R2R3-MYB gene family serves as a pivotal regulatory factor in plant growth, development, and responses to environmental stresses. To investigate its function in the drought stress response of wild jujube (Ziziphus jujuba Mill. var. spinosa), a typical eco-economic forest species, this study performed genome-wide identification and relevant analyses of R2R3-MYB genes. A total of 91 R2R3-MYB genes (designated as ZjMYB1 to ZjMYB91) were identified, which were unevenly distributed across 12 chromosomes. These genes mainly encode hydrophilic and unstable proteins, 97.8% of which are localized in the nucleus. Phylogenetic analysis classified these genes into 25 clades, showing evolutionary conservation and species-specific divergence with the R2R3-MYB protein family. The expansion of the ZjMYB family is mainly characterized by segmental duplication, and all duplicated gene pairs have undergone purifying selection. ZjMYBs are widely involved in plant growth and development as well as abiotic stress responses, with the highest expression level particularly in leaf tissues; a total of 13 genes were specifically annotated as water deficit response-related genes in drought stress and abscisic acid (ABA) signaling pathways. Integrating the above analyses together with transcriptome data and qRT-PCR validation results revealed that ZjMYB5, ZjMYB53, ZjMYB57 and ZjMYB85 function as core drought-responsive genes, which display both tissue-specific and time-dependent expression patterns under drought stress. This study systematically elucidated the functional characteristics and regulatory network of the R2R3-MYB gene family in wild jujube, providing critical genetic resources and a theoretical basis for dissecting the molecular mechanisms underlying drought tolerance in wild jujube and breeding drought-resistant cultivars.
Prunus sibirica possesses substantial ecological and economic value and is recognized as an emerging woody energy crop; however, its regeneration and genetic transformation remain challenging. The present study established an efficient regeneration and Agrobacterium tumefaciens-mediated transformation system for P. sibirica. Stem segments served as explants, and the optimal proliferation medium was Murashige and Skoog medium supplemented with 0.8 mg L-1 6-benzylaminopurine (6-BA), 0.2 mg L-1 thidiazuron (TDZ), and 0.1 mg L-1 1-naphthaleneacetic acid (NAA), resulting in a proliferation coefficient of 6.53. The genetic transformation system utilized A. tumefaciens strain GV3101 carrying reporter vectors pRI101-GFP or pCAMBIA1301-GUS, with optimal parameters including a 3-day preculture, infection at OD600 = 0.6 for 20 min, and a 2-day coculture. Transformants were selected in a medium containing 20 mg L-1 kanamycin and 300 mg L-1 cefotaxime, achieving an average transformation efficiency of 11.27%. As an initial application, PsWRKY17-overexpressing lines were generated, exhibiting transcript levels 7-18 times higher than those in the empty-vector control. Following low-temperature treatment, PsWRKY17-OE lines demonstrated increased SOD and POD activities and reduced relative electrical conductivity and MDA content compared to the control (p < 0.01). These results provide preliminary physiological evidence that PsWRKY17 overexpression is associated with altered low-temperature stress responses in P. sibirica. However, the regulatory mechanism of PsWRKY17 requires further investigation. In summary, an effective regeneration and genetic transformation system for P. sibirica was developed, providing a foundation for future research and biotechnological applications.
Shipeng Wang, Jianhua Chen, Yongqiang Sun et al.· Physiologia Plantarum : An I...· 0 citations
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