Origin of the cultivated passion fruit Passiflora edulis f. flavicarpa and genomic relationships among species of the subgenera Decaloba and Passiflora

• Passiflora edulis f. flavicarpa is the most economically important species in the genus Passiflora. However, the origin of this yellow form of passion fruit remains unclear, being suggested as a hybrid (P. edulis f. edulis × P. ligularis) or wild mutant.
• Here, the origin and genomic relationships of P. edulis f. flavicarpa with some related species in the genus Passiflora (subgenera Decaloba and Passiflora) were investigated using genomic in situ hybridization (GISH). Genomic DNA of 18 species was used as probe, which was hybridized onto chromosomes of P. edulis f. flavicarpa.
• Of all genomic DNA probes tested, none allowed us to identify a specific chromosome set in P. edulis f. flavicarpa. Conversely, probes from the subgenus Passiflora, P. edulis f. edulis, P. alata, P. cincinnata, P. coccinea, P. nitida and P. vitifolia, produced intense and uniform hybridizations on all chromosomes of P. edulis f. flavicarpa. Moreover, probes from P. ligularis, P. foetida and P. sublanceolata produced more intense hybridizations in the terminal region of four chromosomes, corresponding to the DNAr 45S locus, and also dispersed, less intense, hybridization across all chromosomes. Probes from the subgenus Decaloba, P. biflora, P. capsularis, P. cervii, P. coriacea, P. micropetala, P. morifolia, P. rubra and P. suberosa, produced hybridizations restricted to the DNAr 45S sites.
• The hybrid origin of P. edulis f. flavicarpa could not be supported based on the GISH results, and it is suggested that this species is conspecific with P. edulis f. edulis, because the probe with DNA of this form hybridized strongly throughout the target genome. The other putative parent species, P. ligularis, showed only a distant relationship with the target genome. The results also suggest that species of the subgenus Passiflora share many repetitive sequences and that the relationship between subgenera Decaloba and Passiflora is very distant.

     

Development and characterization of microsatellite markers from the yellow passion fruit (Passiflora edulis f. flavicarpa)

Here we described the development of the first set of Passiflora microsatellite loci isolated from an enriched genomic library. A sample of 43 individuals from 12 accessions of the yellow passion fruit was used to characterize those loci, which revealed up to 20 alleles per locus. Two loci were monomorphic. The observed (H_O) and expected (H_E) heterozygosities were very similar, as expected for a self‐incompatible species. Allelic diversity (H_T) was 0.444. This set of markers will permit genetic structure analyses of cultivated and wild populations of Passiflora, and contribute for integrating genetic maps based on dominant markers, as they can provide bridge alleles.     

Identification of intermediates involved in the biosynthetic pathway of 3-mercaptohexan-1-ol conjugates in yellow passion fruit (Passiflora edulis f. flavicarpa)

Yellow passion fruit is one of the most well-known tropical fruits and much of its success comes from its typical aroma. Key compounds in explaining yellow passion fruit scent are volatile thiols. These molecules are reported to be present in several fruits and originate from non-volatile precursors. Such free thiols are particularly appreciated in white wines and considerable efforts have been made to try to maximise their production and understand their biosynthesis.Two main precursors have been identified so far: S-glutathionylated and S-cysteinylated precursors, the latter originating in the breaking down of the glycyl and glutamyl moieties of the former. Improving knowledge about this pathway is currently one of the main challenges in the field of aroma chemistry.Only S-cysteinylated precursors have been reported in the literature for yellow passion fruit, thus much of the biochemical pathway remains unknown.In this paper a combination of organic synthesis, MS and NMR experiments was developed in order to investigate this pathway in yellow passion fruit. The three missing stages leading to the S-cysteinylated precursor were clearly identified. Both intermediate species between S-glutathionyl and S-cysteinyl 3-mercaptohexan-1-ol were found, suggesting that the plant is capable of activating both metabolic routes.The information gained would appear to be crucial for study of this important pathway and for potentially extending this knowledge to other plants, in particular the grapevine.     

Flower development and vasculature in Xyris grandis (Xyridaceae,Poales); a case study for examining petal diversity in monocot flowers with a double perianth

Floral morphology, anatomy and development are examined in Xyris grandis (Xyridaceae: Poales), with an emphasis on petal and sepal organogenesis and vasculature. Xyris is one of relatively few monocots in which the perianth is differentiated into two distinct whorls (here termed a double perianth). Xyris also possesses highly unusual perianth vasculature, with each petal being supplied by three veins and each sepal by a single vein, compared with the opposite condition in most other angiosperms with a double perianth. However, perianth development in X. grandis shows a pattern that is typical for monocots, with petals not markedly delayed in development. Xyris grandis is also remarkable for its petal aestivation, with each petal surrounding a stamen and two branches of adjacent staminodes, a type that is not reported for other Xyridaceae and may contribute to secondary pollen presentation. The results are discussed in the context of the diversity of a double perianth in monocots, compared with eudicots. Based on current data, our preferred hypothesis is that meristic differences are at least partly responsible for the apparently widespread occurrence of three‐traced petals in monocots. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170 , 93–111.     

Genetic variation in a wild population of the 'sleep' passion fruit (Passiflora setacea) based on molecular markers

Little is known about the molecular genetic diversity of most Passiflora species. We used RAPD markers to evaluate the genetic diversity of 24 genotypes of the 'sleep' passion fruit (Passiflora setacea). Twelve primers generated 95 markers, 88% of which were polymorphic. The genetic distance estimated by the complement of the Dice index ranged from 0.29 (among accessions Ps-G1 and Ps-G13) to 0.69 (among accessions Ps-G21 and Ps-G23). Genotype grouping based on the UPGMA algorithm showed considerable variability among genotypes. We conclude that P. setacea has a broad genetic base that could be exploited in breeding programs.     

