Bacterial Leaf Blight Resistance Research Articles

Understanding the nature of blast resistance in combined bacterial leaf blight and blast gene pyramided lines of rice variety tellahamsa.

Rice blast and bacterial leaf blight (BLB) are the most limiting factors for rice production in the world which cause yield losses typically ranging from 20 to 30% and can be as high as 50% in some areas of Asia especially India under severe infection conditions. An improved line of Tellahamsa, TH-625-491 having two BLB resistance genes (xa13 and Xa21) and two blast resistance genes (Pi54 and Pi1) with 95% Tellahamsa genome was used in the present study. TH-625-491 was validated for all four target genes and was used for backcrossing with Tellahamsa. Seventeen IBC1F1 plants heterozygous for all four target genes, 19 IBC1F2 plants homozygous for four, three and two gene combinations and 19 IBC1F2:3 plants also homozygous for four, three and two gene combinations were observed. Among seventeen IBC1F1 plants, IBC1F1-62 plant recorded highest recurrent parent genome (97.5%) covering 75 polymorphic markers. Out of the total of 920 IBC1F2 plants screened, 19 homozygous plants were homozygous for four, three and two target genes along with bacterial blight resistance. Background analysis was done in all 19 homozygous IBC1F2 plants possessing BLB resistance (possessing xa13, Xa21, Pi54 and Pi1 in different combinations) with five parental polymorphic SSR markers. IBC1F2-62-515 recovered 98.5% recurrent parent genome. The four, three and two gene pyramided lines of Tellahamsa exhibited varying resistance to blast. Results show that there might be presence of antagonistic effect between bacterial blight and blast resistance genes since the lines with Pi54 and Pi1 combination are showing better resistance than the combinations with both bacterial blight and blast resistance genes.

Genetic Enhancement of Blast and Bacterial Leaf Blight Resistance in Rice Variety CO 51 through Marker-Assisted Selection

The increased use of chemicals in rice farming poses significant issues regarding the emergence of pesticide/fungicide resistance and environmental sustainability concerns. This study was aimed at the genetic improvement of blast, bacterial leaf blight (BB) and gall midge resistance in a popular rice variety CO 51 which already harbours a blast resistance gene Pi54. Efforts were made to pyramid an additional blast resistance gene Pi9 along with two BB resistance genes (xa13 and Xa21) and two gall midge resistance genes (Gm1 and Gm4) into an elite rice variety CO 51 to enhance the resistance level to biotic stresses. The superior lines were selected using functional markers conferring resistance to blast (NBS4 and Pi54MAS linked to Pi9 and Pi54 genes, respectively) and BB [(xa13Prom (xa13) and pTA248 (Xa21)] and SSR markers linked to Gm1 (RM1328) and Gm4 (RM22550) for phenotypic screening and agronomic evaluation. The genotyping and phenotyping of F6 and BC2F6 progenies of CO 51 X 562-4, for agronomic traits and resistance to BB and blast, identified ten superior progenies in F6 and five superior progenies in BC2F6. The breeding lines harbouring both xa13+Xa21 exhibited high levels of resistance to BB (score ≤ 1 cm) and Pi9+Pi54 exhibited strong resistance to blast (score ≤ 2). Identified lines can be evaluated further for varietal improvement or utilised as genetic stocks in breeding programs.

Cost-effective multiplex PCR assay for simultaneous detection of bacterial leaf blight, blast and brown planthopper resistance genes in rice

Cost-effective multiplex PCR assay for simultaneous detection of bacterial leaf blight, blast and brown planthopper resistance genes in rice

Introgression of bacterial leaf blight (BLB) resistant gene, Xa7 into MARDI elite variety, MR219 by marker assisted backcrossing (MABC) approach.

Bacterial leaf blight (BLB) is one of the major rice diseases in Malaysia. This disease causes substantial yield loss as high as 70%. Development of rice varieties which inherited BLB resistant traits is a crucial approach to promote and sustain rice industry in Malaysia. Hence, this study aims were to enhance BLB disease resistant characters of high yielding commercial variety MR219 through backcross breeding approach with supporting tool of marker-assisted selection (MAS). Broad spectrum BLB resistance gene, Xa7 from donor parent IRBB7 were introgressed into the susceptible MR219 (recurrent parent) using two flanking markers ID7 and ID15. At BC3F4, we managed to generate 19 introgressed lines with homozygous Xa7 gene and showed resistant characteristics as donor parent when it was challenged with Xanthomonas oryzae pv. oryzae through artificial inoculation. Recurrent parent MR219 and control variety, MR263 were found to be severely infected by the disease. The improved lines exhibited similar morphological and yield performance characters as to the elite variety, MR219. Two lines, PB-2-107 and PB-2-34 were chosen to be potential lines because of their outstanding performances compared to parent, MR219. This study demonstrates a success story of MAS application in development of improved disease resistance lines of rice against BLB disease.

