Fusarium head blight (FHB), caused by Fusarium graminearum, is a devastating disease of wheat and barley that leads to reduced yield and mycotoxin contamination of grain, making it unfit for human consumption. FHB is a global problem, with outbreaks in the United States, Canada, Europe, Asia and South America. In the United States alone, total direct and secondary economic losses from 1993 to 2001 owing to FHB were estimated at $7.67 billion. Fhb1 is the most consistently reported quantitative trait locus (QTL) for FHB resistance breeding. Here we report the map-based cloning of Fhb1 from a Chinese wheat cultivar Sumai 3. By mutation analysis, gene silencing and transgenic overexpression, we show that a pore-forming toxin-like (PFT) gene at Fhb1 confers FHB resistance. PFT is predicted to encode a chimeric lectin with two agglutinin domains and an ETX/MTX2 toxin domain. Our discovery identifies a new type of durable plant resistance gene conferring quantitative disease resistance to plants against Fusarium species.

The Cucurbitaceae family (cucurbit) includes several economically important crops, such as melon, cucumber, watermelon, pumpkin, squash and gourds. During the past several years, genomic and genetic data have been rapidly accumulated for cucurbits. To store, mine, analyze, integrate and disseminate these large-scale datasets and to provide a central portal for the cucurbit research and breeding community, we have developed the Cucurbit Genomics Database (CuGenDB; http://cucurbitgenomics.org) using the Tripal toolkit. The database currently contains all available genome and expressed sequence tag (EST) sequences, genetic maps, and transcriptome profiles for cucurbit species, as well as sequence annotations, biochemical pathways and comparative genomic analysis results such as synteny blocks and homologous gene pairs between different cucurbit species. A set of analysis and visualization tools and user-friendly query interfaces have been implemented in the database to facilitate the usage of these large-scale data by the community. In particular, two new tools have been developed in the database, a ‘SyntenyViewer’ to view genome synteny between different cucurbit species and an ‘RNA-Seq’ module to analyze and visualize gene expression profiles. Both tools have been packed as Tripal extension modules that can be adopted in other genomics databases developed using the Tripal system.

BackgroundEarly stages of fruit development from initial set through exponential growth are critical determinants of size and yield, however, there has been little detailed analysis of this phase of development. In this study we combined morphological analysis with 454 pyrosequencing to study transcript level changes occurring in young cucumber fruit at five ages from anthesis through the end of exponential growth.ResultsThe fruit samples produced 1.13 million ESTs which were assembled into 27,859 contigs with a mean length of 834 base pairs and a mean of 67 reads per contig. All contigs were mapped to the cucumber genome. Principal component analysis separated the fruit ages into three groups corresponding with cell division/pre-exponential growth (0 and 4 days post pollination (dpp)), peak exponential expansion (8dpp), and late/post-exponential expansion stages of growth (12 and 16 dpp). Transcripts predominantly expressed at 0 and 4 dpp included homologs of histones, cyclins, and plastid and photosynthesis related genes. The group of genes with peak transcript levels at 8dpp included cytoskeleton, cell wall, lipid metabolism and phloem related proteins. This group was also dominated by genes with unknown function or without known homologs outside of cucurbits. A second shift in transcript profile was observed at 12-16dpp, which was characterized by abiotic and biotic stress related genes and significant enrichment for transcription factor gene homologs, including many associated with stress response and development.ConclusionsThe transcriptome data coupled with morphological analyses provide an informative picture of early fruit development. Progressive waves of transcript abundance were associated with cell division, development of photosynthetic capacity, cell expansion and fruit growth, phloem activity, protection of the fruit surface, and finally transition away from fruit growth toward a stage of enhanced stress responses. These results suggest that the interval between expansive growth and ripening includes further developmental differentiation with an emphasis on defense. The increased transcript levels of cucurbit-specific genes during the exponential growth stage may indicate unique factors contributing to rapid growth in cucurbits.

