A fungus with broad spectrum antifungal activity was isolated from the soil in Qinling Mountain, Shaanxi Province, in China. The fungus was identified as Purpureocillium lilacinum based on ITS rDNA gene analysis. The strain, coded as QLP12, showed high inhibition activity on fungal mycelium growth in vitro, especially to Mucor piriformis, Trichothecium roseum, Rhizoctonia solani, and Verticillium dahliae, and its potential for biocontrol efficacy of eggplant. Verticillium wilt disease caused by Verticillium dahliae among 10 fungal species tested was explored. In greenhouse experiments, QLP12 showed an excellent growth-promoting effect on eggplant seed germination (76.7%), bud growth (79.4%), chlorophyll content (47.83%), root activity (182.02%), and so on. QLP12 can colonize the eggplant interior and also develop in rhizosphere soil. In greenhouse, the incidence of Verticillium wilt decreased by 83.82% with pretreated QLP12 fermentation broth in the soil. In the field, QLP12 showed prominent biocontrol effects on Verticillium wilt by reducing the disease index over the whole growth period, a decline of 40.1%. This study showed that the strain QLP12 is not only an effective biocontrol agent for controlling Verticillium wilt of eggplant, but also a plant growth-promoting fungus that deserves to be further developed.

Excessive phosphorus (P) application can alter soil P availability and limit plant growth by compacting soil and fixation of P into different organic and inorganic forms. However, it remains uncertain whether these changes happen after limited fertilization or an excessive rate applied under the winter wheat cropping system. The current study aimed to identify the transformation of P into different organic (P_o) and inorganic (P_i) fractions, and their role in the plant P uptake and winter wheat (Triticum aestivum L.) production. A long-term study (12 years) was conducted to assess the changes in soil P_i and P_o fractions in response to different P rates (0, 50, 100, 150, and 200 kg P₂O₅ ha⁻¹) applied to winter wheat. Phosphorus fractions were determined using the Hedley modified Tiessen and Moir fractionation scheme. Our findings demonstrated that different P rates significantly increased the available P, particularly NaHCO₃-P_i, in the inorganic P fractions compared to P0 treatment. NaHCO₃-P_i showed a strong relationship with grain yield (R² = 0.91) and P uptake (R² = 0.80). Grain yield was significantly higher in the P100 treatment, but no significant difference was observed between P100 and P200 treatments. The P200 treatment had a maximum grain P content and plant P uptake. Compared with the P0 treatment, all organic fractions yielded the highest P_o with the P rate increase, ranging from 27.3 to 75.6 mg kg⁻¹, 27.2 to 35.6 mg kg⁻¹, and 58.8 to 124 mg kg⁻¹ for NaHCO₃-P_o, NaOH-P_o, and HCl-P_o, respectively. Among all P_i fractions, the maximum fraction, known as apatite (HCl_D-P_i), was found in the P200 treatment with the range of 165 to 245.9 mg kg⁻¹. HCl_D-P_i accounted for 32% of total P, which can be transformed into the available P form with the passage of time. An increase of 78% in residual P was found under the treatment of P200. The residual P fraction was positively correlated with grain yield, P uptake, and other inorganic fractions. It can be concluded that application of P increases P availability and grain yield with an increase in its application rate, but too much use of P can cause soil pollution and higher fixation of P. Consequently, a balanced application of fertilizer is recommended to reduce its fixation and increase its availability for higher crop yield.

Summary: Actin filament assembly in plants is a dynamic process, requiring the activity of more than 75 actin‐binding proteins. Central to the regulation of filament assembly and stability is the activity of a conserved family of actin‐depolymerizing factors (ADFs), whose primarily function is to regulate the severing and depolymerization of actin filaments. In recent years, the activity of ADF proteins has been linked to a variety of cellular processes, including those associated with response to stress. Herein, a wheat ADF gene, TaADF4, was identified and characterized. TaADF4 encodes a 139‐amino‐acid protein containing five F‐actin‐binding sites and two G‐actin‐binding sites, and interacts with wheat (Triticum aestivum) Actin1 (TaACT1), in planta. Following treatment of wheat, separately, with jasmonic acid, abscisic acid or with the avirulent race, CYR23, of the stripe rust pathogen Puccinia striiformis f. sp. tritici, we observed a rapid induction in accumulation of TaADF4 mRNA. Interestingly, accumulation of TaADF4 mRNA was diminished in response to inoculation with a virulent race, CYR31. Silencing of TaADF4 resulted in enhanced susceptibility to CYR23, demonstrating a role for TaADF4 in defense signaling. Using a pharmacological‐based approach, coupled with an analysis of host response to pathogen infection, we observed that treatment of plants with the actin‐modifying agent latrunculin B enhanced resistance to CYR23, including increased production of reactive oxygen species and enhancement of localized hypersensitive cell death. Taken together, these data support the hypothesis that TaADF4 positively modulates plant immunity in wheat via the modulation of actin cytoskeletal organization.

The actin cytoskeleton participates in numerous cellular processes, including less-characterized processes, such as nuclear organization, chromatin remodeling, transcription, and signal transduction. As a key regulator of actin cytoskeletal dynamics, the actin related protein 2/3 complex (Arp2/3 complex) controls multiple developmental processes in a variety of tissues and cell types. To date, the role of the Arp2/3 complex in plant disease resistance signaling is largely unknown. Herein, we identified and characterized wheat ARPC3, TaARPC3, which encodes the C3 subunit of the Arp2/3 complex. Expression of TaARPC3 in the arc18 mutant of Saccharomyces cerevisiae Δarc18 resulted in complementation of stress-induced phenotypes in S. cerevisiae, as well as restore wild-type cell shape malformations. TaARPC3 was found predominantly to be localized in the nucleus and cytoplasm when expressed transiently in wheat protoplast. TaARPC3 was significantly induced in response to avirulent race of Puccinia striiformis f. sp. tritici (Pst). Knock-down of TaARPC3 by virus-induced gene silencing resulted in a reduction of resistance against Pst through a specific reduction in actin cytoskeletal organization. Interestingly, this reduction was found to coincide with a block in reactive oxygen species (ROS) accumulation, the hypersensitive response (HR), an increase in TaCAT1 mRNA accumulation, and the growth of Pst. Taken together, these findings suggest that TaARPC3 is a key subunit of the Arp2/3 complex which is required for wheat resistance against Pst, a process that is associated with the regulation of the actin cytoskeleton.