Molecular markers assisted DNA polymorphism: Implications in mangrove research

Mangroves are defined as woody, evergreen group of plant community; grow on the swampy substrate at tropical and sub-tropical habitatsadjusted to high salinity, periodical tidal influence, strong winds, high temperatures, high precipitation and anaerobic soils. They possessunique morphological and physiological adaptive features to cope with these extreme conditions. Mangrove vegetation is the cradle of several marine fauna and provides first line of defense against devastating sea surges, typhoon, tsunami, etc. However, since industrial era, many of the mangrove members were affected by several environmental constrains and anthropogenic activities that raised the sea level, lowered sweet water influx from the adjacent rivers and encroachment for the new settlement formation, increasing salinity. Hence, mangrove restoration program is the front line topic of interest to the plant biologists across the tropical and subtropical world since it has a productive and protective role for the inhabitants. Sound knowledge of molecular characteristic of the individual taxa will be provide an advantage for this initiative.Recent advancement in molecular markers based on the PCR technique techniqueswill enhance the knowledge about genetic background of each individual taxon, ultimately leading to valid guided references towards the understanding the inherent nature of the plant itself and beneficial to proper restoration program

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Seed Structure and Germination Pattern of Some Indian Mangroves with Taxonomic Relevance

Seed morphology and germination patterns of 17 halophytes belonging to 10 families of Sundarbans, India, were studied in view of their dispersal, rehabilitation and taxonomic interest. Fruits are mostly one seeded in the investigated taxa, except in Acanthus ilicifolius, Excoecaria agallocha, Sonneratia apetala and Xylocarpus spp. Seeds are inseparable from fruits in Aegialitis rotundifolia, Aegiceras corniculatum, Avicennia spp., Nypa fruticans and the investigated species of Rhizophoraceae. Propagules are mostly dispersed by tidal water. They have to float for some distance prior to establishment for a gradual adjustment of the young ones towards the saline environment. Viviparous germination occurs in all members of Rhizophoraceae, where seed germination takes place immediatelyafter fertilization without any dormancy period. In this case the long hypocotyl comes out of the seed and ultimately from the fruit when the fruit is still attached with the mother plant. This phenomenon is considered as the most complex and highly evolved phenomenon in evolutionary line. In Aegialitis rotundifolia, Aegiceras corniculatum, Avicennia spp. And Nypa fruticans, germination occurs following an incipiently viviparous type where the hypocotyl pierces out of the seed coat but not from the exocarp at the time of dispersal. This incident should be defined more appropriately as cryptovivipary. On the basis of seed characters, an identification key was generated for easy identification of the dispersing units

Extrapolative microRNA precursor based SSR mining from tea EST database in respect to agronomic traits

Abstract Tea (Camellia sinensis, (L.) Kuntze) is considered as most popular drink across the world and it is widely consumed beverage for its several health-benefit characteristics. These positive traits primarily rely on its regulatory networks of different metabolic pathways. Development of microsatellite markers from the conserved genomic regions are being worthwhile for reviewing the genetic diversity of closely related species or self-pollinated species. Although several SSR markers have been reported, in tea, the trait-specific Simple Sequence Repeat (SSR) markers, leading to be useful in marker assisted breeding technique, are yet to be identified. Micro RNAs are short, non-coding RNA molecules, involved in post transcriptional mode of gene regulation and thus effects on related phenotype. Present study deals with identification of the microsatellite motifs within the reported and predicted miRNA precursors that are effectively followed by designing of primers from SSR flanking regions in order to PCR validation. In addition to the earlier reports, two new miRNAs are predicting here from tea expressed tag sequence database. Furthermore, 18 SSR motifs are found to be in 13 of all 33 predicted miRNAs. Trinucleotide motifs are most abundant among all followed by dinucleotides. Since, miRNA based SSR markers are evidenced to have significant role on genetic fingerprinting study, these outcomes would pave the way in developing novel markers for tagging tea specific agronomic traits as well as substantiating non-conventional breeding program

Molecular phylogeny and evidence for natural hybridization and historical introgression between Ceriops species (Rhizophoraceae)

Ceriops (Rhizophoraceae) is a genus comprised of five species of mangroves distributed in tropical and subtropical coastal regions. In this study, sequences from nuclear ribosomal ITS and the plastid trnL intron are used to construct molecular phylogenies of this genus revealing two species complexes, the C. tagal complex (C. tagal and C. australis), and the C. decandra complex (C. decandra, C. pseudodecandra and C. zippeliana), each forming a distinct clade. All five species, including the newly designated species C. pseudodecandra, are well supported. However, natural hybridization and historical introgression between Ceriops species are also demonstrated. The ITS sequences of Ceriops species, in contrast to their plastid trnL intron sequences, show a great amount of homoplasy during evolution. Historical introgression originating from natural hybridization was demonstrated based on the additivity of ITS sequences from putative parents. Of the five Ceriops species, C. pseudodecandra is a relatively isolated species. C. decandra and C. zippeliana show mutual introgression in most populations. According to both the nuclear ITS sequences and the plastid trnL intron, an intermediate form from Darwin is likely a natural hybrid, with C. tagal and C. australis respectively the maternal and paternal parents