Cotton polyamine oxidase is required for spermine and camalexin signalling in the defence response to Verticillium dahliae

Abstract

SUMMARYVerticillium dahliae is a destructive, soil-borne fungal pathogen that causes vascular wilt disease in many economically important crops worldwide. A polyamine oxidase (PAO) gene was identified and cloned by screening suppression subtractive hybridisation and cDNA libraries of cotton genotypes tolerant to Verticillium wilt and was induced early and strongly by inoculation with V. dahliae and application of plant hormone. Recombinant cotton polyamine oxidase (GhPAO) was found to catalyse the conversion of spermine (Spm) to spermidine (Spd) in vitro. Constitutive expression of GhPAO in Arabidopsis thaliana produced improved resistance to V. dahliae and maintained putrescine, Spd and Spm at high levels. Hydrogen peroxide (H 2 O 2 ), salicylic acid and camalexin (a phytoalexin) levels were distinctly increased in GhPAO-overexpressing Arabidopsis plants during V. dahliae infection when compared with wild-type plants, and Spm and camalexin efficiently inhibited growth of V. dahliae in vitro. Spermine promoted the accumulation of camalexin by inducing the expression of mitogen-activated protein kinases and cytochrome P450 proteins in Arabidopsis and cotton plants. The three polyamines all showed higher accumulation in tolerant cotton cultivars than in susceptible cotton cultivars after inoculation with V. dahliae. GhPAO silencing in cotton significantly reduced the Spd level and increased the Spm level, leading to enhanced susceptibility to infection by V. dahliae, and the levels of H 2 O 2 and camalexin were distinctly lower in GhPAO-silenced cotton plants after V. dahliae infection. Together, these results suggest that GhPAO contributes to resistance of the plant against V. dahliae through the mediation of Spm and camalexin signalling.

RNAseq analysis reveals pathways and candidate genes associated with salinity tolerance in a spaceflight-induced wheat mutant

“…PAO and ADC genes are critical for PA metabolism, and PAs play important roles in plant resistance to environmental stresses 11, 14, 46–48 . For example, it has been reported that a cotton PAO is required for the mediation of spermine and camalexin signaling to resist a destructive fungal pathogen 16 . Additionally, PAO has also been reported to contribute to improving drought stress tolerance in grapevine 15 .…”

“…Polyamine oxidases (PAOs) catalyze the back conversion of PAs to Spd or Put and help maintain PA homeostasis 14 . It has been suggested that PAOs function in stress resistance by mediating PA homeostasis 15, 16 .…”

Identification of genes related to salt stress tolerance using intron-length polymorphic markers, association mapping and virus-induced gene silencing in cotton

“…The amplification reactions were as follows: 95 °C for 10 min, followed by 40 cycles of 95 °C for 15 s, 58 °C for 15 s, and 72 °C for 30 s. The gene expression levels were calculated according to Livak and Schmittgen 72 . Two reference genes ( GhHis3 73 with abundant transcripts and GhTub1 74 with moderate transcripts), were used simultaneously to confirm the real-time PCR results. The information for the real-time PCR primers were listed in Dataset S6.…”

Characterization, expression, and functional analysis of polyamine oxidases and their role in selenium‐induced hydrogen peroxide production in Brassica rapa

“…Abscisic acid (ABA) induces H 2 O 2 production through a type I PAO in maize . In tobacco and cotton, PAO‐derived H 2 O 2 contributes to a hypersensitive response (HR) upon pathogen infection . In addition, a type I PAO located in apoplast contributes to H 2 O 2 accumulation by coordinating with RBOH in tobacco leaves under salinity stress .…”