pepper leaves
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Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 183
Author(s):  
Ziran Yuan ◽  
Yin Ye ◽  
Lifei Wei ◽  
Xin Yang ◽  
Can Huang

Chlorophyll content is an important indicator of plant photosynthesis, which directly affects the growth and yield of crops. Using hyperspectral imaging technology to quickly and non-destructively estimate the soil plant analysis development (SPAD) value of pepper leaf and its distribution inversion is of great significance for agricultural monitoring and precise fertilization during pepper growth. In this study, 150 samples of pepper leaves with different leaf positions were selected, and the hyperspectral image data and SPAD value were collected for the sampled leaves. The correlation coefficient, stability competitive adaptive reweighted sampling (sCARS), and iteratively retaining informative variables (IRIV) methods were used to screen characteristic bands. These were combined with partial least-squares regression(PLSR), extreme gradient boosting (XGBoost), random forest regression(RFR), and gradient boosting decision tree(GBDT) to build regression models. The developed model was then used to build the inversion map of pepper leaf chlorophyll distribution. The research results show that: (1) The IRIV-XGBoost model demonstrates the most comprehensive performance in the modeling and inversion stages, and its , , and are 0.81, 2.76, and 2.30, respectively; (2) The IRIV-XGBoost model was used to calculate the SPAD value of each pixel of pepper leaves, and to subsequently invert the chlorophyll distribution map of pepper leaves at different leaf positions, which can provide support for the intuitive monitoring of crop growth and lay the foundation for the development of hyperspectral field dynamic monitoring sensors.


Plant Disease ◽  
2021 ◽  
Author(s):  
Tamara Popović ◽  
Jelena Menković ◽  
Marija Pantelić ◽  
Aleksa Obradoviċ

Leaf spot of pepper was observed on different pepper cultivars in central Montenegro during summer and early autumn in three consecutive growing seasons (2017 - 2019). Necrotic spots were numerous, varying in size, irregular in shape, brown, and surrounded by a weak halo. The most intensive symptoms were observed on lower leaves. In conditions conducive or the infection, the lesions merged resulting in the leaf drop. Symptoms were not observed on pepper stems and fruits. A total of seventeen bacterial strains were isolated from infected pepper leaves collected in seven different localities in the seasons of 2017-19. They formed yellow, convex, and mucoid colonies on yeast extract–dextrose–CaCO3 (YDC) medium and induced hypersensitive reaction in tobacco leaves. They were Gram negative, strictly aerobic, oxidase negative, catalase-positive, hydrolyzed gelatine and esculin and did not reduce nitrate, nor grew on 0.1% TTC and at 37°C. Out of tested 17 strains, eight hydrolyzed starch and three showed pectolytic activity, thus differing in these biochemical traits from Xanthomonas euvesicatoria (Xe) the reference strain KFB 1 (Obradović et al., 2004) used in all tests as a positive control. PCR analysis, with primer pair XeF/XeR, produced a single characteristic band of 173 bp in all 17 strains (Koenraadt et al. 2009). Additionally, the BOX-PCR profile of all the strains produced with the BOX A1R primer (Schaad et al. 2001) showed 100% homology with KFB 1. Based on the locality and year of isolation, nine strains were selected for amplification and partial sequencing of the gyrB gene using sets of primers described by Parkinson et al. (2007). Obtained partial DNA sequences showed that all nine strains (GenBank nos. MZ569011, MZ574079, MZ574080, MZ574081, MZ574082, MZ574083, MZ574084, MZ574085, and MZ574086) share 99.86 to 100% identity of gyrB sequence with Xe type strain ICPM:109 as well as 98.71 to 100 % of gyrB sequence identity with Xe strain LMG930 isolated from pepper in The United States. Pathogenicity of all strains was confirmed by spraying young pepper plants (cv. Slonovo uvo) using a handheld sprayer with the bacterial suspension (108 CFU/ml of sterile tap water), in three replicates. Sterile distilled water and reference Xe strain (KFB 1) were used as negative and positive controls, respectively. The inoculated plants were incubated under plastic bags in the greenhouse providing high humidity conditions for 48h. Symptoms were monitored for two weeks after inoculation. Lesions surrounded by a halo appeared on leaves of all inoculated plants within 10 to 15 days after inoculation, while plants inoculated with SDW remained symptomless. Koch’s postulates were confirmed by reisolation of the pathogen from necrotic tissue and identity check by PCR using primer set of Koenraadt et al. (2009). The pathogen race was determined according to the reaction of cv. Early Calwonder (ECW) and its isogenic lines (ECW-10R, ECW-20R, ECW-30R) (Stall et al. 2009). Obtained results indicated that all tested strains and reference strain Xe (KFB 1) belong to the pepper race P8. Based on pathogenic, biochemical, and molecular characteristics, the strains isolated from pepper leaves in Montenegro were identified as X. euvesicatoria. Pepper production is particularly significant for small farmers in Montenegro. Favorable climate, use of noncertified seed and lack of crop rotation contributes to the disease occurrence and severity. The disease has probably been around for years but the etiology was not confirmed so far. This is the first report of X. euvesicatoria affecting pepper in this country.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Balázs Kalapos ◽  
Csilla Juhász ◽  
Eszter Balogh ◽  
Gábor Kocsy ◽  
István Tóbiás ◽  
...  

