Melatonin is a naturally occurring compound in plants. Here, we tested the effect of exogenous melatonin on rapeseed (Brassica napus L.) grown under salt stress. Application of 30 μmol L-1 melatonin alleviatedsalt-induced growth inhibition, and the shoot fresh weight, the shoot dry weight, the root fresh weight, and the root dry weight of seedlings treated with exogenous melatonin increased by 128.2, 142.9, 122.2, and 124.2% respectively, compared to those under salt stress. In addition, several physiological parameters were evaluated. The activities of antioxidant enzymes including peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were enhanced by 16.5, 19.3, and 14.2% compared to their activities in plants without exogenous melatonin application under salt stress, while the H 2 O 2 content was decreased by 11.2% by exogenous melatonin. Furthermore, melatonin treatment promoted solute accumulation by increasing the contents of proline (26.8%), soluble sugars (15.1%) and proteins (58.8%). The results also suggested that higher concentrations (>50 μmol L-1) of melatonin could attenuate or even prevent the beneficial effects on seedling development. In conclusion, application of a low concentration of exogenous melatonin to rapeseed plants under salt stress can improve the H 2 O 2-scavenging capacity by enhancing the activities of antioxidant enzymes such as POD, CAT and APX, and can also alleviate osmotic stress by promoting the accumulation of osmoregulatory substances such as soluble proteins, proline, and water soluble glucan. Ultimately, exogenous melatonin facilitates root development and improves the biomass of rapeseed seedlings grown under salt stress, thereby effectively alleviating the damage of salt stress in rapeseed seedlings.

Summary Sclerotinia sclerotiorum is a devastating necrotrophic fungal pathogen that infects over 400 species of plants worldwide. Reactive oxygen species (ROS) modulations are critical for the pathogenic development of S. sclerotiorum . The fungus applies enzymatic and non‐enzymatic antioxidants to cope with the oxidative stress during the infection processes. Survival factor 1 was identified and characterized to promote survival under conditions of oxidative stress in Saccharomyes cerevisiae . In this research, a gene named SsSvf1 was predicted to encode a survival factor 1 homologue in S. sclerotiorum . SsSvf1 transcripts showed high expression levels in hyphae under oxidative stress. Silencing of SsSvf1 resulted in increased sensitivity to oxidative stress in culture and increased levels of intracellular ROS. Transcripts of SsSvf1 showed a dramatic increase during the initial stage of infection and the gene‐silenced strains displayed reduced virulence on oilseed rape and Arabidopsis thaliana . Inhibition of plant ROS production partially restores virulence of SsSvf1 gene‐silenced strains. SsSvf1 gene‐silenced strains exhibited normal oxalate production, but were impaired in compound appressorium formation and cell wall integrity. The results suggest that SsSvf1 is involved in coping with ROS during fungal‐host interactions and plays a crucial role in the pathogenicity of S. sclerotiorum .

Sclerotinia sclerotiorum is one of the most devastating fungal plant pathogens of oilseed Brassica and is distributed worldwide. In particular, Sclerotinia stem rot has always been a serious threat to rapeseed production in Chongqing City, China. In this study, simple sequence repeat (SSR) markers and mycelial compatibility groups (MCGs) were used to characterize the population structure of 90 geographic isolates of S. sclerotiorum collected from rapeseed in nine counties of Chongqing. A total of 52 microsatellite haplotypes were identified, and a few haplotypes were found with high frequency. Gene diversity ranged from 0.1570 to 0.4700 in nine populations. A constructed unweighted pair group with arithmetic mean dendrogram based on Nei genetic distance and a STRUCTURE analysis revealed that the genetic composition of the isolates collected in the five counties located in western Chongqing are different from those collected in the two eastern counties, suggesting that breed lines should be cultivated in both the western and eastern regions to effectively evaluate resistance levels. A total of 47 MCGs were identified, and 72% of the MCGs was represented by single isolates. Seven of 13 MCGs that included at least two isolates contained isolates from only one county. SSR haplotypes were not correlated with MCGs. A subset of 34 isolates were inoculated on rapeseed stems, and the aggressiveness showed variation. This research revealed the population genetic structure and aggressiveness of this pathogen in Chongqing, and the results will help to develop disease management and resistance screening strategies.

Rice false smut caused by Ustilaginoidea virens is currently one of the most devastating fungal diseases of rice panicles worldwide. In this study, two novel molecular markers derived from SNP-rich genomic DNA fragments and a previously reported molecular marker were used for analyzing the genetic diversity and population structure of 167 U. virens isolates collected from nine areas in Sichuan-Chongqing region, China. A total of 62 haplotypes were identified, and a few haplotypes with high frequency were found and distributed in two to three areas, suggesting gene flow among different geographical populations. All isolates were divided into six genetic groups. The groups Ⅰ and Ⅵ were the largest including 61 and 48 isolates, respectively. The pairwise FST values showed significant genetic differentiation among all compared geographical populations. AMOVA showed that intergroup genetic variation accounted for 40.17% of the total genetic variation, while 59.83% of genetic variation came from intragroup. The UPGMA dendrogram and population structure revealed that the genetic composition of isolates collected from ST (Santai), NC (Nanchong), YC (Yongchuan), and WS (Wansheng) dominated by the same genetic subgroup was different from those collected from other areas. In addition, genetic recombination was found in a few isolates. These findings will help to improve the strategies for rice false smut management and resistance breeding, such as evaluating breeding lines with different isolates or haplotypes at different elevations and landforms.

The ubiquitous WiFi makes it a location service infrastructure and attracts more attention now. We use the cubic spline interpolation method to interpolate the attenuation factor n, and a wide range of indoor corridor environments test results show that the cubic spline interpolation method is more conducive to achieving the precise distance. We also improved the classical trilateration positioning algorithm with a priori knowledge of the specific positioning environment. The improved positioning algorithm significantly reduces positioning errors and improves positioning accuracy. The positioning method is transferred to the embedded positioning node to make distributed positioning with lower calculation cost.