Identification and utilization of resistance to Phytophthora capsici could provide the basis for a viable management strategy against cucumber fruit rot, a persistent threat in cucumber (Cucumis sativus) production. Our objectives were to develop a method for testing detached, nonwounded, cucumber fruit for resistance to P. capsici, and to screen cucumber cultivars and plant introductions (collectively referred to as cultigens) for resistance. Four P. capsici isolates (differing in their sensitivity to the fungicide mefenoxam and compatibility type) were compared for their fruit infection capability in 1999 and 2000. No significant differences were found among isolates, and a single isolate was used for all subsequent screens. From 1999 to 2004, 480 cucumber cultigens were grown according to standard practices at Michigan State University research farms in four fields with no history of P. capsici. Commercially mature fruit were harvested, inoculated with P. capsici, and rated for lesion diameter, pathogen sporulation diameter, and density of pathogen sporulation. Although no fruit exhibited complete resistance to P. capsici, some cultigens exhibited limited pathogen sporulation. In the process of screening, it was observed that younger, smaller fruit were comparatively more susceptible than older, larger fruit. Replicated trials with hand-pollinated fruit showed that the transition from susceptible to more resistant appeared to coincide with the transition from the period of rapid fruit elongation to the period of increased fruit diameter. This is the first report using a nonwounded fruit screen to analyze cucumber resistance to P. capsici.

ABSTRACT. Type XV and type XVIII collagens are classified as part of multiplexin collagen superfamily and their C-terminal parts, endostatin and restin, respectively, have been shown to be anti-angiogenic in vivo and in vitro. The α1(XV) and α1(XVIII) collagen chains are reported to be localized mainly in the basement membrane zone, but their distributions in blood vessels and nonvascular tissues have yet to be thoroughly clarified. In the present study, we raised monoclonal antibodies against synthetic peptides of human α1(XV) and α1(XVIII) chains and used them for extensive investigation of the distribution of these chains. We came to the conclusion that nonvascular BMs contain mainly one of two types: subepithelial basement membranes that contained type XVIII in general, or skeletal and cardiac muscles that harbored mainly type XV. But basement membranes surrounding smooth muscle cells in vascular tissues contained one or both of them, depending on their locations. Interestingly, continuous capillaries contained both type XV and type XVIII collagens in their basement membranes; however, fenestrated or specialized capillaries such as glomeruli, liver sinusoids, lung alveoli, and splenic sinusoids expressed only type XVIII in their basement membranes, lacking type XV. This observation could imply that different functions of basement membranes in various tissues and organs use different mechanisms for the endogenous control of angiogenesis.Key words: basement membrane/type XV collagen/type XVIII collagen/capillary/smooth muscle cellThe collagen family, which consists of 20 collagen types and 38 collagen α-chains (Myllyharju and Kivirikko, 2001), are known to be major components of connective tissues and/or basement membranes (BMs). They not only serve as scaffolds for tissues and organs but also are involved in various biological events such as development, morphogenesis, inflammation, tissue repair, and filtration, as well as in various pathological processes (Olsen and Ninomiya, 1999).The BM, lying beneath epithelia and around muscle, adipose, and Schwann cells, and made visible by the periodic acid-Schiff reaction under light microscopic observation, is composed mainly of type IV collagen, laminin, nidogen, and heparan sulfate proteoglycan. Multiple components of these materials have been reported to comprise BMs in a tissue-specific fashion. For instance, six α(IV) collagen chains have been identified and at least three molecular forms distribute in various BMs‫ (ޓ‬Hudson et al., 1993;Sado et al., 1998). One form, α3/α4/α5, is specifically present in BMs where it functions as a permeability selective barrier such as in the BMs in glomerulus in kidney and alveolus in lung Saito et al., 2000). Such findings suggest the possibility that the composition of collagen IV molecules in various tissues corresponds with specific biological *To whom correspondence should be addressed: Ichiro Naito, Ph. D., Division of Ultrastructural Biology, Shigei Medical Research Institute, 2117 Yamada, Okayama 701-0202, Japan.Tel: +...

