Phylogenetic farming: Can evolutionary history predict crop rotation via the soil microbiome?

Agriculture has long employed phylogenetic rules whereby farmers are encouraged to rotate taxonomically unrelated plants in shared soil. Although this forms a central tenet of sustainable agriculture, strangely, this on-farm "rule of thumb" has never been rigorously tested in a scientific framework. To experimentally evaluate the relationship between phylogenetic distance and crop performance, we used a plant-soil feedback approach whereby 35 crops and weeds varying in their relatedness to tomato (Solanum lycopersicum) were tested in a two-year field experiment. We used community profiling of the bacteria and fungi to determine the extent to which soil microbes contribute to phenotypic differences in crop growth. Overall, tomato yield was ca. 15% lower in soil previously cultivated with tomato; yet, past the species level there was no effect of phylogenetic distance on crop performance. Soil microbial communities, on the other hand, were compositionally more similar between close plant relatives. Random forest regression predicted log10 phylogenetic distance to tomato with moderate accuracy (R 2 = .52), primarily driven by bacteria in the genus Sphingobium. These data indicate that, beyond avoiding conspecifics, evolutionary history contributes little to understanding plant-soil feedbacks in agricultural fields; however, microbial legacies can be predicted by species identity and relatedness.

Conditioning the soil microbiome through plant-soil feedbacks suppresses an aboveground insect pest

Soils and their microbiomes are now recognized as key components of plant health, but how to steer those microbiomes to obtain their beneficial functions is still unknown. Here, we assess whether plant-soil feedbacks can be applied in a crop system to shape soil microbiomes that suppress herbivorous insects in above-ground tissues. We used four grass and four forb species to condition living soil. Then we inoculated those soil microbiomes into sterilized soil and grew chrysanthemum as a focal plant. We evaluated the soil microbiome in the inocula and after chrysanthemum growth, as well as plant and herbivore parameters. We show that inocula and inoculated soil in which a focal plant had grown harbor remarkably different microbiomes, with the focal plant exerting a strong negative effect on fungi, especially arbuscular mycorrhizal fungi. Soil inoculation consistently induced resistance against the thrips Frankliniella occidentalis, but not against the mite Tetranychus urticae, when compared with sterilized soil. Additionally, plant species shaped distinct microbiomes that had different effects on thrips, chlorogenic acid concentrations in leaves and plant growth. This study provides a proof-of-concept that the plant-soil feedback concept can be applied to steer soil microbiomes with the goal of inducing resistance above ground against herbivorous insects.

[QT interval dispersion in hypertensive diabetics and in patients with hypertension with chronic heart failure without diabetes]

AIM

Our aim was to: 1. compare QT dispersion from routine ECG in diabetic and no-diabetic patients with congestive heart failure, 2. describe associations between QT dispersion and circadian blood (BP) pressure variation in type 2 diabetic patients with congestive heart failure (CHF).

PATIENTS AND METHODS

122 patients admitted to hospital due to CHF in the period between years 2000-2001 have been divided into 2 groups: group 1:70 patients (m: 40, f: 30, mean age 64.7 +/- 9 years) with type II diabetes mellitus (DM), group 2:52 patients (m: 28, f:24, mean age 62.5 +/- 10.9 years) without DM. Diagnosis of CHF was made clinically and proved by ECG and ECHO (EF < 40%), DM was defined clinically or by using oral glucose tolerance test (75 g glucose, 2 h blood glucose > 11.1 mmol/l). The QT interval was measured from the beginning of the QRS complex to the end of the T wave from routine 12-lead ECG. QT intervals were corrected for heart rate using Bazett's formula. QT dispersion (QTd) and rate corrected QT dispersion (QTc) were defined as the difference between the maximum and minimum QT and QTc intervals, respectively. Ambulatory blood pressure (AMBP) was measured by an oscillometic technique. Diabetic patients with CHF were divided both according to below and above the median QTc dispersion (65 ms).

STATISTICAL ANALYSIS

Chi-square and Student's t-test. Significant differences were assumed of p < 0.05.

