Phytobiome metabolism: beneficial soil microbes steer crop plants' secondary metabolism

Crops are negatively affected by abiotic and biotic stresses, however, plant‐microbe cooperation allows prompt buffering of these environmental changes. Microorganisms exhibit an extensive metabolic capability to assist plants in reducing these burdens. Interestingly, beneficial microbes may also trigger, at the host side, a sequence of events from signal perception to metabolic responses leading to stress tolerance or protection against biotic threats. Although plants are well known for their vast chemical diversity, plant‐microbial interactions often stimulate the production of a rich and different repertoire of metabolites in plants. The targeted microbial‐plant interactions reprogramming plant metabolism represent potential means to foster various pest managements. However, the molecular mechanisms of microbial modulation of plant metabolic plasticity are still poorly understood. Here, we review an increasing amount of reports providing evidence for alterations to plant metabolism caused by beneficial microbial colonization. In addition, we highlight the vital importance of these metabolic reprograms for plants under stress erratic conditions. © 2019 Society of Chemical Industry     

Energy cost of cows' grazing activity: Use of the heart rate method and the Global Positioning System for direct field estimation

This study with grazing beef cows on the range was designed to explore the possibility of determining incremental energy expenditure (EE) in standing, traveling, and grazing relative to that in lying down, by means of continuous monitoring of EE, location, and activity by the heart-rate method, with Global Positioning System (GPS) collars, and by motion sensors in the GPS collars, respectively. Cows were observed on Mediterranean foothill rangeland covered with herbaceous vegetation through 4 seasons of the year. There were 2 stocking rate treatments, and 14 statistical models were evaluated, including one that was a stepwise model. Total daily EE (TEE) was affected by many interdependent factors apart from activity, including season, stocking rate, herbage quality, standing biomass, and reproductive state of the cow. Each model included all activity variables, plus some of the other factors. Across seasons and treatments TEE, in kJ/(kg of BW(0.75) . d), ranged from 469 in densely stocked, nonlactating cows in June to 1,092 in sparsely stocked, lactating cows in April. The cows' daily vertical and horizontal movements ranged from 75 to 174 m and from 1.5 to 4.2 km, respectively. Within a day, time spent traveling (without grazing) ranged from 0 to 32 min, and grazing time ranged from 4.4 to 12.1 h. Cows spent less time grazing (P < 0.001) in the summer, when herbage quality was low, than in winter and spring. Relative to the baseline EE while lying down, the daily increment incurred by grazing ranged from 13 to 48 kJ/(kg of BW(0.75) . d), and that incurred by grazing, standing, and traveling combined ranged from 38 to 74 kJ/(kg of BW(0.75) . d) or 5.8 to 11.4% of TEE. In conclusion, the estimates of activity costs yielded by 11 of the models were similar to one another, whereas those yielded by the stepwise model and the remaining 2 models were 20% smaller. The cost of grazing activity was estimated to be 6.14 J/(kg of BW(0.75) . m), and that of locomotion during grazing was 6.07 J/(kg of BW(0.75) . m), which agree with values obtained for animals and humans by means of a treadmill. The experimental and statistical approach tested here yielded fairly reliable estimations of energy costs of activities in grazing cows.     

The effects of long-term administration of recombinant bovine somatotropin (Posilac) and Synovex on performance, plasma hormone and amino acid concentration, and muscle and subcutaneous fat fatty acid composition in Holstein-Friesian bull calves.

