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Kenaf (Hibiscus cannabinus L.) is suitable for growing in heavy metal-polluted soil for non-food purposes, and can be used as a potential crop to remediate heavy metal-contaminated soil. The main objective of this study was to investigate kenaf phytoextraction of cadmium (Cd), including uptake, translocation, and accumulation differences in tissues among kenaf cultivars. A field experiment was conducted in a Cd contaminated paddy field in southern China area with 13 kenaf cultivars in 2015 and 2016. Agronomic performance, Cd concentrations in plant tissues (root, xylem, and phloem), and biomass of different tissues of each cultivar were measured and evaluated. Significant differences in Cd concentrations and accumulation among tissues and cultivars were observed. The phloem had the highest Cd accumulation and transfer capability compare with the roots and xylem. Approximately 35 ~ 65g of Cd could be taken up by the aerial parts of different kenaf cultivars within every hectare of soil. The percentage of Cd uptake by the phloem ranged from 47–61% and by the xylem ranged from 38–53%. By evaluating the agronomic traits and Cd bioaccumulation capacity, Fuhong 952, Fuhong 992, and Fuhong R1 were regarded as Cd accumulators for the phytoremediation of Cd-contaminated soil. Our study clearly demonstrated that a significant level of Cd in the soil was taken up through the phytoremediation with kenaf. In addition, harmless utilization of kenaf planting in Cd-contaminated paddy soil was discussed.

The cellulose synthase gene superfamily is vital for cell wall biogenesis during plant growth, particularly for flax fiber development. This study performed asequencing search of key CESA and CSL g...

Industrial hemp (Cannabis sativa L.), as one of the most important traditional natural fiber crops, had almost been forgotten for the last several decades. However, an unprecedented opportunity has...

The present study was intendant to evaluate variations among flaxseed varities in terms of fatty acid composition, phytochemical profiles, and antioxidant activities determined by oxygen radical absorbance capacity (ORAC), 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferrous ion reducing antioxidant power (FRAP) assays. Significant variations in the fatty acid composition, phenolic acids and lignan were observed in flaxseed varieties from different countries. Among these flaxseed verities, the unsaturated fatty acids accounted over four fifths of total fatty acid contents. The highest ratio of linolenic acid of total fatty acid was observed in USPEA, whereas the lowest one was found in Yexiao. USPEA showed the most contents of total phenolics, as well as flaxseed lignans. In general, total phenolics appeared to be the main contributors in the antioxidant capacity of flaxseed, which presented significant positive correlation. Our study revealed that both cultivar and origin of seeds significantly affect fatty acid composition, phenolic acids, lignans and subsequent antioxidant activities in flaxseed. The results provide new aspects of breeding resources of flaxseed cultivars by presenting their quality specification and possible commercial value.

Flax (Linum usitatissimum L.) is suitable for growing in heavy metal polluted soil for non-food purposes and can be used as potential crops for cleaning the soil from heavy metals. The main objecti...

Background: The cellulose synthase gene superfamily, including the cellulose synthase (CESA) and cellulose synthase-like (CSL) gene families, is vital for cell wall construction during plant growth, particularly for fiber development of flax, which is an old and important fiber crop. Results: This study performed a sequencing search of key CESA and CSL genes from several flax stem parts at different fiber development stages by comparing RNA-Seq. Quantitative RT-PCR was used to validate the expression of these genes. This study revealed that CESA4 genes (Lus10008225.g and Lus10008226.g), CESA6 genes (Lus10006161.g and Lus10041063.g), CESA8 genes (Lus10007296.g and Lus10029245.g), CSLD4 gene (Lus10026568.g), CSLE1 (Lus10016625.g) and CSLG genes (Lus10023056.g and Lus10023057.g) were specifically expressed in stem tissue below the snap point where fibers is increased amounts of secondary cell wall deposition. LusCESA4 genes, LusCESA8, genes and LusCSLD4 gene were specifically expressed in fiber development stage during the fast growth period of flax plants. Based on GO and KEGG analyses, it was found that genes involved in pathways of cellulose microfibril organization, galactosyl transferase activity and galactose metabolism were specifically enriched in the stem tissue of the fiber development stage. Other genes involved in cellulose biosynthesis were also analyzed and discussed. Conclusion: The results of this study will provide an important foundation for understanding fiber cell wall biogenesis, particularly the roles of LusCESAs and LusCSLs in the process of fiber development.

Cadmium (Cd) pollution in both water bodies and farmlands seriously threatens human health, removing Cd from these environments is of great importance. Previous studies have proved ramie has great potential to remediate Cd pollution, however, its remediation efficiency depends greatly on the varieties of ramie. Therefore, in the present study, 165 ramie germplasms were selected to investigate their responses to Cd stress and the potential to remediate Cd pollution via a hydroponic trial. Results showed that Cd stress significantly inhibited the growth of ramie, the average ramie plant height, stem diameter, root length, and biomass under Cd stress were significantly decreased compared with that under control treatment; Cd stress can elevate the nutrient contents (B, Fe, K, Mg, P) in the aboveground part of ramie to some extent, but significantly reduce the accumulations of these elements. The Cd content in the aboveground part of ramie under Cd stress ranged from 61.7 mg kg−1 to 643 mg kg-1 with an average of 231 mg kg-1, and the Cd uptake ranged from 0.001 mg plant−1 to 0.71 mg plant-1 with an average of 0.15 mg plant-1. Correlation analysis indicated that the enrichment of K and Mg can significantly reduce the Cd absorption in ramie but the enrichment of P seemed to enhance the Cd accumulation in ramie. Hence, ramie has great potential to be used for phytoremediation of Cd and further studies are needed to explore the suitability of these ramie germplasms for remediation of Cd-contaminated soil as well as the interactions between nutrient elements and Cd, and the results of this study can provide valuable references for finding the genes related to Cd-resistance and Cd-accumulation in ramie and for further breeding transgenic varieties with higher Cd-remediation efficiency.

