Photo-Selective Nets and Pest Control: Searching Behavior of the Codling Moth Parasitoid Mastrus ridens (Hymenoptera: Ichneumonidae) under Varying Light Quantity and Quality Conditions

Photo-selective nets (PSN) are used to manipulate the physiology of fruit crops. Besides their advantages to the crop, PSN potentially affect insect pests and their natural enemies. We aimed to assess the effects of these production systems on the searching behavior of the codling moth parasitoid, Mastrus ridens. We hypothesized that PSN and black standard nets (SN) affect the behavior of the parasitoid by delaying host localization and reducing parasitism. Laboratory experiments were carried out in closed cages under four treatment conditions: black SN, pearl PSN, red PSN, and no PSN as control (uncovered cages). Our results showed that the host localization of M. ridens was delayed under black SN and enhanced by pearl and red PSN. The PSN and the black SN did not affect the parasitism levels. In addition, the initial behavior of the parasitoid during the first 30 min of the bioassays was not affected by treatments. However, females spent most of the time walking around the arena, grooming, or resting, regardless of the color of the net. Parasitism was not affected under the PSN or the black SN; however, this must be verified in field conditions.

Physiological and ecological consequences of the water optical properties degradation on reef corals

Degradation of water optical properties due to anthropogenic disturbances is a common phenomenon in coastal waters globally. Although this condition is associated with multiple drivers that affect corals health in multiple ways, its effect on light availability and photosynthetic energy acquisition has been largely neglected. Here, we describe how declining the water optical quality in a coastal reef exposed to a turbid plume of water originating from a man-made channel compromises the functionality of the keystone coral species Orbicella faveolata. We found highly variable water optical conditions with significant effects on the light quantity and quality available for corals. Low-light phenotypes close to theoretical limits of photoacclimation were found at shallow depths as a result of reduced light penetration. The estimated photosynthetically fixed energy depletion with increasing depth was associated with patterns of colony mortality and vertical habitat compression. A numerical model illustrates the potential effect of the progressive water quality degradation on coral mortality and population decline along the depth gradient. Collectively, our findings suggest that preserving the water properties seeking to maximize light penetration through the water column is essential for maintaining the coral reef structure and associated ecosystem services.

The Potential of High-Anthocyanin Purple Rice as a Functional Ingredient in Human Health

Purple rice is recognized as a source of natural anthocyanin compounds among health-conscious consumers who employ rice as their staple food. Anthocyanin is one of the major antioxidant compounds that protect against the reactive oxygen species (ROS) that cause cellular damage in plants and animals, including humans. The physiological role of anthocyanin in plants is not fully understood, but the benefits to human health are apparent against both chronic and non-chronic diseases. This review focuses on anthocyanin synthesis and accumulation in the whole plant of purple rice, from cultivation to the processed end products. The anthocyanin content in purple rice varies due to many factors, including genotype, cultivation, and management as well as post-harvest processing. The cultivation method strongly influences anthocyanin content in rice plants; water conditions, light quantity and quality, and available nutrients in the soil are important factors, while the low stability of anthocyanins means that they can be dramatically degraded under high-temperature conditions. The application of purple rice anthocyanins has been developed in both functional food and other purposes. To maximize the benefits of purple rice to human health, understanding the factors influencing anthocyanin synthesis and accumulation during the entire process from cultivation to product development can be a path for success.

UBP12 and UBP13 deubiquitinases destabilize the CRY2 blue-light receptor to regulate growth

ABSTRACTAll organisms undergo growth, which is precisely controlled by exogenous and endogenous signals. Unchecked growth often leads to neoplasia and other developmental defects, severely affecting an organism’s fitness. Light is a vital exogenous signal sensed by cryptochrome (CRY) blue light receptors to modulate growth and the circadian clock in plants and animals. Yet, how CRYs interpret light quantity to regulate growth in plants remains poorly understood. We show that UBP12 and UBP13 deubiquitinases physically interact with CRY2 in light. UBP12/13 negatively regulated CRY2 protein levels by promoting its ubiquitination and turnover to fine-tune growth. Unexpectedly, the destabilization of CRY2 by UBP12/13 is contrary to the general view that deubiquitinases stabilize proteins by preventing their degradation. Growth and development were explicitly affected in blue light when UBP12/13 was disrupted or overexpressed, indicating their role alongside CRY2. UBP12/13 also interacted and stabilized COP1, which is partially required for the turnover of CRY2. Despite decades of studies on deubiquitinases, the knowledge on how they are regulated is limited. Our study offers an insight into how exogenous signals and their receptors regulate deubiquitinase activity by protein-protein interaction. Altogether, our results provide a new module of cryptochromes and deubiquitinases in sensing and interpreting light cues to control growth at the most appropriate time.

