Abnormal Stomatal Behaviour and Leaf Anatomy in Capsicum annuum, scabrous diminutive, a Wilty Mutant of Pepper

An attempt is made to explain the tendency to excessive wiltingin scabrous diminutive, a pepper mutant. For this, mutant andnormal plants were compared with respect to leaf anatomy, transpirationof whole plants and detached drying leaves, density and openingof stomata, staining of potassium in epidermal cells and rootpressure. A much greater proportion of intracellular space was found inthe mutant leaf which contains fewer and smaller mesophyll cellsthan the normal plant. The anticlinal walls of the epidermisof the mutant leaf were almost straight whereas those of thenormal were wavy. Transpiration per unit leaf area of wholeplants, percentage of stomata open both day and night, and waterloss from detached drying leaves were all higher in the mutant.Potassium staining in guard cells was similar in both planttypes, slightly less in darkness and marginally higher in light.The subsidiary cells of normal leaves did not stain at all,but those of the mutant leaves stained heavily in both lightand darkness. Root pressure was lower in the mutant. Possible explanations for the tendency of the pepper mutantto wilt are discussed.     

Ion Imbalance in Capsicum annum scarbrous diminutive a Wilty Mutant of pepper: II.RUBIDIUM FLUX

Root tips of the wilty pepper mutant scarbrous diminutive accumulateless rubidium than those of the normal genotype. This phenomenonwas evident in root tips excised from plants maintained for2 d in CaSO₄ solution (low salt plants), especially in the lowerexternal concentration range (0.1– 1.0 mM) of RbCl. Theefflux rate of Rb⁺ from mutant root tips was twice as high asin normal root tips. These results indicate that the ability of the mutant rootsto absorb and accumulate Rb⁺ and K⁺ is impaired. This defectcould be a consequence of either an impaired Na⁺/K⁺ carriersystem, or increased leakiness of mutant membranes, or both. The fact that the normal roots can accumulate Rb⁺ much fasterthan mutant roots supports the first alternative, i.e. thatthe high affinity carrier system was impaired in the mutantroots. However, the higher efflux rate of Rb⁺ from the mutantroots suggests that membrane leakiness was also affected.     

Abnormal Stomatal Behavior and Hormonal Imbalance in flacca, a Wilty Mutant of Tomato: I. Root Effect and Kinetin-like Activity

The wilty tomato mutant, flacca, and the normal variety, Rheinlands Ruhm, were compared for kinetin-like activity in ontogeny. The mutant wilts easily because its stomata resist closure. This stomatal resistance decreases with age. The occurrence of a root factor which induces stomatal opening was inferred from grafting experiments. It was hypothesized that the excessive stomatal openings in the mutant may result from excess of kinetin-like activity in the leaf of that plant. In addition, it was suggested that the closure of stomata in the aging mutant is due to a decrease of kinetin-like activity with age. Kinetin-like activity in the leaf was determined by incorporation of labeled leucine. The concentration of cytokinins in root exudate and leaf extract was determined by the soybean callus assay. Evidence was presented of higher kinetin-like activity in the leaves of the mutant and higher cytokinin concentration in its root exudate. Cytokinin concentration in the shoot was found to be only slightly higher in the mutant than in the normal plants. Kinetin-like activity in the leaf and cytokinin concentration of root exudate decreased with age in both mutant and normal plants. Kinetin-like activity in the leaves of mutant plants, which phenocopy the normal variety as a result of continuous application of abscisic acid, was lower than in control mutant plants. The significance of these findings per se and in connection with stomatal behavior is discussed.     

Verticillium Wilt of Pepper (Capsicum annuum) in Morocco

Pepper crops in Morocco formerly thought to be free from attack by Verticillium were found to be susceptible to this pathogen. Verticillium wilt of pepper was observed in plots where the crop was cultivated in rotation with tomatoes. Strains of Verticillium isolated from pepper possessed different morphological and pathogenic characteristics.     

Virus Diseases of Pepper (Capsicum annuum L.) in Ethiopia

Viruses occurring in hot pepper (Capsicum annuum L.) in Ethiopia during 1984–1986 were identified and their symptomatology, host range, serology, morphology and transmission described. Potyviruses were found to cause severe infections of pepper wherever the crop was observed. Disease incidence and yield loss in most surveyed areas were estimated at 40–100 % and 15–50 %, respectively. Besides potato Y and pepper veinal mottle viruses, a new potyvirus with distinctive properties was found widely distributed in Shewa and Welega Provinces. The virus, tentatively designated Ethiopian pepper mottle virus (EPMV), was shown to have an unusually narrow experimental host range and filamentous particles about 700–750 nm in length, and to be nonpersis-tently transmitted by aphids but not transmissible through pepper seeds. Cucumber mosaic virus was detected in some locations, but appeared to be of minor significance.     