AbstractUpon virus infections, the rapid and comprehensive transcriptional reprogramming in host plant cells is critical to ward off virus attack. To uncover genes and defense pathways that are associated with virus resistance, we carried out the transcriptome-wide Illumina RNA-Seq analysis of pepper leaves harboring the L3 resistance gene at 4, 8, 24 and 48 h post-inoculation (hpi) with two tobamoviruses. Obuda pepper virus (ObPV) inoculation led to hypersensitive reaction (incompatible interaction), while Pepper mild mottle virus (PMMoV) inoculation resulted in a systemic infection without visible symptoms (compatible interaction). ObPV induced robust changes in the pepper transcriptome, whereas PMMoV showed much weaker effects. ObPV markedly suppressed genes related to photosynthesis, carbon fixation and photorespiration. On the other hand, genes associated with energy producing pathways, immune receptors, signaling cascades, transcription factors, pathogenesis-related proteins, enzymes of terpenoid biosynthesis and ethylene metabolism as well as glutathione S-transferases were markedly activated by ObPV. Genes related to photosynthesis and carbon fixation were slightly suppressed also by PMMoV. However, PMMoV did not influence significantly the disease signaling and defense pathways. RNA-Seq results were validated by real-time qPCR for ten pepper genes. Our findings provide a deeper insight into defense mechanisms underlying tobamovirus resistance in pepper.


Plant Disease ◽  
2021 ◽  
Author(s):  
Chunhua Lin ◽  
Lixia Fu ◽  
Zhenzhen Fan ◽  
Chun Fang Duan ◽  
Tailing Jiang ◽  
...  

