Effect of Citric Acid on Growth, Ecophysiology, Chloroplast Ultrastructure, and Phytoremediation Potential of Jute (Corchorus capsularis L.) Seedlings Exposed to Copper Stress.

Soil and water contamination from heavy metals and metalloids is one of the most discussed and caused adverse effects on food safety and marketability, crop growth due to phytotoxicity, and environmental health of soil organisms. A hydroponic investigation was executed to evaluate the influence of citric acid (CA) on copper (Cu) phytoextraction potential of jute (Corchorus capsularis L.). Three-weeks-old seedlings of C. capsularis were exposed to different Cu concentrations (0, 50, and 100 µM) with or without the application of CA (2 mM) in a nutrient growth medium. The results revealed that exposure of various levels of Cu by 50 and 100 µM significantly (p < 0.05) reduced plant growth, biomass, chlorophyll contents, gaseous exchange attributes, and damaged ultra-structure of chloroplast in C. capsularis seedlings. Furthermore, Cu toxicity also enhanced the production of malondialdehyde (MDA) which indicated the Cu-induced oxidative damage in the leaves of C. capsularis seedlings. Increasing the level of Cu in the nutrient solution significantly increased Cu uptake by the roots and shoots of C. capsularis seedlings. The application of CA into the nutrient medium significantly alleviated Cu phytotoxicity effects on C. capsularis seedlings as seen by plant growth and biomass, chlorophyll contents, gaseous exchange attributes, and ultra-structure of chloroplast. Moreover, CA supplementation also alleviated Cu-induced oxidative stress by reducing the contents of MDA. In addition, application of CA is helpful in increasing phytoremediation potential of the plant by increasing Cu concentration in the roots and shoots of the plants which is manifested by increasing the values of bioaccumulation (BAF) and translocation factors (TF) also. These observations depicted that application of CA could be a useful approach to assist Cu phytoextraction and stress tolerance against Cu in C. capsularis seedlings grown in Cu contaminated sites.

Construction of a high-resolution genetic map and identification of quantitative trait loci for salt tolerance in jute (Corchous spp.).

BACKGROUND: Jute (Corchorus spp.) is the most important natural fiber crop after cotton in terms of cultivation area and production. Salt stress greatly restricts plant development and growth. A high-density genetic linkage map is the basis of quantitative trait locus (QTLs) mapping. Several high-density genetic maps and QTLs mapping related to salt tolerance have been developed through next-generation sequencing in many crop species. However, such studies are rare for jute. Only several low-density genetic maps have been constructed and no salt tolerance-related QTL has been mapped in jute to date. RESULTS: We developed a high-density genetic map with 4839 single nucleotide polymorphism markers spanning 1375.41 cM and an average distance of 0.28 cM between adjacent markers on seven linkage groups (LGs) using an F2 jute population, LGs ranged from LG2 with 299 markers spanning 113.66 cM to LG7 with 1542 markers spanning 350.18 cM. In addition, 99.57% of gaps between adjacent markers were less than 5 cM. Three obvious and 13 minor QTLs involved in salt tolerance were identified on four LGs explaining 0.58-19.61% of the phenotypic variance. The interval length of QTL mapping varied from 1.3 to 20.2 cM. The major QTL, qJST-1, was detected under two salt stress conditions that explained 11.81 and 19.61% of the phenotypic variation, respectively, and peaked at 19.3 cM on LG4. CONCLUSIONS: We developed the first high-density and the most complete genetic map of jute to date using a genotyping-by-sequencing approach. The first QTL mapping related to salt tolerance was also carried out in jute. These results should provide useful resources for marker-assisted selection and transgenic breeding for salt tolerance at the germination stage in jute.

Phytomodulatory effects of silver nanoparticles on Corchorus olitorius: Its antiphytopathogenic and hepatoprotective potentials.

This study has reported the effects of biogenic silver nanoparticles (AgNPs) using cocoa pod extract on physiological tolerance indices, antioxidant activity and hepatoprotective potentials of Corchorus olitorius as well as its efficiency for controlling soil phytopathogens. C. olitorius seeds were grown in soil prepared with water (control), 0.05, 0.1, 0.15 and 0.2 mg AgNPs/g soil. C. olitorus grown with AgNPs had significantly (p < 0.05) higher free radical scavenging ability, ferric reducing ability, percentage germination, vigour indices, longer roots and shoots as well as lower moisture content over control. C. olitorius grown with AgNPs attenuated hydrogen peroxide (H2O2)-mediated reduction in catalase concentrations and H2O2-induced malondialdehyde elevations in liver. Efficiency of AgNPs to reduce soil phytopathogens (fungi and nematodes) revealed significant (p < 0.05) reduction in the incidences of soil and shoot Meloidogyne spp., Aspergillus terreus, A. niger, Fusarium spp. and Cladosporium spp. with increase in concentrations of AgNPs. More efficiently, there was complete extermination of A. niger and Fusarium spp. in the leaves of C. olitorius grown with AgNPs. Results in this study have shown the positive influence of AgNPs on C. olitorius by strengthening its resistance against fungi, and nematodes, improvement of its shelf-life, modulation of antioxidant activities and promotion of liver-detoxifying potentials.

Transcriptome Analysis of Two Species of Jute in Response to Polyethylene Glycol (PEG)- induced Drought Stress.

