Pepper Roots Research Articles

Arbuscular mycorrhizal colonization alters biochemical, molecular defense responses and root exudate composition against Phytophthora capsici infection in black pepper

Mycorrhizal symbiosis benefits the host plants in several aspects. Among the soil microbiota, AM fungi have established a substantial potential to decrease crop damage from plant pathogens in several crops, yet the mechanism of its action in black pepper has not yet been studied. In this study, we investigated the effect of mycorrhizal colonization on biochemical, molecular defense responses, and root exudates composition in the Phytophthora capsici -black pepper host-pathosystem. Four biochemical parameters such as total phenols, orthodihydroxy (OD) phenols, peroxidase activity, and lignin were studied to delineate the effect of mycorrhizal colonization upon pathogen inoculation. Total phenol, OD phenol, and lignin content increased consistently upon challenge inoculation with P. capsici as well as in AM alone inoculated plants in both leaves as well as roots. Similar peroxidase activity was noticed in AM alone and challenged inoculated plants. The quantitative polymerase chain reaction analysis showed that AM pre-inoculation led to up regulation of pathogenesis related genes viz., cAPX, Osmotin and β-1,3-glucanase, phenylalanine ammonia-lyase and NPR 1 in black pepper leaves and roots upon of P. capsici inoculation. Sole inoculation of P. capsici also positively influenced the copies of most genes studied. Root exudates of AM colonized plants showed higher fatty acid/fatty acyl compounds viz., tetradecanoic acid, n-hexadecanoic acid, octadecanoic acid, and nonacos-1-ene compared to P. capsici inoculated plants. On the other hand, most of the alkane hydrocarbons such as (z)-3-tetradecene, octylcyclohexane, 4-cyclohexylundecane, and decylcyclohexane were observed majorly in the root exudates of P. capsici inoculated plants. Multivariate analysis of the root exudate data revealed that AM colonization in black pepper roots normalized the content of root exudates during Phytophthora infection comparable to control plants. Our findings indicates that the AM colonization enhances the resistance of P. capsici in black pepper plants by alterations in defense enzymes and gene expression and root exudates composition.

Kontrollü koşullar altında Aspergillus niger kültür filtratının kök-ur nematodu Meloidogyne incognita’ya karşı nematisidal etkisinin belirlenmesi

Amaç: Bu çalışmada Aspergillus niger’in kültür filtratının 4 farklı(25, 50, 75 ve 100%) konsantrasyonunun kontrollü koşullar altında (24±1 ° C, 60±5% nem) domates ve biber köklerinde Meloidogyne incognita gelişimine etkisi araştırılmıştır.Yöntem ve Bulgular: Çalışmada nematod inokulumu olarak 500 II. Dönem larva (J2) kullanılmış ve inokülasyonundan iki gün sonra her saksı toprağına A. niger kültür filtratının her konsantrasyonundan 10 ml uygulama yapılmıştır. Uygulamadan 8 hafta sonra köklerdeki gal ve yumurta paketi sayıları ile topraktaki J2 yoğunluğu tespit edilmiş ve konsantrasyonların bu parametrelerdeki kontrol etki yüzdeleri hesaplanmıştır. Domates ve biber köklerinde M. incognita üzerinde en etkili konsantrasyonların %100 ve %75 olduğu saptanmış ve gal, yumurta paketi sayısı ve topraktaki J2 yoğunluğu üzerindeki etkileri arasında önemli bir fark bulunmamıştır (P≥0.05). A. niger kültür filtratının %50 seyreltmenin altına düştüğünde, nematisidal etkisinin %30’lara kadar düştüğü belirlenmiştir. Domateste kültür filtratının %100 konsantrasyonunda gal, yumurta paketi sayısı ve topraktaki J2 yoğunluğu üzerindeki yüzde kontrol etki sırasıyla %86.3, 86.2 ve 82.0 olarak saptanırken, biber köklerinde %89.1, 88.6 ve 87.2 olduğu bulunmuştur. A. niger’in %75 konsantrasyonunda ise gal, yumurta paketi sayısı ve topraktaki J2 yoğunluğu üzerindeki kontrol etki domateste sırasıyla %79.9, 79.2 ve 73.0 olarak belirlenirken, biberde %82.9, %82.0 ve %79.4 olduğu tespit edilmiştir. Genel Yorum: Yerel A. niger izolatının M. incognita’ya karşı yüksek nematisidal aktivite gösterdiği tespit edilmiştir. Çalışmanın Önemi ve Etkisi: A. niger kültür filtratı domates ve biberde M. incognita kontrolünde yeni bir biyolojik nematisit kaynağı olarak belirlenmiştir.