A New Lignan Amide,Grossamide, from Bell Pepper (Capsicum annuum var. grossurri)

Two new phenolic amides, grossamide (7) and N-cis-feruloyl tyramine (2), have been isolated from the roots of bell pepper (Capsicum annuum var. grossum) together with p-aminobenzaldehyde (1), N-trans-feruloyl tyramine (3), N-trans-p-coumaroyl tyramine (4), N-trans-feruloyl octopamine (5), and N-trans-p-coumaroyl octopamine (6).     

Carbon Partitioning and Export in Mature Leaves of Pepper (Capsicum annuum)

The partitioning of recently fixed carbon by mature pepper leaveshas been examined over a 10 h photoperiod using a constant specificradioactivity ¹⁴CO₂ labelling technique. Changes in the ratesof carbon partitioning into export, starch, sucrose and hexoseswere examined following changes in irradiance during the photoperiod.Leaves grown under 80 W m^–2 PAR were exposed to this irradiancefor the first 4 h of the photoperiod then the iiradiance wasdecreased. Leaves accumulated sufficient reserves in the first4 h to maintain export at the initial rate (approximately 20µg carbon cm^–2 leaf h^–1) over the following6 h of the photoperiod when the net photosynthesis rate (Pn)was decreased to 10% of the initial rate by the decreased irradiance.Export was initially maintained by the depletion of sucroseand hexose and then by carbon from the degradation of starchin the light. If leaves were exposed to low irradiance at the beginning ofthe photoperiod, then the export rate was linearly related tothe Pn during that period. When Pn exceeded that required tomaintain an export rate of approximately 20 µg carboncm^–2 h^–1, then more carbon was partitioned intostarch. At low initial irradiance, a greater proportion of photosynthatewas partitioned into export rather than starch and at high initialirradiancc the reverse occurred. There was a linear relationship between starch accumulationrate and Pn for all leaves but the relationship between Pn andexport rate was only significant for leaves with low levelsof reserve carbon. The results show that mature pepper leaves subjected to differentirradiances maintain constant export rates through alterationsof carbon partitioning. Export at low Pn is maintained at theexpense of sugar and starch reserves, with partitioning in highirradiance being predominantly to starch. Key words: Carbon partitioning, Starch, Export, Pepper (Capsicum annuum L.)     

In Vivo and In Vitro Formation of Dihydrocapsaicin in Sweet Pepper Fruits,Capsicum annuum L. var. grossum

Dihydrocapsaicin, one of pungent principles in Capsicum fruits, was formed and accumulated in sweet pepper fruits after 6 days’ post-harvest ripening under continuous light in a medium containing vanillylamine and isocapric acid. No capsaicinoids were formed in sweet pepper fruits ripened in the dark even in the presence of both vanillylamine and isocapric acid. The capsaicinoid newly formed during the ripening was almost exclusively dihydrocapsaicin, as much as 92.8% of the total capsaicinoids. Dihydrocapsaicin was also formed by cell-free extracts prepared from the sweet pepper fruits in a reaction mixture containing vanillylamine and isocapric acid. Dihydrocapsaicin formed was quantified by TLC, GLC, GC-MS and MF.     

Effects of Low Oxygen on Photosynthesis, Translocation and Growth in Green Pepper (Capsicum annuum)

Green pepper (Capsicum annuum cv. Bell Boy) plants were exposedin chambers to low (2%) oxygen and controlled carbon dioxideconcentrations. Vegetative and fruiting plants showed short-termincreases in net photosynthesis in low oxygen or elevated carbondioxide (up to 900 µl CO₂ l^–1). Photosynthesis ofyoung vegetative plants increased in low oxygen in the short-termbut there was no long-term benefit. Low oxygen enhancement ofphotosynthesis declined with time and after 10 d, leaf areaand root dry weight were less than in plants grown in normalair. Labelled assimilates were translocated from leaves to otherregions at similar rates in low oxygen and normal air. Low oxygenreduced respiratory losses from leaves and reduced the proportionof soluble carbohydrate converted to polysaccharide in all plantparts. Thus, low-oxygen environments decrease the utilisationof assimilates which then may lead to inhibition of photosynthesis. Capsicum annuum, photosynthesis, photorespiration, translocation, utilization of assimilates     

CaMYC,A Novel Transcription Factor,Regulates Anthocyanin Biosynthesis in Color-leaved Pepper (Capsicum annuum L.)