Photosynthesis and Bio-Optical Properties of Fluorescent Mesophotic Corals

Mesophotic coral ecosystems (MCEs) are light-dependent coral-associated communities found at 30–150 m depth. Corals inhabiting these deeper reefs are often acclimatized to a limited and blue-shifted light environment, enabling them to maintain the relationship with their photosynthetic algal symbionts (family Symbiodiniaceae) despite the seemingly suboptimal light conditions. Among others, fluorescent proteins produced by the coral host may play a role in the modulation of the quality and spectral distribution of irradiance within the coral tissue through wavelength transformation. Here we examined the bio-optical properties and photosynthetic performances of different fluorescence morphs of two mesophotic coral species Goniopora minor and Alveopora ocellata, in order to test the photosynthesis enhancement hypothesis proposed for coral fluorescence. The green morph of G. minor and the low fluorescence morph of A. ocellata exhibit, in their natural habitats, higher abundance. The morphs also presented different spectral reflectance and light attenuation within the tissue. Nevertheless, chlorophyll a fluorescence-based, and O2 evolution measurements, revealed only minor differences between the photosynthetic abilities of three fluorescence morphs of the coral G. minor and two fluorescence morphs of A. ocellata. The fluorescence morphs did not differ in their algal densities or chlorophyll concentrations and all corals harbored Symbiodiniaceae from the genus Cladocopium. Thus, despite the change in the internal light quantity and quality that corals and their symbionts experience, we found no evidence for the facilitation or enhancement of photosynthesis by wavelength transformation.

Physiological and ecological consequences of the water optical properties degradation on reef corals

Degradation of water optical properties due to anthropogenic disturbances is a common phenomenon in coastal waters globally. Although this condition is associated with multiple drivers that affect corals health in multiple ways, its effect on light availability and photosynthetic energy acquisition has been largely neglected. Here, we describe how declining the water optical quality in a coastal reef exposed to a turbid plume of water originating from a man-made channel compromise the functionality of the keystone coral species Orbicella faveolata. We found highly variable water optical conditions with significant effects on the light quantity and quality available for corals. Reduction of light penetration into the water column elicits the development of low-light phenotypes close to theoretical limits of photoacclimation despite their occurrence at shallow depths. Predicted photosynthetic energy depletion with increasing depth is associated with patterns of colony mortality and contraction of the habitable space for the population. A numerical model illustrates the potential effect the progressive degradation of water optical properties on the gradual mortality and population decline of O. faveolata. Our findings suggest that preserving the water optical properties seeking to maximize light penetration into the water column may have an extraordinary impact on coral reefs conservation, mostly toward the deeper portions of reefs.

Personal lighting conditions of office workers: An exploratory field study

Light enables us to see and perceive our environment but it also initiates effects beyond vision, such as alertness. Literature describes that at least six factors are relevant for initiating effects beyond vision. The exact relationship between these factors and alertness is not yet fully understood. In the current field study, personal lighting conditions of 62 Dutch office workers (aged 49.7 ± 11.4 years) were continuously measured and simultaneously self-reported activities and locations during the day were gathered via diaries. Each office worker participated 10 working days in spring 2017. Personal lighting conditions were interpreted based on four of the six factors (light quantity, spectrum, timing, and duration of light exposure). Large individual differences were found for the daily luminous exposures, illuminances, correlated colour temperatures, and irradiances measured with the blue sensor area of the dosimeter. The average illuminance (over all participants and all days) over the course of the day peaked three times. The analysis of the duration of light exposure demonstrated that the participants were on average only exposed to an illuminance above 1000 lx for 72 minutes per day. The interpretation of personal lighting conditions based on the four factors provides essential information since all of these factors may be relevant for initiating effects beyond vision. The findings in the current paper give first in-depth insight in the possibilities to interpret personal lighting conditions of office workers.

Light quality signals generated by vegetation shade facilitate acclimation to reduced light quantity in shade-avoider plants

SUMMARYWhen growing in search for light, plants can experience continuous or occasional shading by other plants. Plant proximity causes a decrease in the ratio of red to far red light (low R:FR) due to the preferential absorbance of red light and reflection of far red light by photosynthetic tissues of neighboring plants. This signal is often perceived before actual shading causes a reduction in photosynthetically active radiation (low PAR).Here we investigated elongation, photosynthesis and photoacclimation responses in several Brassicaceae species to explore the possible connections between low R:FR and low PAR.A negative correlation was found in shade-tolerant Cardamine hirsuta and shade-avoider Arabidopsis thaliana seedlings (e.g., shade-tolerance was associated with a good adaptation to low PAR but a poor or null response to low R:FR exposure). However, they could be genetically uncoupled. Most interestingly, exposure to low R:FR of shade-avoider plants improved their photoacclimation to low PAR by triggering changes in photosynthesis-related gene expression, pigment accumulation and chloroplast ultrastructure.These results indicate that low R:FR signaling unleashes molecular, metabolic and developmental responses that allow shade-avoider plants (including most crops) to adjust their photosynthetic capacity in anticipation of eventual shading by nearby plants.

Environmental Signal-Dependent Regulation of Flowering Time in Rice

The transition from the vegetative to the reproductive stage of growth is a critical event in the lifecycle of a plant and is required for the plant’s reproductive success. Flowering time is tightly regulated by an internal time-keeping system and external light conditions, including photoperiod, light quality, and light quantity. Other environmental factors, such as drought and temperature, also participate in the regulation of flowering time. Thus, flexibility in flowering time in response to environmental factors is required for the successful adaptation of plants to the environment. In this review, we summarize our current understanding of the molecular mechanisms by which internal and environmental signals are integrated to regulate flowering time in Arabidopsis thaliana and rice (Oryza sativa).