Pepper (Piper nigrum L.) is one of the economically important spice crops of China and mainly grown in the Hainan and Yunnan provinces. In January 2021, the classic anthracnose lesions were observed on pepper leaves at a plantation (24°57’50"N, 98°53’00"E) in Baoshan city, Yunnan, China. Most of the diseased spots occurred at the tips and margins of the old pepper leaves. Lesions were grayish brown or pale white with a slight yellow halo, concentric whorl black dots or scattered black dots were observed on the leaves spots sometimes (Fig. 1). Five symptomatic leaves from different parts of the field were sampled for pathogen isolation. Lesion tissues removed from the border between symptomatic and healthy tissue were surface sterilized in 75% ethanol, then air-dried, plated on potato dextrose agar medium plates (PDA), and incubated in a 12-h photoperiod at 28℃. Similar fungal colonies developed from all plated tissues after 5 days. And five isolates from different leaves (one isolate per leaf) were sub-cultured using the single-spore method. The colonies appeared white, cottony, aerial mycelium dense and slow-growing (mean 1.01 mm day–1) on PDA plates in 6 days. Conidia were short-cylindric, straight, sometimes slightly constricted near the center, ends broadly rounded, measuring 11.05 to 14.43 × 3.78 to 6.08 µm (average = 12.03 × 5.48 µm, n=200). Appressoria were single, subglobose to elliptic, light brown to dark black. Among them, genomic DNA of two isolates (21HJ0301-1 and 21HJ0301-2) were extracted from mycelium and used as a template for molecular identification. The internal transcribed spacer (ITS) region of ribosomal DNA, and partial sequence of chitin synthase (CHS-1), actin (ACT) and glyceraldehydes-3-phosphate dehydrogenase (GAPDH) gene regions were amplified with primer pairs ITS1/ITS4, CHS-79F/CHS-354R, ACT-512F/ACT-783R, GDF/GDR, respectively (Weir et al. 2012). These four gene sequences were deposited in GenBank (Accession No. MZ725047 and MZ725048 for ITS, MZ733415 and MZ733416 for GAPDH, MZ733408 and MZ733409 for ACT, MZ733422 and MZ733423 for CHS-1). A multilocus phylogenetic analysis performed with the reference sequences revealed that both 21HJ0301-1 and 21HJ0301-2 isolates clustered with C. karstii (Fig.2). Based on morphology and molecular results, isolates were confirmed to be C. karstii. Pathogenicity tests were carried out on potted seedlings in the greenhouse, six healthy leaves per isolate were inoculated with six-day-old cultures of C. karstii mycelial discs of 5 mm in diameter after being wounded with a needle or non-wounded. Control leaves were inoculated with PDA agar. Inoculated plants were incubated under high relative humidity at room temperature. Anthracnose symptoms appeared within 5 days using non-wounded or wounded inoculation methods. All control leaves remained asymptomatic. The fungus was re-isolated from inoculated leaves fulfilling Koch’s postulates, but not on controls. C. karstii has a wide range of hosts, such as rubber tree, tea-oil tree, chili, and some other plants belonging to the family Orchidaceae in China (Cai et al. 2016; Jiang and Li 2018; Diao et al. 2017; Yang et al. 2011). To the best of our knowledge, this is the first report of C. karstii on Piper nigrum in China. This report will help us to recognize the anthracnose disease of Piper nigrum and establish a foundation for future studies on C.karstii to address effective management strategies.


Metabolites ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 649
Author(s):  
Samuel Tilahun Assefa ◽  
Eun-Young Yang ◽  
Gelila Asamenew ◽  
Heon-Woong Kim ◽  
Myeong-Cheoul Cho ◽  
...  

Metabolomics and in vitro α-glucosidase inhibitory (AGI) activities of pepper leaves were used to identify bioactive compounds and select genotypes for the management of type 2 diabetes mellitus (T2DM). Targeted metabolite analysis using UPLC-DAD-QToF-MS was employed and identified compounds that belong to flavone and hydroxycinnamic acid derivatives from extracts of pepper leaves. A total of 21 metabolites were detected from 155 samples and identified based on MS fragmentations, retention time, UV absorbance, and previous reports. Apigenin-O-(malonyl) hexoside, luteolin-O-(malonyl) hexoside, and chrysoeriol-O-(malonyl) hexoside were identified for the first time from pepper leaves. Pepper genotypes showed a huge variation in their inhibitory activity against α-glucosidase enzyme(AGE) ranging from 17% to 79%. Genotype GP38 with inhibitory activity of 79% was found to be more potent than the positive control acarbose (70.8%.). Orthogonal partial least square (OPLS) analyses were conducted for the prediction of the AGI activities of pepper leaves based on their metabolite composition. Compounds that contributed the most to the bioactivity prediction model (VIP >1.5), showed a strong inhibitory potency. Caffeoyl-putrescine was found to show a stronger inhibitory potency (IC50 = 145 µM) compared to acarbose (IC50 = 197 µM). The chemometric procedure combined with high-throughput AGI screening was effective in selecting polyphenols of pepper leaf for T2DM management.


Plant Disease ◽  
2021 ◽  
Author(s):  
Lijuan Wei ◽  
Chengde Yang ◽  
Richard Osei ◽  
Lingxiao Cui ◽  
Mengjun Jin ◽  
...  