Given the special pharmacological value of cannabidiol (CBD), industrial hemp (hemp) has become a real “hot” crop. Though indoor farming of hemp has been widely used, the effects of red and blue light-emitting diode (LED) acting as supplementary light on the CBD synthesis in hemp remains unclear. Herein, a pot experiment with six treatments [CK, high-pressure sodium as light source, (R:B (ratio of red light to blue light) 9.30:1, PPFD (photosynthetic photon flux density) 191); LED1 (R:B 9.20:1; PPFD 129); LED2 (R:B 1.61:1; PPFD 540); LED3 (R:B 6.47:1; PPFD 28.2); LED4 (R:B 7.15:1; PPFD 41.7); LED5 (R:B 16.8:1; PPFD 252)] was carried out to study the effects of LED light quality on the growth and cannabinoid synthesis of hemp. Results showed that LED2 and LED5 could well maintain hemp growth compared with CK in terms of plant height, stem diameter, and leaf numbers. Compared with CK, the treatment of LED1, LED4, and LED3 significantly decreased the aboveground biomass, while LED2 and LED5 notably improved the aboveground biomass with an increment of 15.2 % and 55.1 %; the biomass of hemp flowers for LED2 and LED5 was markedly increased compared with that for CK with increments of 238 % and 61.5 %, respectively, but the other LED light treatments significantly reduced the flowers yield; LED2 could significantly increase the CBD content of both leaves (1.81 %) and flowers (5.83 %) compared to CK (leaves 1.38 %, flowers 4.27 %) while LED5 only notably increased the CBD content of leaves; among the LED treatments, the theoretic CBD yield for a per plant of LED2 and LED5 was 26.8 % and 9.0 % higher than that of CK. In conclusion, different red and blue LED light intensity ratios would dramatically influence the growth and cannabinoid synthesis of hemp, LED2 and LED5 can be good choices for indoor farming of hemp targeted for higher CBD yield.

To better understand the molecular mechanisms and gene expression characteristics associated with development of bast fiber cell within flax stem phloem, the gene expression profiling of flax stem peels and leaves were screened, using Illumina's Digital Gene Expression (DGE) analysis. Four DGE libraries (2 for stem peel and 2 for leaf), ranging from 6.7 to 9.2 million clean reads were obtained, which produced 7.0 million and 6.8 million mapped reads for flax stem peel and leave, respectively. By differential gene expression analysis, a total of 975 genes, of which 708 (73%) genes have protein-coding annotation, were identified as phloem enriched genes putatively involved in the processes of polysaccharide and cell wall metabolism. Differential expression genes (DEGs) was validated using quantitative RT-PCR, the expression pattern of all nine genes determined by qRT-PCR fitted in well with that obtained by sequencing analysis. Cluster and Gene Ontology (GO) analysis revealed that a large number of genes related to metabolic process, catalytic activity and binding category were expressed predominantly in the stem peels. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the phloem enriched genes suggested approximately 111 biological pathways. The large number of genes and pathways produced from DGE sequencing will expand our understanding of the complex molecular and cellular events in flax bast fiber development and provide a foundation for future studies on fiber development in other bast fiber crops.

Flax (Linum usitatissimum) is an important bast fiber crop. High lignin content in the flax fiber greatly affects the per- formance and quality in the flax textile industry. CCoAOMT1, 4CL1, 4CL2, COMT, F5H1, F5H2, and F5H3 are putative genes coding the key enzymes involved in lignin accumulation. The expression patterns of these genes were analyzed by semi-quantitative RT-PCR in different flax tissues and in xylem and phloem (bark) at different development stages of the variety Baihua. The results revealed that all genes were detected to express in seedlings, roots, florescent xylem, florescent phloem, leaves, flowers, and young fruits excluding F5H1 in roots. Expression of CCoAOMT1 was consistently high in all the tissues detected. There existed complementary expression between two 4CL genes and among the three F5H genes in various tissues. In the phloem, all genes lowly expressed except for 4CL2 at florescence and highly expressed after flowering. The expression of 4CL1 was high, and that of F5H3 was low in the phloem at all stages compared with that of other genes. In the xylem, expression of 4CL1 gene was low at all the developing stages, that of F5H1 reached a peak before flowering and that of the other genes in the xylem reached the highest at 30 d after emergence of seedlings and gradually declined at late growing stages, with a sharp de- crease to very lower level after flowering. The expression of 4CL1compared with other genes was significantly higher in phloem

Flax (Linum usitatissimum L.) is the third largest natural fiber crop and one of the five major oil crops in the world. Flax can be used as model plant for the bast fiber plants because of its small size and self pollination characters. Development of highly polymorphic co-dominant markers will be important for the molecular and genomic research in flax. Two microsatellite-enriched flax genomic libraries were constructed for trinucleotide TTC and ATC motifs. A total of 206 new microsatellite-containing sequences were identified and classified. Thirty eight polymorphic microsatellite markers were characterized and evaluated in eight cultivars from different countries and regions. These loci produced 2 to 12 alleles per locus with an average of 3.395. The observed and expected heterozygosities ranged from 0.000 to 1.000 (mean 0.257) and from 0.125 to 0.950 (mean 0.516), respectively. The mean polymorphic information content (PIC) value over 38 loci was 0.429, with 13 locihaving PIC greater than 0.5. These novel polymorphic microsatellite loci will be useful in genetic linkage map construction, germplasm classification and identification, gene identification and QTL mapping, and marker-assisted selection in breeding of L. usitatissimum.Key words: Flax, Linum usitatissimum, microsatellite, polymorphism.