Cotton produces natural fiber for the textile industry. The genetic effects of genomic structural variations underlying agronomic traits remain unclear. Here, we generate two high-quality genomes of Gossypium hirsutum cv. NDM8 and Gossypium barbadense acc. Pima90, and identify large-scale structural variations in the two species and 1,081 G. hirsutum accessions. The density of structural variations is higher in the D-subgenome than in the A-subgenome, indicating that the D-subgenome undergoes stronger selection during species formation and variety development. Many structural variations in genes and/or regulatory regions potentially influencing agronomic traits were discovered. Of 446 significantly associated structural variations, those for fiber quality and Verticillium wilt resistance are located mainly in the D-subgenome and those for yield mainly in the A-subgenome. Our research provides insight into the role of structural variations in genotype-to-phenotype relationships and their potential utility in crop improvement.

Improving plant resistance against systemic diseases remains a challenging research topic. In this study, we developed a dual-action pesticide-loaded hydrogel with the capacity to significantly induce plant resistance against tobacco mosaic virus (TMV) infection and promote plant growth. We produced an alginate–lentinan–amino-oligosaccharide hydrogel (ALA-hydrogel) by coating the surface of an alginate–lentinan drug-loaded hydrogel (AL-hydrogel) with amino-oligosaccharide using electrostatic action. We determined the formation of the amino-oligosaccharide film using various approaches, including Fourier transform infrared spectrometry, the ζ potential test, scanning electron microscopy, and elemental analysis. It was found that the ALA-hydrogel exhibited stable sustained-release activity, and the release time was significantly longer than that of the AL-hydrogel. In addition, we demonstrated that the ALA-hydrogel was able to continuously and strongly induce plant resistance against TMV and increase the release of calcium ions to promote Nicotiana benthamiana growth. Meanwhile, the ALA-hydrogel maintained an extremely high safety to organisms. Our findings provide an alternative to the traditional approach of applying pesticide for controlling plant viral diseases. In the future, this hydrogel with the simple synthesis method, green synthetic materials, and its efficiency in the induction of plant resistance will attract increasing attention and have good potential to be employed in plant protection and agricultural production.

BACKGROUND: Development of anti-plant-virus compounds and improvement of biosafety remain hot research topics in controlling plant viral disease. Tobacco mosaic virus (TMV) infects all tobacco species as well as many other plants worldwide and causes severe losses in tobacco production. To date, no efficient chemical treatments are known to protect plants from virus infection. Therefore, the search for a highly active antiviral compound with high efficacy in field application is required. RESULTS: We reported the synthesis of a novel antiviral halogenated acyl compound Chloroinconazide (CHI) using tryptophan as a substrate and examined its anti-TMV activity. We found that CHI displayed the ability to strongly inhibit the infection of TMV on Nicotiana benthamiana via multiple mechanisms. We observed that CHI was able to impair the virulence of TMV by directly altering the morphological structure of virions and increasing the activity of anti-oxidative enzymes, resulting in reduced TMV-induced ROS production during infection of the plant. In addition, the expression of salicylic acid-responsive genes was significantly increased after CHI application. However, after application of CHI on SA-deficient NahG plants no obvious anti-TMV activity was observed, suggesting that the SA signaling pathway was required for CHI-induced anti-TMV activity associated with reduced infection of TMV. CHI exhibited no effects on plant growth and development. CONCLUSION: The easily synthesized CHI can actively induce plant resistance against TMV as well as act on virus particles and exhibits high biosafety, which provides a potential for commercial application of CHI in controlling plant virus disease in the future.

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Plant NDR1/HIN1-like (NHL) genes play an important role in triggering plant defenses in response to biotic stresses. In this study, we performed a genome-wide identification of the NHL genes in pepper (Capsicum annuum L.) and characterized the functional roles of these CaNHL genes in response to abiotic stresses and infection by different pathogens. Phylogenetic analysis revealed that CaNHLs can be classified into five distinct subgroups, with each group containing generic and specific motifs. Regulatory element analysis showed that the majority of the promoter regions of the identified CaNHLs contain jasmonic acid (JA)-responsive and salicylic acid (SA)-responsive elements, and transcriptomic analysis revealed that CaNHL genes are expressed in all the examined tissues of pepper. The CaNHL1, CaNHL4, CaNHL6, CaNHL10, CaNHL11, and CaNHL12 genes were significantly upregulated under abiotic stress as well as in response to different pathogens, such as TMV, Phytophthora capsici and Pseudomonas syringae. In addition, we found that CaNHL4 localizes to the plasma membrane. CaNHL4-silenced pepper plants display significantly increased susceptibility to TMV, Phytophthora capsici and Pseudomonas syringae, exhibiting reduced expression of JA-related and SA-related genes and reduced ROS production. However, transient overexpression of CaNHL4 in pepper increases the expression of JArelated and SA-related genes, enhances the accumulation of ROS, and inhibits the infection of these three pathogens. Collectively, for the first time, we identified the NHL genes in pepper and demonstrated that CaNHL4 is involved in the production of ROS and that it also regulates the expression of JA-related and SA-related genes in response to different pathogens, suggesting that members of the CaNHL family play an essential role in the disease resistance of pepper.