Confirmations on gene introgression events and hybridity for BLB resistance and yield in rice

A superior variety of rice with high yield and resistance to diseases is expected to meet the increasing demand for this one of the most important carbohydrate sources worldwide. Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the major biotic stresses limiting rice production. Combining BLB resistance and high-yield traits is possible through gene pyramiding. Introgression of targeted traits in the parental genotypes and hybridity confirmation in the F1 generation are important initial steps in gene pyramiding. This study aimed to confirm the presence of targeted genes in parent genotypes using specific molecular markers and to confirm the hybridity of F1 plants generated from three crosses combinations of Inpari 32 (as the female parent) and three Code-qTSN4 lines (as the male parents) using SSR markers. This study successfully confirmed the introgression of BLB-resistance genes in Inpari 32 (Xa4, Xa7, and Xa21) and in Code-qTSN4 (Xa4, Xa7). The introgression of yield-related QTL, qTSN4, was confirmed in the three Code-qTSN4 lines (A10-1, B12-2, and A16-5) by RM17483 marker. Five SSR markers (RM5, RM55, RM105, RM223, and RM561) successfully confirmed the hybridity of F1 derived from Inpari 32xA10-1 (five individuals), Inpari 32xB12-2 (one individual), Inpari 32xA16-5 (two individuals). These confirmed hybrids can be further evaluated in the F2 generation.
 Keywords: Gene pyramiding; molecular marker; SSR; qTSN4; Xoo.

Pyramiding resistance genes for bacterial leaf blight (Xanthomonas oryzae pv. Oryzae) into the popular rice variety, Pratikshya through marker assisted backcrossing.

Bacterial leaf blight (BLB) is one of the major biotic stress in rice cultivation. Management techniques, such as the development of BLB-resistant cultivars, are required to lessen the severity of the disease attack and yield losses. Pratikshya was selected in the present investigation as the recipient parent, as it is one of the popular high-yielding rice varieties of Odisha, India, which is having excellent grain as well as cooking quality. However, Pratikshya is highly susceptible to BLB which is prevalent in Eastern Indian region. Three major BLB resistance genes xa5, xa13, and Xa21 from the donor source Swarna MAS (CR Dhan 800) were attempted to introduce into Pratikshya through a marker-assisted backcross breeding program. Those markers closely linked to the target genes were employed for foreground selection in the segregating generations till BC2F3. In each backcross generation, progenies containing all three targeted resistance genes and phenotypically more similar to the recipient parent, Pratikshya were selected and backcrossed. Screening of 1,598 plants of the BC2F2 population was conducted against BLB using Xoo inoculum and 35 resistant plants similar to Pratikshya were carried forward to the next generation. In the BC2F3 generation, 31 plants were found to possess all the three resistance genes. For background selection of plants carrying resistance genes 45 polymorphic SSR markers were employed. Evaluation of the pyramided lines at BC2F4 generation exhibited that, most pyramided lines were similar to Pratikshya in terms of morphological features and yield parameters, and some lines were superior to the recurrent parent in terms of morphological features and yield parameters. The three-gene pyramided lines showed a high level of resistance to BLB infection and are anticipated to offer a significant yield advantage over the recipient parent Pratikshya.The pyramided lines can further be used for multi-location trial, so as to be released as a variety or can be used as a potential donor for BLB resistance genes.

Targeted editing of OsSWEET11 promoter for imparting bacterial leaf blight resistance in rice

Targeted editing of OsSWEET11 promoter for imparting bacterial leaf blight resistance in rice

Construction of the CRISPR/Cas9 module and genetic transformation of aromatic rice cv. Mentik Wangi for developing bacterial leaf blight resistance

