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Neolamarckia cadamba (Roxb.) Bosser is a fast-growing deciduous tree species and belongs to the Neolamarckia genus of the Rubiaceae family. This species has great economic and medical values in addition to being an important timber species for multiple industrial purposes. However, few studies have examined the genetic diversity and population structure in the natural distribution of this species in China. Here, we applied both the haploid nrDNA ITS (619 bp for aligned sequences) and mtDNA (2 polymorphic loci) markers to investigate 10 natural populations (239 individuals in total) that covered most of the distribution of the species in China. The results showed that the nucleotide diversity was π = 0.1185 ± 0.0242 for the nrDNA ITS markers and π = 0.00038 ± 0.00052 for the mtDNA markers. The haplotype diversity for the mtDNA markers was h = 0.1952 ± 0.2532. The population genetic differentiation was small ( F s t n = 0.0294) for the nrDNA ITS markers but large ( F s t m = 0.6765) for the mtDNA markers. There were no significant effects of isolation by distance (IBD), by elevation, and by two climatic factors (annual average precipitation and tem perature). A geographic structure among populations ( N s t < G s t ) was absent. Phylogenetic analysis showed a highly genetic mixture among individuals of the ten populations. Pollen flow was substantially greater than seed flow ( m p / m s   ≫ 1.0) and played a dominant role in shaping population genetic structure. The nrDNA ITS sequences were neutral and all local populations did not undergo demographic expansion. The overall results provide fundamental information for the genetic conservation and breeding of this miraculous tree. [ABSTRACT FROM AUTHOR]

Introduction: Members of the plant-specific B3 transcription factor superfamily play crucial roles in various plant growth and developmental processes. Despite numerous valuable studies on B3 genes in other species, little is known about the B3 superfamily in pearl millet., Methods and Results: Here, through comparative genomic analysis, we identified 70 B3 proteins in pearl millet and categorized them into four subfamilies based on phylogenetic affiliations: ARF, RAV, LAV, and REM. We also mapped the chromosomal locations of these proteins and analyzed their gene structures, conserved motifs, and gene duplication events, providing new insights into their potential functional interactions. Using transcriptomic sequencing and real-time quantitative PCR, we determined that most PgB3 genes exhibit upregulated expression under drought and high-temperature stresses, indicating their involvement in stress response regulation. To delve deeper into the abiotic stress roles of the B3 family, we focused on a specific gene within the RAV subfamily, PgRAV-04 , cloning it and overexpressing it in tobacco. PgRAV-04 overexpression led to increased drought sensitivity in the transgenic plants due to decreased proline levels and peroxidase activity., Discussion: This study not only adds to the existing body of knowledge on the B3 family's characteristics but also advances our functional understanding of the PgB3 genes in pearl millet, reinforcing the significance of these factors in stress adaptation mechanisms., Competing Interests: The reviewer KS declared a shared affiliation with the authors Y-HW, XY, B-YZ, W-JW, Z-FZ, X-LH, K-XO, T-XZ and F-XL to the handling editor at the time of review. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wang, Ye, Zhao, Wang, Zhou, Zhang, Du, Song, Huang, Ouyang, Zhong and Liao.)