RESULTS

Both groups were matched by gender, age, duration and intensity of hypertension, the presence and intensity of obesity, hyperlipidemia (TC, TG, LDL-C, HDL-C) and smoking habits. Diabetic patients with CHF had significantly longer QTc interval (maximum and minimum), QT dispersion and QTc dispersion compared with non-diabetic patients with CHF. Diabetic patients with CHF with QTc dispersion > 65 ms had significantly higher night systolic (133 +/- 14 vs. 112 +/- 14) and diastolic (80 +/- 11 vs. 65 +/- 6) BP and significantly higher night/day ratio for both systolic (0.94 +/- 0.05 vs. 0.86 +/- 0.06) and diastolic (0.89 +/- 0.07 vs. 0.80 +/- 0.05) compared with diabetic patients with CHF with QTc dispersion < 65 ms.

CONCLUSION

Diabetic patients with CHF are higher risk than non-diabetic. Our data describe both factors related to cardiovascular risk in diabetic patients with CHF-prolongation of the QT and QTc dispersion and reduced nocturnal blood pressure.

[Effect of chronic Chlamydia infection with non-specific inflammation on cardiovascular complications in acute myocardial infarct]

It is known that local and systemic inflammatory processes play an important role in the genesis and development of atheroclerotic lesions and in the pathophysiology of acute coronary syndromes. This hypothesis is supported by findings of elevated parameters of the "inflammatory" reaction in the affected blood vessels but also in the blood of atherosclerotic patients. Known risk factors do not explain quite satisfactorily epidemiological cardiovascular phenomena and different manifestations of coronary heart disease. It is very probable that also Chlamydia pneumoniae is a risk factor. This assumption is based on evaluation of seroepidemiological data, examination of atherosclerotic plaques not only in humans but also in animal models with chlamydial infection. Based on retrospective and prospective evaluation of case-records the authors analyzed the incidence of cardiovascular complications in 83 patients with acute myocardial infarction (AIM), incl. 51 patients (31 men and 20 women, mean age 64.4 +/- 3.4 years who had a non-specific inflammation and chlamydial infection, and 32 patients (24 men and 8 women, mean age 64.7 +/- 3.6 years) who had chlamydial infections but no non-specific inflammation (in the blood). These patients were selected from all patients hospitalized during 1998-2001. When diagnosing acute myocardial infarction we applied WHO criteria, and the presence of at least two of three criteria was necessary: a history of prolonged (more than 20 min). stenocardia, electrocardiographic changes typical for ischaemia and/or necrosis and elevation of myocardial enzymes in serum, Non-specific inflammatory activity was present in patients (i.e. positive) if the following laboratory parameters were recorded: C-reactive protein > 5 mg/l assessed by the radial immunodiffusion method; fibrinogen > 4 mg/l assessed by the coagulation method according to Claus; leukocytes > 9.6 x 10(3)/microliter, leukocytes were counted automatically in a Coulter chamber; lymphocytes > 3.4 x 10(3)/microliter. Red cell sedimentation rate > 20 mm/hour. The activity was evaluated as positive when all parameters were elevated. The presence of chronic infection with Chlamydia pneumoniae was assessed qualitatively by antibody positivity (IgG) in serum using the microimmunoflurescent method (using a set from Labsystems Co.). The incidence of associated risk factors (obesity, smoking, diabetes, hyperlipidaemia and hypertension) is higher in the sub-group of patients with Chlamydia infections without inflammation, however, the difference is not statistically significant. The incidence of cardiovascular attacks was higher in the sub-group of patients with chlamydial infection and concurrent inflammation as compared with the sub-group of patients with chlamydial infection without inflammation. In case of re-infarction of the myocardium, a sudden cerebrovascular attack, death and arrhythmia the difference was statistically significant, while in case of cardiac failure and cardiogenic shock the difference was not significant. Patients with acute myocardial infarction with chlamydial infection and a concurrent non-specific inflammation had to be treated more often by combined (i.e. more intense) treatment, thrombolytic treatment, PTCA and surgery (bypass) of the coronary vessels as compared with patients with Chlamydia infections but without inflammation. The authors assume therefore that not only different risk factors but also the effect of non-specific inflammation and Chlamydia infection contribute towards the increased number of cardiovascular postinfarction complications. Therefore a therapeutic approach involving eradication of infection and suppression of the inflammatory reaction should be considered.