Biomedical subjects

Yasmin J Cardoza

Publications and source records attributed to Yasmin J Cardoza.

5 recordsLinked to original sources

PubMed2006

Compatible and incompatible Xanthomonas infections differentially affect herbivore-induced volatile emission by pepper plants.

Recent studies have alerted us to the potential for conflicts between pathogen- and herbivore-induced plant defenses. The lack of studies on the induced chemical changes that simultaneous insect and pathogen attacks have on the host plant has become apparent. In the present study, we found that pepper plant volatile profiles can be differentially induced by compatible and incompatible bacterial infection and beet armyworm (BAW) damage when applied alone or in combination upon the same host. We also found that plants under simultaneous compatible bacterial and BAW attack are able to produce volatiles in quantities greater than those produced by healthy plants in response to BAW feeding. In contrast, plants exposed to the incompatible pathogen challenge showed a total volatile release below the level of healthy plants exposed to BAW damage. This suppression of BAW-induced volatiles coincided with increased methyl salicylate production from incompatible bacteria-infected plants. Feeding choice experiments revealed that, when given a choice, BAW larvae fed significantly more on leaves of plants infected with the incompatible bacteria as soon as 2 d after inoculation, while a significant increase in insect feeding on the plants infected with the compatible bacterial strain was not seen until day 4 after inoculation. Additionally, survival for third instars to pupation was significantly higher when feeding on infected plants than on healthy plants, regardless of compatibility. These results are indicative of lowered herbivore defenses due to disease progression on the plants.

Animals↗

PubMed2006

Phloem alkaloid tolerance allows feeding on resistant Lupinus angustifolius by the aphid Myzus persicae.

We examined the hypothesis that the polyphagous green peach aphid (Myzus persicae) shows clone-specific adaptation to the narrow-leafed lupin (Lupinus angustifolius) containing toxic quinolizidine alkaloids. We compared the performance of a lupin-feeding clone of M. persicae from Western Australia to that of nine clones of the same species collected from eastern Australian locations, where narrow-leafed lupins rarely occur. Mean relative growth rate (MRGR) and colonization ability varied among the M. persicae clones on one aphid-susceptible and two aphid-resistant lupin varieties. The performance of the lupin-feeding clone was better than that of all other clones on the resistant narrow-leafed lupin varieties "Tanjil" and "Kalya", indicating that successful lupin feeding is not a characteristic of the species. Gas chromatography-mass spectrometry analyses (GC-MS) of phloem from the different lupin varieties detected differences in the quantities of two alkaloid compounds identified as 13-OH-lupanine and lupanine. The lupin-feeding M. persicae clone also showed better performance on artificial diet amended with lupanine. The results suggest that the M. persicae clone collected from Western Australia is adapted to feed successfully on narrow-leafed lupin, and that this adaptation may involve improved tolerance of lupanine in its diet.

Adaptation, Physiological↗

PubMed2003

Differential volatile emissions and salicylic acid levels from tobacco plants in response to different strains of Pseudomonas syringae.

Pathogen-induced plant responses include changes in both volatile and non-volatile secondary metabolites. To characterize the role of bacterial pathogenesis in plant volatile emissions, tobacco plants, Nicotiana tabacum L. K326, were inoculated with virulent, avirulent, and mutant strains of Pseudomonas syringae. Volatile compounds released by pathogen-inoculated tobacco plants were collected, identified, and quantified. Tobacco plants infected with the avirulent strains P. syringae pv. maculicola ES4326 (Psm ES4326) or pv. tomato DC3000 (Pst DC3000), emitted quantitatively different, but qualitatively similar volatile blends of (E)-beta-ocimene, linalool, methyl salicylate (MeSA), indole, caryophyllene, beta-elemene, alpha-farnesene, and two unidentified sesquiterpenes. Plants treated with the hrcC mutant of Pst DC3000 (hrcC, deficient in the type-III secretion system) released low levels of many of the same volatile compounds as in Psm ES4326- or Pst DC3000-infected plants, with the exception of MeSA, which occurred only in trace amounts. Interaction of the virulent pathogen P. syringae pv. tabaci (Pstb), with tobacco plants resulted in a different volatile blend, consisting of MeSA and two unidentified sesquiterpenes. Overall, maximum volatile emissions occurred within 36 h post-inoculation in all the treatments except for the Pstb infection that produced peak volatile emissions about 60 h post-inoculation. (E)-beta-Ocimene was released in a diurnal pattern with the greatest emissions during the day and reduced emissions at night. Both avirulent strains, Psm ES4326 and Pst DC3000, induced accumulation of free salicylic acid (SA) within 6 h after inoculation and conjugated SA within 60 h and 36 h respectively. In contrast, SA inductions by the virulent strain Pstb occurred much later and conjugated SA increased slowly for a longer period of time, while the hrcC mutant strain did not trigger free and conjugated SA accumulations in amounts significantly different from control plants. Jasmonic acid, known to induce plant volatile emissions, was not produced in significantly higher levels in inoculated plants compared to the control plants in any treatments, indicating that induced volatile emissions from tobacco plants in response to P. syringae are not linked to changes in jasmonic acid.

Cyclopentanes↗

PubMed2003

Simultaneous quantification of jasmonic acid and salicylic acid in plants by vapor-phase extraction and gas chromatography-chemical ionization-mass spectrometry.

Jasmonic acid and salicylic acid represent important signaling compounds in plant defensive responses against other organisms. Here, we present a new method for the easy, sensitive, and reproducible quantification of both compounds by vapor-phase extraction and gas chromatography-positive ion chemical ionization-mass spectrometry. The method is based on a one-step extraction, phase partitioning, methylation with HCl/methanol, and collection of methylated and, thus, volatilized compounds on Super Q filters, thereby omitting further purification steps. Eluted samples are analyzed and quantified by GC/MS with chemical ionization. Standard curves were linear over a range of 5-1000 ng for jasmonic acid and salicylic acid. The correlation coefficients were greater than 0.999 and the recovery rates estimated between 70 and 90% for salicylic acid and 90 and 100% for jasmonic acid. The limit of detection was about 500 fg by using single ion detection mode. Both, cis- and trans-isomers for jasmonic acid can be detected. A comparison with established methods indicates the new method to be highly efficient, allowing reliable quantification of both compounds from small amounts of plant material (5-400mg fresh weight).

Alamethicin↗

PubMed2002

In vivo volatile emissions from peanut plants induced by simultaneous fungal infection and insect damage.

Peanut plants, Arachis hypogaea, infected with white mold. Sclerotium rolfsii, emit a blend of organic compounds that differs both quantitatively and qualitatively from the blend emitted from plants damaged by beet armyworm (BAW; Spodoptera exigua) larvae or from uninfected, undamaged plants. Attackby BAW induced release of lipoxygenase products (hexenols, hexenals, and hexenyl esters), terpenoids, and indole. The plant-derived compound methyl salicylate and the fungal-derived compound 3-octanone were found only in headspace samples from white mold infected plants. White mold-infected plants exposed to BAW damage released all the volatiles emitted by healthy plants fed on by BAW in addition to those emitted in response to white mold infection alone. When BAW larvae were given a choice of feeding on leaves from healthy or white mold-infected plants, they consumed larger quantities of the leaves from infected plants. Exposure to commercially available (Z)-3 hexenyl acetate, linalool, and methyl salicylate, compounds emitted by white mold-infected plants, significantly reduced the growth of the white mold in solid-media cultures. Thus, emission of these compounds by infected plants may constitute a direct defense against this pathogen.

Animals↗