Novel Bisamide Alkaloids Enantiomers from Pepper Roots (Piper nigrum L.) with Acetylcholinesterase Inhibitory and Anti-Neuroinflammatory Effects.

The roots of Piper nigrum L., a seasoning for cooking various types of broths, are renowned for their high nutritional content and potential medicinal benefits. In this study, nine pairs of novel cyclohexene-type bisamide alkaloids (1a/1b-9a/9b) were isolated from the pepper roots using molecular network analysis strategies. Their structures were determined by extensive spectroscopic data, electronic circular dichroism (ECD) calculations, and X-ray diffraction analyses. Using an intermolecular Diels-Alder reaction, a strategy for the synthesis of bisamide alkaloids from different monomeric amide alkaloids was developed. Furthermore, these compounds were chirally separated for the first time, and compounds 3a and 5a/5b showed significant anti-neuroinflammation effects in the models of lipopolysaccharide(LPS)-induced BV2 microglial cells. Meanwhile, compounds 6b and 7a displayed concentration-dependent inhibitory activities against acetylcholinesterase with IC50 values of 6.05 ± 1.10 and 3.81 ± 0.10 μM, respectively. These findings confirmed that these bisamide alkaloids could be applied in functional food formulations and pharmaceutical products as well as facilitate the further development and usage of pepper roots.

Screening for resistance and genetic population structure associated with Phytophthora capsici-pepper root and crown rot

Pepper, Capsicum spp. (Solanaceae) is one of the vegetable crops with significant and multiple roles in human diet, as a vegetable, spice, food colorant and ornamental purposes worldwide. Pepper root and crown rot (RCR), and or Phytophthora-blight caused by Phytophthora capsici (Oomycetes) is one of the most destructive diseases of Capsicum species globally. To this aim, we screened 37 pepper-accessions for resistance to RCR, P. capsici and characterized their population-genetic-diversity using 21 Inter-Simple-Sequence-Repeats-(ISSR) primer-pairs, and 27 morphological-attributes. Of which, five accessions; including three-ornamental; 11BlockyP-YToran, 19OrnP-PBI, 23CherryP-Orsh, and two-longs; 32OrnP-China, 37ChilP-Paleo were resistant to RCR with the least-infection-rates, RCR <10%. To estimate the genetic-distance, based on morphological-attributes, we used simple-matching, Jaccard and Dice-similarity-coefficient-(SC), following clustering by UPGMA, and also Cophenetic-coefficient and correlation between similarity-matrices. Similarity-coefficient among genotypes was 0.26–0.93, revealed significant differences among five distinct pepper groups, predominantly in size, color, and shape of leaf and fruit. Genetic-similarity was determined by simple-matching-coefficient-(SSM), and dendrogram was constructed by clustering-analysis with un-weighted-pair-groups using arithmetic-averages-(UPGMA), showed the presence of high genetic-variability among the peppers, and assembled the peppers into five distinct genetic groups. According to ISSR analysis, the highest-resolving-power, (Rp) (≥0.77), and heterozygosity-values, Hv (≥0.26) was recorded accordingly. 19 out of 21-primers produced polymorphism, of which MBP-7, MBP -14 and MBP-18 primers (0.499) had the best performance in genetic-diversity of the related pepper population, respectively. The ISSR-assay generated 188-bands, of which 185-bands were polymorphic. Polymorphism-mean-percentage-(P%) varied from 78% to 100% with a mean of 98.5%, and an average of 9.9 bands per primer. Average polymorphism-information-content-(PIC) was 0.449, and matrix-index 4.29. Association between genotypic-phenotypic-traits-(r-0.346**), phenotypic-RCR-resistance-(r = 0.197**), and RCR-resistance-ISSR (r-0.029**) was significant, respectively. There was also a high correlation between RCR resistance and some morphological-attributes, such as node anthocyanin-pigment and its intensity (r = 0.251**), node-woolly (r = 0.255**), fruit-shape (r = 0.273**), exocarp-wavy in fruit-base-(r = 0.208**), and hollow-depth-(r = 0.358**). The genetic markers revealed much genetic variation that can be used both in genotyping and in selecting appropriate breeding strategies against P. capsici, given the documented correlations between disease resistance and certain morphological and genotyping traits.

