Cloning,Purification, and Polymerization of Capsicum annuum Recombinant α and β Tubulin

α and β tubulin genes were cloned from the Capsicum annuum leaves using rapid amplification of cDNA ends (RACE)-PCR. Nucleotide sequence analysis revealed that 1,353 bp Capsicum annuum α?β-tubulin (CAnm α?β-TUB) encodes a protein of 450 amino acids (aa) each. The recombinant α?β tubulin was overexpressed mainly as an inclusion body in Escherichia coli BL21 (DE3), upon induction with 0.2 mM isopropyl-β-D-thiogalactopyranoside (IPTG), and its content was as high as 50% of the total protein content. Effective fusion protein purification and refolding are described. The average yields of α and β tubulin were 2.0 and 1.3 mg/l of culture respectively. The apparent molecular weight of each tubulin was estimated to be 55 kDa by SDS-polyacrylamide gel electrophoresis (PAGE). The tubulin monomers were found to be assembly competent using a standard dimerization assay, and also retained antigenicity with anti-His/T7 antibodies. The purified tubulins were polymerized to microtubule-like structures in the presence of 2 mM guanosine 5′-triphosphate (GTP).     

Nitric oxide functions as a signal in induced systemic resistance

The study was aimed to search out the probable molecule behind the activation of a broad spectrum resistance during Pseudomonas aeruginosa WS-1 mediated induced systemic resistance (ISR) in Capsicum annuum where plants were challenged inoculated with its pathogen Colletotrichum capsici 24 h after induction of ISR. On the fourth day after pathogen inoculation a significant increase of pathogenesis-related (PR) proteins, other defence enzymes and phenolics as well as a two-fold increase of nitric oxide (NO) a potent defence signalling molecule were observed. Treatment of the host with NO donor also induced the same defence molecule in a similar manner. Results suggest the possible signalling role of NO in ISR during crosstalk between ISR inducing agent and pathogen within the host system.     

Effect of tissue wounding and time of soil inoculation on pepper root rot development

Five-week-old pepper plants with wounds created on stems and roots were transplanted to soils having inoculum of Phytophthora capsici incorporated for different lengths of time. Disease severity (39.99%) on root trimmed seedlings was not significantly different (P ≤ 0.05) from the severity (36.24%) obtained on stem lacerated seedlings. The wound treatments did not result in significantly different rates of lesion extension per day; stem lacerated seedling had the fastest, 1.99 mm/day lesion extension rate, followed by 1.90 and 1.89 mm/day extension rates obtained on root trimmed and unwounded treatments, respectively. However, time of soil inoculation had significant effect on severity; root trimmed and stem lacerated treatments had 46.3% and 39.8% severities, respectively. Tissue wounding × time of soil inoculation interaction did not have significant effect on disease severity; stem lacerated seedlings transplanted to 1-day and 3-day inoculated soils gave highest severity (49.9%), followed by seedlings inoculated at the time of transplantation. Root trimmed seedlings inoculated at the time of transplantation had highest severity (61.1%), while the lowest severity was obtained on seedlings transplanted to 5-day inoculated soil.     

4种(变种)辣椒的核型研究

本文研究了辣椒属4种(变种)的核型,各个种的核型可简式为小米辣2n=24=23m+1sm:簇生辣2n=24=20m+2sm+2st:樱桃辣2n=24=20m+4sm(2SAT):“印度辣”2n=24=22m+2st。按照Stebbins的核型分类,小米辣为2A型;簇生辣和樱桃辣为2A型,印度辣为2B型。     

Anionic Antimicrobial and Anticancer Peptides from Plants

Anionic antimicrobial peptides (AAMPs) have been identified in a wide variety of plant species with net charges that range between ?1 and ?7 and structures that include: extended conformations, α-helical architecture and cysteine stabilized scaffolds. These peptides commonly exist as multiple isoforms within a given plant and have a range of biological activities including the ability to kill cancer cells as well as phytopathogenic bacteria, fungi, pests, molluscs, and other predatory species. In general, the killing mechanisms underpinning these activities are poorly understood although they appear to involve attack on intracellular targets such as DNA along with compromise of cell envelope integrity through lysis of the cell wall via chitin-binding and/or permeabilisation of the plasma membrane via lipid interaction. It is now becoming clear that AAMPs participate in the innate immune response of plants and make a major contribution to the arsenal of defence toxins produced by these organisms to compensate for their lack of some defence mechanisms possessed by mammals, such as mobility and a somatic adaptive immune system. Based on their biological properties, a number of potential uses for plant AAMPs have been suggested, including therapeutically useful anticancer agents and novel antimicrobial compounds, which could be utilized in a variety of scenarios, ranging from the protection of crops to the disinfection of hospital environments.     

