieback disease management strategy in papaya.

Similar to animals, plants possess ‘immune memory’ in response to invading pathogens that lead to enhanced defense reaction following pathogen exposure. Systemic acquired resistance (SAR) is a well-characterized type of plant immunity and is associated with coordinated expression of a set of pathogenesis-related (PR) genes and proteins also known as SAR markers. Induction of SAR in plants was shown to be initiated by group of chemicals and biological compounds known as SAR inducers that can be used for the management of important plant diseases. Elucidation and characterization of potential SAR inducers as potential elicitors that can protect papaya from the papaya dieback disease pathogen were carried out using HRPX protein, which was produced as a recombinant protein in an Escherichia coli system. Disease severity analysis in a glasshouse experiment indicated lower disease infection rates in the HRPX-treated plants than in water-treated plants. Selected SAR-associated defense gene expression was also shown to increase in treated plants, via quantitative real-time PCR analysis, confirming enhanced disease response through SAR activation. In this report, the selected recombinant protein was shown to activate the SAR mechanism in papaya for increased tolerance against papaya dieback disease, which was proven via physiological and molecular analysis.

Mango, or Mangifera indica as it is scientifically known, is a fruit crop that has significant importance to the global economy. This study characterised 10 commercially potential mango progenies using a total of 10 SSR markers. The analysis of the 10 SSR markers revealed the presence of 34 alleles. Each locus had 2–6 alleles equal to an average of 3.40 alleles per locus. The data also showed 0.115 (MiIIHR21) to 0.692 (MiIIHR28) polymorphic information content (PIC), equal to an average of 0.431. Each locus had heterozygosity and gene diversity values ranging from 0.044 (M1) to 0.957 (MiIIHR29) and from 0.122 (MiIIHR21) to 0.730 (MiIIHR29), respectively, averaging 0.480 and 0.476 each. The range of the pairwise genetic distance was 0.000 (ND014«ND019) to 0.611 (ND020«SB003). The dendrogram analysis showed that each mango progeny was successfully differentiated using the 10 SSR markers except for ND014 and ND019. The allele combination using these 10 SSR markers could be used to develop a DNA profile for fingerprinting purposes for each progeny except for ND014 and ND019, which can only be differentiated with the addition of an extra marker. The developed DNA fingerprinting profile could be used for cultivar identification and authentication. Additionally, breeders could also use the developed DNA profiles for plant variety protection (PVP) purposes.

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