Drought stress can reduce strawberry yield and quality and is one of the main abiotic factors restricting strawberry production in China. Nano-agricultural technology has significant regulatory effects in improving crop yield and quality and reducing agricultural environmental pollution. We performed a pot experiment using FenYu No. 1 strawberry and applied copper nanoparticles (CuNPs) and selenium NPs (SeNPs) to study their effects on the growth, quality, photosynthetic parameter indexes, and physiological characteristics of strawberry plants under drought stress. The growth and photosynthesis of strawberry plants were significant adversely affected by moderate drought stress (DS, 60% field capacity (FC)) and severe drought stress (SS, 25% FC). Compared with normal water-holding conditions, the application of CuNPs, SeNPs, and their combination effectively increased the agronomic traits of strawberry plants; improved fruit quality; and enhanced the content of photosynthetic pigments (chlorophyll a, chlorophyll b, and total chlorophyll), photosynthetic characteristic parameters, chlorophyll fluorescence parameters, and water-use efficiency. In addition, the exogenous application of CuNPs and SeNPs improved the drought tolerance of plants by increasing the activities of antioxidant enzymes catalase, peroxidase, and superoxide dismutase, and decreasing the malondialdehyde content, with the following overall trend among the treatments: control < CuNPs < SeNPs < CuNPs + SeNPs. The results of the principal component analysis showed that the two extracted principal components could reflect 85.54% of the information of the original data, leaf photosynthetic pigments, photosynthetic characteristic parameters, chlorophyll fluorescence parameters, and strawberry agronomic traits indexes and could be used as the primary indexes for evaluating the improvement of strawberry growth by nanofertilizers under drought-stress conditions. Taken together, our results indicate that nanofertilizers have potential for improving the growth, quality, and physiological characteristics of strawberries under drought stress.

Background: Strawberries (Fragaria ananassa) reproduce asexually through stolons, which have strong tendencies to form adventitious roots at their second node. Understanding how the development of the proximal (I-1) and distal (I-2) internodes of stolons differ should facilitate nursery cultivation of strawberries. Results: Herein, we compared the proteomic profiles of the strawberry stolon I-1 and I-2 internodes. Proteins extracted from the internodes were separated by two-dimensional gel electrophoresis, and 164 I-1 protein spots and 200 I-2 protein spots were examined further. Using mass spectrometry and database searches, 38 I-1 and 52 I-2 proteins were identified and categorized (8 and 10 groups, respectively) according to their cellular compartmentalization and functionality. Many of the identified proteins are enzymes necessary for carbohydrate metabolism and photosynthesis. Furthermore, identification of proteins that interact revealed that many of the I-2 proteins form a dynamic network during development. Finally, given our results, we present a mechanistic scheme for adventitious root formation of new clonal plants at the second node. Conclusions: Comparative proteomic analysis of I-1 and I-2 proteins revealed that the ubiquitin-proteasome pathway and sugar-hormone pathways might be important during adventitious root formation at the second node of new clonal plants.

Fusarium oxysporum causes crown rot, wilt, root rot, and many other major plant diseases worldwide. During the progression of strawberry crown rot disease, the pathogen is transmitted from the mother plant to the seedling through the stolon, with obvious characteristics of latent infection. Therefore, rapid and timely detection of F. oxysporum is important for efficient disease management. In this study, a recombinase polymerase amplification–lateral flow dipstick (RPA-LFD) detection technique was developed for the rapid detection of F. oxysporum on strawberry plants by targeting the CYP51C gene, which is unique to Fusarium spp. Because this RPA-LFD detection technique was highly specific to F. oxysporum, other Fusarium and non-Fusarium fungi were not detected. The optimal reaction temperature and time for this technique were 39°C and 8 min, respectively. The detection limit was 1 pg of F. oxysporum genomic DNA in a 50-μl reaction system. A total of 46 strawberry plants with or without crown rot symptoms collected from Jiande, Changxing, and Haining in Zhejiang Province were further assessed for F. oxysporum infection using both RPA-LFD and traditional tissue isolation techniques. The RPA-LFD test showed that 32 of the 46 strawberry plants tested were positive for F. oxysporum, while in the traditional isolation technique, F. oxysporum was isolated from 30 of the 46 strawberry plants. These results suggest that our established RPA-LFD method is rapid, sensitive, and highly specific in detecting F. oxysporum infection in strawberry plants.

