For inoculating the fungus expressing DsRed, the maize roots 1 cm in length were immersed in a suspension of spores (105 conidia mL− 1) for 5 min before transfer

to 1 mL of BNM medium on a slide. The growth and colonization of F. verticillioides were subjected to epifluorescent microscopy. Following infection with F. verticillioides, the dyes of neutral red (0.01%, W/V) and Evans blue (0.2%, W/V) (Sigma, St. Louis, MO, USA) were used to stain the cross and longitudinal sections of the roots for 5 min each, rinsed with water, and then observed under a microscope. GSI-IX molecular weight Dead cells were stained blue with Evans blue, whereas living cells were stained red with neutral red. Certain characteristic indicators, e.g., accumulation of peroxide, can be detected when PCD occurs. To investigate whether infection of F. verticillioides induced PCD in maize leaves, peroxide

staining using 3,3-diaminobenzidine (DAB) as the substrate was performed to detect the accumulation of H2O2 following infection of F. verticillioides as described previously [33]. At the two-leaf-stage, the leaves of maize plants inoculated with the F. verticillioides strain expressing DsRed were excised and incubated in a 1 mg mL− 1 solution of DAB (pH 3.8) for 2 h under light at 25 °C and then boiled in ethanol (96%) for 10 min. After cooling, the leaves were extracted with fresh ethanol at room temperature. The degree of dark brown polymerization indicated the amount of H2O2 accumulated in the treated leaves. MK-2206 ic50 Selective Fusarium Idelalisib agar (SFA) [29] and [30] medium was used to analyze the colonization of F. verticillioides on/in maize roots. DsRed-labeled fungus-infected and mock-inoculated roots and basal stems of maize were sampled at different times after the inoculation from two replicated greenhouse trials to determine the numbers of colony forming units (CFU) as previously described [31]. A randomized complete block design with four replicates consisting of two plants each was used to arrange the inoculated maize plants. The roots

were removed from the vermiculite, washed thoroughly with tap water, and surface sterilized for 3 min in 0.5% (V/V) NaOCl solution. After rinsing with sterile deionized water several times, roots were wiped with sterile filter paper. Roots and basal stems from the two plants in each replicate were weighted, ground, and mixed into 10 ml of sterile deionized water with a Fast-Prep-24 Instrument (MP Biomedicals, Solon, OH, USA) at high speed for 1 min. Homogenized suspensions of root and basal stem samples were filtered through four layers of cheesecloth to remove plant debris and diluted 20-fold with sterile deionized water. The diluted samples were separately spread with a sterile glass rod onto the SFA plates. Each inoculated sample consisted of five replicated plates with 50 μL of diluted tissue suspension.