Journal of Plant Growth Regulation - Anthocyanins are secondary metabolites derived from the general phenylpropanoid pathway and are widespread throughout the plant kingdom. Anthocyanin...     

辣椒开花期的主基因+多基因遗传分析

应用植物数量性状主基因+多基困混合遗传模型对早熟辣椒‘E100’与‘L101’杂交组合多个世代群体开花期进行了联合分析.结果表明:开花期由两对加性-显性-上位性主基因+加性-显性-上位性多基因的控制;主基因遗传率在B1、B2和F2世代分别为55.27%、53.83%和76.05%;B1、B2和F2世代多基因遗传率分别为34.13%、42.78%和16.94%.     

Formation of Pungent Principles in Fruits of Sweet Pepper,Capsicum annuum L. var. grossum during Post-harvest Ripening under Continuous Light

Pungent principles (Capsaicinoid(s)) were found to be produced in fruits of sweet pepper, Capsicum annuum L. var. grossum, during post-harvest ripening under continuous light. The initial formation was observed after 4 days’ ripening. After 7 days’ ripening, the capsaicinoids content in placenta increased to 12.9 μg per fruit, which was 2.5-fold of that in pericarp. No pungent principles were detected in fruits during ripening in the dark and in seeds under continuous light. In placenta, the formation of dihydrocapsaicin and nordihydrocapsaicin which are the vanillylamides of saturated branched fatty acids was higher than that of capsaicin which is the vanillylamide of an unsaturated one. Remarkable formation and accumulation of carotenoid were also observed during post-harvest ripening under continuous light.     

Abnormal Stomatal Behavior and Hormonal Imbalance in flacca, a Wilty Mutant of Tomato: V. Effect of Abscisic Acid on Indoleacetic Acid Metabolism and Ethylene Evolution

The wilty tomato mutant flacca, the normal cultivar Lycopersicon esculentum Mill. Rheinlands Ruhm, and abscisic acid-induced phenotypic revertants were compared with respect to ethylene evolution, activity of tryptophan aminotransferase, and [1-¹⁴C]indoleacetic acid decarboxylation.     

Response of Resistant and Susceptible Bell Pepper (Capsicum annuum) to a Southern California Meloidogyne incognita Population from a Commercial Bell Pepper Field

To determine the presence and level of root-knot nematode (Meloidogyne spp.) infestation in Southern California bell pepper (Capsicum annuum) fields, soil and root samples were collected in April and May 2012 and analyzed for the presence of root-knot nematodes. The earlier samples were virtually free of root-knot nematodes, but the later samples all contained, sometimes very high numbers, of root-knot nematodes. Nematodes were all identified as M. incognita. A nematode population from one of these fields was multiplied in a greenhouse and used as inoculum for two repeated pot experiments with three susceptible and two resistant bell pepper varieties. Fruit yields of the resistant peppers were not affected by the nematodes, whereas yields of two of the three susceptible pepper cultivars decreased as a result of nematode inoculation. Nematode-induced root galling and nematode multiplication was low but different between the two resistant cultivars. Root galling and nematode reproduction was much higher on the three susceptible cultivars. One of these susceptible cultivars exhibited tolerance, as yields were not affected by the nematodes, but nematode multiplication was high. It is concluded that M. incognita is common in Southern California bell pepper production, and that resistant cultivars may provide a useful tool in a nonchemical management strategy.     

BABA and Phytophthora nicotianae Induce Resistance to Phytophthora capsici in Chile Pepper (Capsicum annuum)

Induced resistance in plants is a systemic response to certain microorganisms or chemicals that enhances basal defense responses during subsequent plant infection by pathogens. Inoculation of chile pepper with zoospores of non-host Phytophthora nicotianae or the chemical elicitor beta-aminobutyric acid (BABA) significantly inhibited foliar blight caused by Phytophthora capsici. Tissue extract analyses by GC/MS identified conserved change in certain metabolite concentrations following P. nicotianae or BABA treatment. Induced chile pepper plants had reduced concentrations of sucrose and TCA cycle intermediates and increased concentrations of specific hexose-phosphates, hexose-disaccharides and amino acids. Galactose, which increased significantly in induced chile pepper plants, was shown to inhibit growth of P. capsici in a plate assay.     

