Deterioration of Antioxidant Competence in Barley Lesion Mimic Mutant 194

Abstract

A barley mutant, 194, was observed to exhibit a leaf spot phenotype over the whole course of its growing period. In this study, the phenotype and antioxidant competence were studied in the lesion mimic mutant 194. Plant height was slightly higher in mutant 194 than in the wild type (WT). In addition, leaf spot per plant in mutant 194 was significantly higher than in WT. Antioxidant competence, as indicated by reactive oxygen species (ROS) accumulation, antioxidant enzyme activity, and the expression of antioxidant enzyme-encoding genes was also assessed in mutant 194. Compared to the WT, mutant 194 displayed a relatively higher accumulation of ROS, accompanied by lower activities of some antioxidant enzymes and downregulation of antioxidant enzyme-encoding genes. This demonstrated reduced antioxidant competence in mutant 194. The results suggested that this lower antioxidant competence of mutant 194 could lead to the accumulation of excessive ROS. This excess of ROS could induce programmed cell death and has the potential to promote disease resistance in mutant 194.

Effects of Exogenous Manganese (Mn) on Mineral Elements, Polyamines and Antioxidants in Apple Rootstock Malus robusta Rehd.

“…The protection of cells from oxidative injury under abiotic stress condition largely depends on the competence of plants managing its resistant systems. Antioxidant enzymes such as superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and antioxidants such as non-protein thiol (NPT), anthocyanin and soluble sugar, play a crucial role in protecting plant cells from oxidative damage [6][7][8]. Due to the chemical similarity and common transporters of heavy metal, considerable attention has been paid to the involvement of plant nutrient elements in the acquisition of tolerance to various environmental stresses [9].…”

Role of reactive oxygen species in lesion mimic formation and conferred basal resistance to Fusarium graminearum in barley lesion mimic mutant 5386

“…Brown spot phenotype of LMM 5386 lines Barley (Hordeum vulgare, 2n = 14), the fourth largest cereal crop in the world, offers high yields and good stress tolerance (Hao et al, 2019) and presents diverse morphological and genetic features, making it a model species for the Triticeae tribe. LMs are common in plant mutation populations, and LMMs with abundant phenotype have been reported in rice and Arabidopsis thaliana (Meskauskiene et al, 2011;Harkenrider et al, 2016), such as small red, reddish-brown, tiny black, and yellow leaf spots (Hao et al, 2019). We identified the novel LMM 5386 in barley, which spontaneously produced many large and severe brown spots at the four-leaf stage and then spread throughout the plant in the whole growth stage (Figure 1).…”

“…LMM 5386 lines confer basal resistance to Fusarium graminearum Currently, more than 30 LMMs have been identified exhibiting blast disease resistance (Zhu et al, 2016). Salicylic acid (SA), jasmonic (JA), and ethylene (ET) are important to the disease resistance of LMMs (Lorenzo et al, 2003;Vlot et al, 2009;Hao et al, 2019). SA protects plants from biotrophic pathogens, whereas JA and ET protect plants from necrotrophic pathogens (Glazebrook, 2005).…”

“…LMMs are crucial for studying hypersensitive responses (HRs) in plants (Bruggeman et al, 2015), and the level of reactive oxygen species (ROS) has been identified as capable of producing LMMs (Sindhu et al, 2018). Hao et al (2019) reported that autonomic lesions associated with LMM194 were often accompanied by excessive ROS, occasionally leading to cell death. Rice containing LMM6 were more resistant to blast fungus and had higher ROS accumulations (Xiao et al, 2015).…”

“…Rice containing LMM6 were more resistant to blast fungus and had higher ROS accumulations (Xiao et al, 2015). Oxidative stress genes are also expressed in LMM lines (Devadas et al, 2002;Torres et al, 2002), as are enzymes involved in antioxidant systems such as glutathione S-transferase (GST), peroxidase (POD), and superoxide dismutase (SOD) (Klibenstein et al, 1999;Hao et al, 2019), suggesting that oxidative stress signals are activated by LM genes. Some LMMs have been isolated in plants, most of which displaying enhanced pathogen resistance; for example, lls1 mutations exhibit enhanced resistance to fungal pathogens in maize (Simmons et al, 1998), spl mutations exhibit resistance to the blast fungus in rice (Yin et al, 2000), M66 mutations show increased resistance to yellow rust and powdery mildew (Kinane and Jones, 2001), and lm1 and lm2 mutations enhance leaf rust resistance in wheat (Yao et al, 2009).…”