Strigolactone signaling inhibition increases adventitious shoot formation on internodal segments of ipecac.

MAIN CONCLUSION: SL inhibited adventitious shoot formation of ipecac, whereas the SL-related inhibitors promoted adventitious shoot formation. SL-related inhibitors might be useful as new plant growth regulators for plant propagation. In most plant species, phytohormones are required to induce adventitious shoots for propagating economically important crops and regenerating transgenic plants. In ipecac (Carapichea ipecacuanha (Brot.) L. Andersson), however, adventitious shoots can be formed without phytohormone treatment. Here we evaluated the effects of GR24 (a synthetic strigolactone, SL), SL biosynthetic inhibitors, and an SL antagonist on adventitious shoot formation during tissue culture of ipecac. We found that exogenously applied GR24 suppressed indole-3-acetic acid transport in internodal segments and decreased the number of adventitious shoots formed; in addition, the distribution of adventitious shoots changed from the apical to middle region of the internodal segments. In contrast, the SL-related inhibitors promoted adventitious shoot formation on both apical and middle regions of the segments. In particular, SL antagonist treatment increased endogenous cytokinin levels and induced multiple shoot development. These results indicate that SL inhibits adventitious shoot formation in ipecac. In ipecac, one of the shoots in each internodal segment becomes dominant and auxin derived from that shoot suppresses the other shoot growth. Here, this dominance was overcome by application of SL-related inhibitors. Therefore, SL-related inhibitors might be useful as new plant growth regulators to improve the efficiency of plant propagation in vitro.

Endogenous auxin determines the pattern of adventitious shoot formation on internodal segments of ipecac.

MAIN CONCLUSION: Endogenous auxin determines the pattern of adventitious shoot formation. Auxin produced in the dominant shoot is transported to the internodal segment and suppresses growth of other shoots. Adventitious shoot formation is required for the propagation of economically important crops and for the regeneration of transgenic plants. In most plant species, phytohormones are added to culture medium to induce adventitious shoots. In ipecac (Carapichea ipecacuanha (Brot.) L. Andersson), however, adventitious shoots can be formed without phytohormone treatment. Thus, ipecac culture allows us to investigate the effects of endogenous phytohormones during adventitious shoot formation. In phytohormone-free culture, adventitious shoots were formed on the apical region of the internodal segments, and a high concentration of IAA was detected in the basal region. To explore the relationship between endogenous auxin and adventitious shoot formation, we evaluated the effects of auxin transport inhibitors, auxin antagonists, and auxin biosynthesis inhibitors on adventitious shoot formation in ipecac. Auxin antagonists and biosynthesis inhibitors strongly suppressed adventitious shoot formation, which was restored by exogenously applied auxin. Auxin biosynthesis and transport inhibitors significantly decreased the IAA level in the basal region and shifted the positions of adventitious shoot formation from the apical region to the middle region of the segments. These data indicate that auxin determines the positions of the shoots formed on internodal segments of ipecac. Only one of the shoots formed grew vigorously; this phenomenon is similar to apical dominance. When the largest shoot was cut off, other shoots started to grow. Naphthalene-1-acetic acid treatment of the cut surface suppressed shoot growth, indicating that auxin produced in the dominant shoot is transported to the internodal segment and suppresses growth of other shoots.

The Effects of a Yoga Exercise and Nutritional Guidance Program on Pregnancy Outcomes Among Healthy Pregnant Japanese Women: A Study Protocol for a Randomized Controlled Trial.

OBJECTIVES: This report provides an experimental protocol for a study designed to verify the effects of yoga exercise and a nutritional guidance program during pregnancy on several key pregnancy and birth outcomes among Japanese women. DESIGN: This is a study protocol of a randomized controlled trial. SETTING/LOCATION: This intervention will be carried out in a university hospital in Tokyo. SUBJECTS: Healthy primiparous women will be recruited at 18-23 gestational weeks in the hospital. A total of 400 participants will be randomly assigned to one of four groups in this trial, with 100 participants in each group-group with yoga exercise, with nutritional guidance, with both yoga and nutritional guidance, and with standard care alone, as the control group. Yoga exercise consists of yoga classes held at the hospital 3 or 5 days a month, duration 60 min, and home practice using a digital video disk, duration 30 or 60 min per session. We recommend participants do yoga at least 3 days a week for a total of 60 min per day. Nutritional guidance is based on individual dietary intake assessed using a brief-type diet history questionnaire. RESULTS: The primary outcome is rate of pregnant women with adequate gestational weight gain. Secondary outcomes include physiologic and psychologic status assessed via biomarkers and health-related scales, dietary nutrition intake, and birth outcomes. CONCLUSIONS: This study shows the effects of a yoga exercise and nutritional intervention. If the intervention is found to be effective, our results will be useful for healthcare providers and pregnant women.