First report of leaf spot caused by Botrytis cinerea on Bletilla striata in Anhui province, China.

Bletilla striata (Thunb.) is a perennial herb plant of the orchidaceous family and is used as an ornamental plant in Europe and the United States. Furthermore, it is important as traditional Chinese medicine (TCM) in East Asian countries, such as China, Japan, Korea, Mongolia, and Myanmar (Gou et al. 2022). In April 2023, a severe disease similar to gray mold occurred in a B. striata plantation in Anqing, Anhui province, China (N30°27'15″, E116°18'32″), causing disease on about 20% of the plants in the field. Early symptoms were characterized by brown spots or stripes on the leaves of B. striata, and as the disease progressed, large brown irregular spots appeared. Eventually disease spots coalesced, covering the entire leaf surface and causing leaf death. A gray mildew layer was observed on the senescent leaves. To investigate the causal agent, 10 plants with typical symptoms were collected from the field. Leaf pieces (5 × 5 mm) from the border of infected areas were soaked in 75% ethanol for 10 seconds, and then transferred into 0.1% mercury bichloride for three min, rinsed three times with sterile water, and transferred to PDA at 25 °C for three days. Pure cultures were obtained by single spore isolation, and the resulting colonies were morphologically similar, indicating a single pathogen, of which the representative BSFC-7 was selected for further study. BSFC-7 colonies were initially white to gray-brown, and cottony aerial hyphae grew over the entire petri dish after five days of incubation. Grayish, branched conidiophores and their terminal unicellular conidia were observed under a microscope after additional two days at 25 °C. Conidia were colorless or gray, elliptical or oval, and 7.06-12.54 × 8.33-13.55 µm (n=30). Sclerotia appeared in BSFC-7 culture up to about two weeks and were black, hard, and round or irregularly shaped (0.81-4.32 × 0.97-5.68 mm, n=20). The morphological characteristics fit the description of Botrytis cinerea (Li et al. 2016). To further identify the species, genomic DNA of BSFC-7 was extracted. PCR analysis was performed with species-specific primer pairs C729+/C729- and two nuclear genes G3PDH and RPB2 with their corresponding primer pairs G3PDH-F/G3PDH-R and RPB2-F/RPB2-R (Rigotti et al. 2002; Aktaruzzaman et al. 2018). The sequences for all three PCR products of C729, G3PDH, and RPB2 (GenBank accession nos. OR287069, OR255923, and OR255924 respectively) exhibited 99 to 100% similarity with other B. cinerea isolates. In the pathogenicity test, detached leaves of B. striata were inoculated with the BSFC-7 isolate. The leaves were soaked in sodium hypochlorite (1%) for two min, washed with sterile distilled water, and then inoculated with 10 µl of conidial suspension (106 conidia/ml). Sterile water was used as control and samples were incubated at 25 °C. After three days, all leaves inoculated with conidia showed dark brown water-soaked lesions similar to those observed in the field, while the control leaves remained healthy. The pathogen was re-isolated from the affected leaves, fulfilling Koch's postulates. B. cinerea is a common pathogen on a wide range of host plant species worldwide and has been reported to infect B. striata in Yunnan province, China (Romanazzi and Feliziani 2014; Zhang et al. 2020). To our knowledge, this is the first report of B. cinerea causing leaf spots on B. striata in Anhui province, China. This study will provide a basis for controlling the prevalence and economic losses of gray mold on B. striata.

Robotic Manipulation Planning for Automatic Peeling of Glass Substrate Based on Online Learning Model Predictive Path Integral.

Autonomous planning robotic contact-rich manipulation has long been a challenging problem. Automatic peeling of glass substrates of LCD flat panel displays is a typical contact-rich manipulation task, which requires extremely high safe handling through the manipulation process. To this end of peeling glass substrates automatically, the system model is established from data and is used for the online planning of the robot motion in this paper. A simulation environment is designed to pretrain the process model with deep learning-based neural network structure to avoid expensive and time-consuming collection of real-time data. Then, an online learning algorithm is introduced to tune the pretrained model according to the real-time data from the peeling process experiments to cover the uncertainties of the real process. Finally, an Online Learning Model Predictive Path Integral (OL-MPPI) algorithm is proposed for the optimal trajectory planning of the robot. The performance of our algorithm was validated through glass substrate peeling tasks of experiments.

Genome-wide association study of maize plant architecture using F1 populations.

KEY MESSAGE: Genome-wide association study of maize plant architecture using F1 populations can better dissect various genetic effects that can provide precise guidance for genetic improvement in maize breeding. Maize grain yield has increased at least eightfold during the past decades. Plant architecture, including plant height, leaf angle, leaf length, and leaf width, has been changed significantly to adapt to higher planting density. Although the genetic architecture of these traits has been dissected using different populations, the genetic basis remains unclear in the F1 population. In this work, we perform a genome-wide association study of the four traits using 573 F1 hybrids with a mixed linear model approach and QTXNetwork mapping software. A total of 36 highly significant associated quantitative trait SNPs were identified for these traits, which explained 51.86-79.92% of the phenotypic variation and were contributed mainly by additive, dominance, and environment-specific effects. Heritability as a result of environmental interaction was more important for leaf angle and leaf length, while major effects (a, aa, and d) were more important for leaf width and plant height. The potential breeding values of the superior lines and superior hybrids were also predicted, and these values can be applied in maize breeding by direct selection of superior genotypes for the associated quantitative trait SNPs. A total of 108 candidate genes were identified for the four traits, and further analysis was performed to screen the potential genes involved in the development of maize plant architecture. Our results provide new insights into the genetic architecture of the four traits, and will be helpful in marker-assisted breeding for maize plant architecture.