Inheritance of a novel flaccid mutant in Capsicum annuum

A mutant that causes a novel flaccidity phenotype in bell pepper (Capsicum annuum L.) was generated by treating seeds with ethyl methanesulfonate (EMS). Inheritance studies indicated that the mutant was controlled by a single recessive gene. It is proposed that the gene designation representing this mutation be flc (flaccid). The mutation may be useful for investigations of the genetic basis for turgor maintenance and drought stress physiology.     

Abnormal Stomatal Behavior and Hormonal Imbalance in flacca, a Wilty Mutant of Tomato: IV. Effect of Abscisic Acid and Water Content on RNase Activity and RNA

Plants of the wilty tomato (Lycopersicum esculentum) mutant, flacca, and of the normal cultivar Rheinlands Ruhm growing under either “normal” or high humidity were used in this research. Under normal humidity, RNase activity was much higher in mutant plants in which abscisic acid (ABA) and water content were lower than in the normal plant. The mutant also contained less RNA and protein per cell and less soluble RNA relative to ribosomal RNA as compared with the normal genotype. In ABA-treated mutant plants, RNase activity decreased while RNA, protein, the ratio of soluble to ribosomal RNA and water content increased.     

Role of l-Cysteine Desulfhydrase in Epibrassinolide-Induced Tolerance to Boron Toxicity in Pepper (Capsicum annuum L.) Plants

Journal of Plant Growth Regulation - Although the effect of epibrassinolide (EBL) on plants under boron (B) toxicity has been studied, the participation of l-cysteine desulfhydrase (l-DES) in...     

Abnormal Stomatal Behaviour and Hormonal Imbalance in flacca, a Wilty Mutant of Tomato: EFFECT OF ABSCISIC ACID AND AUXIN ON STOMATAL BEHAVIOUR AND PEROXIDASE ACTIVITY

The wilty tomato mutant flacca and the normal variety RheinlandsRuhm were compared in terms of: (1) potassium transport intoand out of the guard cells, (2) cell wall properties which includeprotein, hydroxyproline and peroxidase activity, and (3) activityof indol-3yl-acetic acid oxidase. Also studied were the effectsof auxin on stomatal behaviour and peroxidase activity whenapplied to normal plants during development, and the short-termeffect of abscisic acid on the resistance of flacca stomatato closure under plasmolysis. Potassium transport, wall protein and hydroxyproline all seemedto be equal in mutant and normal plants. Peroxidase activitywas higher in the soluble and wall fractions of the mutant,and decreased toward normal in the mutant treated with abscisicacid. More stomata were open and peroxidase activity was higherin normal plants treated with auxin during development. Thepercentage of open stomata under plasmolysis was lower and theiraperture size was smaller in the epidermal strips taken fromabscisic-acid-treated mutant plants than from control mutantplants.     

Intracellular localization of capsaicin and its analogues, capsaicinoid, in Capsicum fruit 1. Microscopic investigation of the structure of the placenta of Capsicum annuum var. annuum cv. Karayatsubusa

Transverse sections of the placenta of hot pepper, Capsicumannuum var. annuum cv. Karayatsubusa, at different stages afterflowering were examined microscopically. Examination of thecellular structure of the placenta using a light microscoperevealed that some morphological changes took place mainly inthe epidermal tissue of the placenta during maturation. Elongationof the epidermal cells and many osmiophilic granules were recognizedin the epidermal cells of the placenta in which capsaicinoidwas being formed and actively accumulated. Moreover, a granule-likestructure having an absorption at 280 nm was also recognizedby ultraviolet microscopy around the same region where the osmiophilicgranules were observed. By electron microscopy, many electron-densegranules stained with glutaraldehyde and osmium tetroxide wereobserved both in the small vesicles and vacuoles of epidermalcells of the placenta. The electron-dense granules varied insize from smaller than 1 µm to larger than 2 µmin diameter. They were thought to be capsaicinoid and were observedonly in the epidermal cells. Therefore, the epidermal tissueappeared to be the site of capsaicinoid accumulation. ¹Formation and metabolism of pungent principle of Capsicum fruits.Part V. (Received December 27, 1979; )