Appearance of antibiotic resistance in bacteria is a convoluted topic, particularly in treating pestiferous immunodeficiency correlated diseases. The main objective of the current research is to fabricate antibacterial pads by utilizing of graphene quantum dots (GQDs) as a linker, stabilizing, and reduction agent of in situ synthesized Ag nanoparticles (Ag NPs) on cotton pad. Five different antibacterial pads including cotton/Ag pad, cotton/GQDs/Ag pad, cotton/Ag/GQDs pad, cotton/GQDs/Ag/GQDs pad, and cotton/Ag/GQDs/Ag were fabricated and their antibacterial activities were compared to those of as-synthesized Ag/GQDs nanocomposites. The results indicate that cotton/GQDs/Ag pad shows a very promising minimum inhibitory concentration(MIC) of 0.09 and 0.01 against S. aureus and E. coli, respectively. Using GQDs as a linker (cotton/GQDs/Ag) and as a stabilizing agent (cotton/Ag/GQDs) significantly improves the antibacterial activity of Ag NPs.

In environmental conditions, crop plants are extremely affected by multiple abiotic stresses including salinity, drought, heat, and cold, as well as several biotic stresses such as pests and pathogens. However, salinity, drought, and wilt diseases (e.g., Fusarium and Verticillium) are considered the most destructive environmental stresses to cotton plants. These cause severe growth interruption and yield loss of cotton. Since cotton crops are central contributors to total worldwide fiber production, and also important for oilseed crops, it is essential to improve stress tolerant cultivars to secure future sustainable crop production under adverse environments. Plants have evolved complex mechanisms to respond and acclimate to adverse stress conditions at both physiological and molecular levels. Recent progresses in molecular genetics have delivered new insights into the regulatory network system of plant genes, which generally includes defense of cell membranes and proteins, signaling cascades and transcriptional control, and ion uptake and transport and their relevant biochemical pathways and signal factors. In this review, we mainly summarize recent progress concerning several resistance-related genes of cotton plants in response to abiotic (salt and drought) and biotic (Fusarium and Verticillium wilt) stresses and classify them according to their molecular functions to better understand the genetic network. Moreover, this review proposes that studies of stress related genes will advance the security of cotton yield and production under a changing climate and that these genes should be incorporated in the development of cotton tolerant to salt, drought, and fungal wilt diseases (Verticillium and Fusarium).

ABSTRACT Detection and molecular identification of viruses are fundamental to define control strategies against viral diseases, particularly for whitefly-transmitted viruses. Cotton (Gossypium) plants showing leaf mosaic symptoms and yield reduction were observed in commercial cultivars (G. hirsutum) and in plants of the cotton germplasm collection of Embrapa maintained in the field (G. hirsutum, G. barbadense, G. mustelinum). DNA was extracted from cotton plants with symptoms of mosaic and interveinal chlorosis, and a begomovirus-specific genome was amplified with degenerated universal primers, which indicated their association with a begomovirus. This virus was identified as an isolate of sida micrantha mosaic virus (SiMMV) after the amplicon sequencing. The virus could not be transmitted by whiteflies (Bemisia tabaci MEAM1) to cotton plants when the latter were used as inoculum source under protected cultivation house, suggesting a complex interaction among viruses, plants and vectors.

Detection and molecular identification of viruses are fundamental to define control strategies against viral diseases, particularly for whitefly-transmitted viruses. Cotton (Gossypium) plants showing leaf mosaic symptoms and yield reduction were observed in commercial cultivars (G. hirsutum) and in plants of the cotton germplasm collection of Embrapa maintained in the field (G. hirsutum, G. barbadense, G. mustelinum). DNA was extracted from cotton plants with symptoms of mosaic and interveinal chlorosis, and a begomovirus-specific genome was amplified with degenerated universal primers, which indicated their association with a begomovirus. This virus was identified as an isolate of sida micrantha mosaic virus (SiMMV) after the amplicon sequencing. The virus could not be transmitted by whiteflies (Bemisia tabaci MEAM1) to cotton plants when the latter were used as inoculum source under protected cultivation house, suggesting a complex interaction among viruses, plants and vectors.

Cotton has high production costs compared to other annual crops because large numbers of plant protection product (PPP) applications can be needed to control insect pests, diseases, and growth. The hypothesis underlying this study was that vegetation indices (VIs) could be used to estimate application rates for cotton. Our objectives were to (i) evaluate the relationship between different VIs and the application rates for cotton; (ii) propose a modification to the canopy chlorophyll content index (CCCI); and (iii) to develop a VI based equation that will indicate the ideal application rate needed to maximize deposition in the middle layer of a cotton crop. The experiments were carried out during the crop seasons 2017/18, and 2018/19 in the State of Mato Grosso do Sul, Brazil. A multispectral sensor installed in an unmanned aerial vehicle (UAV) was used to obtain the VIs, and the application rates evaluated were 40, 70, 100, and 130 L ha⁻¹. The spray deposits on cotton leaves were measured using the mass balance analysis method. Our findings revealed that an increase in the VIs led to a rise in the application rate needed to maintain spray deposition on the middle layer of cotton plants. The CCCI is related to the rate variation in the cotton crop. However, our results showed that the proposed modified equation (the simplified modified canopy chlorophyll content index), which is based on the relative deposition, improves the estimation of the application rate that will optimize spray deposition in the middle layer of cotton plants.

