Identification and characterization of a spotted-leaf mutant spl40 with enhanced bacterial blight resistance in rice

Abstract

Background Spotted leaf mutants show typical necrotic lesions that appear spontaneously in the absence of any pathogen attack. These mutants are often characterized to exhibit programmed cell death (PCD) and activation of plant defense responses resulting in enhanced disease resistance to multiple pathogens. Here, we reported a novel spotted-leaf mutant, spl40 that showed enhanced disease resistance response. Results Initially lesions appeared at leaf tips during seedling stage and gradually covered the whole leaf at the tillering stage. The lesion development was light-dependent. spl40 showed obvious cell death at and around the lesion, and burst of reactive oxygen species (ROS) was accompanied by disturbed ROS scavenging system. Photosynthetic capacity was compromised as evidenced by significant reductions in chlorophyll content, important photosynthesis parameters and downregulated expression of photosynthesis-related genes which ultimately led to poor performance of major agronomic traits. spl40 exhibited enhanced resistance to 14 out of 16 races of bacterial blight pathogen of rice, caused by Xanthomonas oryzae pv. oryzae , most probably though activation of SA and JA signaling pathways, owing to upregulated expression of SA and JA signaling genes, though the exact mechanism remain to be elucidated. The spotted-leaf phenotype was controlled by a novel single recessive nuclear gene. Genetic mapping combined with high throughput sequencing analysis identified Os05G0312000 as the most probable candidate gene. Sequencing of ORF revealed a single SNP change from C to T that resulted in non-synonymous change in amino acid residue from leucine to phenylalanine. Interestingly, the complementation plants did not display lesions before heading but showed lesions at the heading stage and the transgenic T 1 progenies could be classified into 3 categories based on their lesion intensity, indicating the complex genetic nature of the spl40 mutation. Conclusion The results obtained here clearly show that genes related to defense and PCD were upregulated in accordance with enhanced disease resistance and occurrence of PCD, whereas the photosynthetic capacity and overall ROS homeostasis was compromised in spl40 . Our data suggest that a novel spotted-leaf mutant, spl40 , would help to elucidate the mechanism behind lesion development involving programmed cell death and associated defense responses. Electronic supplementary material The online version of this article (10.1186/s12284-019-0326-6) contains supplementary material, which is available to authorized users.

Transcriptome Analysis of Early Defenses in Rice against Fusarium fujikuroi

“…Relative gene expression was measured (on an individual plant basis) in three technical replicates with the ABI Prism 7500 sequence detection system (Applied Biosystems, Carlsbad, CA, USA). Each qRT-PCR reaction contained 5 μl SYBR Premix EX Taq II (Ti RNase H Plus) (Takara Bio, Shiga, Japan), 0.5 μl of 10 μM forward primer, 0.5 μl of 10 μM reverse primer, 1 μl cDNA, and 3 μl ddH 2 O. Primer sequences for qRT-PCR are listed in Additional file 1 : Table S1 (Jain et al 2017 ; Li et al 2016 ; Sathe et al 2019 ; Manosalva et al 2009 ; Zhang et al 2009 ). Primers were designed using Primer 3 Plus (Version 2.4.1) (Untergasser et al 2012 ).…”

PREMATURE SENESCENCE LEAF 50 Promotes Heat Stress Tolerance in Rice (Oryza sativa L.)

“…2 a, c). Hydrogen peroxide (H 2 O 2 ) over-accumulation is shown to induce plant cell death (He et al 2020 ; Sathe et al 2019 ). We hence detected H 2 O 2 accumulation and cell death of psl50 seedlings with and without heat treatment by using 3,3′-diaminobenzidine (DAB) and trypan blue staining.…”

Premature Senescence Leaf 50 Promotes Heat Stress Tolerance in Rice (Oryza Sativa L.)

“…2a, c). Hydrogen peroxide (H 2 O 2 ) over-accumulation is shown to induce plant cell death (He et al 2020;Sathe et al 2019). We hence detected H 2 O 2 accumulation and cell death of psl50 seedlings with and without heat treatment by using 3,3'-diaminobenzidine (DAB) and trypan blue staining.…”