Reduced Glutathione Mediates Pheno-Ultrastructure, Kinome and Transportome in Chromium-Induced Brassica napus L.

Abstract

Chromium (Cr) as a toxic metal is widely used for commercial purposes and its residues have become a potential environmental threat to both human and plant health. Oilseed rape (Brassica napus L.) is one of the candidate plants that can absorb the considerable quantity of toxic metals from the soil. Here, we used two cultivars of B. napus cvs. ZS 758 (metal-tolerant) and Zheda 622 (metal-susceptible) to investigate the phenological attributes, cell ultrastructure, protein kinases (PKs) and molecular transporters (MTs) under the combined treatments of Cr stress and reduced glutathione (GSH). Seeds of these cultivars were grown in vitro at different treatments i.e., 0, 400 μM Cr, and 400 μM Cr + 1 mM GSH in control growth chamber for 6 days. Results had confirmed that Cr significantly reduced the plant length, stem and root, and fresh biomass such as leaf, stem and root. Cr noticeably caused the damages in leaf mesophyll cells. Exogenous application of GSH significantly recovered both phenological and cell structural damages in two cultivars under Cr stress. For the PKs, transcriptomic data advocated that Cr stress alone significantly increased the gene expressions of BnaA08g16610D, BnaCnng19320D, and BnaA08g00390D over that seen in controls (Ck). These genes encoded both nucleic acid and transition metal ion binding proteins, and protein kinase activity (PKA) and phosphotransferase activities in both cultivars. Similarly, the presence of Cr revealed elite MT genes [BnaA04g26560D, BnaA02g28130D, and BnaA02g01980D (novel)] that were responsible for water transmembrane transporter activity. However, GSH in combination with Cr stress significantly up-regulated the genes for PKs [such as BnaCnng69940D (novel) and BnaC08g49360D] that were related to PKA, signal transduction, and oxidoreductase activities. For MTs, BnaC01g29930D and BnaA07g14320D were responsible for secondary active transmembrane transporter and protein transporter activities that were expressed more in GSH treatment than either Ck or Cr-treated cells. In general, it can be concluded that cultivar ZS 758 is more tolerant toward Cr-induced stress than Zheda 622.

Chromium-Induced Reactive Oxygen Species Accumulation by Altering the Enzymatic Antioxidant System and Associated Cytotoxic, Genotoxic, Ultrastructural, and Photosynthetic Changes in Plants

“…It has been also reported that mitochondria were underdeveloped in the Brassica napus seedlings that were exposed to 400 µM Cr as compared seedlings exposed to control conditions [41,120]. The ultrastructural investigations also revealed that Cr(VI) stress alters plastid structure, more specifically, chloroplast, with a spherical and contracted morphology [120][121][122][123]. The irregular shape and size of the chloroplast with contained large plastoglobuli and starch grains were reported in Spirodela poyrhiza seedlings that were exposed to high Cr(VI)-level [23].…”

“…Exposure to high Cr-concentration causes mitochondrial damages, such as outer membrane rupture, swelling, deformed or altered internal cristae, dense electron accumulated materials, and spherical morphology [23,118,119]. It has been also reported that mitochondria were underdeveloped in the Brassica napus seedlings that were exposed to 400 µM Cr as compared seedlings exposed to control conditions [41,120]. The ultrastructural investigations also revealed that Cr(VI) stress alters plastid structure, more specifically, chloroplast, with a spherical and contracted morphology [120][121][122][123].…”

“…The irregular shape and size of the chloroplast with contained large plastoglobuli and starch grains were reported in Spirodela poyrhiza seedlings that were exposed to high Cr(VI)-level [23]. Cell membrane injury, disruption of cytoplasm, and vacuole upon Cr exposure are frequently reported [23,120,121]. Table 5 summarizes the ultrastructural changes reported in the different plant species exposed to Cr-stress.…”

Effect of industrial wastewater on wheat germination, growth, yield, nutrients and bioaccumulation of lead

“…Studies have indicated that chlorophyll b contents is more disturbed then chlorophyll a 39 . Rafaqat et al, reported the decline in photosynthetic rate in Brassica napus L. due to the elevated stress of chromium 5 . All the Pb treatments significantly (p ≤ 0.01; 0.05) decrease the mineral contents and the quality attributes of the wheat (Table 4).…”

“…Gill et al ., reported increased size and number of starch grains due to chromium in oilseed rape cultivars 24 . The presence of heavy metals revealed elite molecular transporters (MTs) genes that were responsible for water transmembrane transporter activity 5 . The results of the Pb accumulation in wheat plant including root, shoot and seed were depicted in the (Table 6).…”