Background: Apocynum venetum L. is an important medicinal plant that is mainly distributed in the coastal areas and northwest of China. In addition to its high medical and economic value, its adaptation to saline-alkali and coastal saline lands makes A. venetum an ideal candidate for use in vegetation restoration. To date, the study of A. venetum has been limited in the northwest region of China, little attention has been paid to the genetic diversity and population structure of A. venetum populations in the coastal region. Here, we performed transcriptome sequencing of total RNA from A. venetum leaves and developed efficient expressed sequence tag-simple sequence repeat (EST-SSR) markers for analyzing the genetic diversity and population structure of A. venetum in the coastal region. Results: A total of 86,890 unigenes were generated after de novo assembly, and 68,751 of which were successfully annotated by searching against seven protein databases. Furthermore, 14,072 EST-SSR loci were detected and 10,243 primer pairs were successfully designed from these loci. One hundred primer pairs were randomly selected and synthesized, twelve primer pairs were identified as highly polymorphic and further used for population genetic analysis. Population genetic analyses showed that A. venetum exhibited low level of genetic diversity (mean alleles per locus, N_A = 3.3; mean expected heterozygosity, H_E = 0.342) and moderate level of genetic differentiation among the populations (genetic differentiation index, F_ST = 0.032–0.220) in the coastal region. Although the contemporary (mean m_c = 0.056) and historical (mean m_h = 0.106) migration rates among the six A. venetum populations were moderate, a decreasing trend over the last few generations was detected. Bayesian structure analysis clustered six populations into two major groups, and genetic bottlenecks were found to have occurred in two populations (QG, BH). Conclusions: Using novel EST-SSR markers, we evaluated the genetic variation of A. venetum in the coastal region and determined conservation priorities based on these findings. The large dataset of unigenes and SSRs identified in our study, combining samples from a broader range, will support further research on the conservation and evolution of this important coastal plant and its related species.

Abiotic stresses seriously limit plant development and productivity and harm the agricultural economy. It is important, therefore, to understand the mechanism of salt tolerance in plants. Lateral organ boundaries domain (LBD) proteins are plant-specific transcription factors that have been reported to regulate plant lateral organ development, plant regeneration, and abiotic stress. In this study, we identify 69 LBD family members from switchgrass genome-wide sequences, and classify them according to their homology with LBD genes in Arabidopsis. Sixty-two cis-acting elements were identified from switchgrass LBD genes, and we found that most cis-acting elements can respond to light, control plant growth and development, regulate circadian rhythm, and respond to stress. Similarly, the results of qRT-PCR showed that PvLBD genes had different expression patterns under abiotic stress conditions, indicating that they may play important roles in stress response. In addition, candidate PvLBD target genes were enriched in many GO and KEGG pathways that play vital roles in the whole growth process and environmental stress response. PvLBD12 was selected as a candidate gene for functional analysis, and overexpression of PvLBD12 enhanced salt tolerance of transgenic switchgrass by altering a wide range of physiological responses. Overall, this study provides valuable information for better understanding the potential biological functions of LBD genes in plants.

Pennisetum hybrid (Pennisetum glaucum x P. purpureum), a perennial forage grass of the Poaceae family, it has a well-developed root system, strong tillering ability, high biomass yield, and rich nutritional content, making it a premium forage grass. However, Pennisetum genera grasses are sensitive to low-temperature stress and lacks the ability to adapt to cold environments, severely limiting its cultivation in temperate and high-altitude regions. C-repeat binding factor (CBF) members belong to the AP2/ERF (APETALA2/ethylene-responsive element-binding factor) type transcription activators, which play important roles in plants’ response to cold stress. We identified 23 PgCBF genes, unevenly distributed across chromosomes 1 to 7. Physicochemical property analysis revealed that the amino acid count of PgCBF family members ranged from 187 to 324, with molecular weights between 19688.36 and 34271.70 Da and theoretical isoelectric points between 4.57 and 9.82. Promoter region analysis of PgCBF genes indicated the presence of various cis-acting elements involved in hormone response, tissue-specific expression, and stress response. Additionally, qRT-PCR results showed significant upregulation of PgCBF11 expression in stems following cold treatment, with increasing over 40-fold after 32 h of cold treatment and about 20-fold after 8 h of cold treatment. PgCBF21 exhibited a strong response in leaves after 8 h of cold treatment, with expression levels rising more than 37-fold. Furthermore, through the overexpression of PgCBF21, we ascertained its capacity to enhance cold tolerance in yeast. This study analyzed the molecular characteristics of the PgCBF family members in P. glaucum and identified several candidate genes responsive to cold stress, providing a theoretical foundation for future research on the innovative utilization of cold-resistant resources.

Switchgrass (Panicum virgatum L.) is widely cultivated in China as a forage and model bioenergy crop. In August 2019, a new leaf spot disease on ‘Alamo’ switchgrass was found in Guangrao, Shandong,...