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Maize is the third most vital global cereal, playing a key role in the world economy and plant genetics research. Despite its leadership in production, maize faces a severe threat from banded leaf and sheath blight, necessitating the urgent development of eco-friendly management strategies. This study aimed to understand the resistance mechanisms against banded leaf and sheath blight (BLSB) in maize hybrid “Vivek QPM-9”. Seven fungicides at recommended doses (1000 and 500 ppm) and two plant defense inducers, salicylic acid (SA) and jasmonic acid (JA) at concentrations of 50 and 100 ppm, were applied. Fungicides, notably Azoxystrobin and Trifloxystrobin + Tebuconazole, demonstrated superior efficacy against BLSB, while Pencycuron showed limited effectiveness. Field-sprayed Azoxystrobin exhibited the lowest BLSB infection, correlating with heightened antioxidant enzyme activity (SOD, CAT, POX, β-1,3-glucanase, PPO, PAL), similar to the Validamycin-treated plants. The expression of defense-related genes after seed priming with SA and JA was assessed via qRT-PCR. Lower SA concentrations down-regulated SOD, PPO, and APX genes but up-regulated CAT and β-1,3-glucanase genes. JA at lower doses up-regulated CAT and APX genes, while higher doses up-regulated PPO and β-1,3-glucanase genes; SOD gene expression was suppressed at both JA doses. This investigation elucidates the effectiveness of certain fungicides and plant defense inducers in mitigating BLSB in maize hybrids and sheds light on the intricate gene expression mechanisms governing defense responses against this pathogen.

A field investigation was carried out during the consecutive kharif seasons of 2021 and 2022 to assess the resistance response of 38 maize genotypes against banded leaf and sheath bight (BLSB). The trials were conducted at CCS Haryana Agricultural University, Regional Research Station, Karnal (India) under artificial epiphytotic conditions. Throughout both seasons, six genotypes (HKI 163, HKI 193‐2, HKI 488, IQPMH‐18‐2, HKI 194‐7 and HKI 1128) exhibited resistant reactions, one genotype (HM 8) showed susceptible reaction, whereas 19 genotypes showed moderately resistant response to BLSB. To analyse molecular aspects of BLSB resistance, genomic DNA was extracted and PCR amplification was performed using 22 SSR markers. Ten SSR markers (bnlg238, bnlg161, bnlg127, bnlg339, bnlg615, bnlg1272, phi077, phi080, phi035 and umc1275) revealed distinct banding patterns in resistant and susceptible genotypes. Among these, marker bnlg339 exhibited a band size of 120 bp across 14 genotypes, with six (HKI 163, HKI 193‐2, HQPM 5, IQPMH‐18‐2, HKI 194‐7 and HKI 1128) classified as resistant and eight (HKI 193‐1, HKI 1657, HKI 1378, HPQM 1, HKI 1659, HPQM 2, T Bio 259 ER and HKI 191‐2‐5) as moderately resistant, resembling the amplified profile of the resistant check genotype (HKI 163). Similarly, the markers phi080 and bnlg1272 exhibited differential amplified profile of approximately 150 bp and 240 bp, respectively, in 10 (five resistant and five moderately resistant) and 12 (four resistant and eight moderately resistant) maize genotypes throughout the study. The percentage of polymorphism for the SSR markers varied from 0 to 100%, with an average value of 95.45% per primer among all genotypes. The identification of resistant and moderately resistant genotypes and characterization of specific SSR markers associated with resistance offer practical tools for breeders to develop BLSB‐resistant maize varieties, ultimately enhancing crop resilience and food security. [ABSTRACT FROM AUTHOR]

Maize is the third most vital global cereal, playing a key role in the world economy and plant genetics research. Despite its leadership in production, maize faces a severe threat from banded leaf and sheath blight, necessitating the urgent development of eco-friendly management strategies. This study aimed to understand the resistance mechanisms against banded leaf and sheath blight (BLSB) in maize hybrid "Vivek QPM-9". Seven fungicides at recommended doses (1000 and 500 ppm) and two plant defense inducers, salicylic acid (SA) and jasmonic acid (JA) at concentrations of 50 and 100 ppm, were applied. Fungicides, notably Azoxystrobin and Trifloxystrobin + Tebuconazole, demonstrated superior efficacy against BLSB, while Pencycuron showed limited effectiveness. Field-sprayed Azoxystrobin exhibited the lowest BLSB infection, correlating with heightened antioxidant enzyme activity (SOD, CAT, POX, β-1,3-glucanase, PPO, PAL), similar to the Validamycin-treated plants. The expression of defense-related genes after seed priming with SA and JA was assessed via qRT-PCR. Lower SA concentrations down-regulated SOD, PPO, and APX genes but up-regulated CAT and β-1,3-glucanase genes. JA at lower doses up-regulated CAT and APX genes, while higher doses up-regulated PPO and β-1,3-glucanase genes; SOD gene expression was suppressed at both JA doses. This investigation elucidates the effectiveness of certain fungicides and plant defense inducers in mitigating BLSB in maize hybrids and sheds light on the intricate gene expression mechanisms governing defense responses against this pathogen.

Maize (Zea mays L.) crop is attacked by number of fungal, bacterial and viral diseases, out of which banded leaf and sheath blight (BLSB) caused by anastomosis group 1-IA of Rhizoctonia solani f. sp. sasakii Exner. is one of the most widespread and destructive disease of maize in Southeast Asian countries. The occurrence of this disease has also been reported from other parts of the world, which causes significant yield loss up to 100%. R. solani can survive in the soil for several years and able to infect plants belonging to more than 32 families, including many economically important monocots and dicots plants. The severity of the disease favoured by humid weather with temperature around 28°C, poses challenge to maize growers due to its soil borne nature and lack of resistance cultivars. It is indicated that none of the disease management approaches are effective against BLSB. Banded leaf and sheath blight is difficult to control through either fungicide or crop rotation alone. A number of quantitative trait loci (QTLs) controlling BLSB have been identified that would help the development of maize hybrids resistance to this disease. Management of BLSB requires an integrated approach based on the knowledge of each stage of the disease and molecular aspect of maize defence responses against R. solani. Mention conclusion statement and novelty of the work. The present review summarizes consolidated information on distribution, yield loss, symptoms, pathogen life cycle, epidemiology, genetic structure of the pathogen population, molecular aspect of pathogenicity and its integrated management through cultural, biological, chemical and genetic means. The consolidated knowledge presented in this review should help better disease management and reduce crop yield loss due to banded leaf and sheath blight pathogen. [ABSTRACT FROM AUTHOR]