Use of advanced recombinant lines to study the impact and potential of mutations affecting starch synthesis in barley

The effects on barley starch and grain properties of four starch synthesis mutations were studied during the introgression of the mutations from diverse backgrounds into an elite variety. The lys5f (ADPglucose transporter), wax (granule-bound starch synthase), isa1 (debranching enzyme isoamylase 1) and sex6 (starch synthase IIa) mutations were introgressed into NFC Tipple to give mutant and wild-type BC₂F₄ families with different genomic contributions of the donor parent. Comparison of starch and grain properties between the donor parents, the BC₂F₄ families and NFC Tipple allowed the effects of the mutations to be distinguished from genetic background effects. The wax and sex6 mutations had marked effects on starch properties regardless of genetic background. The sex6 mutation conditioned low grain weight and starch content, but the wax mutation did not. The lys5 mutation conditioned low grain weight and starch content, but exceptionally high β-glucan contents. The isa1 mutation promotes synthesis of soluble α-glucan (phytoglycogen). Its introgression into NFC Tipple increased grain weight and total α-glucan content relative to the donor parent, but reduced the ratio of phytoglycogen to starch. This study shows that introgression of mutations into a common, commercial background provides new insights that could not be gained from the donor parent.     

EFFECT OF DAY-NIGHT TEMPERATURE REGIMES ON GROWTH AND MORPHOLOGICAL DEVELOPMENT OF TIMOTHY PLANTS DERIVED FROM WINTER AND SUMMER TILLERS

Winter (vernalized) and summer (non-vernalized) timothy tillers were grown to anthesis in day/night temperature regimes of 32/26°, 27/21°, 21/15°, and 15/10°C. Herbage and total plant yields, total leaf-blade number and area, and total plant growth-rate were highest, or very nearly so, in the 21/15°C regime for both the winter and summer plants. However, summer plants reached anthesis 13 to 14 days later than winter plants in each temperature regime. Even though virtually all primary shoots produced an infiorescence, summer plants had significantiy more leaves and leaf-blade area, produced significantiy higher yields of leaf blade, stem plus sheath, stubble, and root tissues and had a significantly higher total plant growth rate than winter plants in each temperature regime.     

Microbial regulation in gorgonian corals

Gorgonian corals possess many novel natural products that could potentially mediate coral-bacterial interactions. Since many bacteria use quorum sensing (QS) signals to facilitate colonization of host organisms, regulation of prokaryotic cell-to-cell communication may represent an important bacterial control mechanism. In the present study, we examined extracts of twelve species of Caribbean gorgonian corals, for mechanisms that regulate microbial colonization, such as antibacterial activity and QS regulatory activity. Ethanol extracts of gorgonians collected from Puerto Rico and the Florida Keys showed a range of both antibacterial and QS activities using a specific Pseudomonas aeruginosa QS reporter, sensitive to long chain AHLs and a short chain N-acylhomoserine lactones (AHL) biosensor, Chromobacterium violaceium. Overall, the gorgonian corals had higher antimicrobial activity against non-marine strains when compared to marine strains. Pseudopterogorgia americana, Pseusopterogorgia acerosa, and Pseudoplexuara flexuosa had the highest QS inhibitory effect. Interestingly, Pseudoplexuara porosa extracts stimulated QS activity with a striking 17-fold increase in signal. The stimulation of QS by P. porosa or other elements of the holobiont may encourage colonization or recruitment of specific microbial species. Overall, these results suggest the presence of novel stimulatory QS, inhibitory QS and bactericidal compounds in gorgonian corals. A better understanding of these compounds may reveal insight into coral-microbial ecology and whether a therapeutic potential exists.     

