We developed a new method using 13 CO 2 and mass spectrometry to elucidate the role of photorespiration as an alternative electron dissipating pathway under drought stress. This was achieved by experimentally distinguishing between the CO 2 fluxes into and out of the leaf. The method allows us to determine the rates of gross CO 2 assimilation and gross CO 2 evolution in addition to net CO 2 uptake by attached leaves during steady-state photosynthesis. Furthermore, a comparison between measurements under photorespiratory and non-photorespiratory conditions may give information about the contribution of photorespiration and mitochondrial respiration to the rate of gross CO 2 evolution at photosynthetic steady state. In tomato (Lycopersicon esculentum Mill. cv Moneymaker) leaves, drought stress decreases the rates of net and gross CO 2 uptake as well as CO 2 release from photorespiration and mitochondrial respiration in the light. However, the ratio of photorespiratory CO 2 evolution to gross CO 2 assimilation rises with water deficit. Also the contribution of re-assimilation of (photo) respiratory CO 2 to gross CO 2 assimilation increases under drought.Water deficit limits plant growth and productivity because it decreases net CO 2 assimilation due to reduced stomatal conductance for CO 2 and/or because of non-stomatal effects like inhibition of enzymatic processes by changes in ionic or osmotic conditions (Lawlor, 1995). At high light intensities the lowered consumption of redox equivalents in the Calvin cycle makes it necessary to degrade photosynthetic electrons in processes other than CO 2 fixation to avoid photo-inhibition. Sharkey et al. (1988) showed that the activity of photosystem II can be regulated in a way that the rate of electron transport matches the capacity of the electron consuming reactions and that linear electron transport depends not only on light intensity and CO 2 concentration but also on the O 2 concentration. Oxygen can function as alternative electron acceptor directly in the Mehler reaction or indirectly in photorespiration (Badger, 1985).By combined measurements of O 2 and CO 2 gas exchange it should be possible to investigate the distribution of photosynthetic electrons between the electron consuming reactions CO 2 assimilation, photorespiration, and Mehler reaction (Haupt-Herting, 2000). The influence of drought stress on photosystem II activity, gross O 2 evolution, and gross O 2 uptake in tomato (Lycopersicon esculentum Mill. cv Moneymaker) plants has been published elsewhere (Haupt-Herting and Fock, 2000). This paper deals with the corresponding carbon fluxes determined by a new CO 2 gas exchange method.

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Previous research has supported the positive effects of health-oriented leadership (HoL) on follower health. However, effectiveness in times of crisis is unknown. This study examines whether crises weaken or strengthen the positive relationships of health-oriented leadership with follower strain and performance. Effectiveness was tested for (1) follower irritation and performance (extra effort) in smaller crises on the team level with a vignette study (N = 257) and (2) follower exhaustion and performance (task proficiency) during the Covid-19 crisis in a cross-sectional survey study (N = 196). As expected, the results provided evidence for an increase in follower health with higher health-oriented leadership but a decrease in health in crises. The positive relationship between health-oriented leadership and follower health was even stronger in crises. Health-oriented leadership had a positive relationship with job performance in both studies. Our findings provide initial evidence that health-oriented leadership is particularly important for followers affected by a crisis, and that leaders should display health-oriented leadership in both small-scale and large-scale crises. Findings suggest that health-oriented leadership does not undermine goal achievement but relates positively to performance. More generally, the study contributes to the clarification and deeper understanding of situational contingencies of health-specific leadership concepts.

Health-oriented leadership consists of three dimensions that contribute to employee health: staff care, i.e., health-specific follower-directed leadership, as well as both leaders’ and followers’ self care, i.e., health-specific self-leadership. This study explores profiles of follower self care, leader self care and staff care, and investigates the relationships with follower health in two samples. We identified four patterns of health-oriented leadership: A consistently positive profile (high care), a consistently negative profile (low care), and two profiles showing inconsistencies between follower self care, leader self care, and staff care (leader sacrifice and follower sacrifice). The high care profile reported the best health compared to both the low care profile and the inconsistent profiles. The follower sacrifice profile reported more strain than the leader sacrifice profile, while strain and health levels were the least favorable in the low care profile. Findings reveal that (in-)consistency between follower-directed leadership and self-leadership contributes to follower strain and health.

The Botrytis cinerea VELVET complex regulates light-dependent development and virulence. The goal of this study was to identify common virulence defects of several VELVET mutants and to reveal their molecular basis. Growth, differentiation, physiology, gene expression and infection of fungal strains were analyzed, and quantitative comparisons of in planta transcriptomes and secretomes were performed. VELVET mutants showed reduced release of citric acid, the major acid secreted by the wild-type, whereas no significant role for oxalic acid was observed. Furthermore, a common set of infection-related and secreted proteins was strongly underexpressed in the mutants. Quantitative secretome analysis with N metabolic labeling revealed a correlation of changes in protein and mRNA levels between wild-type and mutants, indicating that transcript levels determine the abundance of secreted proteins. Infection sites kept at low pH partially restored lesion expansion and expression of virulence genes by the mutants. Drastic downregulation of proteases in the mutants was correlated with incomplete degradation of cellular host proteins at the infection site, but no evidence was obtained that aspartyl proteases are required for lesion formation. The B. cinerea VELVET complex controls pathogenic differentiation by regulating organic acid secretion, host tissue acidification, gene expression and protein secretion.