Integration of Physical, Genetic, and Cytogenetic Mapping Data for Cellulose Synthase (CesA) Genes in Flax (Linum usitatissimum L.)

Genes Associated with the Flax Plant Type (Oil or Fiber) Identified Based on Genome and Transcriptome Sequencing Data

As a result of the breeding process, there are two main types of flax (Linum usitatissimum L.) plants. Linseed is used for obtaining seeds, while fiber flax is used for fiber production. We aimed to identify the genes associated with the flax plant type, which could be important for the formation of agronomically valuable traits. A search for polymorphisms was performed in genes involved in the biosynthesis of cell wall components, lignans, fatty acids, and ion transport based on genome sequencing data for 191 flax varieties. For 143 of the 424 studied genes (4CL, C3'H, C4H, CAD, CCR, CCoAOMT, COMT, F5H, HCT, PAL, CTL, BGAL, ABC, HMA, DIR, PLR, UGT, TUB, CESA, RGL, FAD, SAD, and ACT families), one or more polymorphisms had a strong correlation with the flax type. Based on the transcriptome sequencing data, we evaluated the expression levels for each flax type-associated gene in a wide range of tissues and suggested genes that are important for the formation of linseed or fiber flax traits. Such genes were probably subjected to the selection press and can determine not only the traits of seeds and stems but also the characteristics of the root system or resistance to stresses at a particular stage of development, which indirectly affects the ability of flax plants to produce seeds or fiber.

Copper-induced oxidative stress, initiation of antioxidants and phytoremediation potential of flax (Linum usitatissimum L.) seedlings grown under the mixing of two different soils of China

Flax (Linum usitatissimum L.), one of the oldest cultivated crops, continues to be widely grown for oil, fiber and food. Furthermore, the plants show a metal tolerance dependent on species so is ideal for research. Present study was conducted to find out the influence of copper (Cu) toxicity on plant biomass, growth, chlorophyll content, malondialdehyde (MDA) contents, proline production, antioxidative enzymes and metal up taken by L. usitatissimum from the soil grown under mixing of Cu-contaminated soil with natural soil by 0:1 (control), 1:0, 1:1, 1:2 and 1:4. Results revealed that, high concentration of Cu in the soil affected plant growth and development by reducing plant height, plant diameter and plant fresh and dry biomass and chlorophyll contents in the leaves compared with the control. Furthermore, Cu in excess causes generation of reactive oxygen species (ROS) such as superoxide radical (O^-) and hydroxyl radicals (OH), which is manifested by high malondialdehyde (MDA) and proline contents also. The increasing activities of superoxidase dismutase (SOD) and peroxidase (POD) in the roots and leaves of L. usitatissimum are involved in the scavenging of ROS. Results also showed that L. usitatissimum also has capability to revoke large amount of Cu from the contaminated soil. As Cu concentration in the soil increases, the final uptake of Cu concentration by L. usitatissimum increases. Furthermore, the soil chemical parameters (pH, electrical conductivity and cation exchange capacity) were increasing to highest levels as the ratio of Cu concentration to the natural soil increases. Thus, Cu-contaminated soil is amended with the addition of natural soil significantly reduced plant growth and biomass, while L. usitatissimum is able to revoke large amount of Cu from the soil and could be grown as flaxseed and a potential candidate for phytoremediation of Cu.

Flax tubulin and CesA superfamilies represent attractive and challenging targets for a variety of genome- and base-editing applications

Flax is both a valuable resource and an interesting model crop. Despite a long history of flax genetic transformation only one transgenic linseed cultivar has been so far registered in Canada. Implementation and use of the genome-editing technologies that allow site-directed modification of endogenous genes without the introduction of foreign genes might improve this situation. Besides its potential for boosting crop yields, genome editing is now one of the best tools for carrying out reverse genetics and it is emerging as an especially versatile tool for studying basic biology. A complex interplay between the flax tubulin family (6 α-, 14 β-, and 2 γ-tubulin genes), the building block of microtubules, and the CesA (15-16 genes), the subunit of the multimeric cellulose-synthesizing complex devoted to the oriented deposition of the cellulose microfibrils is fundamental for the biosynthesis of the cell wall. The role of the different members of each family in providing specificities to the assembled complexes in terms of structure, dynamics, activity, and interaction remains substantially obscure. Genome-editing strategies, recently shown to be successful in flax, can therefore be useful to unravel the issue of functional redundancy and provide evidence for specific interactions between different members of the tubulin and CesA gene families, in relation to different phase and mode of cell wall biosynthesis.

Novel dye for detection of callus embryo by confocal laser scanning fluorescence microscopy

In the present study a new luminescent dye 3-N-(2-pyrrolidinylacetamido)benzanthrone (AZR) was synthesized. Spectroscopic measurements of the novel benzanthrone 3-aminoderivative were performed in seven organic solvents showing strong fluorescence. The capability of the prepared dye for visualization has been tested on flax, red clover and alfalfa to determinate the embryo in plant callus tissue cultures. Callus cells were stained with AZR and further analysed utilizing confocal laser scanning fluorescence microscopy. Performed experiments show high visualization effectiveness of newly synthesized fluorescent dye AZR that is efficient in fast and relatively inexpensive diagnostics of callus embryos that are problematic due to in vitro culture specificity.

Molecular Cytogenetics of Pisum sativum L. Grown under Spaceflight-Related Stress

The ontogenesis and reproduction of plants cultivated aboard a spacecraft occur inside the unique closed ecological system wherein plants are subjected to serious abiotic stresses. For the first time, a comparative molecular cytogenetic analysis of Pisum sativum L. (Fabaceae) grown on board the RS ISS during the Expedition-14 and Expedition-16 and also plants of their succeeding (F1 and F2) generations cultivated on Earth was performed in order to reveal possible structural chromosome changes in the pea genome. The karyotypes of these plants were studied by multicolour fluorescence in situ hybridization (FISH) with five different repeated DNA sequences (45S rDNA, 5S rDNA, PisTR-B/1, microsatellite motifs (AG)12, and (GAA)9) as probes. A chromosome aberration was revealed in one F1 plant. Significant changes in distribution of the examined repeated DNAs in karyotypes of the "space grown" pea plants as well as in F1 and F2 plants cultivated on Earth were not observed if compared with control plants. Additional oligo-(GAA)9 sites were detected on chromosomes 6 and 7 in karyotypes of F1 and F2 plants. The detected changes might be related to intraspecific genomic polymorphism or plant cell adaptive responses to spaceflight-related stress factors. Our findings suggest that, despite gradual total trace contamination of the atmosphere on board the ISS associated with the extension of the space station operating life, exposure to the space environment did not induce serious chromosome reorganizations in genomes of the "space grown" pea plants and generations of these plants cultivated on Earth.