Shikimate dehydrogenase from pepper (Capsicum annuum) seedlings. Purification and properties

Shikimate dehydrogenase (SKDH, EC 1.1.1.25) was extracted from seedlings of pepper ( Capsicum annuum L.) and purified 347-fold. The purification procedure included precipitation with ammonium sulphate and chromatography in columns of Reactive Red-agarose, Q-Sepharose and Sephadex G-100. Pepper SKDH isozymes are separable only using PAGE. The purified enzyme has a relative molecular mass of 67 000 as estimated by gel filtration. The optimum pH of enzyme activity is 10.5 and the optimum temperature is 50°C, but the enzyme is quickly inactivated at temperatures higher than 40°C. The purified enzyme exhibited typical Michaelis-Menten kinetics and K_m values are 0.087 m M for shikimic acid and 0.017 m M for NADP. The mechanism of reaction is sequential considering NADP as a cosubstrate. Ions such as Ca²⁺, Mg²⁺ and Mn²⁺ activate the enzyme, but Zn²⁺ and Cu²⁺ are strong inhibitors. Some phenolic compounds such as guaiacol, protocatechuic acid and 2,4-D are competitive inhibitors of pepper SKDH, showing K_i values of 0.38 m M , 0.27 m M and 0.16 m M , respectively.     

观赏辣椒一步成苗诱导条件的筛选

采用正交试验设计方法探讨6-BA、NAA和2,4-D对观赏辣椒一步成苗影响的结果表明:6-BA与NAA的浓度比对丛生芽诱导的影响最大。筛选出的观赏辣椒一步成苗的最适培养基为1/2MS 1.0mg·L-16-BA 0.5mg·L-1NAA 0.2mg·L-12,4-D,并获得移栽后的成活植株。     

Development of pepper (Capsicum annuum) seed quality

Changes in seed quality in pepper (Capsicum annuum L.) were monitored during seed development and maturation in two seasons. Seed quality was assessed by a number of different tests, but principally by determining seed storage longevity in laboratory tests and seedling growth in glasshouse tests. Mass maturity (defined as the end of the seed-filling phase) occurred 49–53 days after anthesis (DAA) in 1989 (varying among fruit layers) and 53 DAA in 1990 when seed moisture contents were 51–53%. The onset of both germinability and desiccation tolerance occurred either just before or at mass maturity. Maximum potential longevity (assessed by the value of the seed lot constant K_i) was achieved 63–65 DAA, i.e. not until 10–12 days after mass maturity (DAMM), in both years. Seedling dry weights in the glasshouse growth tests were maximal later still - for seeds harvested 17–21 DAMM in 1989 and 17 DAMM in 1990; the effects on seedling weight arose from differences in times from sowing to emergence (P < 0.005) among different seed harvests, with no significant differences in subsequent relative growth rates (P > 0.25). Seed priming reduced mean germination times for seeds harvested at all stages of development, but had little effect on germination capacity and potential longevity, and did not affect the pattern of changes in potential longevity during seed development and maturation. The results contradict the hypothesis that seed quality is maximal at the end of the seed-filling phase and that viability and vigour begin to decline immediately thereafter.     

Feeding‐induced phenol production in Capsicum annuum L. influences Spodoptera litura F. larval growth and physiology

We studied the role of induced plant phenols as a defense response to insect herbivory. Phenolic compounds were induced in Capsicum annuum L., the source of many culinary peppers, after feeding by different stages of the insect pest, Spodoptera litura F. The phenols were identified and quantified using high performance liquid chromatography (HPLC) and effects produced by these phenols on larval development were studied. Vanillic acid was identified in plants challenged by second, fourth, and fifth instar larvae, but not in plants challenged by third instar nor unchallenged plants. Syringic acid production was induced in chili plants infested with second (0.429 ± 0.003 μg/g fresh weight, fourth (0.396 ± 0.01 μg/g fresh weight), and fifth instar (5.5 ± 0.06 μg/g fresh weight) larvae, compared to untreated plants (0.303 ± 0.01 μg/g fresh weight) plants. Leaves surface treated with the rutin deterred oviposition. Dietary exposure to chlorogenic acid, vanillic acid, syringic acid, sinapic acid, and rutin led to enhanced activities of detoxifying enzymes, β‐glucosidase, carboxyl esterase, glutathione S‐transferase, and glutathione reductase in the midgut tissues of all the larval instars, indicating the toxic nature of these compounds. Protein carbonyl content and acetylcholinesterase activity was analyzed to appreciate the role of induced plant phenols in insect protein oxidation and terminating nerve impulses.     

Gas Exchange and Flowering in Verticillium-wilted Pepper Plants

In Navarra, Northern Spain, Verticillium dahliae Kleb. is one of the pathogens that causes drastic reductions in pepper production. The aim of this study therefore was to describe how infection by V. dahliae affects gas exchange during the flowering of pepper in order to determine some possible factors contributing to the significant decrease of plant yield. Verticillium was inoculated when plants had started flowering. The first leaf wilting symptoms appeared on day 18 after inoculation, but leaf water potential rapidly decreased after infection. The inoculated plants produced more flowers than the controls between 15 and 33 days after inoculation, but flower production declined after day 33. Inoculated plants also suffered more defoliation and chlorophyll degradation. Leaf conductance and photosynthesis clearly decreased in both groups of plants as a consequence of senescence, but the values in those inoculated were significantly lower. Results suggest that the decrease in photosynthesis was in part due to defoliation and chlorophyll degradation, as well as premature flower fall. These factors contributed to the negative effects of Verticillium infection on pepper yield.