Abstract. Rifhani NF, Apriana A, Sisharmini A, Santoso TJ, Trijatmiko KR, Slamet-Loedin IH, Yunus A. 2023. Construction of the CRISPR/Cas9 module and genetic transformation of aromatic rice cv. Mentik Wangi for developing bacterial leaf blight resistance. Biodiversitas 24: 3258-3268.Rice cv. Mentik Wangi is a local aromatic rice that is susceptible to pests and diseases, such as bacterial leaf blight (BLB) caused by Xanthomonas oryzae(Xoo). This bacteria can cause damage to plants thereby reducing crop yields. This study aimed to obtain the CRISPR/Cas9 module construct as well as introducing the construct into rice cv. Mentik Wangi for developing BLB resistance. The manufacture of the CRISPR/Cas9 module was carried out using the Golden Gate method, and the introduction of that construct into rice cv. Mentik Wangi was carried out using Agrobacterium tumefaciens. Constructing a CRISPR/Cas9 module with multiple gRNA of OsSWEET11 and OsSWEET14 genes has succeeded, 129 putative transformant lines of T0 generation produced with the regeneration and transformation efficiency values ??are respectively 9.4% and 9.8%. The results showed that 36 lines were positive for the hpt gene, indicating that the CRISPR/Cas9-gRNAOsSWEET module construct was successfully entered into rice cv. Mentik Wangi. Further analysis is needed to identify mutagenesis in the target gene region of TI generation transgenic plants as well as phenotypic tests for BLB resistance.

RESISTANCE OF DOUBLED HAPLOID RICE LINES TO BACTERIAL LEAF BLIGHT (Xanthomonas oryzae pv. oryzae)

Developing new high-yielding rice varieties resistant to bacterial leaf blight (BLB) is an effective strategy for controlling BLB. Several advanced doubled haploid rice lines derived from anther culture previously selected need assessment for BLB resistance. This study aimed to evaluate the resistance of these lines to BLB pathotypes III, IV, and VIII in the vegetative and generative phases. The experiment took place in a greenhouse using 16 rice genotypes comprising 12 doubled haploid rice lines, two commercial check varieties (Inpari 18 and Inpari 34), and a BLB-resistant and susceptible check variety (Code and TN-1, respectively). Inoculation began with the leaf clipping method using a suspension of the pathogen Xanthomonas oryzae pv. oryzae (Xoo) at a concentration of 109 cfu/ml. The results indicated significant influences on disease severity and intensity of BLB of pathotype, genotype, and the interactions between pathotype and genotype, finding their values higher in the vegetative phase. Six doubled haploid lines ranged from resistant to moderately resistant (disease severity 2.0%–10.7%, disease intensity 6.7%–36.8%) to pathotypes III and IV in two growth phases, i.e., HS1-35-1-4, HS4-15-1-9, HS4-15-1-16, HS4-15-1-24, HS4-15-1-26, and HS4-15-1-28. All those doubled haploid lines were susceptible to BLB pathotype VIII in the vegetative phase and moderately susceptible in the generative phase.

Bulk segregant analysis coupled with transcriptomics and metabolomics revealed key regulators of bacterial leaf blight resistance in rice

BackgroundBacterial leaf blight (BLB) is a highly destructive disease, causing significant yield losses in rice (Oryza sativa). Genetic variation is contemplated as the most effective measure for inducing resistance in plants. The mutant line T1247 derived from R3550 (BLB susceptible) was highly resistant to BLB. Therefore, by utilizing this valuable source, we employed bulk segregant analysis (BSA) and transcriptome profiling to identify the genetic basis of BLB resistance in T1247.ResultsThe differential subtraction method in BSA identified a quantitative trait locus (QTL) on chromosome 11 spanning a 27-27.45 Mb region with 33 genes and 4 differentially expressed genes (DEGs). Four DEGs (P < 0.01) with three putative candidate genes, OsR498G1120557200, OsR498G1120555700, and OsR498G1120563600,0.01 in the QTL region were identified with specific regulation as a response to BLB inoculation. Moreover, transcriptome profiling identified 37 resistance analogs genes displaying differential regulation.ConclusionsOur study provides a substantial addition to the available information regarding QTLs associated with BLB, and further functional verification of identified candidate genes can broaden the scope of understanding the BLB resistance mechanism in rice.

