The barley (Hordeum vulgare) cellulose synthase‐like D2 gene (HvCslD2) mediates penetration resistance to host‐adapted and nonhost isolates of the powdery mildew fungus

Abstract

Cell walls and cellular turgor pressure shape and suspend the bodies of all vascular plants. In response to attack by fungal and oomycete pathogens, which usually breach their host's cell walls by mechanical force or by secreting lytic enzymes, plants often form local cell wall appositions (papillae) as an important first line of defence. The involvement of cell wall biosynthetic enzymes in the formation of these papillae is still poorly understood, especially in cereal crops. To investigate the role in plant defence of a candidate gene from barley (Hordeum vulgare) encoding cellulose synthase-like D2 (HvCslD2), we generated transgenic barley plants in which HvCslD2 was silenced through RNA interference (RNAi). The transgenic plants showed no growth defects but their papillae were more successfully penetrated by host-adapted, virulent as well as avirulent nonhost isolates of the powdery mildew fungus Blumeria graminis. Papilla penetration was associated with lower contents of cellulose in epidermal cell walls and increased digestion by fungal cell wall degrading enzymes. The results suggest that HvCslD2-mediated cell wall changes in the epidermal layer represent an important defence reaction both for nonhost and for quantitative host resistance against nonadapted wheat and host-adapted barley powdery mildew pathogens, respectively.

EgJUB1 and EgERF113 transcription factors as master regulators of defense response in Elaeis guineensis against the hemibiotrophic Ganoderma boninense

“…Consistently, CESA4, CESA7 and CESA9 were reported as regulators of secondary cell wall cellulose synthesis [63]. In addition, local cell wall reinforcement by CSLD2 has been proven under biotroph challenge of powdery mildew fungus (Douchkov et al, 2016). Thus, it is strongly postulated that EgJUB1 binding to SNBE1 motifs in the promoter regions of EgGAMYB-X2 activates oil palm defense response through regulation of secondary cell wall biosynthesis.…”

Plant cell wall‐mediated immunity: cell wall changes trigger disease resistance responses

“…These results with Arabidopsis CESA mutants illustrate that specific cell wall damage (CWD) of either the primary or secondary cell wall causes differential wall alterations, activating distinct immune responses. However, impairment of cellulose synthesis does not always lead to disease resistance since transient silencing of barley Cellulose Synthase Like D2 (CSLD2) has been described to enhance susceptibility to powdery mildew (Table S1; Douchkov et al, 2016). Cellulose biosynthesis can be impaired genetically but also by chemical inhibition upon treatment of the plant with specific inhibitors (for a recent review see Tateno et al, 2016).…”

Impact of biochemical changes on the development of powdery mildew of pea​

“…However, the amounts of phosphorus in the plant cells were analyzed in the range of mM (Hnatowich et al 2012). It is evidenced from the fact that infection of barley with powdery mildew or rust fungi has been shown to lead to increased P concentration in leaves, either through increased root uptake and subsequent transport to shoots or decreased re-translocation out of infected leaves (Douchkov et al 2016).…”