Characterization, Expression Profiling, and Functional Analysis of PtDef, a Defensin-Encoding Gene From Populus trichocarpa

Abstract

PtDef cloned from Populus trichocarpa contained eight cysteine domains specific to defensins. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis showed that PtDef was expressed in all tissues tested, with lower expression in leaves and higher expression in petioles, stems, and roots. Purified fused PtDef inhibited Aspergillus niger, Alternaria Nees, Mucor corymbifer, Marssonina populi, Rhizopus sp., and Neurospora crassa. PtDef also inhibited the growth of Escherichia coli by triggering autolysis. PtDef overexpression in Nanlin895 poplar (Populus × euramericana cv. Nanlin895) enhanced the level of resistance to Septotinia populiperda. qRT-PCR analysis also showed that the expression of 13 genes related to salicylic acid (SA) and jasmonic acid (JA) signal transduction differed between transgenic and wild-type (WT) poplars before and after inoculation, and that PR1-1 (12-72 h), NPR1-2, TGA1, and MYC2-1 expression was higher in transgenic poplars than in WT. During the hypersensitivity response (HR), large amounts of H 2 O 2 were produced by the poplar lines, particularly 12-24 h after inoculation; the rate and magnitude of the H 2 O 2 concentration increase were greater in transgenic lines than in WT. Overall, our findings suggest that PtDef, a defensin-encoding gene of P. trichocarpa, could be used for genetic engineering of woody plants for enhanced disease resistance.

Genome-Wide Comparative Analysis of R2R3 MYB Gene Family in Populus and Salix and Identification of Male Flower Bud Development-Related Genes

“…Poplar and willow belong to the Salicaceae family, which is widely distributed in the northern hemisphere ( Wei et al, 2020 ). Both species adapt easily to different ecological environments, grow rapidly, and reproduce without difficulty.…”

Plant Defense Proteins as Potential Markers for Early Detection of Forest Damage and Diseases

“…So far only very few genomes of perennial woody plants have been screened using specific AMP-targeting approaches. In addition, only very few studies have addressed the functions of AMPs in trees [e.g., Pinus sylvestris (Hrunyk et al, 2017;Khairutdinov et al, 2017), Picea glauca (Picart et al, 2012), and P. trichocarpa (Major and Constabel, 2008;Wei et al, 2020)]. Nevertheless, the results of these studies support the following statements: (a) There is a high diversity of AMPs in long-living woody plants.…”

“…In response to infestation with necrotrophic fungi and bacteria, these AMPs are upregulated both locally at the inoculation site and systemically in tissues distal to the infection site as early as 6 h after the infection and remain detectable during at least the following 3 days (Hsiao et al, 2017). A broad-spectrum defensin PtDef from Populus trichocarpa showed a graduate increase of its expression levels in response to abiotic stresses, such as drought and cold, during seven days of the experiment (Wei et al, 2020). Further examples of systemic AMPs involved in either hormone-mediated or reactive oxygen species-activated MAPK signaling cascades are described in the review by Bolouri Moghaddam et al (2016).…”

Respiratory allergies: Salicaceae sensitization (Review)

“…The poplar is among the most widely adaptable and distributed tree species in the Northern Hemisphere (latitude 22-70˚ N), including large areas in countries such as the United States, Canada, Russia, China, Italy and France (7). In Romania, the poplar has been for decades the most used ornamental tree along all the important roads between different towns and villages, in order to prevent the snow in winter.…”

“…In Romania, the poplar has been for decades the most used ornamental tree along all the important roads between different towns and villages, in order to prevent the snow in winter. Among the many species of poplar that grow worldwide, some of them were investigated regarding their role in pollinosis: Populus trichocarpa (7), Populus deltoides (8), Populus tomentosa (9), Populus hybrida (10). Recent studies evaluated the allergenic capacity of Populus pollen.…”