Root hair image processing based on deep learning and prior knowledge

In situ measurement of root traits is very essential for better understanding of root development. However, difficulty in acquisition of root traits, fine roots and root hairs in particular, from low contrast background presents challenges for root traits segmentation. In this paper, an in-ground device termed microrhizotron was used for local root area observation and capture. An efficient and accurate model was proposed for segmenting local detailed root (fine roots and root hairs) image by constructing region of interest and adding prior knowledge in convolutional neural network. In order to reduce complexity of root image, regional growth result was used to position the root area and thus construct the region of interest. Transfer learning was applied to pre-train models on relevant dataset as initial parameters. Root axes and root hairs were separated using a pruning method, and root hair parameters were extracted based on it. The result showed that pre-trained features on relevant dataset could somewhat overcome small dataset, and prior knowledge reduced mislearning of background. The P-T-U-Net model (U-Net base on prior knowledge and transfer learning) had the best performance in root segmentation among all the applied models. The Intersection over Union (IoU), Pixel accuracy (PA), and F1 was 0.869, 0.977, and 0.872 respectively for pepper root hairs. It succeed in root traits segmentation with an average F1 score over 0.9. Plant species has little influence on the segmentation. It was able to figure out details on crossing and overlapping roots, and was able to focus on local root areas over time.

Melatonin enhanced low-temperature combined with low-light tolerance of pepper (Capsicum annuum L.) seedlings by regulating root growth, antioxidant defense system, and osmotic adjustment.

Melatonin (MT) is an important biologically active hormone that plays a vital role in plant growth and development. In particular, it has been investigated for its roles in abiotic stress management. In this study, pepper seedlings were subjected to low-temperature combined with low-light stress (LL) (15/5°C, 100 μmol m-2s-1) prior to a foliar spray of 200mM MT for 168h to investigate the protective role of MT in pepper seedlings. Our results demonstrated that LL stress negatively affected root growth, and accelerated the accumulation of reactive oxygen species (ROS), including H2O2 and , changed the osmolytes contents, and antioxidative system. However, these were reversed by exogenous MT application. MT effectively promoted the root growth as indicated by significant increase in root length, surface area, root volume, tips, forks, and crossings. In addition, MT reduced the burst of ROS and MDA contents induced by LL, enhanced the activities of SOD, CAT, POD, APX, DHAR, and MDHAR resulted by upregulated expressions of CaSOD, CaPOD, CaCAT, CaAPX, CaDHAR, and CaMDHAR, and elevated the contents of AsA and GSH, declined DHA and GSSH contents, which prevented membrane lipid peroxidation and protected plants from oxidative damages under LL stress. Furthermore, seedlings treated with MT released high contents of soluble sugar and soluble protein in leave, which might enhance LL tolerance by maintaining substance biosynthesis and maintaining cellular homeostasis resulted by high levels of osmolytes and carbohydrate in the cytosol. Our current findings confirmed the mitigating potential of MT application for LL stress by promoting pepper root growth, improving antioxidative defense system, ascorbate-glutathione cycle, and osmotic adjustment.

Kinetics of Phosphorus Uptake through Roots of Habanero Pepper (Capsicum chinense Jacq. cv. Mayapán)

