Effect of the light and dark conditions on flower opening time between cultivated rice (Oryza sativa) and a near-isogenic early-morning flowering line.

Flower opening time (FOT) is affected by genetic and environmental factors, but little is known about the effect of light and dark conditions on FOT in cereal crops. FOT of an indica rice cultivar, IR64, and its near-isogenic line carrying a QTL for an early-morning flowering trait (IR64+qEMF3) were investigated in a natural-light and temperature-controlled small greenhouse by exposing either the panicle or stem or both plant organs to different light and dark conditions. FOT did not change in either genotype when panicles were exposed to light. A large difference in FOT was found between genotypes when panicles were exposed to dark conditions; no flower opening was observed in IR64, whereas flower opening was delayed but observed in IR64+qEMF3. These results suggest that the panicle is the organ that perceives light for flower opening in both genotypes, whereas the light requirement to reach flower opening was quite different between genotypes. Flower opening of IR64 occurred concomitantly with elongation of anther filament in the light after the dark treatment stopped, whereas approximately half of flowering of IR64+qEMF3 resulted in apparent cleistogamy even during dark treatment. An extended duration of the dark treatment until 1730H (30-50 min before sunset) made FOT of IR64 spikelets on the next day shifted to a time as early as that of IR64+qEMF3, with significant advancement of FOT compared to the control IR64 spikelets. Our results indicated that different flowering responses to light and dark conditions exist between IR64 and IR64+qEMF3. These findings provide clues for understanding the unique genetic controls of flowering in an EMF line in rice. This study also showed evidence that artificial light environments can shift the FOT of IR64 to that of IR64+qEMF3.

Factors affecting mental illness and social stress in hospital workers treating COVID-19: Paradoxical distress during pandemic era.

BACKGROUND: The coronavirus disease 2019 (COVID-19) has affected all countries in the world. Hospital workers are at high risk of mental illness, such as anxiety and depression. Furthermore, they also face many social stresses, such as deterioration of human relations and income reduction. Apart from mental illness, these social stresses can reduce motivation and lead to voluntary absenteeism, which contribute to a collapse of medical systems. Thus, for maintaining medical systems, it is crucial to clarify risk factors for both mental illness and increased social stress among hospital workers. However, little attention has been paid to factors affecting social stress, and thus, we aimed to address this gap. METHODS: In this cross-sectional survey of 588 hospital workers, the levels of anxiety, depression, and social stress were assessed using the 7-item Generalized Anxiety Disorder scale (GAD-7), 9-item Patient Health Questionnaire (PHQ-9), and Tokyo Metropolitan Distress Scale for Pandemic (TMDP). Multiple regression analyses were conducted to identify the demographic variables affecting these problems. RESULTS: Older age and female sex were common risk factors for anxiety, depression, and social stress. Moreover, occupational exposure to COVID-19 and hospital staff other than doctors/fewer non-work days were risk factors for increased anxiety and depression, respectively. Furthermore, living with families/others was a risk factor for increased social stress during this pandemic. CONCLUSION: Our findings could be useful for developing policies and practices to minimize the risk of mental illness and increased social stress among hospital workers, highlighting that attention should be paid to social factors, such as an individual's household situation.