Assessment of Gene Flow from Genetically Modified Anthracnose-Resistant Chili Pepper (Capsicum annuum L.) to a Conventional Crop

We conducted a 2-year field assessment of the gene flow from genetically modified (GM) chili pepper (Capsicum annuum L.), containing the PepEST (pepper esterase) gene, to a non-GM control line “WT512” and two commercial hybrid cultivars, “Manidda” and “Cheongpung Myeongwol (CM).” After seeds were collected from the pollen-recipient non-GM plants, hybrids between them and the GM peppers were screened by a hygromycin assay. PCR with the targeting hpt gene was performed to confirm the presence of transgenes in hygromycin-resistant seedlings. Out of 7,071 “WT512” seeds and 6,854 “Manidda” seeds collected in 2006, eight and 12 hybrids, respectively, were detected. In 2007, 33 hybrids from 3,456 “WT512” seeds and 50 hybrids from 3,457 “CM” seeds were found. The highest frequency of gene flow, 6.19%, was observed in that 2007 trial. These results suggest that a limited isolation distance would be sufficient to prevent gene flow from GM to conventionally bred chili peppers.     

Destructive and non-destructive microanalysis of biocarbonates applied to anomalous otoliths of archaeological and modern sciaenids (Teleostei) from Peru and Chile

Anomalous otoliths were discovered among modern and archaeological (8th millennium BP) sciaenids. The two species concerned, Cilus gilberti and Sciaena deliciosa, are common on the Peruvian-Chilean coast and do not seem to be affected by this morphological anomaly that maintained in their populations for thousands of years. The carbonates of the anomalous forms, determined by X-ray diffraction, are different from that of the normal otoliths, i.e. calcite and vaterite instead of aragonite. A method of non-destructive analysis by cathodoluminescence is tested and assumptions on the origin of the anomaly and its possible implications on environmental studies are advanced.     

A field test of the directed deterrence hypothesis in two species of wild chili

The directed deterrence hypothesis posits that secondary metabolites in ripe fruit function to deter fruit consumption by vertebrates that do not disperse seeds, while not impacting consumption by those that do. We tested this hypothesis in two species of wild chilies (Capsicum spp.). Both produce fruits that contain capsaicinoids, the compounds responsible for the pungency of chilies. Previous work suggests seed-dispersing birds but not seed-destroying rodents consume chili fruits, presumably because rodents are deterred by capsaicin. However, fruit removal from chili plants by rodents and other mammals has not been previously explored. Because laboratory rodents can develop a preference for capsaicin, it is quite possible that wild rodents are natural consumers of chili fruits. We monitored the fate of 125 marked fruits of Capsicum chacoense and 291 fruits of Capsicum annuum. For both species, essentially all fruit removal occurred during the day, when rodents are inactive. Video monitoring revealed fruit removal only by birds, mostly by species known to disperse chili seeds in viable condition. Furthermore, these species are from taxonomic groups that tend to specialize on lipid-rich fruits. Both species of chili produce fruits that are unusually high in lipids (35% in C. chacoense, 24% in C. annuum). These results support the directed deterrence hypothesis and suggest that fruiting plants distinguish between seed predators and seed dispersers by producing fruits that repel the former and attract the latter.     

Virus-induced silencing of <Emphasis Type="Italic">Comt</Emphasis>, p<Emphasis Type="Italic">Amt</Emphasis> and <Emphasis Type="Italic">Kas</Emphasis> genes results in a reduction of capsaicinoid accumulation in chili pepper fruits

Capsaicinoids are responsible for the pungent taste of chili pepper fruits of Capsicum species. Capsaicinoids are biosynthesized through both the phenylpropanoid and the branched-fatty acids pathways. Fragments of Comt (encoding a caffeic acid O-methyltransferase), pAmt (a putative aminotransferase), and Kas (a β-keto-acyl-[acyl-carrier-protein] synthase) genes, that are differentially expressed in placenta tissue of pungent chili pepper, were individually inserted into a Pepper huasteco yellow veins virus (PHYVV)-derived vector to determine, by virus-induced gene silencing, irrespective of whether these genes are involved in the biosynthesis of capsaicinoids. Reduction of the respective mRNA levels as well as the presence of related siRNAs confirmed the silencing of these three genes. Morphological alterations were evident in plants inoculated with PHYVV::Comt and PHYVV::Kas constructs; however, plants inoculated with PHYVV::pAmt showed no evident alterations. On the other hand, fruit setting was normal in all cases. Biochemical analysis of placenta tissues showed that, indeed, independent silencing of all three genes led to a dramatic reduction in capsaicinoid content in the fruits demonstrating the participation of these genes in capsaicinoid biosynthesis. Using this approach it was possible to generate non-pungent chili peppers at high efficiency.     