Vitamins, capsaicin and capsochrome are abundant in pepper (Capsicum annuum), a fruit that is also used as a spice. During hot and rainy seasons, anthracnose disease caused by Colletotrichum spp. affects pepper crops and causes significant yield losses in the pre- and post-harvest stages(Liu et al. 2016). Unidentified disease spots were discovered on peppers leaves in a field in Wei yuan (35°8'10" N, 104°12'54" E), Gansu Province, China, in September 2019. The diseases was found to have a 100% incidence in a 0.07-ha area, which drew our attention. The lesions were mostly found in the middle and upper parts of the leaves, and the symptoms mostly showed up as roughly circular patches on the leaves with dark brown, and yellowish center. 18 tissues with a diameter of 1 cm were obtained from the line between healthy and diseased portions. They were sterilized for 45 s in 1% mercuric chloride, then rinsed 5 times in sterile distilled water and dried with sterile filter paper. After 4 days of culture on a plate with a PDA media 5 strains were recovered from the treated tissue. Healthy pepper plants grown in the lab were inoculated with conidia suspension (50 mL, 107 conidia/mL) for pathogenicity while sterile distilled water was used as control. Each treatment had three duplicates. Leaves infected with the BYL strain 16 days later showed obvious symptoms, which were comparable to those found in the field. The control leaves showed no sign of disease. The pathogen was re-isolated from the infected pepper leaves and it had the same features as strain BYL. Koch's postulate was proven correct. The BYL colony started out white, then turned gray-brown with black sclerotia in the center. Conidia were hyaline, smooth, cylindrical, typically straight, with rounded ends, and ranged in size from11.754-16.477(14.587±0.139×2.833-4.220(3.348±0.037) μm. Appressoria solitary or in loose clusters, 6.910-9.078×5.386-7.119 μm in size, medium brown, smooth-walled, ellipsoidal or irregular in form, with noticeable piercing pore with dark halo. The isolate was identified as Colletotrichum species based on the morphological characteristics (Damm et al. 2014).It was then re-identified using multi-molecular analysis. To amplify and sequence of the isolates, the genes ITS, TUB2, CHS1, ACT, GAPDH and HIS3 were employed (Weir et al. 2012, Crous et al. 2004). They were deposited in GenBank (MW581857 for ITS, MW595706 for ACT, MW595707 for CHS1, MW595708 for GAPDH, MW595709 for HIS3, and MW595710 for TUB2). The sequence of ITS, ACT, CHS1, and HIS3 in GenBank were found to be 100% identical to those of Colletotrichum tabaci (JQ005763 for ITS, KM105414 for ACT, JQ005784 for CHS1 and KM105346 for HIS3). The primers GAPDH and TUB2 amplified a gene sequence that was 99% identical to Colletotrichum tabaci in GenBank (KM105559 for GAPDH and JQ005847 for TUB2). Based on appearance and sequencing analysis, the isolate was identified as Colletotrichum tabaci. The optimal light condition for BYL growth was 12 h light/12 h dark cycle, temperature 30 o C, pH 8, sucrose as carbon source, and yeast extract as nitrogen source according to the biological features. Colletotrichum tabaci caused anthracnose in peppers in the field. This is the first report of Colletotrichum tabaci causing anthracnose in peppers in China that we are aware of.


2021 ◽  
Vol 12 ◽  
Author(s):  
Zhoubin Liu ◽  
Jingshuang Song ◽  
Wu Miao ◽  
Bozhi Yang ◽  
Zhuqing Zhang ◽  
...  