Global transcriptome and weighted gene co-expression network analyses reveal hybrid-specific modules and candidate genes related to plant height development in maize.

KEY MESSAGE: Weighted gene co-expression network analysis was explored to find key hub genes involved in plant height regulation. Plant height, an important trait for maize breeding because of its close relatedness to lodging resistance and yield, has been reported to be determined by multiple qualitative and quantitative genes. However, few genes related to plant height have been characterized in maize. Herein, three different maize hybrids, with extremely distinct plant height, which were further classified into low (L), middle (M) and high (H) group, were selected for RNA sequencing at three key developmental stages, namely, jointing stage (I), big flare period (II) and tasseling stage (III). Intriguingly, transcriptome profiles for hybrids ranging from low to high group exhibited significantly similarity in both jointing stage and big flare period. However, remarkably larger differentially expressed genes could be detected between hybrid from low to either middle or high group in tasseling stage. These results were repeatedly observed in both phenotyping and gene ontology enrichment analysis, indicating that transition from big flare period to tasseling stage plays a critical role in determination of plant height. Furthermore, weighted gene co-expression network analysis was explored to find key hub genes involved in plant height regulation. Hundreds of candidate genes, encoding various transcription factors, and regulators involved in internode cell regulation and cell wall synthesis were identified in our network. More importantly, great majority of candidates were correlated to either metabolism or signaling pathway of several plant phytohormones. Particularly, numerous functionally characterized genes in gibberellic acid as well as brassinosteroids signaling transduction pathways were also discovered, suggesting their critical roles in plant height regulation. The present study could provide a modestly comprehensive insight into networks for regulation of plant height in maize.

Metagenomic analysis of soil microbial communities associated with Poa alpigena Lindm in Haixin Mountain, Qinghai Lake.

To investigate the impact of Poa alpigena Lindm on rhizosphere and bulk soil microorganisms in Haixin Mountain, Qinghai Lake, this study employed metagenomics technology to analyze the microbial communities of the samples. Results showed that 65 phyla, 139 classes, 278 orders, 596 families, 2376 genera, and 5545 species of soil microorganisms were identified from rhizosphere and bulk soil samples. Additionally, a microbial gene library specific to Poa alpigena Lindm was established for Qinghai Lake. Through α-diversity analysis, the richness and diversity of bulk microorganisms both significantly had a higher value than that in rhizosphere soil. The indicator microorganisms of rhizosphere and bulk soil at class level were Actinobacteria and Alphaproteobacteria, respectively. KEGG pathway analysis indicated that Carotenoid biosynthesis, Starch and sucrose metabolism, Bacterial chemotaxis, MAPK signaling pathway, Terpenoid backbone biosynthesis, and vancomycin resistance were the key differential metabolic pathways of rhizosphere soil microorganisms; in contrast, in bulk soil, the key differential metabolic were Benzoate degradation, Glycolysis gluconeogenesis, Aminobenzoate degradation, ABC transporters, Glyoxylate and dicarboxylate metabolism, oxidative phosphorylation, Degradation of aromatic compounds, Methane metabolism, Pyruvate metabolism and Microbial metabolism diverse environments. Our results indicated that Poa alpigena Lindm rhizosphere soil possessed selectivity for microorganisms in Qinghai Lake Haixin Mountain, and the rhizosphere soil also provided a suitable survival environment for microorganisms.

Molecular mechanism of Chuanxiong Rhizoma in treating coronary artery diseases.

Objective: Most of the studies on the herb Chuanxiong Rhizoma (CR) have focused on the l-arginine-nitric oxide (NO) pathway, but the nitrate-nitrite-NO (NO3 --NO2 --NO) pathway was rarely investigated. Therefore, the aim of this study was to evaluate the effects and mechanisms of action of CR in coronary artery disease (CAD). Methods: The NO3 -, NO2 - and NO levels were examined in the NO3 --NO2 --NO pathway. High-performance ion chromatography was used to quantify NO3 - and NO2 - levels. Then, NO was quantified using a multifunctional enzyme marker with a fluorescent probe. The tension of aortic rings was measured using a multi myograph system. Results: High content of NO3 - and low content of NO2 - was found in CR, and which could potently convert NO3 - to NO2 - in the presence of endogenous reductase enzyme. Incubating human coronary artery endothelial cells (HCAECs) with CR-containing serum showed that CR significantly decreased the NO3 - content and increased the levels of NO2 - and NO in the cells under hypoxic conditions. In addition, CR significantly relaxed isolated aortic rings when the l-arginine -NO pathway was blocked. The optimal concentration of CR for relaxation was 200 mg/mL. Conclusion: CR supplements large amounts of NO in cells and vessels to achieve relaxation via the NO3 --NO2 --NO pathway, thereby making up for the deficiency caused by the lack of NO after the l-arginine-NO pathway is suppressed. This study also supports the potential use of a traditional Chinese herb for future drug development.