Project description:Chevallier is a heritage english landrace of barley first planted in 1820 while Tipple is modern cultivar of barley released in 2004. Pseudomonas strains were isolated from the rhizospheres of the two varieties and 22 and 20 of the most phylogenetically distinct ones were sequenced to find out the difference in genotypes preferentially selected in the rhizospheres of the two cultivars.
Project description:Mangrove Kandelia obovata, an important coastal shelterbelt and landscape tree, is distributed in tropical and subtropical shores and likely delimited in the latitudinal range by varying sensitivity to cold. Here, we explored the temporal variations in physiological status and transcriptome profiling of K. obovata under natural frost conditions at ~32oN, as well as the positive role of exogenous abscisic acid (ABA) in cold resistance.
Project description:Environmental variation along the geographical space can shape populations by natural selection. In the context of global warming and changing precipitation regimes, it is crucial to understand the role of environmental heterogeneity in tropical trees adaptation, given their disproportional contribution to water and carbon biogeochemical cycles. Here, we investigated how heterogeneity in freshwater availability along tropical wetlands has influenced molecular variations of the black mangrove (Avicennia germinans). A total of 57 trees were sampled at seven sites differing markedly in precipitation regime and riverine freshwater inputs. Using 2,297 genome‐wide single nucleotide polymorphic markers, we found signatures of natural selection by the association between variations in allele frequencies and environmental variables, including the precipitation of the warmest quarter and the annual precipitation. Additionally, we found candidate loci for selection based on statistical deviations from neutral expectations of interpopulation differentiation. Most candidate loci within transcribed sequences were functionally associated with central aspects of drought tolerance or plant response to drought. Moreover, our results suggest the occurrence of the rapid evolution of a population, probably in response to sudden and persistent limitations in plant access to soil water, following a road construction in 1974. Observations supporting rapid evolution included the reduction in tree size and changes in allele frequencies and in transcript expression associated with increased drought tolerance through the accumulation of osmoprotectants and antioxidants, biosynthesis of cuticles, protection against protein degradation, stomatal closure, photorespiration and photosynthesis. We describe a major role of spatial heterogeneity in freshwater availability in the specialization of this typically tropical tree.
Project description:Preparation of proteins from salt-gland-enriched tissues of mangrove plant is necessary for a systematic study of proteins involved in the plant’s unique desalination mechanism. Extraction of high-quality proteins from the leaves of mangrove tree species, however, is difficult due to the presence of high levels of endogenous phenolic compounds. In our study, preparation of proteins from only a part of the leaf tissues was required, rendering extraction even more challenging. By comparing several extraction methods, we developed a reliable procedure for obtaining sufficient proteins from salt gland-enriched tissues of the mangrove species Avicennia officinalis. Protein extraction was markedly improved using a phenol-based extraction method. Despite the lower protein yield obtained, one-dimensional protein gel profiles with greater resolution could be obtained, with more than twice the number of proteins detected when 1D-LC-MS/MS analyses were compared. Further analysis of proteins that were solely present in each extraction method favoured the phenol-based extraction. Phenol-based extracts contained nearly 10 times more solely-detected proteins than those were detectable in the extracts without using phenol. The protocol established could thus be applied for downstream high-throughput proteomic analyses involving LC-MS/MS or equivalent.
Project description:The roots of halophytes such as mangroves provide the first line of defense against the constant salt stress they experience. Such adaptation should include major reprogramming of the gene expression profiles. Using RNA-sequencing approach we identified 101,446 ‘all-unigenes’ from the seedling roots of the mangrove tree Avicennia officinalis. From the data 6618 genes were identified to be differentially regulated by salt when two-month-old greenhouse-grown seedlings without prior exposure to sea water were subjected to 24 h of 500 mM NaCl treatment. About 1,404 genes were significantly up-regulated, while 5214 genes were down-regulated. Based on Gene Ontology analysis, they could be classified under various categories, including metabolic processes, stress and defense response, signal transduction, transcription-related and transporters. Our analysis provides the baseline information towards understanding salt balance in mangroves and hence mechanism of salt tolerance in plants.
Project description:Temperature is an important factor that affects the growth and reproduction of mangrove plants. Laguncularia racemosa (L.) C.F. Gaertn is a controversial species in China, in terms of being a pioneer species for mangrove restoration and a putative invasive species occupying the natural habitats. One of its advantages is the strong resistance to low temperature, which makes L. racemose more adaptive to extreme climate change than local mangrove species. However, little is known about the regulatory mechanisms underlying the cold-stress tolerance in L. racemose, which restricted our understanding on its biological features and invasion potential. In this study, In the current study, we investigated the physiological and molecular mechanisms involved in chilling-stress adaptation in L. racemose. Freezing temperature caused damage to cell membrane system and reduced photosynthesis efficiency in L. racemose. To combat the adverse impacts, plasma membrane biosynthesis and antioxidant processes were substantially enhanced. Furthermore, we showed that there was a difference between the responses to freeze-thaw injury in L. racemose from different locations. It may provide new clues to the different genetic background between varieties of L. racemose. These novel findings could provide biochemical and genetic basis for the cultivation and restoration of L. racemose.
Project description:Plant salt glands are nature’s desalination devices that harbour potentially useful information pertaining to salt and water transport during secretion. As part of the program toward deciphering secretion mechanisms in salt glands, we adopted a shotgun approach to look into the proteome of salt-gland enriched tissues of the mangrove tree species Avicennia officinalis. To achieve this, we isolated the adaxial epidermal peels (which harbour the salt glands), and separated them from the mesophyll tissues of the leaves. Three biological replicates were prepared and total proteins were extracted from these tissues. Proteins that were found to be unique in salt gland-enriched tissues were obtained by eliminating proteins found in the mesophyll tissues. The proteins that are uniquely present in salt gland-enriched tissues were then selected and categorized by GO analysis.