Genome-Wide Association Study Using Genotyping by Sequencing for Bacterial Leaf Blight Resistance Loci in Local Thai Indica Rice

Bacterial leaf blight (BLB) is a devastating disease caused by Xanthomonas oryzae pv. oryzae (Xoo), which poses a significant threat to global rice production. In this study, a genome-wide association study (GWAS) was conducted using the genotyping-by-sequencing (GBS) approach to identify candidate single nucleotide polymorphisms (SNPs) associated with BLB resistance genes. The study utilized 200 indica rice accessions inoculated with seven distinct Xoo isolates and filtered highly significant SNPs using a minor allele frequency (MAF) of &gt;5% and a call rate of 75%. Four statistical models were used to explore potential SNPs associated with BLB resistance, resulting in the identification of 32 significant SNPs on chromosomes 1–8 and 12 in the rice genome. Additionally, 179 genes were located within ±100 kb of the SNP region, of which 49 were selected as candidate genes based on their known functions in plant defense mechanisms. Several candidate genes were identified, including two genes in the same linkage disequilibrium (LD) decay as the well-known BLB resistance gene (Xa1). These findings represent a valuable resource for conducting further functional studies and developing novel breeding strategies to enhance the crop’s resistance to this disease.

Pheno-Genotypic Screening of Medium Slender Rice Genotypes for Bacterial Leaf Blight (BLB) Disease Resistance

The bacterial leaf blight of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is an economically important and one of the most destructive disease of rice in both irrigated and rainfed environments in Asia. In particular, in recent years, the occurrence of abnormal climate and warming phenomena has produced a good environment for bacterial leaf blight. The rice yield continues to decrease, causing 30 to 50% yield loss. Since bacterial pathogen is difficult to manage by other means effectively, developing host plant resistance is the most effective way to control this disease. So, the study was carried out during rain-fed season (July–November 2019) at Agricultural Research Station (ARS) Gangavati, Karnataka, India to identify the bacterial leaf blight resistance reaction among 22 medium slender genotypes of rice by both phenotyping and genotyping by using molecular markers linked with resistance governing bacterial leaf blight genes. Alongside TN-1 was used as susceptible check and screening was done by artificial clip inoculation method. The disease reactions were recorded one week after inoculation, with Standard Evaluation Scale (SES) for BLB ranging from 0–9, when the susceptible check (TN-1) was completely killed. None of the genotypes showed a resistant reaction, but three genotypes viz. IET-27904, IET-25520 and Rp Bio-226 showed resistant reaction against BLB. The six major BLB resistant genes genetic frequencies varied from 42.85% to 14.28% in the molecular evaluation of promising genotypes for major BLB resistant genes using three Simple Sequence Repeats (SSR) and Sequence Tagged Sites (STS) markers respectively.

Distribution of Xanthomonas oryzae pv. oryzae Pathotypes in Basmati-Rice-Growing Areas of Jammu and Kashmir, India

Rice is an important staple food for more than half of the world’s population. Though the genetic potential of commonly cultivated varieties of rice is diminished due to various biotic and abiotic constraints, bacterial leaf blight (BLB) of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is considered one of its most destructive diseases in India. Based on morpho-cultural characteristics, bacterial pathogens isolated from the leaves of a rice plant showing typical BLB symptoms were identified as Xanthomonas oryzae pv. oryzae. Morphological studies revealed that the pathogen is Gram-negative, a short rod, with rounded ends, single or in pairs, light yellow, circular, whitish yellow to straw-colored, convex, yellow, slightly raised, motile with a single polar flagellum, capsulate and non-spore-forming. Biochemical tests, viz., the Gram reaction, KOH test and catalyst test, showed a positive reaction for all the isolates. Twenty isolates of Xoo were collected from the basmati-growing areas of the Jammu, Samba and Kathua districts in the Jammu sub-tropics during 2019, and their pathogenicity was confirmed on five susceptible rice cultivars, viz., Basmati-370, Pusa-1121, TN-1, SJR and Jaya, by the leaf-clipping method, and subsequently, Koch’s postulate was established in each case. Seven Xoo pathotypes, viz., Pathotype 1, Pathotype 2, Pathotype 3, Pathotype 4, Pathotype 5, Pathotype 6 and Pathotype 7, were identified from the total sample of 20 isolates. Pathotype 2 was the most dominant (100%), followed by Pathotype 5 (44.44%), Pathotype 4 (40%), Pathotype 6 (40%), Pathotype 7 (33.33%), Pathotype 3 (22.22%) and Pathotype 1 (20%), in the Jammu sub-tropics. In Jammu district, Pathotype 5 was highly distributed (44.44%) followed by Pathotype 7 (33.33%) and Pathotype 3 (22.22%). Pathotype 4 and Pathotype 6 each showed a 40 percent distribution in Kathua district, followed by Pathotype 1 (20%). Only one pathotype, i.e., Pathotype 2, was recorded in Samba district with a 100 percent distribution. Five genes, viz., Xa13, Xa4, Xa13 and Xa5 + Xa13, showed complete resistance, whereas Xa4, Xa5, Xa7, Xa8, Xa21, Xa4 + Xa5 and Xa4 + Xa21 showed susceptible response against the test isolates. It was observed that most of the single BLB-resistant genes were moderately to highly susceptible to almost all the Xoo isolates, whereas combinations of BLB resistance genes possessed high resistance against all the Xoo isolates. The studies revealed that diverse pathogenic variations existed in the Xoo population in the basmati-growing region of Jammu and Kashmir. Based on the response exhibited by Xoo isolates on differential lines, seven pathotypes (Pathotype 1–7) were identified, and their virulence spectrum on rice differentials showed the occurrence of 5, 3, 10, 10, 20, 10 and 15 percent, respectively, in the Jammu sub-tropics. To develop durable and sustainable resistant cultivars, it is essential to identify predominate race(s) in a specific geographical area and continuously monitor the virulence pattern there.

