Studies on genetic diversity and phylogenetic relationships of limpograss (Hemarthria altissima) and related species based on combined chloroplast DNA intergenic spacer data

Metabolomics and microbiome analysis elucidate the detoxification mechanisms of Hemarthria compressa, a low cadmium accumulating plant, in response to cadmium stress

Cadmium (Cd) is recognized as one of the most toxic heavy metal in the environment that causes pronounced phytotoxicity. This study investigated the physiological and biochemical responses and detoxification mechanisms of Hemarthria compressa under various concentrations of Cd stress (0, 30, 60, 90, and 270 mg·kg-1). Our research findings indicate that the growth and photosynthetic capacity of H. compressa reach their peak at a Cd concentration of 60 mg·kg-1. At this concentration, the Cd concentration in the shoots of H. compressa is 0.67 mg·kg-1, the total Cd accumulation is 0.25 μg, and the MDA content is 6.25 nmol·g-1, which represents the lowest values among all treatments.Metabolomics analysis reveals that sugar is related to Cd stress resistance, and the levels of organic acids involved in metabolic processes show only minor changes. H. compressa alters the composition of its root exudates by secreting substantial quantities of organic acids (such as citric acid, fumaric acid, and malic acid), sugars (such as trehalose, maltose, and glucose), and fatty acids (such as citraconic acid). These organic acids modulate the pH of the rhizosphere soil and recruit beneficial microorganisms, including Gp6, Sphingoaurantiacus, Devosia, and Neobacillus species, thereby enhancing plant growth and mitigating Cd accumulation.

Reference gene selection for real-time quantitative PCR normalization in Hemarthria compressa and Hemarthria altissima leaf tissue

Hemarthria compressa and Hemarthria altissima are widely used as livestock forage and play important roles in tropical and subtropical grassland agricultural systems promoting healthy ecological environment and the development of animal husbandry. Leaf tissue of "Yaan" limpograss (H. compressa) and "H255" whip grass (H. altissima) were used to test the mRNA expression levels of 12 reference genes using RT-qPCR. The Delta-Ct method, BestKeeper (ver. 1.0), Genorm (ver. 3.5), Normfinder (ver. 0.953) and RefFinder were used to analyze the expression stability of the 12 reference genes under drought, salt, acid-aluminum and cold stresses to provide significant technical support for the study of gene expression under various abiotic stresses in Hemarthria. The results showed that the candidate reference genes showed divergent expression levels under various abiotic stresses. Among the genes that were selected, CL18892 showed the highest expression stability under salt stress in the leaf tissue. eEF-1α was the most stable gene under cold and acid-aluminum stresses and CL16384 was comparatively the most suitable genes under drought stress. As a whole, according to RefFinder analysis, CYP5, BMK.74327 and CL21527 were the most suitable reference genes for studying the effects of abiotic stress in Hemarthria. In general, CL16812 and CL18038 were not suitable reference genes under abiotic stress conditions that were examined in this study.