The application of enzymatic kinetics theory on the nutrition of horticultural species is scarce. Imax and Km describe the kinetics of nutrient absorption by the plant. Imax and Km are necessary to predict phosphorus (P) uptake from soil using mathematical models, and their estimation gives information about the efficient use of P in plants. Imax and Km for habanero pepper (Capsicum chinense Jacq. cv. Mayapán) were determined using the modified exhaustion method. Depletion of P by the roots was obtained with 0.01, 0.125, 0.25, 0.50, and 1.00 mM P L−1. P-depletion data over time were fitted to an exponential-regression model to obtain the initial P-uptake rates by the roots. Initial P-uptake rates were significantly different (p &lt; 0.001) depending on the levels of P in the solution. Imax and Km were predicted by iteratively fitting the initial P-absorption rates in terms of the concentration of P to the Michaelis–Menten model. The average Imax was 3.49 × 10−7 mM cm2 s−1 and Km was 2.59 × 10−2 mM P L−1. These results show that the habanero pepper root can uptake 1.08 × 10−5 mg P L−1 per cm2 in the soil solution per second and P transporters are saturated with 2.59 × 10−2 mM P L−1.

Reuse of post-culture mushroom substrate in horticultural seedbeds

The agronomic use of mushroom post-harvest substrates (SPCHs) in horticultural seedbeds could be an interesting alternative for the reuse of these wastes in line with the European circular economy strategy. This work evaluates the potential use of four treatments with different SPCHs, mushroom (-Ch), mushroom (-St), mushroom compost (-CO), and a mixture (SPCH-Ch and SPCH-St) as substrates for lettuce and chili pepper seed germination. The trial was carried out in a germination chamber using commercial compost as a control treatment. The evaluation was based on its chemical (salinity, N and C content), physical (bulk and real density, porosity and water retention) and plant effect (germination and biomass) characteristics. Of the chemical properties studied, the high salinity in SPCH-Ch and SPCH-CO was a limiting factor for the development of the horticultural species evaluated (electrical conductivity 1:2.5; p/v; ~11 dS m-1), and low germination percentages were observed. Regarding physical properties, porosity and water retention, the SPCH-CO, SPCH-St and mixture treatments presented some values outside the optimal range established for germination substrates. In the case of SPCH-St, its high C/N ratio could be a limitation for supplying N to the crop. In relation to biomass production (aerial and root) of lettuce and chili pepper, all the treatments evaluated obtained similar values to the control treatment. The mixed treatment presented the highest biomass values, significantly higher in the lettuce crop. In general, the mixed treatment proved to be the best alternative for use in the seedbed.

Multiplex PCR assay for simultaneous detection of Phytophthora, Pythium and Fusarium associated with foot rot and yellowing diseases of black pepper

In this study, a multiplex PCR assay was developed to detect Phytophthora, Pythium and Fusarium infecting black pepper. Genus-specific primers were designed from the conserved region of ITS and a multiplex PCR was optimized by manipulating the annealing temperature and primer as well as MgCl2 concentrations. The black pepper 18S rRNA gene-specific primers were also included in the multiplex PCR assay as internal control. The assay successfully detected the pathogens from artificially inoculated black pepper roots and did not show any cross amplification with other fungal pathogens of black pepper such as Rhizoctonia solani, Sclerotium rolfsii and Colletotrichum sp. Hence, the developed multiplex PCR assay will help in early diagnosis of the cause of black pepper yellowing leading to timely adoption of management strategies.

Biocontrol effects of endophytic and rhizospheric bacteria against the root pathogen Fusarium oxysporum of hot pepper (Capsicum annum L.)

Plant disease needs to be controlled to keep the quality ofproducts and the abundance of food produced by farmersall over the world. Hot pepper production in Ethiopia hasbeen reduced from time to time. This is mainly due to theoutbreak of different diseases especially fusarium wilt inthe hot pepper growing areas. The objective of this studywas to isolate and characterize Plant Growth PromotingBacteria from the hot pepper rhizosphere and internal tissueswith potential biocontrol activity against Fusariumoxysporum. Thirty healthy and vigorous hot pepper plantswith intact roots and soil from the rhizospheric region werecollected randomly from hot pepper growing areas of YimaliKebele. A total of 23 endophytic and rhizospheric bacteriawere isolated from the hot pepper root and rhizosphericsoil. The combined endophytic and rhizospheric bacteriashowed a significant effect on the growth of F. oxysporumthan single isolates (P d”0.05). The bacteria isolated fromMarkofana hot pepper varieties of black clay soil showed abetter antagonistic effect on F. oxysporum than bacteriaisolated from local hot pepper varieties of reddish sandysoil. A significant percentage of inhibition between combinedendophytic and rhizospheric bacteria [endophytic (GE) +rhizospheric (GR) isolates] compared to GE+GE and GR+GR(P =0.002) was obtained. Antagonistic bacterial isolates wereable to produce different hydrolytic enzymes such aschitinase, protease, and cellulase. Bacillus species showedbetter antagonistic performance and decreased radial growthof F. oxysporum than Pseudomonas species.

