Highbush blueberry (Vaccinium corymbosum) fruits contain substantial quantities of flavonoids, which are implicated in a wide range of health benefits. Although the flavonoid constituents of ripe blueberries are known, the molecular genetics underlying their biosynthesis, localization, and changes that occur during development have not been investigated. Two expressed sequence tag libraries from ripening blueberry fruit were constructed as a resource for gene identification and quantitative realtime reverse transcription-polymerase chain reaction primer design. Gene expression profiling by quantitative real-time reverse transcription-polymerase chain reaction showed that flavonoid biosynthetic transcript abundance followed a tightly regulated biphasic pattern, and transcript profiles were consistent with the abundance of the three major classes of flavonoids. Proanthocyanidins (PAs) and corresponding biosynthetic transcripts encoding anthocyanidin reductase and leucoanthocyanidin reductase were most concentrated in young fruit and localized predominantly to the inner fruit tissue containing the seeds and placentae. Mean PA polymer length was seven to 8.5 subunits, linked predominantly via B-type linkages, and was relatively constant throughout development. Flavonol accumulation and localization patterns were similar to those of the PAs, and the B-ring hydroxylation pattern of both was correlated with flavonoid-3#-hydroxylase transcript abundance. By contrast, anthocyanins accumulated late in maturation, which coincided with a peak in flavonoid-3-O-glycosyltransferase and flavonoid-3#5#-hydroxylase transcripts. Transcripts of VcMYBPA1, which likely encodes an R2R3-MYB transcriptional regulator of PA synthesis, were prominent in both phases of development. Furthermore, the initiation of ripening was accompanied by a substantial rise in abscisic acid, a growth regulator that may be an important component of the ripening process and contribute to the regulation of blueberry flavonoid biosynthesis.Highbush blueberry (Vaccinium corymbosum; Ericaceae) is one of the most economically important fruit crops in North America. Blueberry fruit have been the focus of much recent attention due to numerous reports of their positive effects on human health. These benefits are generally attributed to high levels of polyphenolics, in particular the flavonoids (Rasmussen et al., 2005). Highbush blueberries have one of the highest in vitro antioxidant capacities of any fruit or vegetable (Prior and Gu, 2005;Wu et al., 2006). The major health benefits linked to the consumption of blueberries include a reduced risk for cardiovascular (Basu et al., 2010) and neurodegenerative (Neto, 2007) diseases. Furthermore, experiments on rodents suggest that blueberry extracts may also prevent cancer, slow tumor growth, and reverse cognitive and behavioral deficits related to stroke and aging (Lau et al., 2005;Gordillo et al., 2009).The three common types of flavonoids that accumulate in blueberry fruit are the flavonols, anthocya-

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Bud formation is an adaptive trait that temperate forest trees have acquired to facilitate seasonal synchronization. We have characterized transcriptome-level changes that occur during bud formation of white spruce [Picea glauca (Moench) Voss], a primarily determinate species in which preformed stem units contained within the apical bud constitute most of next season's growth. Microarray analysis identified 4460 differentially expressed sequences in shoot tips during short day-induced bud formation. Cluster analysis revealed distinct temporal patterns of expression, and functional classification of genes in these clusters implied molecular processes that coincide with anatomical changes occurring in the developing bud. Comparing expression profiles in developing buds under long day and short day conditions identified possible photoperiod-responsive genes that may not be essential for bud development. Several genes putatively associated with hormone signalling were identified, and hormone quantification revealed distinct profiles for abscisic acid (ABA), cytokinins, auxin and their metabolites that can be related to morphological changes to the bud. Comparison of gene expression profiles during bud formation in different tissues revealed 108 genes that are differentially expressed only in developing buds and show greater transcript abundance in developing buds than other tissues. These findings provide a temporal roadmap of bud formation in white spruce.

Fusarium head blight (FHB or scab) caused by Fusarium spp. is a destructive disease of wheat. Since the most effective sources of FHB resistance are typically associated with unfavorable agronomic traits, breeding commercial cultivars that combine desired agronomic traits and a high level of FHB resistance remains a considerable challenge. A better understanding of the molecular mechanisms governing FHB resistance will help to design more efficient and precise breeding strategies. Here, multiple molecular tools and assays were deployed to compare the resistant variety Sumai3 with three regionally adapted Canadian cultivars. Macroscopic and microscopic disease evaluation established the relative level of Type II FHB resistance of the four varieties and revealed that the F. graminearum infection process displayed substantial temporal differences among organs. The rachis was found to play a critical role in preventing F. graminearum spread within spikes. Large-scale, organ-specific RNA-seq at different times after F. graminearum infection demonstrated that diverse defense mechanisms were expressed faster and more intensely in the spikelet of resistant varieties. The roles of plant hormones during the interaction of wheat with F. graminearum was inferred based on the transcriptomic data obtained and the quantification of the major plant hormones. Salicylic acid and jasmonic acid were found to play predominantly positive roles in FHB resistance, whereas auxin and ABA were associated with susceptibility, and ethylene appeared to play a dual role during the interaction with F graminearum.

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We tested the hypotheses that responses to the mountain pine beetle fungal associate Grosmannia clavigera will differ between the evolutionarily co-evolved host lodgepole pine (Pinus contorta var. latifolia) and the naïve host jack pine (Pinus banksiana) and that these responses will be influenced by water availability. G. clavigera inoculation resulted in more rapid stem lesion development in lodgepole than in jack pine; water deficit delayed lesion development in both species. Decreased hydraulic conductivity was observed in inoculated lodgepole pine seedlings, likely because of tracheid occlusion by fungal hyphae and/or metabolite accumulation. Drought but not inoculation significantly impacted bark abscisic acid levels. Jasmonic and salicylic acid were implicated in local and systemic responses of both species to G. clavigera, with salicylic acid appearing to play a greater role in jack pine response to G. clavigera than lodgepole pine. Water deficit increased constitutive levels and/or attenuated induced responses to G. clavigera for several monoterpenes in lodgepole but not jack pine. Instead, inoculation of well-watered but not water deficit jack pine resulted in a greater number of xylem resin ducts. These findings reveal mechanisms underlying differences in G. clavigera-induced responses between lodgepole and jack pine hosts, and how water availability modulates these responses.

The plant hormone abscisic acid (ABA) induces a developmental switch in the aquatic fern Marsilea quadrifolia, causing the formation of aerial type characteristics, including the elongation of petioles and roots, a change in leaf morphology, the expansion of leaf surface area, and the shortening of the internodes. A number of ABA-responsive heterophylly (ABRH) genes are induced early during the transition. Using optically pure isomers of ABA, it was found that both the natural S-(+)-ABA and the unnatural R-(-)-ABA are capable of inducing a heterophyllous switch and regulating ABRH gene expression. When dose responses are compared, the unnatural ABA gives stronger morphogenic effects than the natural ABA at the same concentration, it is effective at lower concentrations, and its optimal concentration is also lower compared with the natural ABA. Deuterium-labelled ABA enantiomers were used to trace the fate of applied ABA and to distinguish the applied compound and its metabolites from the endogenous counterparts. In tissues, the supplied (+)-ABA was metabolized principally to dihydrophaseic acid, while the supplied (-)-ABA was converted at a slower rate to 7'-hydroxy abscisic acid. Treatment with either enantiomer resulted in increased biosynthesis of ABA, as reflected in the accumulation of endogenous dihydrophaseic acid. Taken together, these results suggest two distinct mechanisms of action for (-)-ABA: either (-)-ABA is intrinsically active, or its activity is due to the stimulation of ABA biosynthesis.