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Pepper is a high-economic-value agricultural crop that faces diverse disease challenges such as blight and anthracnose. These diseases not only reduce the yield of pepper but, in severe cases, can also cause significant economic losses and threaten food security. The timely and accurate identification of pepper diseases is crucial. Image recognition technology plays a key role in this aspect by automating and efficiently identifying pepper diseases, helping agricultural workers to adopt and implement effective control strategies, alleviating the impact of diseases, and being of great importance for improving agricultural production efficiency and promoting sustainable agricultural development. In response to issues such as edge-blurring and the extraction of minute features in pepper disease image recognition, as well as the difficulty in determining the optimal learning rate during the training process of traditional pepper disease identification networks, a new pepper disease recognition model based on the TPSAO-AMWNet is proposed. First, an Adaptive Residual Pyramid Convolution (ARPC) structure combined with a Squeeze-and-Excitation (SE) module is proposed to solve the problem of edge-blurring by utilizing adaptivity and channel attention; secondly, to address the issue of micro-feature extraction, Minor Triplet Disease Focus Attention (MTDFA) is proposed to enhance the capture of local details of pepper leaf disease features while maintaining attention to global features, reducing interference from irrelevant regions; then, a mixed loss function combining Weighted Focal Loss and L2 regularization (WfrLoss) is introduced to refine the learning strategy during dataset processing, enhancing the model’s performance and generalization capabilities while preventing overfitting. Subsequently, to tackle the challenge of determining the optimal learning rate, the tent particle snow ablation optimizer (TPSAO) is developed to accurately identify the most effective learning rate. The TPSAO-AMWNet model, trained on our custom datasets, is evaluated against other existing methods. The model attains an average accuracy of 93.52% and an F1 score of 93.15%, demonstrating robust effectiveness and practicality in classifying pepper diseases. These results also offer valuable insights for disease detection in various other crops.

The study of crop origins has traditionally involved identifying geographic areas of high morphological diversity, sampling populations of wild progenitor species, and the archaeological retrieval of macroremains. Recent investigations have added identification of plant microremains (phytoliths, pollen, and starch grains), biochemical and molecular genetic approaches, and dating through ¹⁴C accelerator mass spectrometry. We investigate the origin of domesticated chili pepper, Capsicum annuum , by combining two approaches, species distribution modeling and paleobiolinguistics, with microsatellite genetic data and archaeobotanical data. The combination of these four lines of evidence yields consensus models indicating that domestication of C. annuum could have occurred in one or both of two areas of Mexico: northeastern Mexico and central-east Mexico. Genetic evidence shows more support for the more northern location, but jointly all four lines of evidence support central-east Mexico, where preceramic macroremains of chili pepper have been recovered in the Valley of Tehuacán. Located just to the east of this valley is the center of phylogenetic diversity of Proto-Otomanguean, a language spoken in mid-Holocene times and the oldest protolanguage for which a word for chili pepper reconstructs based on historical linguistics. For many crops, especially those that do not have a strong archaeobotanical record or phylogeographic pattern, it is difficult to precisely identify the time and place of their origin. Our results for chili pepper show that expressing all data in similar distance terms allows for combining contrasting lines of evidence and locating the region(s) where cultivation and domestication of a crop began.

Capsicum L. (tribe Capsiceae, Solanaceae) is an American genus distributed ranging from the southern United States of America to central Argentina and Brazil. The genus includes chili peppers, bell peppers, ajíes, habaneros, jalapeños, ulupicas and pimientos, well known for their economic importance around the globe. Within the Solanaceae, the genus can be recognised by its shrubby habit, actinomorphic flowers, distinctive truncate calyx with or without appendages, anthers opening by longitudinal slits, nectaries at the base of the ovary and the variously coloured and usually pungent fruits. The highest diversity of this genus is located along the northern and central Andes. Although Capsicum has been extensively studied and great advances have been made in the understanding of its taxonomy and the relationships amongst species, there is no monographic treatment of the genus as a whole. Based on morphological and molecular evidence studied from field and herbarium specimens, we present here a comprehensive taxonomic treatment for the genus, including updated information about morphology, anatomy, karyology, phylogeny and distribution. We recognise 43 species and five varieties, including C. mirum Barboza, sp. nov. from São Paulo State, Brazil and a new combination C. muticum (Sendtn.) Barboza, comb. nov. ; five of these taxa are cultivated worldwide (C. annuum L. var. annuum, C. baccatum L. var. pendulum (Willd.) Eshbaugh, C. baccatum L. var. umbilicatum (Vell.) Hunz. & Barboza, C. chinense Jacq. and C. frutescens L.). Nomenclatural revision of the 265 names attributed to chili peppers resulted in 89 new lectotypifications and five new neotypifications. Identification keys and detailed descriptions, maps and illustrations for all taxa are provided.

