The circadian system in plants is characterized by substantial cellular oscillations over an approximately 24-h period. Interactions between cellular oscillators trigger phase resets near the root meristem, resulting in localized regions of arrhythmic expression of the clock gene CCA1. The arrhythmicity of the circadian rhythm significantly impacts physiologic processes and growth; however, the exact nature of these arrhythmic regions remains unknown. In this study, we analyzed spatiotemporal patterns in CCA1 expression in arrhythmic regions using a nondestructive imaging technique. We found that formation of root arrhythmic regions involves the emergence of small spiral waves. Near the small spiral waves, the synchrony of cellular oscillations was low. Our findings provide experimental evidence that the arrhythmias are based on desynchronization of cellular oscillators and enhance our understanding of the role of circadian phenomena in root growth.
Flower color is one of the most important traits in ornamental plants. Poor coloration of pink flower chrysanthemum during the high temperature season is a serious problem. To determine the effect of high temperature on the pigmentation, inflorescence development was divided into five stages. Plants were exposed to both 20 and 30℃ during various developmental stages of inflorescence. HPLC analysis showed the main anthocyanins of pink flower chrysanthemum(cv. Pelican) were cyanidin 3-O-(6"-O-monomalonyl-ß-glucopyranoside) and cyanidin 3-O-(3",6"-O-dimalonyl-ß-glucopyranoside). The content of the two anthocyanins at 20℃ was much higher than that at 30℃. In the inflorescence exposed to 30℃ during bud break to vertical stage, pigmentation was not enhanced, even though the plants were subjected to 20℃ from the vertical stage to 1-week-old. On the other hand, when the plants were exposed to 30℃ during vertical stage to 1-week-old, pigment content decreased drastically, even though the inflorescence was kept at 20℃ from the bud break to vertical stage. The results indicate that the petal extension to vertical stage is the most temperature sensitive and important for pigmentation. Expression of the anthocyanin biosynthesis-related genes (CmplCHS1, CmplCHS2, CmplCHI, CmplF3H2, CmplC3'H, CmplDFR1, CmplDFR2, and CmplANS) was depressed at 30℃ compared with those at 20℃.
A program library for use on open-source hardware was developed in order to construct a low-cost environmental control system for greenhouses. The library facilitated the development of environmental sensing and control devices that conform to the protocols of the Ubiquitous Environment Control System (UECS). The open-source hardware used was the "Arduino Ethernet" and the "Arduino Mega 2560 with Ethernet Shield" microcontroller boards. UECS is a system for controlling greenhouse environments that communicates information via a local area network, and devices utilizing the library that we developed can perform the UECS defined communication tasks automatically. With the help of this library, device developers no longer need to program the communications aspects of the device and can concentrate on programming setting and control logic of the device. The library occupies about 29 kilobytes of the read only memory area of the target board. The library and associated open-source microcontroller boards are powerful tools for developing low-cost environmental control systems.
We investigated the efficacy of hyperbaric storing for preserving ascorbic acid (AsA) in fresh-cut broccoli florets. The samples were stored in a container pressurized at 0.3 and 2.1 MPa of air at 8 ℃ for 14 d. Florets stored under atmospheric pressure (0.1 MPa) were used as a control. We assayed AsA content, enzyme activities involved in AsA degradation and recycling, including ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), as well as antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT). Changes in partial pressure of O2 and CO2 in the storage container were also determined. AsA content was successfully maintained for 14 d under both of our hyperbaric treatments and was approximately twice as high as the AsA content in the control treatment. Activities of CAT, APX, GR and SOD increased at 0.3 MPa, except DHAR, whereas florets stored at 2.1 MPa showed almost no enzymatic activity. The respiration was slowed down in florets stored under hyperbaric conditions. Our results suggest that the physiological response of fresh-cut broccoli florets to the hyperbaric condition varied with the magnitude of pressure applied, especially the enhancement of CAT enzyme activity leads to the AsA retention at 0.3 MPa.
Heat tolerance enhancers are chemicals which prevent the physiological damages of plants by heat. Phenethyl isothiocyanate (ITC), which is known as the heat tolerance enhancer, induced the expression of heat shock protein genes in Arabidopsis. Here we measured the heat shock response (HSR)-inducing activities of ITCs to find more active ITCs than phenethyl ITC. We prepared transgenic Arabidopsis possessing the ß-glucuronidase reporter gene driven by the promoter of a small heat shock protein (HSP17.6C-CI) gene which was induced by heat tolerance enhancers. We tested 16 naturally occurring ITCs for their HSR-inducing activities: 5 aromatic ITCs, 7 aliphatic ITCs, and 4 sulfur-containing aliphatic ITCs. The results showed that the short-chain aliphatic ITCs, especially isobutyl ITC, promoted the HSR more strongly than the aromatic and sulfur-containing aliphatic ITCs. Isobutyl ITC induced the HSR in the whole Arabidopsis seedlings. The isobutyl ITC-treated plants showed higher heat tolerance than the phenethyl ITC-treated plants. These results suggest that isobutyl ITC is a more potent heat tolerance enhancer than phenethyl ITC.