Diversity and efficiency of arbuscular mycorrhizal fungi in soils from organic chili (Capsicum frutescens) farms

No previous studies have been conducted on the diversity and population of arbuscular mycorrhizal fungi (AMF) in relation to organically grown chili (Capsicum frutescens L.) in Thailand. This study was carried out to investigate the diversity and status of AMF populations at four organically managed farms in Ubon Ratchathani and Sisaket provinces. The effects of each AMF species on the growth and nutrient uptake of chili grown in sterile, organically managed soil were determined. Fourteen AM fungal taxa belonging to the genera Acaulospora (4 spp.), Entrophospora (1 sp.), Glomus (7 spp.) and Scutellospora (2 spp.) were found. Among these, Glomus was the dominant genus found at all sites, followed by Acaulospora. The spore density and root colonization of AMF on chili did not vary significantly among the sites. The effects of ten selected AMF species on the growth of chili showed that Gl. clarum RA0305 increased the growth, flowering, and fruit production of chili, and also increased the P uptake significantly, compared to non-mycorrhizal plants. This fungus showed the highest potential as a promoter of growth, flowering and yield in organically managed chili production.     

Starving Aphelinus asychis negatively affects host feeding and parasitism on Myzus persicae

Aphelinus asychis (Walker) is an effective biological control agent for many species of aphids found on various crops. To provide strategies for releasing these parasitoids into a crop ecosystem, the effects of a short-duration starvation experiment on A. asychis were measured under laboratory conditions using Myzus persicae (Sulzer) as the host on cabbage and chili pepper plants. The survival rate of starved A. asychis female adults decreased sharply as the starving time increased, and the longevity of the starved parasitoids also decreased significantly. The number of aphids killed by the parasitoids decreased gradually with the extended duration of starvation. In addition, the number of aphids on chili peppers and cabbages killed by starved A. asychis females over their lifespan was significantly lower than that in the control group. Our results indicated that a short period of starvation might not cause significantly negative effects on the parasitoids and may be beneficial for the control of M. persicae at low densities after 1?day; however, starvation for >1?day seriously affected the performance of A. asychis females over their entire lifespan. The parasitoids performed similarly when aphids were fed chili pepper or cabbage plants.     

The use of seed protein electrophoresis in the study of phylogenetic relationships in Chili pepper (Capsicum L.)

Summary The seed protein profile of eight taxa of Chili peppers obtained by disc electrophoresis was found to be a diagnostic character in the study of phylogenetic relationships. The distinctness of each species and the wild and cultivated nature of concerned taxa has been confirmed. While the clustering of wildC. annuum var. glabriusculum withC. baccatum types indicated that the former is the progenitor of the latter group, the marked differences discernible in the seed protein profile of all other taxa suggest a polyphyletic origin for the genusCapsicum.     

A CAPS marker associated with the partial restoration of cytoplasmic male sterility in chili pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.)

Cytoplasmic male sterility (CMS), an economically important trait for hybrid seed production in many crops, is a maternally inherited trait in which a plant fails to produce functional anthers, pollen grains, or male gametes. It has long been reported that the restoration of CMS in chili pepper is controlled by a major nuclear gene termed restorer-of-fertility (Rf), along with several modifiers and some environmental factors. In this study, we identified the partial restoration (pr) locus related to the fertility restoration of CMS, demonstrated the inheritance of the trait, and developed a CAPS marker closely linked to the locus. The partially restored plant had normal anthers that produced a mix of normal and aborted pollen grains that stuck tightly to the anther wall, even after dehiscence. This trait was expressed only when the pepper plant had the sterile (S) cytoplasm and homozygous recessive pr alleles. A total of 768 AFLP primer combinations were screened, and bulked segregant analysis (BSA) was performed by preparing two pools of eight Pr/Pr (fully fertile) and eight pr/pr (partially fertile) plants, respectively, selected from the 87 individuals of the F₂ segregating population. Of the eight Pr-linked AFLP markers that were identified, E-AGC/M-GCA₁₂₂ and E-TCT/M-CCG₁₁₆ were the closest to the locus, estimated at about 1.8 cM in genetic distance. E-AGC/M-GCA₁₂₂ was converted into a CAPS marker, PR-CAPS, based on the sequences of the internal and flanking regions of the AFLP fragment. This PR-CAPS marker could be useful in selecting fully fertile lines (Pr/Pr) and eliminating partially fertile (pr/pr) and potential (Pr/pr) lines in segregant populations during the development of new inbred restorer lines.