During mining activities, deep-sea mining vehicles (DSMVs) are highly susceptible to causing massive disturbance to the seafloor sediment, resulting in the formation of plumes due to underlying turbulence and currents. To gain a better understanding of the dispersion mechanism of sediment plumes, both experimental and numerical methods were employed. The numerical model was primarily used to characterize the solidity and liquidity of the sediment plume through volume of fluid and discrete phase model methods, respectively. The experimental data were validated against the numerical results. The plume distribution was studied in physical experiments for three different DSMV parameters. The study findings indicate that the discharge of the plume in the near field occurs in three stages due to a combination of plume release inertial forces, negative buoyancy in the water column, and wall restoring forces. Additionally, the increase in the travel velocity of the DSMV reduces the propagation of the plume in the direction of discharge and instead increases its lateral spread across the bottom surface. As the size of the DSMV decreases in three dimensions, changes in the vertical vortex structure become dominant in the plume distribution. This leads to a reduction in the length of the plume head and a faster sinking of the plume. When the wake Froude number Frw is between 0.7 and 6.8, representing the wake turbulence effect of DSMV on plume discharge, the diffusion width of the plume on the bottom surface is linearly related to Frw.

Considering that the presence of a leafy head is a key morphological characteristic that determines the yield and quality of Chinese cabbage, identifying the major genes regulating the formation of a leafy head is crucial for variety improvement. A heading-related gene, BrKS, was previously predicted from a non-heading mutant, nhm1, derived from a heading variety, which encodes a key enzyme involved in gibberellin biosynthesis. Here, another mutant, nhm2, was identified from the same EMS-mutagenized population, and the phenotype of nhm2 was consistent with that of nhm1. We crossed mutants nhm1 and nhm2, and their F₁ plants exhibited the mutant phenotype, which indicated that their mutant genes were allelic. A single non-synonymous mutation in the fourth exon of BrKS in mutant nhm1 and another single non-synonymous mutation in the tenth exon of BrKS in mutant nhm2. The same gene mutation in mutants nhm1 and nhm2 produced a similar non-heading phenotype, which confirmed the role of BrKS in the leafy head formation of Chinese cabbage. RNA-Seq analysis indicated that a transcription factor gene, BrERF1A, which is associated with leaf development, significantly down-regulated expression in mutant nhm1, and after the mutant was treated with GA₃, the expression level of BrERF1A was recovered, which indicated that BrKS might be involved in leafy head formation through regulating the expression level of BrERF1A. Our findings provide important clues for revealing the molecular mechanism of leafy head formation in Chinese cabbage.

Potassium (K) is an essential nutrient for the growth and development of plants. Root hairs are the main parts of plants that absorb K⁺. The regulation of plant root hair growth in response to a wide range of environmental stresses is crucially associated with the dynamics of actin filaments, and the thick actin bundles at the apical and sub-apical regions are essential for terminating the rapid elongation of root hair cells. However, the dynamics and roles of actin filaments in root hair growth in plants’ response to low K⁺ stress are not fully understood. Here, we revealed that root hairs grow faster and longer under low K⁺ stress than the control conditions. Compared to control conditions, the actin filaments in the sub-apex of fast-growing wild-type root hairs were longer and more parallel under low K⁺ stress, which correlates with an increased root hair growth rate under low K⁺ stress; the finer actin filaments in the sub-apex of the early fully grown Col-0 root hairs under low K⁺ stress, which is associated with low K⁺ stress-induced root hair growth time. Further, Arabidopsis thaliana actin bundling protein Villin1 (VLN1) and Villin4 (VLN4) was inhibited and induced under low K⁺ stress, respectively. Low K⁺ stress-inhibited VLN1 led to decreased bundling rate and thick bundle formation in the early fully grown phase. Low K⁺ stress-induced VLN4 functioned in keeping long filaments in the fast-growing phase. Furthermore, the analysis of genetics pointed out the involvement of VLN1 and VLN4 in the growth of root hairs under the stress of low potassium levels in plants. Our results provide a basis for the dynamics of actin filaments and their molecular regulation mechanisms in root hair growth in response to low K⁺ stress.