OsGLP participates in the regulation of lignin synthesis and deposition in rice against copper and cadmium toxicity

Abstract

Copper (Cu) and cadmium (Cd) are common heavy metal pollutants. When Cd and excessive Cu accumulate in plants, plant growth is reduced. Our previous study showed that Germin-like proteins (GLPs), which exist in tandem on chromosomes, are a class of soluble glycoproteins that respond to Cu stress. In this study, hydroponic cultures were carried out to investigate the effect of GLP on Cd and Cu tolerance and accumulation in rice. The results showed that knockout of a single OsGLP8-2 gene or ten OsGLP genes (OsGLP8-2 to OsGLP8-11) resulted in a similar sensitivity to Cd and Cu toxicity. When subjected to Cu and Cd stress, the glp8-2 and glp8-(2-11) mutants displayed a more sensitive phenotype based on the plant height, root length, and dry biomass of the rice seedlings. Correspondingly, Cu and Cd concentrations in the glp8-2 and glp8-(2-11) mutants were significantly higher than those in the wild-type (WT) and OsGLP8-2-overexpressing line. However, Cu and Cd accumulation in the cell wall was the opposite. Furthermore, we determined lignin accumulation. The overexpressing-OsGLP8-2 line had a higher lignin accumulation in the shoot and root cell walls than those of the WT, glp8-2, and glp8-(2-11). The expression of lignin synthesis genes in the OsGLP8-2-overexpressing line was significantly higher than that in the WT, glp8-2, and glp8-(2-11). The SOD activity of OsGLP8-2, Diaminobe-nzidine (DAB), propidium iodide (PI) staining, and Malondialdehyde (MDA) content determination suggested that OsGLP8-2 is involved in heavy metal-induced antioxidant defense in rice. Our findings clearly suggest that OsGLPs participate in responses to heavy metal stress by lignin deposition and antioxidant defense capacity in rice, and OsGLP8-2 may play a major role in the tandem repeat gene clusters of chromosome 8 under heavy metal stress conditions.

Comparison of the Effects of Gradual and Acute Treatment with Mn on Physiological Responses of Rumex hydrolapathum Plants

“…The relatively small but significant increase in peroxidase activity in control plants during cultivation could be related to increased lignification of plant leaf vasculature, leading to increased mechanical resistance of leaves in adult plants [19]. Further, increased lignification as a response to heavy metal treatment has been pointed out, which also could be associated with peroxidase functions [61][62][63].…”

Rice physical defenses and their role against insect herbivores

“…According to Kawasaki et al ( 2006 ), OsRac1, belonging to GTPases is the enzyme responsible for regulating the lignin deposition in the cells as a defense reaction and this is through the regulation of NADPH oxidase and the activities of cinnamoyl-CoA reductase 1 (OsCCR1) that is an effector of OsRac1. Similarly, another protein, named GLPs (Germin-like proteins), is also responsible for altering the lignin synthesis genes and helps regulate the lignin accumulation in the cell walls (Shanguan et al 2023 ). Needless to say, more comprehensive studies incorporating genomics and transcriptomics are needed to elucidate the genetic and molecular networks involved in the physical defense mechanisms in rice.…”

Research Progress on Mechanical Strength of Rice Stalks

“…Lignin is a class of aromatic polymers that are widely present in plant cell walls and are closely related to the mechanical strength of the stalk [20], the waterproofness of the cells, and the resistance of the plant to abiotic aggression [21]. Lignin monomers are direct precursors that make up lignin, including coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol, which are produced from phenylpropane derivatives via hydroxylation, methylation, and a series of reduction reactions [22].…”