The use of organic fertilizers instead of chemical fertilizers can improve soil pH, help to maintain soil health and enable landowners to achieve organic or ecological-status agriculture. Rapeseed cake, sheep manure, and biofungal fertilizer are considered to be effective amendments to improve soil quality. However, there have been few studies on the effects of the three fertilizers on strawberry production, soil physicochemical properties, and inter-root soil microbial community structure. In this study, field experiments were conducted to investigate the differences in strawberry growth, quality, yield, and the structure and diversity of strawberry soil bacterial and fungal communities under four treatments: no organic fertilizer (CK), rapeseed cake organic fertilizer (T1), sheep manure organic fertilizer (T2) and bio-organic fertilizer (algae-optimized bacteria) (T3), the relationship between soil physicochemical properties and soil microbial diversity were analyzed. Our results have shown that these three amendments promoted the growth of strawberry to some extent. The effects of available phosphorus, ammonium nitrogen, sucrase, protease and urease under T2 treatment were significantly increased by 50.62%, 54.14%, 276.50%, 129.47%, 232.61%, and 232.00%, respectively, compared with the control. The soil bacterial and fungi community were the most abundant and diversified under the T2 treatment. Soil physicochemical properties and soil key enzyme activities varied significantly under different fertilizer treatments, with the soil nutrient content and soil carbon and nitrogen metabolizing enzyme activities being highest under T2 treatment. A Pearson correlation analysis showed that soil organic matter was closely related to the diversity of soil microbial communities. A redundancy analysis (RDA) showed that the main variables of the bacterial community included nitrate nitrogen (NN) and rapidly available potassium (RAP), while the main variables of the fungal community included alkaline dissolved nitrogen (ADN) and ammonium nitrogen (AN). Overall, different fertilizers promoted the release and transformation of soil nutrients by affecting the structure and diversity of bacterial and fungal communities in strawberry soils, which was beneficial to the supply of soil nutrients and the improvement of soil quality. The application of sheep manure organic fertilizer had the best soil improvement effect.

Anthracnose is a devastating fungal disease in strawberry nurseries. Multiple Colletotrichum species are responsible for strawberry anthracnose. In this study, 105 Colletotrichum isolates were obtained from strawberry seedlings with anthracnose symptoms in fifteen nurseries located in Zhejiang province, China, and were classified based on multilocus sequence and morphological characteristic analyses. Analysis of ITS, ACT, CAL, CHS-1, and GAPDH revealed that four species within C. gloeosporioides species complex, including C. siamense (56 isolates, 53.3%), C. fructicola (37 isolates, 35.2%), C. gloeosporioides (7 isolates, 6.7%), and C. aenigma (5 isolates, 4.8%), were detected in diseased seedlings. Thiophanate-methyl is one of the benzimidazole fungicides, and has long been used to control strawberry anthracnose in China. Here, thiophanate-methyl resistance of Colletotrichum isolates was determined by the minimum inhibitory concentration (MIC) method. Our results indicated that the resistance frequency was up to 96.2%, containing 94.3% of highly resistant isolates. Only four sensitive isolates (two C. fructicola, one C. gloeosporioides, and one C. siamense isolates) and two moderately resistant isolates (one C. aenigma isolate and one C. siamense isolate) were detected. Our data indicated that the high resistance was mainly caused by the E198A mutation in the β-tubulin protein. In addition, F200Y (TTC→TAC) in the β-tubulin protein were detected in two moderately resistant isolates. Based on the point mutation at codon 198 (GAG→GCG) in the β-tubulin gene of Colletotrichum isolates, we developed a loop-mediated isothermal amplification (LAMP) assay to rapidly detect the E198A mutants. Collectively, our study indicated that four species within the C. gloeosporioides species complex were associated with anthracnose symptoms in strawberry nurseries in Zhejiang province, and serious resistance was widespread in each Colletotrichum species.

Strawberry crown rot is a serious fungal disease that poses a great threat to strawberry production in the growth cycle. The dominant pathogens of strawberry crown rot pathogens were different in different periods. The main pathogen of strawberry crown rot at the seedling stage is unclear. In this study, 74 Colletotrichum spp. were isolated from 100 strawberry plants at the seedling stage. Based on the morphological observations and phylogenetic analysis of multiple genes (ACT, CAL, CHS, GAPDH, and ITS), all 74 tested isolates were identified as C. gloeosporioides species complex, including 69 isolates of C. siamense and 5 isolates of C. fructicola. Colletotrichum siamense is the main pathogen of strawberry crown rot at the seedling stage in Zhejiang, China. The sterol demethylation inhibitors (DMIs) were used to control strawberry crown rot, and their target was the CYP51 gene. The role of the homologous CYP51 gene in growth, reproduction, pathogenicity, and sensitivity to DMI fungicides in C. siamense has not been determined. Our study found that the pathogenicity of CsCYP51A deletion mutants to strawberry leaves and stems was weakened. The hyphae growth rate of CsCYP51B deletion mutants was significantly slower than that of the wild type, but the sporulation and appressorium production rates increased. CsCYP51B deletion mutants had significantly increased pathogenicity to the stem. Deletion of CsCYP51A led to increased sensitivity to prothioconazole, ipconazole, hexaconazole, triadimefon, prochloraz, tebuconazole, metconazole, propiconazole, and difenoconazole. CsCYP51B deletion mutants were more insensitive. Our results indicate that the effect of the homologous CsCYP51 gene on hyphae growth, pathogenicity, and sensitivity to DMI fungicides differs.