Caudal autotomy in rodents is an evolutionarily acquired phenomenon enabling escape from predators, by discarding the tail skin after traumatic injuries. The histological mechanisms underlying caudal autotomy seem to differ among species. Cotton rats (Sigmodon hispidus), which are important laboratory rodents for human infectious diseases, possess a fragile tail. In this study, we compared the tail histology of cotton rats with that of laboratory rats (Rattus norvegicus), which have no fragility on their tail, to elucidate the process of rodent caudal autotomy. First, the cotton rats developed a false autotomy characterized by loss of the tail sheath with the caudal vertebrae remaining without tail regeneration. Second, we found the fracture plane was continuous from the interscale of the tail epidermis to the dermis, which was lined with an alignment of E-cadherin+ cells. Third, we found an obvious cleavage plane between the dermis and subjacent tissues of the cotton-rat tail, where the subcutis was composed of looser, finer, and fragmented collagen fibers compared with those of the rat. Additionally, the cotton-rat tail was easily torn, with minimum bleeding. The median coccygeal artery of the cotton rat had a thick smooth muscle layer, and its lumen was filled with the peeled intima with fibrin coagulation, which might be associated with reduced bleeding following caudal autotomy. Taken together, we reveal the unique histological features of the tail relating to the caudal autotomy process in the cotton rat, and provide novel insights to help clarify the rodent caudal autotomy mechanism.

Verticillium wilt caused by the soilborne fungus Verticillium dahliae, is one of the most challenging and economically significant diseases of cotton in Australia and worldwide. Host resistance is regarded as the most effective control strategy, however the biological complexity of the pathogen and controversy regarding the mechanisms of resistance hinder plant breeding efforts. Previous studies have utilised GFP-tagged isolates of V. dahliae to investigate the host – pathogen interaction on cotton, providing insights into the host resistance response and little understood areas of the disease cycle. Here, we establish GFP-tagged isolate Vd71-3 as a tool for evaluating infection and colonization on cotton cultivars tolerant and susceptible to Verticillium wilt. Isolate Vd71-3 was obtained by transforming a GFP vector construct into highly virulent non-defoliating strain Vd71171 isolated from a diseased Upland cotton plant in NSW, Australia. Prior to study on cotton, pathogenicity of Vd71-3 was deemed consistent with that of the parent wildtype, indicating that GFP expression does not dramatically alter virulence. Confocal laser scanning microscopy observations confirmed existing descriptions of early infection on cotton, including germination of conidia by 24 hours post-inoculation, formation of an infection peg, intercellular colonisation of the root tips but not lateral root junctions, preferential colonisation of the xylem vessels, and acropetal movement of conidia in vessels. Extensive fungal occlusion of the vessels was also observed, not previously captured elsewhere on cotton. V. dahliae was recovered from six of the eight weed species that were inoculated with the transformed VCG 1A and 2A strains. The VCG 2A transformant was recovered more frequently from weeds than the VCG 1A transformant, suggesting that V. dahliae VCG 2A may have higher infectivity towards weed hosts in Australian cotton fields. V. dahliae was not recovered from seeds from cotton plants that were subject to direct stem inoculation, although vascular tissue adjacent to the site of inoculation was colonised. Further investigation is needed to understand whether V. dahliae VCG 1A and 2A strains are capable of infecting Australian cotton seed using alternative inoculation techniques.

Verticillium wilt, caused by Verticillium dahliae, is one of the most damaging and widespread soil-borne cotton diseases. The molecular mechanisms underlying the cotton defense against V. dahliae remain largely elusive. Here, we compared the transcriptional differences between Upland cotton cultivars: one highly resistant (HR; Shidalukang 1) and one highly susceptible (HS; Junmian 1). This was done at multiple time points after V. dahliae inoculation, which identified 2010 and 1275 differentially expressed genes (DEGs) in HR and HS, respectively. Plant hormone signal transduction-related genes were enriched in HR, whereas genes related to lignin biosynthesis were enriched in both HR and HS. Weighted gene co-expression network analysis (WGCNA) using the 2868 non-redundant genes differentially expressed between the V. dahliae infected and uninfected samples in HR or HS identified 10 different gene network modules and 22 hub genes with a potential role in regulating cotton defense against V. dahliae infection. GhGDH2, encoding glutamate dehydrogenase (GDH), was selected for functional characterization. Suppressing the expression level of GhGDH2 by virus-induced gene silencing (VIGS) in HS led to inhibition of the salicylic acid (SA) biosynthesis/signaling pathways and activation of the jasmonic acid (JA) biosynthesis/signaling pathways, which resulted in an increase of 42.1% JA content and a reduction of 78.9% SA content in cotton roots, and consequently enhanced V. dahliae resistance. Our finding provides new insights on the molecular mechanisms of cotton resistance to V. dahliae infection and candidate genes for breeding V. dahliae resistance cotton cultivars by genetic modification.