The effect of recombinant somatotropin (rbST), Synovex (Syn), and their combination (rbST+Syn) on intact male calves was examined in an experiment that lasted an average of 238 d. Holstein-Friesian bull calves were allotted to one of four subtreatments (n = 14/treatment) in a factorial arrangement. There were two levels of rbST (0; rbST) and two levels of the estrogenic growth promoter Synovex (0; Syn). The rbST was administered once every 2 wk as injections of 500 mg of Posilac. Synovex (C and S) was implanted at 90-d intervals. The animals were fed for ad libitum consumption a diet with a metabolizable energy concentration of 11.7 MJ/kg DM and 15% crude protein. The hot carcasses were weighed after the removal of kidney, pelvic, and cod fats, which were weighed separately. The 12th rib cut was saved for analysis. Average daily gain and feed conversion efficiency were increased by rbST treatment by 9% (P < .005) and 10% (P < .016), respectively. There was no significant effect of Syn treatment, nor was there a rbST x Syn interaction. The proportion of the fat of the large depots in the carcass was reduced by 34% (P < .0001) and in the longissimus muscle by 32% (P < .16) owing to the rbST treatment. The plasma concentrations of GH, insulin, and thyroxin were increased by rbST treatment (P < .001, P < .01, and P < .03, respectively). The concentration of IGF-I was not affected. Synovex had no effect on plasma hormone concentration. Plasma essential and nonessential amino acid concentrations were reduced by 14 and 9%, respectively, when rbST was injected. Concentrations of cholesterol and fatty acids in muscle and subcutaneous fat were not affected (P > .072) by the rbST treatment. Synovex increased the monounsaturated fatty acids (MUFA), and the combinaton of Syn with rbST reduced polyunsaturated fatty acid (PUFA) concentration in the longissimus muscle (at the 12th rib). The reduced muscle fat content of the rbST-treated animals was associated with a trend toward an increase in polyunsaturated fatty acids.     

Reduction of postharvest losses of Galia melon by a short hot-water rinse

A rapid method for simultaneously rinsing and disinfecting fresh harvested produce using a hot-water rinse and brushes (HWRB) was tested on Galia melon ( Cucumis melo cv. reticulatus ) fruit. The optimal treatment to reduce decay while maintaining fruit quality after prolonged storage and marketing simulation was 59 ± 1°C for 15 s. Trial shipments by sea transport to Europe demonstrated that treating melon with a commercial-scale HWRB machine (3 tonnes fruit h⁻¹) maintained significantly better overall quality of treated fruit compared with untreated fruit. Exposing spores of Alternaria alternata and Fusarium solani to 60°C for about 15 s in vitro reduced germination by 48% and 42%, respectively. Employing HWRB resulted in a 3-log reduction in total colony-forming units (CFU) of the epiphytic microbial population, compared with untreated fruit. Scanning electron microscopy (SEM) showed that HWRB removed soil, dust and fungal spores from the fruit surface, and partially or entirely sealed natural openings in the epidermis.     

Effects of vitamin E supplementation on lipid peroxidation and color retention of salted calf muscle from a diet rich in polyunsaturated fatty acids.

The color of fresh meat is one of the most important quality criteria of raw muscle foods. This red color is principally due to the presence of oxymyoglobin. The present study was undertaken to examine the effect of a diet rich in polyunsaturated fatty acids (PUFA), the addition of NaCl, and the influence of dietary supplementation with vitamin E on calf muscle oxymyoglobin oxidation (color) and lipid peroxidation. Vitamin E was added to the feed at a concentration of 4000 mg/day for 90 days before slaughter. This diet increased the alpha-tocopherol concentration in muscle membrane from 2.6-2.8 to 6.5-7.0 microg/g of fresh weight. It was found that the diet rich in PUFA and, especially, the addition of NaCl increased muscle lipid peroxidation and oxymyoglobin oxidation as indicated by the contents of thiobarbituric acid-reactive substances and substances that impaired color value readings during storage at 4 degrees C. Both undesirable reactions during storage were controlled very efficiently by the presence of a critically high concentration of alpha-tocopherol in the muscle tissues. The findings concerning the antioxidant activity of alpha-tocopherol in this study form additional evidence of its efficient protection against oxidative reactions during storage of muscle tissues and its potential to maintain a high nutritional value in them.     

