plant-growth-agrobacterium-mediated-floral-dip-transformation

Plant Growth and Agrobacterium-mediated Floral-dip Transformation of the Extremophyte <em>Schrenkiella parvula</em>

Schrenkiella parvula is an extremophyte adapted to various abiotic stresses, including multiple ion toxicity stresses. Despite high-quality genomic ...

Louisiana State University

Endopolyploidy occurs when DNA replication takes place without subsequent mitotic nuclear division, resulting in cell-specific ploidy levels within tissues. In plants, endopolyploidy plays an important role in sustaining growth and development, but only a few studies have demonstrated a role in abiotic stress response. In this study, we investigated the function of ploidy level and nuclear and cell size in leaf expansion throughout development and tracked cell type-specific ploidy in the halophyte  In addition to developmental endopolyploidy, we examined the effects of salinity stress on ploidy level. We focused specifically on epidermal bladder cells (EBC), which are modified balloon-like trichomes, due to their large size and role in salt accumulation. Our results demonstrate that ploidy increases as the leaves expand in a similar manner for each leaf type, and ploidy levels up to 512C were recorded for nuclei in EBC of leaves of adult plants. Salt treatment led to a significant increase in ploidy levels in the EBC, and these cells showed spatially related differences in their ploidy and nuclear and cell size depending on the positions on the leaf and stem surface. Transcriptome analysis highlighted salinity-induced changes in genes involved in DNA replication, cell cycle, endoreduplication, and trichome development in EBC. The increase in cell size and ploidy observed in  under salinity stress may contribute to salt tolerance by increasing the storage capacity for sodium sequestration brought about by higher metabolic activity driving rapid cell enlargement in the leaf tissue and EBC.

Making Epidermal Bladder Cells Bigger: Developmental- and Salinity-Induced Endopolyploidy in a Model Halophyte.

Seedling establishment in an extreme environment requires an integrated genomic and physiological response to survive multiple abiotic stresses. The extremophyte, Haloxylon ammodendron is a pioneer species capable of colonizing temperate desert sand dunes. We investigated the induced and basal transcriptomes in H. ammodendron under water-deficit stress during early seedling establishment. We find that not only drought-responsive genes, but multiple genes in pathways associated with salt, osmotic, cold, UV, and high-light stresses were induced, suggesting an altered regulatory stress response system. Additionally, H. ammodendron exhibited enhanced biotic stress tolerance by down-regulation of genes that were generally up-regulated during pathogen entry in susceptible plants. By comparing the H. ammodendron basal transcriptome to six closely related transcriptomes in Amaranthaceae, we detected enriched basal level transcripts in H. ammodendron that shows preadaptation to abiotic stress and pathogens. We found transcripts that were generally maintained at low levels and some induced only under abiotic stress in the stress-sensitive model, Arabidopsis thaliana to be highly expressed under basal conditions in the Amaranthaceae transcriptomes including H. ammodendron. H. ammodendron shows coordinated expression of genes that regulate stress tolerance and seedling development resource allocation to support survival against multiple stresses in a sand dune dominated temperate desert environment.

Article	Year
Making Epidermal Bladder Cells Bigger: Developmental- and Salinity-Induced Endopolyploidy in a Model Halophyte. Plant physiology\| PubMed ID: 29724770	2018
Transcriptomic view of survival during early seedling growth of the extremophyte Haloxylon ammodendron. Plant physiology and biochemistry : PPB\| PubMed ID: 30292980	2018

Kieu-Nga Tran

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