Flower and fruit volatiles assist host‐plant location in the Tomato fruit fly Neoceratitis cyanescens

Mature females of the tomato fruit fly Neoceratitis cyanescens can detect host fruit at a short distance using only visual stimuli, but little is known about the role of airborne volatile cues in the host searching strategy. A series of experiments is conducted in a laboratory wind tunnel, in which the behavioural responses of individual flies to volatiles from Solanaceae host plants (including tomato Lycopersicum esculentum Mill., bug weed Solanum mauritianum Scop. and Turkey berry Solanum torvum Sw.) are observed, according to some environmental (air speed) and physiological (age and mating status of females, time of day) factors. Mature females respond primarily to specific olfactory cues from blends of flowers or host fruit, preferentially unripe fruit for bug weed, as opposed to ripe fruit for Turkey berry or tomato. Males are also highly attracted by the odour of unripe fruit of bug weed. Wind plays a key role, as shown by the proportion of flies that reach the upwind section of the tunnel in the presence of both fruit odour and air flow (66.7%) and in the absence of either fruit odour (13.3%) or wind (36.7%). In response to fruit volatiles carried by wind, flies embark in a ‘plume tracking’ or ‘aim and shoot' flight, consistent with odour‐conditioned anemotaxis. Females respond to host fruit odour regardless of their age, egg load or mating status, and also more consistently in the afternoon, which is their preferential time of day for egg‐laying. Searching behaviour and response to host volatiles in N. cyanescens are discussed in the light of host‐finding and an adaptive strategy.     

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.     

Advances in the treatment of acute graft‐versus‐host disease

Allogeneic hematopoietic stem cell transplantation (HSCT) has been widely used for the treatment of hematologic malignant and non‐malignant hematologic diseases and other diseases. However, acute graft‐versus‐host disease (GVHD) is a life‐threatening complication of allogeneic transplantation. Acute GVHD may occur in 30% of transplant recipients, which is a syndrome of erythematous skin eruption, cholestatic liver disease and intestinal dysfunction, resulting from the activation of donor T lymphocytes by host antigen‐presenting cells, resulting in an immune‐mediated inflammatory response. Recent scientific advances in the understanding of the pathogenesis involved in the development of acute GVHD and clinical investigation have provided more effective therapeutic strategies for acute GVHD. This review focuses on major scientific and clinical advances in the treatment of acute GVHD.     

Roots drive oligogalacturonide‐induced systemic immunity in tomato

Oligogalacturonides (OGs) are fragments of pectin released from the plant cell wall during insect or pathogen attack. They can be perceived by the plant as damage signals, triggering local and systemic defence responses. Here, we analyse the dynamics of local and systemic responses to OG perception in tomato roots or shoots, exploring their impact across the plant and their relevance in pathogen resistance. Targeted and untargeted metabolomics and gene expression analysis in plants treated with purified OGs revealed that local responses were transient, while distal responses were stronger and more sustained. Remarkably, changes were more conspicuous in roots, even upon foliar application of the OGs. The treatments differentially activated the synthesis of defence‐related hormones and secondary metabolites including flavonoids, alkaloids and lignans, some of them exclusively synthetized in roots. Finally, the biological relevance of the systemic defence responses activated upon OG perception was confirmed, as the treatment induced systemic resistance to Botrytis cinerea. Overall, this study shows the differential regulation of tomato defences upon OGs perception in roots and shoots and reveals the key role of roots in the coordination of the plant responses to damage sensing.     

Ethylene production in Botrytis cinerea‐ and oligogalacturonide‐induced immunity requires calcium‐dependent protein kinases

Plant immunity against pathogens is achieved through rapid activation of defense responses that occur upon sensing of microbe‐ or damage‐associated molecular patterns, respectively referred to as MAMPs and DAMPs. Oligogalacturonides (OGs), linear fragments derived from homogalacturonan hydrolysis by pathogen‐secreted cell wall‐degrading enzymes, and flg22, a 22‐amino acid peptide derived from the bacterial flagellin, represent prototypical DAMPs and MAMPs, respectively. Both types of molecules induce protection against infections. In plants, like in animals, calcium is a second messenger that mediates responses to biotic stresses by activating calcium‐binding proteins. Here we show that simultaneous loss of calcium‐dependent protein kinases CPK5, CPK6 and CPK11 affects Arabidopsis thaliana basal as well as elicitor‐ induced resistance to the necrotroph Botrytis cinerea, by affecting pathogen‐induced ethylene production and accumulation of the ethylene biosynthetic enzymes 1‐aminocyclopropane‐1‐carboxylic acid (ACC) synthase 2 (ACS2) and 6 (ACS6). Moreover, ethylene signaling contributes to OG‐triggered immunity activation, and lack of CPK5, CPK6 and CPK11 affects the duration of OG‐ and flg22‐induced gene expression, indicating that these kinases are shared elements of both DAMP and MAMP signaling pathways.     

Differences in photoperiod‐induced diapause plasticity among different populations of the bark beetle Ips typographus and its predator Thanasimus formicarius

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High responsiveness in <Emphasis Type="Italic">de novo</Emphasis> shoot organogenesis induction of <Emphasis Type="Italic">Passiflora cristalina</Emphasis> (Passifloraceae), a wild Amazonian passion fruit species

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