Search for: All records

Abstract Previously, sugarcane mosaic virus (SCMV) was developed as a vector for transient expression of heterologous genes inZea mays(maize). Here, we show that SCMV can also be applied for virus‐induced gene silencing (VIGS) of endogenous maize genes. Comparison of sense and antisense VIGS constructs targeting maizephytoene desaturase(PDS) showed that antisense constructs resulted in a greater reduction in gene expression. In a time course of gene expression after infection with VIGS constructs targetingPDS,lesion mimic 22(Les22), andIodent japonica 1(Ij1), efficient expression silencing was observed 2, 3, and 4 weeks after infection with SCMV. However, at Week 5, expression ofLes22andIj1was no longer significantly reduced compared with control plants. The defense signaling molecule jasmonate‐isoleucine (JA‐Ile) can be inactivated by 12C‐hydroxylation and hydrolysis, and knockout of these genes leads to herbivore resistance. JA‐Ile hydroxylases and hydrolases have been investigated in Arabidopsis, rice, andNicotiana attenuata. To determine whether the maize homologs of these genes function in plant defense, we silenced expression ofZmCYP94B1(predicted JA‐Ile hydroxylase) andZmJIH1(predicted JA‐Ile hydrolase) by VIGS with SCMV, which resulted in elevated expression of two defense‐related genes,Maize Proteinase Inhibitor(MPI) andRibosome Inactivating Protein 2(RIP2). AlthoughZmCYP94B1andZmJIH1gene expression silencing increased resistance toSpodoptera frugiperda(fall armyworm),Schistocerca americana(American birdwing grasshopper), andRhopalosiphum maidis(corn leaf aphid), there was no additive effect from silencing the expression of both genes. Further work will be required to determine the more precise functions of these enzymes in regulating maize defenses.