Pepper is a typical warmth-loving vegetable that lacks a cold acclimation mechanism and is sensitive to cold stress. Lysine acetylation plays an important role in diverse cellular processes, but limited knowledge is available regarding acetylation modifications in the resistance of pepper plants to cold stress. In this study, the proteome and acetylome of two pepper varieties with different levels of cold resistance were investigated by subjecting them to cold treatments of varying durations followed by recovery periods. In total, 6,213 proteins and 4,574 lysine acetylation sites were identified, and this resulted in the discovery of 3,008 differentially expressed proteins and 768 differentially expressed acetylated proteins. A total of 1,988 proteins were identified in both the proteome and acetylome, and the functional differences in these co-identified proteins were elucidated through GO enrichment. KEGG analysis showed that 397 identified acetylated proteins were involved in 93 different metabolic pathways. The dynamic changes in the acetylated proteins in photosynthesis and the “carbon fixation in the photosynthetic organisms” pathway in pepper under low-temperature stress were further analyzed. It was found that acetylation of the PsbO and PsbR proteins in photosystem II and the PsaN protein in photosystem I could regulate the response of pepper leaves to cold stress. The acetylation levels of key carbon assimilation enzymes, such as ribulose bisphosphate carboxylase, fructose-1,6-bisphosphatase, sedoheptulose-1,7-bisphosphatase, glyceraldehyde 3-phosphate dehydrogenase, phosphoribulokinase, and triosephosphate isomerase decreased, leading to decreases in carbon assimilation capacity and photosynthetic efficiency, reducing the cold tolerance of pepper leaves. This study is the first to identify the acetylome in pepper, and it greatly expands the catalog of lysine acetylation substrates and sites in Solanaceae crops, providing new insights for posttranslational modification studies.


Separations ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 134
Author(s):  
Nenghui Li ◽  
Jing Li ◽  
Dongxia Ding ◽  
Jianming Xie ◽  
Jing Zhang ◽  
...  

To determine the optimum parameters for extracting three carotenoids including zeaxanthin, lutein epoxide, and violaxanthin from pepper leaves by response surface methodology (RSM), a solvent of acetone and ethyl acetate (1:2) was used to extract carotenoids with four independent factors: ultrasound time (20–60 min); ratio of sample to solvent (1:12–1:4); saponification time (10–50 min); and concentration of saponification solution (KOH–methanol) (10–30%). A second-order polynomial model produced a satisfactory fitting of the experimental data with regard to zeaxanthin (R2 = 75.95%, p < 0.0197), lutein epoxide (R2 = 90.24%, p < 0.0001), and violaxanthin (R2 = 73.84%, p < 0.0809) content. The optimum joint extraction conditions of zeaxanthin, lutein epoxide, and violaxanthin were 40 min, 1:8, 32 min, and 20%, respectively. The optimal predicted contents for zeaxanthin (0.823022 µg/g DW), lutein epoxide (4.03684 µg/g dry; DW—dry weight), and violaxanthin (16.1972 µg/g DW) in extraction had little difference with the actual experimental values obtained under the optimum extraction conditions for each response: zeaxanthin (0.8118 µg/g DW), lutein epoxide (3.9497 µg/g DW), and violaxanthin (16.1590 µg/g DW), which provides a theoretical basis and method for cultivating new varieties at low temperatures and weak light resistance.


2021 ◽  
Vol 22 (16) ◽  
pp. 8667
Author(s):  
Xiaoxia Wu ◽  
Yan Ren ◽  
Hailong Jiang ◽  
Yan Wang ◽  
Jiaxing Yan ◽  
...  

Annexin (Ann) is a polygenic, evolutionarily conserved, calcium-dependent and phospholipid-binding protein family, which plays key roles in plant growth, development, and stress response. However, a comprehensive understanding of CaAnn genes of pepper (Capsicum annuum) at the genome-wide level is limited. Based on the available pepper genomic information, we identified 15 members of the CaAnn gene family. Phylogenetic analysis showed that CaAnn proteins could be categorized into four different orthologous groups. Real time quantitative RT-PCR analysis showed that the CaAnn genes were tissue-specific and were widely expressed in pepper leaves after treatments with cold, salt, and drought, as well as exogenously applied MeJA and ABA. In addition, the function of CaAnn9 was further explored using the virus-induced gene silencing (VIGS) technique. CaAnn9-silenced pepper seedlings were more sensitive to salt stress, reflected by the degradation of chlorophyll, the accumulation of reactive oxygen species (ROS), and the decrease of antioxidant defense capacity. This study provides important information for further study of the role of pepper CaAnn genes and their coding proteins in growth, development, and environmental responses.


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