TaMCA1, a regulator of cell death, is important for the interaction between wheat and Puccinia striiformis

Abstract

Metacaspase orthologs are conserved in fungi, protozoa and plants, however, their roles in plant disease resistance are largely unknown. In this study, we identified a Triticum aestivum metacaspase gene, TaMCA1, with three copies located on chromosomes 1A, 1B and 1D. The TaMCA1 protein contained typical structural features of type I metacaspases domains, including an N-terminal pro-domain. Transient expression analyses indicated that TaMCA1 was localized in cytosol and mitochondria. TaMCA1 exhibited no caspase-1 activity in vitro, but was able to inhibit cell death in tobacco and wheat leaves induced by the mouse Bax gene. In addition, the expression level of TaMCA1 was up-regulated following challenge with the Puccinia striiformis f. sp. tritici (Pst). Knockdown of TaMCA1 via virus-induced gene silencing (VIGS) enhanced plant disease resistance to Pst, and the accumulation of hydrogen peroxide (H2O2). Further study showed that TaMCA1 decreased yeast cell resistance similar to the function of yeast metacaspase, and there was no interaction between TaMCA1 and TaLSD1. Based on these combined results, we speculate that TaMCA1, a regulator of cell death, is important during the compatible interaction of wheat and Pst.

Maize metacaspases modulate the defense response mediated by the NLR protein Rp1‐D21 likely by affecting its subcellular localization

“…The type II Arabidopsis AtMC4 gene plays a positive role in the cell death induced by the mycotoxin fumonisin B1, oxidative stresses, and Pseudomonas syringae carrying the effector AvrRpt2 (Watanabe and Lam, 2011a,b). In wheat ( Triticum aestivum L.), the type I TaMCA1 gene inhibited Bax‐mediated cell death in both wheat and N. benthamiana (Hao et al ., 2016); however, the type II TaMCA4 gene enhanced cell death triggered by Bax and a candidate effector from Pst (Wang et al ., 2012). Silencing of TaMCA1 or TaMCA4 by virus‐induced gene silencing in wheat enhanced and decreased disease resistance to stripe rust in wheat, respectively (Wang et al ., 2012; Hao et al ., 2016).…”

“…In wheat ( Triticum aestivum L.), the type I TaMCA1 gene inhibited Bax‐mediated cell death in both wheat and N. benthamiana (Hao et al ., 2016); however, the type II TaMCA4 gene enhanced cell death triggered by Bax and a candidate effector from Pst (Wang et al ., 2012). Silencing of TaMCA1 or TaMCA4 by virus‐induced gene silencing in wheat enhanced and decreased disease resistance to stripe rust in wheat, respectively (Wang et al ., 2012; Hao et al ., 2016). In N. benthamiana , virus‐induced silencing of the type II MC NbMCA1 results in increased susceptibility to Colletotrichum destructivum (Hao et al ., 2007).…”

“…Plant MCs have diverse subcellular localizations. Type I TaMCA1 was localized in the cytoplasm and mitochondria (Hao et al ., 2016). VvMC2 is localized at the ER while VvMC5 is located in both the cytoplasm and the nucleus (Gong et al ., 2019).…”

“…A number of studies have shown that MCs play important roles in the plant defense response (Coll et al ., 2011; Watanabe and Lam, 2011a, 2011b; Wang et al ., 2012; Kim et al ., 2013; Hao et al ., 2016). For instance, the function of two type I AtMCs was investigated.…”

Proteomics Analysis Reveals That Caspase-Like and Metacaspase-Like Activities Are Dispensable for Activation of Proteases Involved in Early Response to Biotic Stress in Triticum aestivum L.

“…Moreover, the degradome of wheat has not yet been characterized despite its importance for immunity and PCD-related processes. It is known that expression of the wheat metacaspase 1 gene (TaMCA1) increases when infected with Puccinia striiformis [38]. However, there are no data available on proteolytic cascades and proteases that regulate wheat immunity in healthy and infected plants.…”