Abstract
A barley mutant, 194, was observed to exhibit leaf spot phenotype during the whole growing period. In the current research, the phenotype and antioxidant competence were studied in lesion mimic mutant 194. The plant height was slightly higher in mutant 194. In addition, the leaf spot per plant in mutant 194 was significantly higher than that in wild-type (WT). Antioxidant competence, as indicated by ROS accumulation, antioxidant enzymes activity, and the expression of antioxidant enzyme-encoding genes were also detected in mutant 194. Compared to the WT, mutant 194 displayed relatively higher accumulation of ROS and accompanied by lower activity of some antioxidant enzymes, and the down-regulation of antioxidant enzyme-encoding genes further demonstrated the deterioration of antioxidant competence in mutant 194. The results suggested that the lower antioxidant competence of mutant 194 could accumulate excessive ROS. The excessive ROS could induce PCD and has the potential in the disease resistant in mutant 194.
Highlights
Lesion mimic mutants (LMMs) display spontaneous programmed cell death (PCD) under normal growth conditions, form disease spots on the leaves
49 lesion mimic genes have been cloned and identified; two of them are from barley, namely the nec1 gene [8] and the tigrina-d.12 gene [9], which are homologous genes of hlm1 (At5g54250) and flu (At3g14110) in Arabidopsis thaliana, respectively
The results clearly showed that the reactive oxygen species (ROS) content was upregulated in the LMM, which will provide a basis for further study and application of LMMs
Summary
Lesion mimic mutants (LMMs) display spontaneous programmed cell death (PCD) under normal growth conditions, form disease spots on the leaves. At least 100 LMMs have been identified over the past four decades, including those in Arabidopsis thaliana [3], maize [4], rice [5] and barley [6]. 49 lesion mimic genes have been cloned and identified; two of them are from barley, namely the nec gene [8] and the tigrina-d.12 gene [9], which are homologous genes of hlm (At5g54250) and flu (At3g14110) in Arabidopsis thaliana, respectively. Some disease resistance genes appear to be associated with the lesion mimic phenotype. Hordei; while under the condition of no pathogen infection, mlo plants have a phenotype with cell wall thickening and disease spots [6,11]. The LMM genes were classified as either PCD inhibition or PCD excitation pathway genes according to the phenotype of the LMM and its relationship
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