Diane Beckles

A typical symptom of postharvest chilling injury (PCI) in pineapple fruit (Ananas comosus (L.) Merr.) is internal browning (IB) near the fruit core. Since vascular bundles (VBs) are localized to this region, it was hypothesized that the VBs might be the site of IB. To test this, the anatomy and histochemistry of VBs during chilling stress in four pineapple cultivars with different levels of sensitivity to PCI were examined. Fruit were stored at 10°C for up to three weeks to stimulate translucency symptoms (TS; the initiation of IB). After three weeks of chilling exposure, the cultivars 'MD2' showed 0%, 'Pattavia' and 'Savee' showed 10-16%, and 'Trad Sri Thong' showed 100% TS and IB symptom. Scanning electron microscopy and in situ histochemical staining techniques that detect enzymes and substrates commonly associated with IB initiation were used in parallel. The TS of pineapple fruit coincided with the collapse of the phloem tissue. The VBs in the tissue where IB was initiated (i.e., the flesh adjacent to the core or F/C) had the highest activity of polyphenol oxidase, hydrogen peroxide, and phenolic compounds. The IB-resistant 'MD2' genotype had fewer VBs, but a greater proportion of sclerenchyma fibers (P<0.05) than did the susceptible 'Trad Sri Thong'. Based on these data, the first report of pineapple IB occurrence in the phloem was proposed.

This invention relates to an isolated nucleic acid fragment encoding a starch synthase DUI homolog. The invention also relates to the construction of a chimeric gene encoding all or a portion of the starch synthase DUI homolog, in sense or antisense orientation, Wherein expression of the chimeric gene results in production of altered levels of the starch synthase DUI homolog in a transformed host cell.

In this chapter we will outline what is known about the general organization of metabolite networks and use it to illustrate broad concepts of metabolic control and regulation, information necessary for metabolite engineering. We will then survey the analytical and data-mining tools available as this will allow us to ascertain what can be measured and how biological information can be extracted from these measurements. We will then outline how metabolomics is being used to support biotechnology. There has literally been an explosion in the number, scope, and depth of applications of metabolomics in recent years and we will not be able to comprehensively address them all. Finally, we will look at the challenges ahead and the key issues that must be addressed if the full potential of this discipline is to be realized for improving agriculture.

This invention relates to an isolated nucleic acid fragment encoding a starch branching enZyme. The invention also relates to the construction of a chimeric gene encoding all or a portion of the starch branching enZyme, in sense or antisense orientation, Wherein expression of the chimeric gene results in production of altered levels of the starch branching enZyme in a transformed host cell.

The aim of this work was to examine agronomic, compositional, and functional changes in rice (Oryza sativa L. cv. Nipponbare) grains from plants grown under low-to-moderate salinity stress. Plants were grown in sodium chloride-containing soil (2 or 4 dS/m2 electrical conductivity), which was imposed 4-weeks after transplant (called Seedling EC2 and EC4) or after the appearance of the anthers (called Anthesis EC2 and EC4). The former simulates field conditions while the latter permits observation of the isolated effect of salt on grain filling processes. Key findings of this study are that: (i) Plants showed adaptive responses to prolonged salt treatment with no negative effects on grain weight or fertility. Seedling EC2 plants had more panicles and enhanced caryopsis dimensions, while surprisingly, Anthesis EC4 plants did not differ from the control group in the agronomic parameters measured. (ii) Grain starch increased in Seedling EC4 (32.6%) and Anthesis EC2 (39%) respectively, suggesting a stimulatory effect of salt on starch accumulation. (iii) The salinity treatment of 2 dS/m2 was better tolerated at anthesis than the 4 dS/m2 treatment as the latter led to reduced grain weight (28.8%) and seed fertility (19.4%) and compensatory increases in protein (20.1%) and Nitrogen contents (19.8%). (iv) Although some salinity treatments led to changes in starch content, these did not alter starch fine structure, morphology, or composition. We observed no differences in sugar and amylose content or starch granule size distribution among any of the treatments. The only alterations in starch were limited to small changes in thermal properties and glucan chain distribution, which were only seen in the Anthesis EC4 treatment. This similarity of compositional and functional features was supported by multivariate analysis of all variables measured, which suggested that differences due to treatments were minimal. Overall, this study documents the specific response of rice under defined conditions, and illustrates that the plasticity of plant response to mild stress is complex and highly context-dependent, even under greenhouse conditions in which other potential environmental stress impacts are minimized.

The starch accumulated in rice, wheat, maize, sorghum, and millet grain is indispensible for human survival
as it accounts for most of the consumed calories. In addition, cereal starch is used in its natural or modified
state as a healthful food, and as an environmentally friendly additive or replacement for petroleum-derived
fuel and polymers. Therefore, developing cereals that accumulate higher endosperm starch and starches
with novel polymeric properties could help to meet the dual challenges of sustaining human population
growth needs while minimizing some of the harmful environmental impacts. Despite its fundamental importance,
comparatively little is known about the mechanistic basis of starch biosynthesis. This entry provides a
basic overview of the “starch field” for the beginner. First, the various uses of starch, its structural organization
and biosynthesis, and how its functionality relates to its structure are outlined. Second, how recent biotechnological
advancements are leading to the discovery of new genes that modulate starch and to novel
starches generated through genetic engineering are described. Finally, some of the remaining questions
and challenges that must be tackled in order to meet the goal of increasing starch production for use as a
food, feed, fiber, and polymer in the next 50 years and beyond are illustrated

A knockout mutant line of Arabidopsis thaliana, produced with a promoter trap vector carrying a promoterless gus (uidA) as a reporter gene, showed GUS induction in response to mechanical wounding and bacterial infection. Cloning of the T-DNA flanked ...

ADPglucose pyrophosphorylase (AGPase) was believed to be confined to the plastid in all starch synthesising tissue. It was also believed that this exclusive plastidic location was central to its role in controlling starch synthesis. However, we now know that in maize and ...