Evaluation of Blast Resistance in Zinc-Biofortified Rice

Area of Science:

• Agricultural Science
• Plant Pathology
• Genetics

Background:

• Rice blast disease, caused by *Magnaporthe oryzae*, poses a significant threat to global food security, causing substantial crop losses.
• Breeding for disease resistance is a sustainable strategy to mitigate yield losses and reduce reliance on fungicides.
• Biofortification with micronutrients like zinc (Zn) is explored to enhance nutritional value, but its impact on disease resistance requires investigation.

Purpose of the Study:

• To assess the relationship between rice blast disease severity and zinc or anthocyanin content in biofortified rice genotypes.
• To evaluate the efficacy of foliar zinc supplementation in managing rice blast.
• To determine the agronomic performance of zinc-biofortified rice varieties.

Main Methods:

• A panel of 23 rice genotypes varying in grain zinc content and pigmentation was challenged with *Magnaporthe oryzae* isolates in screenhouse and field assays.
• Foliar and panicle blast severity, anthocyanin content, grain yield, and agronomic traits were assessed.
• The impact of foliar zinc supplementation on blast-susceptible seedlings was evaluated.

Main Results:

• Significant variation in foliar blast severity was observed among genotypes; some, including BASMATI 370, showed high susceptibility.
• Foliar zinc supplementation significantly reduced susceptibility to blast.
• Leaf zinc content was negatively correlated with foliar blast severity, but grain zinc content showed no correlation with blast or yield. Anthocyanin content was unrelated to blast severity.
• Panicle blast negatively correlated with grain yield, and zinc-biofortified genotypes were not agronomically superior.

Conclusions:

• Grain zinc biofortification does not appear to enhance resistance to rice blast (foliar or panicle).
• Foliar zinc application can be a viable strategy to reduce blast susceptibility.
• Future breeding strategies should focus on combining desirable traits using genomic selection within adapted genetic backgrounds.