Fruit development proceeds from cell division to expansion, maturation, and ripening. Expansion is critical for size, yield, and quality; however, this period of development has received little attention. We used 454-pyrosequencing to develop a cucumber (Cucumis sativus) fruit transcriptome, identify highly expressed transcripts, and characterize key functions during exponential fruit growth. The resulting 187,406 expressed sequence tags (ESTs) were assembled into 13,878 contigs. Quantitative real-time polymerase chain reaction (qRT-PCR) verification of differentially expressed genes from fruit of different ages, and high correlation in transcript frequency between replicates, indicated that number of reads/contig reflects transcript abundance. Putative homologs were identified in Arabidopsis thaliana for 89% of the contigs represented by at least 10 ESTs; another 4% had homologs in other species. The remainder had homologs only in cucurbit species. The most highly expressed contigs were strongly enriched for growth (aquaporins, vacuolar ATPase, phloem proteins, tubulins, actins, cell wall-associated, and hormone-related), lipid, latex, and defense-related homologs. These results provide a resource for gene expression analysis in cucumber, profile gene expression in rapidly growing fruit, and shed insight into an important, but poorly characterized, developmental stage influencing fruit yield and quality.

Phytophthora capsici causes severe losses in vegetable production, including many cucurbit crops. Our previous work showed that cucumber (Cucumis sativus) fruit are most susceptible to P. capsici when they are very young and rapidly elongating, but develop resistance as they approach full length at 10 to 12 days postpollination (DPP). In this study, fruit from seven additional cucurbit crops representing four species, melon (Cucumis melo), butternut squash (Cucurbita moschata), watermelon (Citrullus lanatus), and zucchini, yellow summer squash, acorn squash, and pumpkin (Cucurbita pepo), were tested for the effect of fruit development on susceptibility to P. capsici. Field-grown fruit of the different crops varied in overall susceptibility. Zucchini and yellow summer squash were the most susceptible, with the majority of fruit exhibiting water-soaking symptoms within 24 hours postinoculation. Fruit from all of the crops exhibited size-related decrease in susceptibility, but to varying degrees. Cucumber had the most pronounced effect. In infested fields, cucumber fruit were found to be most frequently infected at the blossom end. Comparison of the peduncle and blossom end showed a difference in susceptibility along the length of the fruit for cucumber, butternut squash, and zucchini. Greenhouse-grown, hand-pollinated pumpkin, acorn squash, and butternut squash showed an age-related decrease in susceptibility similar to field-grown fruit. For all of these fruit, a pronounced reduction in susceptibility accompanied the transition from the waxy green to green stage at ≈3 to 8 DPP.

Very young cucumber (Cucumis sativus) fruit are highly susceptible to infection by the oomycete pathogen, Phytophthora capsici. As the fruit complete exponential growth, at approximately 10–12 days post pollination (dpp), they transition to resistance. The development of age-related resistance (ARR) is increasingly recognized as an important defense against pathogens, however, underlying mechanisms are largely unknown. Peel sections from cucumber fruit harvested at 8 dpp (susceptible) and 16 dpp (resistant) showed equivalent responses to inoculation as did whole fruit, indicating that the fruit surface plays an important role in defense against P. capsici. Exocarp from 16 dpp fruit had thicker cuticles, and methanolic extracts of peel tissue inhibited growth of P. capsici in vitro, suggesting physical or chemical components to the ARR. Transcripts specifically expressed in the peel vs. pericarp showed functional differentiation. Transcripts predominantly expressed in the peel were consistent with fruit surface associated functions including photosynthesis, cuticle production, response to the environment, and defense. Peel-specific transcripts that exhibited increased expression in 16 dpp fruit relative to 8 dpp fruit, were highly enriched (P<0.0001) for response to stress, signal transduction, and extracellular and transport functions. Specific transcripts included genes associated with potential physical barriers (i.e., cuticle), chemical defenses (flavonoid biosynthesis), oxidative stress, penetration defense, and molecular pattern (MAMP)-triggered or effector-triggered (R-gene mediated) pathways. The developmentally regulated changes in gene expression between peels from susceptible- and resistant- age fruits suggest programming for increased defense as the organ reaches full size.