Backcrossing with Marker Assistance to Introduce Broad-Spectrum Bacterial Leaf Blight Resistance in the Malaysian Elite Variety MR297

A significant part of marker-assisted backcross breeding (MABB) is recurrent parent genome recovery (RPGR). The purpose of this study was to introduce MABB-mediated resistance genes against numerous bacterial leaf blight (BLB) pathogens. Here, we examine the introgression of four Xoo resistance genes to the high-yielding Malaysian MR297 lineage Xa21, xa13, xa5, and Xa4 from the IRBB60 lineage. To accomplish both foreground and background selection, we employed polymorphic functional linked markers to target genes and simple sequence repeat (SSR) markers. We used 83 of the 475 authorized polymorphic microsatellite markers to determine the proportion of RPGR in the chosen lines. According to the data, the RPGR at BC1F1, BC2F1, and BC2F2 are 81.94, 92.30, and 95.04%, respectively. Incorporating the four BLB resistance genes into the newly created lines would result in long-lasting and comprehensive protection against BLB. Therefore, a resistant gene may be introduced into a population more quickly with MABB than through conventional breeding. All ten lines tested showed a significant level of resistance to BLB, with three lines displaying very high levels of resistance. Consequently, it was recommended that new lines should be used to produce commercially viable rice varieties.

SCREENING OF RICE LINES OF DIVERSE ORIGIN RESISTANT TO BACTERIAL LEAF BLIGHT UNDER LOCAL CONDITIONS

&#x0D; &#x0D; &#x0D; Current study comprised of 20 donor parent lines and four indica elite strains resistant against bacterial leaf blight having diversity in origin viz. Bangladesh, Philippine, Indonesia, Senegal and India. The lines were tested to check resistance against Bacterial Leaf Blight (BLB), having BLB resistance genes Xa-4, xa-5, Xa-7 and xa-13. The experiment was conducted at Agronomic Research Station, Farooqabad, Sheikhupura. Artificial inoculation was done to study disease reaction. DNA marker analysis was also conducted to study the gene status of these lines. Results indicated that seven donor lines were completely resistant to Bacterial Leaf Blight whereas twelve lines exhibited moderate resistance. Among rest of the five susceptible genotypes, three were showing comparatively low susceptibility whereas two completely susceptible to BLB. Most of the lines with three or four gene combinations showing resistant behavior against BLB except AUS-298 that showed moderately susceptible behavior. Combination of genes for Bacterial Leaf Blight resistance can be explored further in targeted research program for disease resistance.&#x0D; &#x0D; &#x0D;

Linkage mapping and identification of quantitative trait loci associated with bacterial leaf blight resistance and gum content in cluster bean using the interspecific population (HG563 × Cyamopsis serrata)

Linkage mapping and identification of quantitative trait loci associated with bacterial leaf blight resistance and gum content in cluster bean using the interspecific population (HG563 × Cyamopsis serrata)

Targeted editing of OsSWEET13, a bacterial leaf blight susceptible gene in rice using CRISPR tool