The terminal enzymatic step in piperine biosynthesis is co-localized with the product piperine in specialized cells of black pepper (Piper nigrum L.).

Piperine (1-piperoyl piperidine) is responsible for the pungent perception of dried black pepper (Piper nigrum) fruits and essentially contributes to the aromatic properties of this spice in combination with a blend of terpenoids. The final step in piperine biosynthesis involves piperine synthase (PS), which catalyzes the reaction of piperoyl CoA and piperidine to the biologically active and pungent amide. Nevertheless, experimental data on the cellular localization of piperine and the complete biosynthetic pathway are missing. Not only co-localization of enzymes and products, but also potential transport of piperamides to the sink organs is a possible alternative. This work, which includes purification of the native enzyme, immunolocalization, laser microdissection, fluorescence microscopy, and electron microscopy combined with liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS), provides experimental evidence that piperine and PS are co-localized in specialized cells of the black pepper fruit perisperm. PS accumulates during early stages of fruit development and its level declines before the fruits are fully mature. The product piperine is co-localized to PS and can be monitored at the cellular level by its strong bluish fluorescence. Rising piperine levels during fruit maturation are consistent with the increasing numbers of fluorescent cells within the perisperm. Signal intensities of individual laser-dissected cells when monitored by LC-ESI-MS/MS indicate molar concentrations of this alkaloid. Significant levels of piperine and additional piperamides were also detected in cells distributed in the cortex of black pepper roots. In summary, the data provide comprehensive experimental evidence of and insights into cell-specific biosynthesis and storage of piperidine alkaloids, specific and characteristic for the Piperaceae. By a combination of fluorescence microscopy and LC-MS/MS analysis we localized the major piperidine alkaloids to specific cells of the fruit perisperm and the root cortex. Immunolocalization of native piperine and piperamide synthases shows that enzymes are co-localized with high concentrations of products in these idioblasts.

Suppression of Pepper Root Rot and Wilt Diseases Caused by Rhizoctonia solani and Fusarium oxysporum.

Pepper is vulnerable to soil-borne fungal pathogens such as Rhizoctonia solani and Fusarium oxysporum. The potential of beneficial rhizosphere microorganisms to control R. solani and F. oxysporum f.sp. capsici was evaluated in pepper plants. Paenibacillus polymyxa and Trichoderma longibrachiatum were isolated from rhizospheric soil samples of healthy pepper plants. In vitro, both isolates caused clear reductions in the radial growth of root rot and wilt pathogens. Scanning electron microscopy displayed lysis and abnormal shape of the pathogens in dual cultures with P. polymyxa and T. longibrachiatum. The incidence and severity of root rot and wilt diseases were significantly reduced in pepper plants treated with the growth-promoting fungi (PGPF isolates; Fusarium equiseti GF19-1, Fusarium equiseti GF18-3, and Phoma sp. GS8-3), P. polymyxa, or T. longibrachiatum in comparison to the control. Moreover, the induction treatments led to increased pepper growth compared with their control. The defense related gene (CaPR4) expression was shown to be significantly higher in the treated plants than in the control plants. In conclusion, the antagonistic isolates (P. polymyxa and T. longibrachiatum) and PGPF isolates have a clear impact on the prevention of root rot and wilt diseases in pepper plants incited by R. solani and F. oxysporum f.sp. capsici. The expression of the CaPR4 gene added to the evidence that PGPF isolates generate systemic resistance to pathogen infections.

