Strigolactones (SLs) are phytohormones that play a central role in regulating shoot branching. SL perception and signaling involves the F-box protein MAX2 and the hydrolase DWARF14 (D14), proposed to act as an SL receptor. We used strong loss-offunction alleles of the Arabidopsis thaliana D14 gene to characterize D14 function from early axillary bud development through to lateral shoot outgrowth and demonstrated a role of this gene in the control of flowering time. Our data show that D14 distribution in vivo overlaps with that reported for MAX2 at both the tissue and subcellular levels, allowing physical interactions between these proteins. Our grafting studies indicate that neither D14 mRNA nor the protein move over a long range upwards in the plant. Like MAX2, D14 is required locally in the aerial part of the plant to suppress shoot branching. We also identified a mechanism of SLinduced, MAX2-dependent proteasome-mediated degradation of D14. This negative feedback loop would cause a substantial drop in SL perception, which would effectively limit SL signaling duration and intensity.

A study was undertaken to examine the effects of inulin, alone or in combination with enzyme complex (primarily xylanase and beta-glucanase), on growth performance, ileal and cecal microflora, cecal short-chain fatty acids, and d-lactic acid and jejunal histomorphology of broiler chickens fed a wheat- and barley-based diet from 7 to 35 d of age. A total of 240 seven-day-old male Cobb broilers were allocated to 1 of 6 treatments, with 8 replicate pens per treatment and 5 birds per pen. The experiment consisted of a 3x2 factorial arrangement of the treatments with 3 concentrations of inulin (0, 10, or 20 g/kg of diet) and 2 concentrations of enzyme complex (0 or 100 mg/kg of diet). At the end of the experiment, 8 birds per treatment (one from each pen) were randomly chosen and slaughtered. Birds fed inulin-containing diets exhibited significantly (P=0.043) improved final BW gain. Dietary inulin had a positive and significant (P<0.002 to 0.009) effect on bifidobacteria and lactobacilli counts in both ileal and cecal contents and, to an extent, also altered the fermentation patterns in the ceca, increasing the concentration of n-butyric and d-lactic acids and the n-butyric acid:acetic acid ratio. Inulin inclusion had no effect on villus height and crypt depth or microvillus length, width, and density in the jejunum. Enzyme supplementation of the control diet and inulin-containing diets had no effect on many of the variables studied and only resulted in a decrease in crypt depth and an increase in villus height:crypt depth ratio in the jejunum.

A study was conducted to evaluate the effect of adding inulin to diets containing 2 different types of fat as energy sources on performance, blood serum metabolites, liver lipids, and fatty acids of abdominal adipose tissue and breast and thigh meat. A total of 240 one-day-old female broiler chicks were randomly allocated into 1 of 6 treatments with 8 replicates per treatment and 5 chicks per pen. The experiment consisted of a 3 x 2 factorial arrangement of treatments including 3 concentrations of inulin (0, 5, and 10 g/kg of diet) and 2 types of fat [palm oil (PO) and sunflower oil (SO)] at an inclusion rate of 90 g/kg of diet. The experimental period lasted from 1 to 34 d. Dietary fat type did not affect BW gain but impaired feed conversion (P < 0.001) in birds fed the PO diets compared with birds fed the SO diets. The diets containing PO increased abdominal fat deposition and serum lipid and glucose concentrations. Triacylglycerol contents in liver were higher in the birds fed PO diets. Dietary fat type also modified fatty acids of abdominal and i.m. fat, resulting in a higher concentration of C16:0 and C18:1n-9 and a lower concentration of C18:2n-6 in the birds fed PO diets. The addition of inulin to diets modified (P = 0.017) BW gain quadratically without affecting feed conversion. Dietary inulin decreased the total lipid concentration in liver (P = 0.003) and that of triacylglycerols and very low density lipoprotein cholesterol (up to 31%) in blood serum compared with the control groups. The polyunsaturated fatty acid:saturated fatty acid ratio increased in abdominal and i.m. fat when inulin was included in the SO-containing diets. The results from the current study suggest that the addition of inulin to broiler diets has a beneficial effect on blood serum lipids by decreasing triacylglyceride concentrations The results also support the use of inulin to increase the capacity of SO for enhancing polyunsaturated fatty acid:saturated fatty acid ratio of i.m. fat in broilers.