The advantage of tbz + iprodione treatment for control of gray mold decay of celery caused by the heterogenic spore population ofBotrytis cinerea in Israel

A combined TBZ — iprodione treatment was more effective in inhibiting growthin vitro ofBotrytis cinerea isolates obtained from decayed celery than either of the fungicides applied separately. This was exhibited for both TBZ-resistant and TBZ-sensitive isolates. TBZ at 500 (μg ml^-1 plus iprodione at 1000 μg ml^-1 reduced celery decay beyond the reduction obtained by each fungicide alone. When applied prior to inoculation, the combined treatment prevented decay by the TBZ-sensitive/iprodione-resistant isolates and reduced initial decay by the TBZ-resistant/iprodione-sensitive isolates to 3–10% of the level without treatment. Under natural infection conditions iprodione showed better decay control than TBZ, and at 1500 μg ml^-1 it reduced initial decay during prolonged storage to 3% of the no-treatment level. Although TBZ (500 μg ml^-1) or iprodione (1000 μg ml^-1) applied separately reduced decay significantly, the combination of lower concentrations of each fungicide was sufficient to eliminate decay development almost totally. The combined treatment also inhibited decay bySclerotinia sclerotiorum, which contributed 3% of the total soft rot in stored celery.     

Impact of celery age and infection byBotrytis cinerea on linear furanocoumarin (Psoralens) content in stored celery

The concentration of psoralens in celery (Apium graveolens L.), variety ‘Tender Crisp’, harvested 120 days after planting, was 12 μg g^-1 f.wt, compared with 18 μg g^-1 f.wt in celery harvested 150 days after planting. After 1 month of storage at 2°C, concentrations of psoralens in the 120- and 150-day-old celery were 82 and 118 μg g^-1 f.wt, respectively. Concentrations of psoralens in the 120- and 150-day-old celery inoculated withBotrytis cinerea Pers., after 1 month of storage at 2°C, were 266 and 294 μg g^-1 f.wt, respectively.     

The influence of recombinant bovine somatotropin on dietary energy level-related growth of Holstein-Friesian bull calves

Our objective for this study was to assess the effect of recombinant bovine somatotropin (rbST) in overcoming the biological effects attributed to live weight increase and age on growth and fat deposition in male cattle. Holstein-Friesian bull calves (n = 56; 182.2 +/- 14.7 d old) were allotted to four subtreatments in a randomized complete block with a factorial arrangement of two levels of rbST: 0 and 500 mg of Posilac, every 2 wk, and two dietary metabolizable energy (ME) concentrations: low metabolizable energy (LME) and high metabolizable energy (HME); 10 vs 11.3 MJ/kg DM, respectively. The effect of rbST treatment on daily gain was expressed mostly on the HME diets. The rbST treatment had no effect on the animals fed the LME diets before the age of 240 d was reached. Dry matter intake and the effect of rbST treatment on DM intake were inversely related to the energy concentration of the diet. The degree of fatness of the animals was significantly reduced by rbST treatment and significantly increased by energy concentration of the diet. The major effect of rbST, under the experimental conditions, in regards to adipose tissue deposition, was on the fat depots and not on the intramuscular fat. The concentration of bST, IGF-I, and insulin in the plasma was increased (P < .001) owing to rbST treatment. Lower metabolizable energy supply led to a higher (P < .001) plasma bST concentration, nonsignificantly lower plasma IGF-I and thyroid hormone concentrations, and lower (P < .001) plasma insulin concentration. A trend (P = .065) toward an increase in PUFA was found in the muscle of the rbST-treated and the HME diet animals. At a young age, when the natural growth potential is high, rbST treatment will be efficient only when a diet allowing a high digestible energy intake is provided.     

Acquired tolerance of tomato fruits to sunscald

The effect of various conditions on tolerance of tomato fruits to sunscald injury was studied. Tolerance was acquired either during a developmental period in the field or during a short period of exposure to sub-damage temperature of sensitive detached fruits. Heat treatment, rather than light, was found to be the factor influencing the development of tolerance. Saturating the fruits with water increased their sensitivity to sunscald injury.