Nonspecific lipidtransfer proteins (nsLTPs), which are small, cysteine‐rich proteins, belong to the pathogenesis‐related protein family, and several of them act as positive regulators during plant disease resistance. However, the underlying molecular mechanisms of these proteins in plant immune responses are unclear. In this study, a typical nsLTP gene, StLTP10, was identified and functionally analysed in potato. StLTP10 expression was significantly induced by Phytophthora infestans, which causes late blight in potato, and defence‐related phytohormones, including abscisic acid (ABA), salicylic acid, and jasmonic acid. Characterization of StLTP10‐overexpressing and knockdown lines indicated that StLTP10 positively regulates plant resistance to P. infestans. This resistance was coupled with enhanced expression of reactive oxygen species scavenging‐ and defence‐related genes. Furthermore, we identified that StLTP10 physically interacts with ABA receptor PYL4 and affects its subcellular localization. These two proteins work together to regulate stomatal closure during pathogen infection. Interestingly, we also found that wound‐induced protein kinase interacts with StLTP10 and positively regulates its protein abundance. Taken together, our results provide insight into the role of StLTP10 in resistance to P. infestans and suggest candidates to enhance broad‐spectrum resistance to pathogens in potato.

Many plant and animal viruses counteract RNA silencing-mediated defense by encoding diverse RNA silencing suppressors. We characterized HVT063, a multifunctional protein encoded by turkey herpesvirus (HVT), as a silencing suppressor in coinfiltration assays with green fluorescent protein transgenic Nicotiana benthamiana line 16c. Our results indicated that HVT063 could strongly suppress both local and systemic RNA silencing induced by either sense RNA or double-stranded RNA (dsRNA). HVT063 could reverse local silencing, but not systemic silencing, in newly emerging leaves. The local silencing suppression activity of HVT063 was also verified using the heterologous vector PVX. Further, single alanine substitution of arginine or lysine residues of the HVT063 protein showed that each selected single amino acid contributed to the suppression activity of HVT063 and region 1 (residues 138 to 141) was more important, because three of four single amino acid mutations in this region could abolish the silencing suppressor activity of HVT063. Moreover, HVT063 seemed to induce a cell death phenotype in the infiltrated leaf region, and the HVT063 dilutions could decrease the silencing suppressor activity and alleviate the cell death phenotype. Collectively, these results suggest that HVT063 functions as a viral suppressor of RNA silencing that targets a downstream step of the dsRNA formation in the RNA silencing process. Positively charged amino acids in HVT063, such as arginine and lysine, might contribute to the suppressor activity by boosting the interaction between HVT063 and RNA, since HVT063 has been demonstrated to be an RNA binding protein.

Antiviral defense of plants is usually enhanced by an elevated temperature under natural conditions. In order to better understand this phenomenon, we carried out temperature shift experiments with Nicotiana glutinosa plants that were infected with Potato virus X (PVX) or the necrotic strain of Potato virus Y (PVY^N). The virus titer of the plants was found to be much lower when they were maintained at 30°C compared with 22°C, particularly in the upper leaves. PVX resistance at 30°C persisted for a short period even when temperature was shifted back to 22°C. In contrast, N. benthamiana lost the virus resistance immediately after the temperature dropped to 22°C. Expression analysis of two RNA-dependent RNA polymerases in N. glutinosa (NgRDR) showed that a 12-day treatment at 30°C increased the expression of NgRDR1, while NgRDR6 was not affected. In addition, the NgRDR6 mRNA level correlated with the PVX titer but was unaffected by PVY^Ninfection. These observations indicate that PVX and PVY^N, although they are both RNA viruses, might trigger different defense responses at elevated temperatures. Our study provides valuable data for a better understanding of the temperature-regulated host virus interaction.

In order to widen gene germplasm for kernel hardness in triticale, 60 synthetic hexaploid triticales were tested by the single kernel characterization system (SKCS) and secaloindoline alleles were identified by sequencing. Phenotyping showed that frequencies of soft, mixed and hard genotypes were 43.3%, 48.3%, and 8.4%, respectively. Genotyping identified three known secaloindoline-a alleles and four known secaloindoline-b alleles. Three new Sina-R1 alleles were designated Sina-R1d, Sina-R1e and Sina-R1f. Compared to Sina-D1c, Sina-R1d showed four point mutations causing changes in four amino acids, Sina-R1e had one point mutation causing an alanine to glycine substitution, and Sina-R1f possessed five point mutations but produced the same amino acid sequence as Sina-R1d. Two new Sinb-R1 alleles were discovered and designated Sinb-R1e and Sinb-R1f. Compared to Sinb-R1a, Sinb-R1e possessed a triplet-code insertion and four point mutations causing a cysteine insertion and two amino acid substitutions, and Sinb-R1f possessed three point mutations causing a cysteine insertion and a change of arginine to glycine. Association of hardness index with secaloindoline alleles indicated that SKCS of the Sina-R1d genotype was significantly lower than that of Sina-R1e, and Sinb-R1e was significantly lower than that of the Sinb-R1d genotype. A total of eight allelic combinations of secaloindoline genes were identified; Sina-R1d/Sinb-R1e and Sina-R1e/Sinb-R1d were relatively prevalent in the triticales surveyed. The results provide valuable information for further use of these germplasms in triticale breeding program due to the diverse polymorphism in secaloindoline genes