The tryptophan-rich domain of puroindoline is directly associated with the starch granule surface as judged by tryptic shaving and mass spectrometry

The starch granule surface is a frontline of microbial attack and defence, operating in the background of normal starch granule metabolism. Puroindoline, a wheat protein which binds starch granule surfaces, contains a unique tryptophan-rich domain likely responsible for this property, though direct evidence is lacking. To test puroindoline’s tight association, prime starch granule extracts were water-washed 8 or 20 times and residual puroindoline removed using a solution of 50% isopropanol/50 mM NaCl. We found that this solvent was consistent in the amount of protein extracted from wheat flour and washed starch, regardless of initial protein content. Relative quantification of puroindoline following water-washing was performed using dot blot. Washing more than 8 times did not further reduce puroindoline content of starch granules suggesting a strong association with the starch granule surface. To identify the tryptophan-rich domain tightly associated with the starch granule surface, a combination of in situ tryptic digestion and mass spectrometry was used. Following digestion and water-washing, 50% isopropanol/50 mM NaCl was used to remove tightly-associated peptides for identification by mass spectrometry. Using this method, we identified the tryptophan-rich domain of puroindoline directly bound to the starch granule surface of wheat.     

Modelling the distribution of isopropyl N-(3-chlorophenyl) carbamate [CIPC] in box potato stores

Summary A numerical model has been produced to predict the distribution of deposits of the sprout suppressant isopropyl N-(3-chlorophenyl) carbamate [CIPC] in box potato stores. The model considers the movements of the CIPC by forced convection, sedimentation, natural convection and diffusion. Measurements have mostly shown high levels of CIPC on the top of the uppermost box, with levels decreasing towards the floor of the store. The model predicts this pattern and indicates that particle size, the temperature difference between the air inside and around the boxes, and the application rate of the chemical have a large effect on the levels and uniformity of CIPC deposits. Smaller particles (2 μm) can lead to better uniformity of distribution, but they are prone to natural convection effects which are difficult to control and they are slow to deposit which could lead to greater losses from the store.     

Evaluation in beef cattle of six deoxyribonucleic acid markers developed for dairy traits reveals an osteopontin polymorphism associated with postweaning growth

The objectives of this study were to 1) estimate the allelic frequencies in US beef cattle of 6 DNA markers reported to be associated with variation in dairy production traits; and 2) evaluate the association of these markers with beef production traits. Several genetic markers have been associated with milk yield or composition, including polymorphisms in secreted phosphoprotein 1 (SPP1; also called osteopontin), growth hormone receptor (GHR), casein S1 (CSN1S1), diacylglycerol O-acyltransferase 1 (DGAT1), peroxisome proliferator-activated receptor gamma co-activator-1alpha (PPARGC1A), and ATP-binding cassette subfamily G (white) member 2 (ABCG2). Allelic frequencies for these 6 markers, and their association with 21 phenotypes, were evaluated in 2 crossbred beef cattle populations that sample influential industry sires. Five of 6 markers were segregating in beef cattle populations; the exception was ABCG2. The SPP1 marker was associated with yearling weight (P = 0.025), live weight at slaughter (P = 0.016), postweaning ADG (P = 0.007), and HCW (P = 0.007) in a large, multisire population representing the 7 most populous beef breeds in the United States. Postweaning growth trait associations were confirmed in an independent population of similar construction, including sires from tropically adapted breeds. The SPP1 marker was associated with yearling weight (P = 0.034), live weight at slaughter (P = 0.011), and postweaning ADG (P = 0.015) and showed a trend toward association with HCW (P = 0.083) in this population. Whereas DGAT1, GHR, and CSN1S1 polymorphisms showed association with some traits in individual populations, the lack of consistent predictive merit between populations indicates they may not be suited for beef cattle selection. No significant associations were observed for the PPARGC1A marker and any of 21 recorded traits, indicating this marker had no apparent value in selection for the beef cattle traits tested in these populations. The SPP1 marker had consistent associations and effect sizes (10.5 to 11.5 kg of live weight at slaughter) in both populations, providing strong evidence for utility of the SPP1 marker for postweaning growth in beef cattle.