Silicon potentiates biochemical defense responses of wheat against tan spot

Wheat leaf resistance to Pyrenophora tritici‐repentis induced by silicon activation of phenylpropanoid metabolism

“…The two wheat cultivars used were Fundacep Horizonte (Cooperativa Central Gaúcha Ltda Tecnologia/FUNDACEP) and Quartzo (OR Sementes), classified as susceptible and moderately resistant to tan spot, respectively, according to the crop technical information (Cunha et al ., ). Seeds were sown in four rows (two for Fundacep Horizonte and two for Quartzo) in 20 L plastic trays (0.6 m long × 0.38 m wide × 0.15 m deep) containing 19 kg of soil (Dorneles et al ., ). After the emergence of seedlings, they were thinned to leave 20 plants per line.…”

“…Fungal growth and inoculum production were performed according to Dorneles et al . (). Plants were inoculated by spraying a conidial suspension (6 × 10 3 conidia mL −1 ) onto leaves of 40‐day‐old wheat plants at growth stage 8 (Large, ) as a fine mist using a hand‐held manual sprayer (Tecblas, REF: 359–60 mL) until run‐off.…”

“…Resistance components evaluated on the third and fourth leaves of each plant included: incubation period (IP), rate of lesion expansion ( r ), final lesion size (FLS) and total number of lesions (TNL) (Dorneles et al ., ). Briefly, the IP (h) was assessed by examining leaves every 3 h after inoculation and was defined as the interval between inoculation and the onset of visible symptoms.…”

“…Sample tissue was cleared by boiling in 70% ethanol followed by immersion in a chloral hydrate solution (Sigma‐Aldrich) for 2 weeks. Samples were then placed and fixed with the adaxial side up on slides containing drops of Hoyer's solution (Dorneles et al ., ) and observed under a fluorescence microscope (BX51WI) coupled with BP460–490 filters for visualization of the presence of fluorescent compounds such as phenolics.…”

“…Thereafter, Dorneles et al . () demonstrated that the partial resistance of wheat to P . tritici‐repentis conferred by Si was associated with increases in superoxide dismutase, peroxidase and chitinase activities as well as the accumulation of hydrogen peroxide at the penetration sites at the beginning of infection.…”