Developing F3 transgenic segregants has significant potential to improve cayenne pepper varieties. However, current evaluation methods are often inconsistent and inaccurate, hindering the identification of effective traits. Traditional approaches only focus on a few aspects, thus not covering the full potential performance of the genotype. Utilizing morphometric image processing and categorical parameter assessment can fill the gap of traditional approaches to improving accuracy and objectivity in evaluation. In addition, environmental factors affecting the evaluation process are not adequately considered, making the results unreliable. Therefore, a systematic evaluation framework integrating morphometric analysis, categorical assessment, and environmental correction is essential for optimizing F3 cayenne transgressive segregants. The study aims to develop a synchronized assessment and selection approach based on agronomic, fruit morphometric, and categorical traits in evaluating F3 cayenne transgressive segregants. This research was designed with a randomized completed block design with 16 transgressive segregant genotypes and three check varieties. Each genotype was repeated three times, resulting in 57 experimental units. Based on the results of this study, quantitative and categorical indices could be used to selectively and systematically evaluate potential transgressive segregants in F3 cayenne peppers. The quantitative index is formed from outcome selection criteria, number of productive branches, area, and major axes weighted through an unbiased linear estimation approach, heritability, and best path analysis. Seven genotypes demonstrated superior transgressive performance based on quantitative indices, with G10.9.2, G10.7.1, and G6.8.5 excelling in both agronomic traits and categorical evaluations. These lines can be recommended for yield evaluation and hybrid cross-parents.

Background Ammonium (NH 4 + ) is a key nitrogen source supporting plant growth and development. Proteins in the ammonium transporter (AMT) family mediate the movement of NH 4 + across the cell membrane. Although several studies have examined AMT genes in various plant species, few studies of the AMT gene family have been conducted in chili pepper. Results Here, a total of eight AMT genes were identified in chili pepper, and their exon/intron structures, phylogenetic relationships, and expression patterns in response to arbuscular mycorrhizal (AM) colonization were explored. Synteny analyses among chili pepper, tomato, eggplant, soybean, and Medicago revealed that the CaAMT2;1 , CaAMT2.4 , and CaAMT3;1 have undergone an expansion prior to the divergence of Solanaceae and Leguminosae. The expression of six AMT2 genes was either up-regulated or down-regulated in response to AM colonization. The expression of CaAMT2;1/2;2/2;3 and SlAMT2;1/2;2/2;3 was significantly up-regulated in AM fungi-inoculated roots. A 1,112-bp CaAMT2;1 promoter fragment and a 1,400-bp CaAMT2;2 promoter fragment drove the expression of the β-glucuronidase gene in the cortex of AM roots. Evaluation of AM colonization under different NH 4 + concentrations revealed that a sufficient, but not excessive, supply of NH 4 + promotes the growth of chili pepper and the colonization of AM. Furthermore, we demonstrated that CaAMT2;2 overexpression could mediate NH 4 + uptake in tomato plants. Conclusion In sum, our results provide new insights into the evolutionary relationships and functional divergence of chili pepper AMT genes. We also identified putative AMT genes expressed in AM symbiotic roots.

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Region-specific local landraces represent a germplasm diversity adapted and acclimatized to local conditions, and are ideal to breed for targeted market niches while maintaining the variability of heirloom traits. A collection of 180 pepper accessions, collected from 62 diverse locations across six Balkan countries, were characterized and evaluated for phenotypic and biochemical variation during a multi-year environment. An assortment of 32 agro-morphological, fruit quality, and virus resistance traits were evaluated, and the top 10% accessions were identified. A wide range of trait variation concerning plant architecture, inflorescence and fruit traits, yield and fruit quality was observed, and appreciable variation was noticed. According to hierarchical clustering, six distinct clusters were established based on pre-defined varietal groups. Divergence among accessions for phenotypic and fruit compositional variability was analyzed, and eight principal components were identified that contributed ~71% of the variation, with fruit shape, width, wall thickness, weight, and fruit quality traits being the most discriminant. Evaluation of the response to tobacco mosaic virus (TMV) and pepper mild mottle mosaic virus (PMMoV) showed that 24 and 1 accession were resistant, respectively while no tomato spotted wilt virus (TSWV) resistance was found. Considerable diversity for agro-bio-morphological traits indicates the Balkan pepper collection as good gene sources for pre-breeding and cultivar development that are locally adapted.

Despite its known significance in plant abiotic stress responses, the role of the RAV gene family in the response of Capsicum annuum to chilling stress remains largely unexplored. In this study, we identified and characterized six members of the CaRAV gene subfamily in pepper plants through genome-wide analysis. Subsequently, the CaRAV subfamily was classified into four branches based on homology with Arabidopsis thaliana, each exhibiting relatively conserved domains within the branch. We discovered that light response elements accounted for the majority of CaRAVs, whereas low-temperature response elements were specific to the NGA gene subfamily. After pepper plants were subjected to chilling stress, qRT-PCR analysis revealed that CaRAV1, CaRAV2 and CaNGA1 were significantly induced in response to chilling stress, indicating that CaRAVs play a role in the response to chilling stress. Using virus-induced gene silencing (VIGS) vectors, we targeted key members of the CaRAV gene family. Under normal growth conditions, the MDA content and SOD enzyme activity of the silenced plants were slightly greater than those of the control plants, and the REC activity was significantly greater than that of the control plants. The levels of MDA and electrolyte leakage were greater in the silenced plants after they were exposed to chilling stress, and the POD and CAT enzyme activities were significantly lower than those in the control, which was particularly evident under repeated chilling stress. In addition, the relative expression of CaPOD and CaCAT was greater in V2 plants upon repeated chilling stress, especially CaCAT was significantly greater in V2 plants than in the other two silenced plants, with 3.29 and 1.10 increases within 12 and 24 h. These findings suggest that CaRAV1 and CaNGA1 positively regulate the response to chilling stress. Silencing of key members of the CaRAV gene family results in increased susceptibility to chilling damage and reduced antioxidant enzyme activity in plants, particularly under repeated chilling stress. This study provides valuable information for understanding the classification and putative functions of RAV transcription factors in pepper plants.