Proteomic analysis of naturally occurring boron tolerant plant Gypsophila sphaerocephala L. in response to high boron concentration.

Gypsophila sphaerocephala is a naturally Boron (B) tolerant species that can grow around the B mining areas in Turkey, where the B concentration in soil reaches a lethal dose for plants (up to ∼8900mgkg-1 (∼140mM). While its interesting survival capacity in extremely B containing soils, any molecular research has been conducted to understand its high tolerance mechanism yet. In the present study, we have performed a proteomic analysis of this plant to understand its high tolerance towards B-stress. Seedlings of G. sphaerocephala were collected from B mining area and were adapted to greenhouse conditions. An excessive level of Boric acid (3mM)was applied to the plantlets for 24h. Total proteins were precipitated by using TCA/Acetone method. 2D-PAGE (two-dimensional polyacrylamide gel electrophoresis) analysis of the proteins was carried out. Out of 121 protein spots, 14 were differentially expressed between the control and B-exposed G. sphaerocephala roots. The peptide profile of each protein was determined by MALDI-TOF mass spectrometer after in-gel trypsin digestion. The identified proteins are involved in different mechanisms in the cell such as in antioxidant mechanism, energy metabolism, protein degradation, lipid biosynthesis and signaling pathways, indicating that G. sphaerocephala has multiple cooperating mechanisms to protect itself from high B levels. Overall, this study sheds light on to the possible regulatory switches (gene/s) controlling the B-tolerance proteins and their possible roles in plant's defense mechanism.

Transcriptome-wide identification of R2R3-MYB transcription factors in barley with their boron responsive expression analysis.

MYB family of transcription factors (TF) comprises one of the largest transcription factors in plants and is represented in all eukaryotes. They include highly conserved MYB repeats (1R, R2R3, 3R, and 4R) in the N-terminus. In addition to this, they have diverse C-terminal sequences which help the protein gain wide distinct functions, such as controlling development, secondary metabolism, hormonal regulation and response to biotic and abiotic stress. Stress-responsive roles of the MYB TFs were reported for drought, salt, wounding, cold, freezing, dehydration and osmotic stresses. This study describes the identification of barley R2R3-MYB TFs including their expression analysis in tissues under control and Boron (B) toxic conditions. Conserved motifs for MYB proteins were searched into barley full-transcriptome RNA-seq data and a total of 320 protein sequences were filtered as MYB TFs in which 51 of them corresponded to R2R3 MYB TFs. Using various bioinformatics tools, their conserved domain structures, chromosomal distributions, gene duplications, comparative functional analysis, as well as phylogenetic relations with Arabidopsis thaliana, were conducted. Beside the RNA-seq data-based expression pattern analysis of 51 R2R3 MYB TFs, quantitative analysis of selected R2R3 MYB TF genes was assessed in control and B-stressed root and leaf tissues. Critical B-induced R2R3 MYB TFs were identified. It was concluded that the results would be useful for functional characterizations of R2R3-type MYB transcription factors that are possibly involved in both B stress and divergent regulation mechanisms in plants.