Drought stress results in significant crop yield losses. Comparative transcriptome analysis between tolerant and sensitive species can provide insights into drought tolerance mechanisms in jute. We present a comprehensive study on drought tolerance in two jute species-a drought tolerant species (Corchorus olitorius L., GF) and a drought sensitive species (Corchorus capsularis L., YY). In total, 45,831 non-redundant unigenes with average sequence length of 1421 bp were identified. Higher numbers of differentially expressed genes (DEGs) were discovered in YY (794) than in GF (39), implying that YY was relatively more vulnerable or hyper-responsive to drought stress at the molecular level; the two main pathways, phenylpropanoid biosynthesis and peroxisome pathway, significantly involved in scavenging of reactive oxygen species (ROS) and 14 unigenes in the two pathways presented a significant differential expression in response to increase of superoxide. Our classification analysis showed that 1769 transcription factors can be grouped into 81 families and 948 protein kinases (PKs) into 122 families. In YY, we identified 34 TF DEGs from and 23 PK DEGs, including 19 receptor-like kinases (RLKs). Most of these RLKs were downregulated during drought stress, implying their role as negative regulators of the drought tolerance mechanism in jute.

De novo transcriptome sequencing of two cultivated jute species under salinity stress.

Soil salinity, a major environmental stress, reduces agricultural productivity by restricting plant development and growth. Jute (Corchorus spp.), a commercially important bast fiber crop, includes two commercially cultivated species, Corchorus capsularis and Corchorus olitorius. We conducted high-throughput transcriptome sequencing of 24 C. capsularis and C. olitorius samples under salt stress and found 127 common differentially expressed genes (DEGs); additionally, 4489 and 492 common DEGs were identified in the root and leaf tissues, respectively, of both Corchorus species. Further, 32, 196, and 11 common differentially expressed transcription factors (DTFs) were detected in the leaf, root, or both tissues, respectively. Several Gene Ontology (GO) terms were enriched in NY and YY. A Kyoto Encyclopedia of Genes and Genomes analysis revealed numerous DEGs in both species. Abscisic acid and cytokinin signal pathways enriched respectively about 20 DEGs in leaves and roots of both NY and YY. The Ca2+, mitogen-activated protein kinase signaling and oxidative phosphorylation pathways were also found to be related to the plant response to salt stress, as evidenced by the DEGs in the roots of both species. These results provide insight into salt stress response mechanisms in plants as well as a basis for future breeding of salt-tolerant cultivars.

Stability analysis of a high fibre yield and low lignin content "thick stem" mutant in tossa jute (Corchorus olitorius L.).

A "thick stem" mutant of Corchorus olitorius L. was induced at M2 (0.50%, 4 h, EMS) and the true breeding mutant is assessed across generations (M5 to M7) considering morphometric traits as well as SEM analysis of pollen grains and raw jute fibres, stem anatomy, cytogenetical attributes, and lignin content in relation to control. Furthermore, single fibre diameter and tensile strength are also analysed. The objective is to assess the stability of mutant for its effective exploration for raising a new plant type in tossa jute for commercial exploitation and efficient breeding. The mutant trait is monogenic recessive to normal. Results indicate that "thick stem" mutant is stable across generations (2n = 14) with distinctive high seed and fibre yield and significantly low lignin content. Stem anatomy of the mutant shows significant enhancement in fibre zone, number of fibre pyramids and fibre bundles per pyramid, and diameter of fibre cell in relation to control. Moreover, tensile strength of mutant fibre is significantly higher than control fibre and the trait is inversely related to fibre diameter. However the mutant is associated with low germination frequency, poor seed viability, and high pollen sterility, which may be eliminated through mutational approach followed by rigorous selection and efficient breeding.

Characterization of a lignified secondary phloem fibre-deficient mutant of jute (Corchorus capsularis).

BACKGROUND AND AIMS: High lignin content of lignocellulose jute fibre does not favour its utilization in making finer fabrics and other value-added products. To aid the development of low-lignin jute fibre, this study aimed to identify a phloem fibre mutant with reduced lignin. METHODS: An x-ray-induced mutant line (CMU) of jute (Corchorus capsularis) was morphologically evaluated and the accession (CMU 013) with the most undulated phenotype was compared with its normal parent (JRC 212) for its growth, secondary fibre development and lignification of the fibre cell wall. KEY RESULTS: The normal and mutant plants showed similar leaf photosynthetic rates. The mutant grew more slowly, had shorter internodes and yielded much less fibre after retting. The fibre of the mutant contained 50 % less lignin but comparatively more cellulose than that of the normal type. Differentiation of primary and secondary vascular tissues throughout the CMU 013 stem was regular but it did not have secondary phloem fibre bundles as in JRC 212. Instead, a few thin-walled, less lignified fibre cells formed uni- or biseriate radial rows within the phloem wedges of the middle stem. The lower and earliest developed part of the mutant stem had no lignified fibre cells. This developmental deficiency in lignification of fibre cells was correlated to a similar deficiency in phenylalanine ammonia lyase activity, but not peroxidase activity, in the bark tissue along the stem axis. In spite of severe reduction in lignin synthesis in the phloem cells this mutant functioned normally and bred true. CONCLUSIONS: In view of the observations made, the mutant is designated as deficient lignified phloem fibre (dlpf). This mutant may be utilized to engineer low-lignin jute fibre strains and may also serve as a model to study the positional information that coordinates secondary wall thickening of fibre cells.