Boron supplying alters cadmium retention in root cell walls and glutathione content in Capsicum annuum

Large areas of farmland in southern China are facing environmental problems such as cadmium (Cd) contamination and boron (B) deficiency. The aim of this study was to investigate the biochemical and molecular mechanisms underlying the reduction in Cd accumulation in hot pepper (Capsicum annuum) by B application. A hydroponic experiment was conducted to compare the subcellular distribution of Cd, transcriptome profile, degree of pectin methylation, and glutathione (GSH) synthesis in the roots of hot pepper under different B and Cd conditions. Boron supply promoted root cell wall biosynthesis and pectin demethylation by upregulating related genes and increasing cell wall Cd concentration by 28%. In addition, with the application of B, the proportion of Cd in root cell walls increased from 27% to 37%. Boron supplementation upregulated sulfur metabolism-related genes but decreased cysteine and GSH contents in the roots. As a result, shoot Cd concentration decreased by 27% due to the decrease in GSH, a critical long-distance transport carrier of Cd. Consequently, B supply could reduce the uptake, translocation, and accumulation of Cd in hot pepper by retaining Cd in the root cell walls and decreasing GSH content.

Effects of aerated subsurface drip irrigation on rhizosphere soil environment and pepper (Capsicum annum L.) growth in three soil types

ABSTRACT Aerated subsurface drip irrigation (ASDI) has been considered an effective method to unlock the growth potential of crops. An experiment was undertaken to monitor the effects of three aeration rates (40% aeration rate, 15% aeration rate, CK: no-aeration) on rhizosphere soil environment and growth parameters of pepper in three soil types (YC: yellow clay, SL: silt loam, HL: heavy loam). ASDI significantly increased the soil enzyme and microbial abundance, and enhanced the soil respiration compared to the control. ASDI significantly increased the pepper yield, fruit quality, and biomass of stem and leaf. The 40% aeration rate was more beneficial to these parameters than that of 15% aeration rate in YC and SL, whereas, in HL, the 40% was less effective than 15% aeration rate. Soil type significantly affected pepper rhizosphere soil environment and the yield, quality, and biomass of stem and leaf. The benefits of ASDI in YC were better than those in SL and HL. However, aeration rate and soil type had no significant effects on the fresh/dry weight of pepper root. The recommended ASDI patterns for pepper in YC and SL were 40% aeration rates, while in HL it was the 15% aeration rate.

Deciphering the influence of Bacillus subtilis strain Ydj3 colonization on the vitamin C contents and rhizosphere microbiomes of sweet peppers.

Bacillus subtilis strain Ydj3 was applied to sweet peppers to understand the influence of this bacterium on the growth, fruit quality, and rhizosphere microbial composition of sweet pepper. The promotion of seed germination was observed for sweet pepper seeds treated with the Ydj3 strain, indicating that Ydj3 promoted seed germination and daily germination speed (131.5 ± 10.8 seeds/day) compared with the control (73.8 ± 2.5 seeds/day). Strain Ydj3 displayed chemotaxis toward root exudates from sweet pepper and could colonize the roots, which enhanced root hair growth. Following the one-per-month application of strain Ydj3 to sweet pepper grown in a commercial greenhouse, the yield, fruit weight, and vitamin C content significantly increased compared with those of the control. Additionally, the composition of the rhizosphere bacterial community of sweet pepper changed considerably, with the Bacillus genus becoming the most dominant bacterial genus in the treated group. These results suggested that B. subtilis Ydj3 promotes seed germination and enhances fruit quality, particularly the vitamin C content, of sweet pepper. These effects may be partly attributed to the B. subtilis Ydj3 colonization of sweet pepper roots due to Ydj3 chemotaxis toward root exudates, resulting in the modulation of the rhizosphere bacterial community.

Genome-wide identification and expression analysis of HAK/KUP/KT potassium transporter provides insights into genes involved in responding to potassium deficiency and salt stress in pepper (Capsicum annuum L.).

The online version contains supplementary material available at 10.1007/s13205-022-03136-z.

