A method for generating genome edited plant lines from CRISPR-transformed Shanxin poplar plants

An R2R3-MYB transcription factor PdbMYB6 enhances drought tolerance by mediating reactive oxygen species scavenging, osmotic balance, and stomatal opening

Drought is a major environmental challenge that hinders the growth and development of plants. R2R3-MYB transcription factors (TFs) play a vital role in mediating responses to abiotic stress; however, their specific functions in Populus davidiana × Populus bolleana hybrid poplar plants remain underexplored. This study focused on PdbMYB6, a novel R2R3-MYB TF identified in P. davidiana × P. bolleana plants. We found that PdbMYB6 acts as a transcriptional activator. By conducting functional analyses of both overexpression and knockout models, we demonstrated that PdbMYB6 enhances drought tolerance in plants by improving reactive oxygen species scavenging and modulating osmotic balance. Additionally, PdbMYB6 plays a role in regulating stomatal openings to minimize water loss. The qRT-PCR and RNA sequencing results revealed that PdbMYB6 influences the expression of genes related to stress tolerance. TF-centered Yeast One-Hybrid (Y1H) and chromatin immunoprecipitation (ChIP) assays indicated that PdbMYB6 binds to two novel core sequences (C [A/G/C]TG and [T/A/G]GTA) as well as GT-1 (GGAAA) and MYBCORE (AACGG) elements, which are associated with light responses and stress resistance, thereby promoting the expression of stress-resistant genes. Furthermore, Y1H and ChIP assays identified four upstream factors that regulate PdbMYB6 expression by interacting with specific elements in its promoter. Notably, the overexpression of these four factors enhances plant drought resistance and affects the expression of stress-response genes. Our findings highlight the role of the PdbMYB6 TF in the drought regulatory mechanism and provide potential gene sources for the molecular breeding of drought-resistant plants through genetic engineering.

Microecological Shifts in the Rhizosphere of Perennial Large Trees and Seedlings in Continuous Cropping of Poplar

The cultivation of poplar trees is hindered by persistent cropping challenges, resulting in reduced wood productivity and increased susceptibility to soil-borne diseases. These issues primarily arise from alterations in microbial structure and the infiltration of pathogenic fungi. To investigate the impact on soil fertility, we conducted an analysis using soil samples from both perennial poplar trees and three successive generations of continuously cropped poplar trees. The quantity and community composition of bacteria and fungi in the rhizosphere were assessed using the Illumina MiSeq platform. The objective of this study is to elucidate the impact of continuous cropping challenges on soil fertility and rhizosphere microorganisms in poplar trees, thereby establishing a theoretical foundation for investigating the mechanisms underlying these challenges. The study found that the total bacteria in the BT group is 0.42 times higher than the CK group, and the total fungi is 0.33 times lower than the CK group. The BT and CK groups presented relatively similar bacterial richness and diversity, while the indices showed a significant (p < 0.05) higher fungal richness and diversity in the CK group. The fractions of Bacillus were 2.22% and 2.41% in the BT and CK groups, respectively. There was a 35.29% fraction of Inocybe in the BT group, whereas this was barely observed in the CK group. The fractions of Geopora were 26.25% and 5.99%, respectively in the BT and CK groups. Modifying the microbial community structure in soil subjected to continuous cropping is deemed as the most effective approach to mitigate the challenges associated with this agricultural practice.