Manganese (Mn) is an essential element for plant growth due to its participation in a series of physiological and metabolic processes. Mn is also considered a heavy metal that causes phytotoxicity when present in excess, disrupting photosynthesis and enzyme activity in plants. Thus, Mn toxicity is a major constraint limiting plant growth and production, especially in acid soils. To cope with Mn toxicity, plants have evolved a wide range of adaptive strategies to improve their growth under this stress. Mn tolerance mechanisms include activation of the antioxidant system, regulation of Mn uptake and homeostasis, and compartmentalization of Mn into subcellular compartments (e.g., vacuoles, endoplasmic reticulum, Golgi apparatus, and cell walls). In this regard, numerous genes are involved in specific pathways controlling Mn detoxification. Here, we summarize the recent advances in the mechanisms of Mn toxicity tolerance in plants and highlight the roles of genes responsible for Mn uptake, translocation, and distribution, contributing to Mn detoxification. We hope this review will provide a comprehensive understanding of the adaptive strategies of plants to Mn toxicity through gene regulation, which will aid in breeding crop varieties with Mn tolerance via genetic improvement approaches, enhancing the yield and quality of crops.

Carpetgrass [ Axonopus compressus (Sw.) Beauv.] is an important warm-season perennial turfgrass that is widely used in tropical and subtropical areas. The genetic diversity of 63 carpetgrass accessions in China was studied using simple sequence repeat (SSR) markers. Fourteen SSR primer combinations generated a total of 49 distinct bands, 48 (97.96%) of which were polymorphic. The number of observed alleles ranged from 2 to 6, with an average of 3.5. Coefficients of genetic similarity among the accessions ranged from 0.24 to 0.98. Unweighted pair-group method with arithmetic means (UPGMA) clustered the 63 accessions into three groups, and not all samples from the same region belonged to the same group. SSR markers will promote marker-assisted breeding and the assessment of genetic diversity in wild germplasm resources of carpetgrass.

Background: DNA methylation, as an epigenetic modification, is crucial in the regulatory mechanism of salt resistance in plants. Methods: To gain deeper insight into the relationship between DNA methylation and mRNA exons in halophytes and their potential roles in regulating salt tolerance, this study employed whole-genome bisulfite sequencing (WGBS) and transcriptome sequencing data to analyze the leaves of the halophyte Paspalum vaginatum, widely distributed in tropical regions. Results: The findings revealed that the methylation level of 5-methylcytosine (5mC) in the genomic elements of P. vaginatum increased with prolonged salt treatment under salt stress conditions. This observation suggested that the methylation level plays a pivotal role in the salt stress response of P. vaginatum. Notably, under salt stress, the number of variants at the mRNA exon level was significantly higher than that at the DNA level. Furthermore, comparative analysis revealed sequence variants within exonic regions of mature mRNA transcripts for several genes in salt-treated samples relative to pre-stress controls, and these changes were found to be enriched in several salt-tolerance pathways, including unsaturated fatty acid metabolism and ascorbic acid metabolism, among others. Further analysis demonstrated that the occurrence of these variants changed concomitantly with the dynamic changes in CG methylation levels in the gene body of some salt-tolerant genes. Therefore, it was speculated that mRNA exon variations probably promoted the elevation of CG 5mC methylation levels at the DNA level under salt stress conditions, further enabling the plant to adapt to the salt-stress environment. Conclusions: These findings offer preliminary insights into the relationship between DNA methylation and mRNA exon variations in P. vaginatum under salt stress, providing valuable information and avenues for further investigation into the regulatory role of mRNA in DNA methylation.

Molecular genetic diversity and relationships among 86 Chrysopogon aciculatus (Retz.) Trin. accessions were assessed using intersimple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) markers. Twenty-five ISSR markers generated 283 amplification bands, of which 266 were polymorphic. In addition, 576 polymorphic bands were detected from 627 bands amplified using 30 SRAP primers. Both marker types revealed a high level of genetic diversity, with ISSR markers showing a higher proportion of polymorphic loci (PPL; 94%) than SRAP markers (91.87%). The ISSR and SRAP data were significantly correlated ( r = 0.8023). Cluster analysis of the separate ISSR and SRAP data sets clustered the accessions into three groups, which generally were consistent with geographic provenance. Cluster analysis of the combined ISSR and SRAP data set revealed four major groups similar to those based solely on ISSR or SRAP markers. The findings demonstrate that ISSR and SRAP markers are reliable and effective tools for analysis of genetic diversity in C. aciculatus .

Chrysopogon aciculatus (Retz.) Trin. is a perennial turfgrass for its low management and resistance. To develop simple sequence repeat (SSR) markers for C. aciculatus , we used four Roche 454 pyrosequencing, combined with the magnetic bead enrichment method FIASCO (fast isolation by amplified fragment length polymorphism of sequences containing repeats) to isolate from the C. aciculatus . A total of 66,198 raw sequencing reads were obtained with 4289 sequences (6.48%) were fit for primer pair design. One hundred microsatellite loci were selected to test the primer amplification efficiency in 20 accessions, and out of these, 11 loci were polymorphic. The amount of observed alleles ranged from three to six, with an average of 3.64. Nei’s genetic diversity values ranged from 0.085 to 0.493, with an average of 0.293. Shannon’s information index values ranged from 0.141 to 0.686, with an average of 0.428. Twenty accessions were clustered into three groups by unweighted pair-group method with arithmetic means (UPGMA). These SSR markers will provide an ideal marker system to assist with gene targeting, cultivar variety or species identification, and marker-assisted selection in C. aciculatus species.