The Influence of Residue Mixing on the Decomposition of Pepper Root Residues

(1) Background: Residue degradation plays a very important role in terrestrial ecosystems and residue mixing is the main factor affecting the degradation rates. However, in the agricultural systems, the effect of residue mixing on the degradation of pepper residues and the microbial community in pepper root residues is not clear. (2) Methods: In this study, we added different residues into soil by using double-layered nylon litterbags in culture bottles. The treatments including pepper root (P: Capsicum annuum L.), soybean [S: Glycine max (L.) Merr.] and maize (M: Zea mays L.) residue, as well as mixtures of soybean + pepper (SP), maize + pepper (MP), maize + soybean + pepper (MSP) mixtures. Litterbags were harvested after 7, 14, 28, and 56 days, respectively. Mass loss and nitrogen and phosphorus contents in pepper residue were quantified and bacterial and fungal community levels in pepper residues were analyzed using quantitative PCR and high throughput amplicon sequencing; (3) Results: The study showed that the mass loss and fungal community abundance of pepper root residue in mixtures were higher than P, except day 7. The phosphorus contents in MSP-P and MP-P were significantly lower than that for P at day 28 and day 56. Illumina MiSeq sequencing showed that the presence of maize residue significantly altered the microbial community composition of pepper root pepper. Day 56. (4) Conclusions: Our results suggest that residue mixing changed the microbial community abundance in pepper residue and promoted the degradation of pepper residues compared to pepper residue decomposition alone, especially for mixtures with soybean.

Phytonematodes associated with the yellowing disease of Javanese long pepper plants in Sumenep, East Java

One of the major pathogen infecting the Javanese long pepper plantation is phytonematode. This study aims to identify the population of phytonematodes associated with the yellowing disease of Javanese long pepper. Root and soil samples were collected from Javanese long pepper with monoculture and polyculture cropping systems purposively in Sumenep Regency, East Java Province. Phytonematodes were extracted from root samples by mist chamber technique and soil samples by centrifugation flotation technique. Morphology character was observed from the permanent nematode slides. Based on morphological characters, six phytonematodes were found in the root and soil of Javanese long pepper, namely Paratylenchus nanus, Meloidogyne spp., Rotylenchulus reniformis, Rotylenchulus parvus, Coslenchus paramaritus, and Coslenchus cancellatus. The highest phytonematode population from root extraction is P. nanus with an average of 165 nematodes/10 g roots. R. reniformis was the highest phytonematode population from soil extraction with an average of 1314 nematodes/100 ml soil.

Solanaceous plants switch to cytokinin-mediated immunity against Ralstonia solanacearum under high temperature and high humidity.

Plant diseases generally tend to be more serious under conditions of high temperature and high humidity (HTHH) than under ambient temperature, but plant immunity against pathogen attacks under HTHH remains elusive. Herein, we used pepper as an example to study how Solanaceae cope with Ralstonia solanacearum infection (RSI) under HTHH by performing RNA-seq combined with the reverse genetic method. The result showed that immunities mediated by salicylic acid(SA) and jasmonic acid (JA) in pepper roots were activated by RSI under ambient temperature. However, upon RSI under HTHH, JA signalling was blocked and SA signalling was activated early but its duration was greatly shortened in pepper roots, instead, expression of CaIPT5 and Glutathione S-transferase encoding genes, as well as endogenous content of trans-Zeatin, were enhanced. In addition, by silencing in pepper plants and overexpression in Nicotiana benthamiana, CaIPT5 was found to act positively in the immune response to RSI under HTHH in a way related to CaPRP1 and CaMgst3. Furthermore, the susceptibility of pepper, tomato and tobacco to RSI under HTHH was significantly reduced by exogenously applied tZ, but not by either SA or MeJA. All these data collectively suggest that pepper employs cytokinin-mediated immunity to cope with RSI under HTHH.

Characterisation of arbuscular mycorrhizal fungi community on black pepper (Piper nigrum L.) in Northern

Mycorrhiza was considered to enhance plant growth, especially in unfavourable environmental conditions. From 60 samples of rhizospheric soils and roots of black pepper (Piper nigrum) grown in Ba Ria - Vung Tau, Dong Nai, and Gia Lai provinces, the presence of Acaulospora, Gigaspora, Glomite, Glomus,and Scutellospora genera were detected, of which Glomus and Acaulospora were dominants. After 40 days of inoculation, mycorrhiza multiplied 8.5 fold on corn (Zea mays) and 6.5 fold on sorghum (Sorghum bicolor) or goosegrass (Eleusine indica). Black-pepper cuttings on substrate supplemented mycorrhiza showed better growth than the non-inoculated cuttings. Results suggest the potential of applying mycorrhizal fungi as biological agents in sustainable black pepper cultivation, adapting to climate change