Bacterial leaf blight (BLB) of rice is considered to be a disease of economic importance as the disease causes severe yield losses in all rice growing regions. Transcription activator like effector (TALE) molecules are produced by the pathogen, Xanthomonas oryzae pv. oryzae (Xoo) bind to the effector binding element (EBE) of the promoter of SWEET gene and activates transcription of SWEET genes, making the plant susceptible to the disease.&nbsp; Innate resistance to Xoo in certain rice genotypes is due to mutations in EBE present in the upstream regulatory region of SWEET genes. CRISPR–mediated targeted modification of susceptibility gene/promoter is an effective approach to develop BLB resistance in rice. The present study was an attempt to repress TALE triggered signalling via introducing indels in the EBE of OsSWEET13 gene in a local popular rice genotype, CO51 employing CRISPR/Cas9 mediated genome editing tool with a view to imparting BLB resistance. Agrobacterium-mediated transformation using immature embryos followed by regeneration resulted in four independent transformation events. Five plants representing three events were found to have one nucleotide deletion in the target sequence. These deletion mutations in EBE could potentially interfere with the binding of the corresponding TALE to confer resistance against certain strains of BLB.&nbsp; Keywords: Rice, Bacterial Leaf Blight, SWEET13 gene, Effector Binding Element, CRISPR/Cas9.

Genotypic and Phenotypic Selection of Newly Improved Putra Rice and the Correlations among Quantitative Traits

This experiment was conducted to genotypically and phenotypically select new rice lines pyramided with blast and bacterial leaf blight disease resistance genes after a marker-assisted backcross breeding programme. The inter-relationship among agro-morphological characteristics and their effect on yield was also studied. The polymorphic functional and microsatellite markers Xa21FR and pTA248 (Xa21), Xa13prom (xa13), RM21 (xa5), MP (Xa4), RM6836 (Pi2, Pi9 &amp; Piz) and RM8225 (Piz) were first confirmed for the target genes. The selected markers were used for foreground selection of BC2F2 homozygous progenies with the target genes. Plants that had homozygous IRBB60 alleles for these markers were evaluated for their recovery of the recurrent parent genome. IRBB60 was used as the donor parent for bacterial blight resistance genes while Putra-1 served as a recipient/recurrent parent with background blast-resistance genes and high yield. After the foreground selection, 79 polymorphic simple sequence repeat markers identified from the marker polymorphism survey were used for marker-assisted background selection to determine the percentage recovery of the recurrent parent genome. In order to make a selection on a phenotypic basis, 14 agro-morphological traits were measured and recorded. The result obtained from the study showed that 16 lines received the seven resistance genes in sufficiently varied numbers and were selected. The distribution of yield per hectare showed that about 50% of the selected lines had yields as high as 5 t/ha and above. Some of the lines produced as high as 8.4 t/ha. These lines demonstrated the potential of recording uniform 8t/ha upon recombination at BC2F2. The study also indicated that the number of panicles per hill correlated strongly, significantly and positively with the number of tillers (r = 0.962 **), total grain weight per hill (r = 0.928 **) and yield per hectare (r = 0.927 **). It was concluded that the newly improved resistant lines which were selected have the capability to compete with Putra-1 in terms of its productivity and yield. The newly developed lines would be useful in future breeding programmes as donors for bacterial leaf blight and blast resistance genes. These lines are recommended for release to farmers in Malaysia and other rice-growing agro-ecologies for commercial cultivation.

Osa-miR160a confers broad-spectrum resistance to fungal and bacterial pathogens in rice.

Rice production is threatened by multiple pathogens. Breeding cultivars with broad-spectrum disease resistance is necessary to maintain and improve crop production. Previously we found that overexpression of miR160a enhanced rice blast disease resistance. However, it is unclear whether miR160a also regulates resistance against other pathogens, and what the downstream signaling pathways are. Here, we demonstrate that miR160a positively regulates broad-spectrum resistance against the causative agents of blast, leaf blight and sheath blight in rice. Mutations of miR160a-targeted Auxin Response Factors result in different alteration of resistance conferred by miR160a. miR160a enhances disease resistance partially by suppressing ARF8, as mutation of ARF8 in MIM160 background partially restores the compromised resistance resulting from MIM160. ARF8 protein binds directly to the promoter and suppresses the expression of WRKY45, which acts as a positive regulator of rice immunity. Mutation of WRKY45 compromises the enhanced blast resistance and bacterial leaf blight resistance conferred by arf8 mutant. Overall, our results reveal that a microRNA coordinates rice broad-spectrum disease resistance by suppressing multiple target genes that play different roles in disease resistance, and uncover a new regulatory pathway mediated by the miR160a-ARF8 module. These findings provide new resources to potentially improve disease resistance for breeding in rice.

Screening of RIL mapping population derived from the rice variety- Rasi, for low soil phosphorous tolerance and bacterial leaf blight resistance

Screening of RIL mapping population derived from the rice variety- Rasi, for low soil phosphorous tolerance and bacterial leaf blight resistance