Fertilization controls tiller numbers via transcriptional regulation of a MAX1-like gene in rice cultivation

低施肥でも穂数が減らず、収量を確保できるイネを開発 --ゲノム編集技術で、SDGs時代の新しいイネ遺伝資源を創成--. 京都大学プレスリリース. 2023-06-13.Fertilization controls various aspects of cereal growth such as tiller number, leaf size, and panicle size. However, despite such benefits, global chemical fertilizer use must be reduced to achieve sustainable agriculture. Here, based on field transcriptome data from leaf samples collected during rice cultivation, we identify fertilizer responsive genes and focus on Os1900, a gene orthologous to Arabidopsis thaliana MAX1, which is involved in strigolactone biosynthesis. Elaborate genetic and biochemical analyses using CRISPR/Cas9 mutants reveal that Os1900 together with another MAX1-like gene, Os5100, play a critical role in controlling the conversion of carlactone into carlactonoic acid during strigolactone biosynthesis and tillering in rice. Detailed analyses of a series of Os1900 promoter deletion mutations suggest that fertilization controls tiller number in rice through transcriptional regulation of Os1900, and that a few promoter mutations alone can increase tiller numbers and grain yields even under minor-fertilizer conditions, whereas a single defective os1900 mutation does not increase tillers under normal fertilizer condition. Such Os1900 promoter mutations have potential uses in breeding programs for sustainable rice production

Smoking-the Behavior, Attitude and Knowledge of Junior and Senior High School Students

The smoking behavior and related factors were studied in 1078 junior and senior high school students in five prefectures in Japan. The results were as follows; 1) Forty per cent had tried smoking and 8 per cent were current smokers at the time of the inquiry. 2) While 71 per cent were found to have a negative attitude toward adolescent smoking, only 28 per cent had a negative attitude toward adult men\u27s smoking. 3) Most of the subjects knew about the relation between cigarette smoking and lung cancer, but smaller numbers knew about the important role of cigarette smoking in causing chronic obstructive pulmonary disease, and even fewer knew about that in causing coronary heart disease. 4) The smoking behavior of the subjects was related to that of their parents and of their peers

A Study on the Instruction of "Smoking and Health" in School Health Education

School health education can play an important role in informing youth of the harm of smoking and helping them avoid smoking. The object of this study is to make it clear how the instruction of "smoking and health" is conducted in school health education. To accomplish it, an investigation of the health education text books for senior and junior high school students, and a survey of teachers\u27 attitude and practice of smoking-preventing education in junior high schools were conducted. In text books descriptions about the effects of smoking on body have increased. But there remains tendency to regard smoking mainly as an antisocial behavior, and to prevent students from smoking in their youth, setting aside the lifelong avoidance. Increasing number of text books refer to the relation between smoking and several chronic illnesses, but they have not been satisfactorily provided with experimental or epidemiological data. Few mention the subject of passive smoking. Questionnaires were sent by mail to 2, 105 health education teachers in a randomly selected national sample schools representing 20% of all junior high schools in Japan. Eight hundred and thirty-four teachers answered the questions about their instruction of "smoking and health", their views and attitude towards smoking and smoking-preventing education. Percentage of teachers who mentioned smoking in their health education class in some forms amounted to sixty-five, but most of them spent not more than half a school-hour for it. In many cases instruction was conducted with the aid of text books or in such a way that the teacher talked his or her own experience. Many conducted their instruction of "smoking and health" under such a rather passive goal as to prevent students from smoking merely in their youth

The Influences of the Tohaku Shinkansen Noise on the Daily Life of School Children

This study was carried out in order to measure the noise levels of Tohoku Shinkansen and to examine the influences of that noise on the daily life of elementary school children by the questionnaires

North, east, south, west: mapping vascular tissues onto the Arabidopsis root

The Arabidopsis root has provided an excellent model for understanding patterning processes and cell fate specification. Vascular patterning represents an especially interesting process, as new positional information must be generated to transform an approximately radially symmetric root pole into a bisymmetric structure with a single xylem axis. This process requires both growth of the embryonic tissue alongside the subsequent patterning. Recently researchers have identified a series of transcription factors that modulate cell divisions to control vascular tissues growth. Spatial regulation in the signalling of two hormones, auxin and cytokinin, combine with other transcription factors to pattern the xylem axis. We are now witnessing the discovery of increasingly complex interactions between these hormones that can be interpreted through the use of mathematical models

Adventitious rooting declines with the vegetative to reproductive switch and involves a changed auxin homeostasis

Adventitious rooting, whereby roots form from non-root tissues, is critical to the forestry and horticultural industries that depend on propagating plants from cuttings. A major problem is that age of the tissue affects the ability of the cutting to form adventitious roots. Here, a model system has been developed using Pisum sativum to differentiate between different interpretations of ageing. It is shown that the decline in adventitious rooting is linked to the ontogenetic switch from vegetative to floral and is mainly attributed to the cutting base. Using rms mutants it is demonstrated that the decline is not a result of increased strigolactones inhibiting adventitious root formation. Monitoring endogenous levels of a range of other hormones including a range of cytokinins in the rooting zone revealed that a peak in jasmonic acid is delayed in cuttings from floral plants. Additionally, there is an early peak in indole-3-acetic acid levels 6h post excision in cuttings from vegetative plants, which is absent in cuttings from floral plants. These results were confirmed using DR5:GUS expression. Exogenous supplementation of young cuttings with either jasmonic acid or indole-3-acetic acid promoted adventitious rooting, but neither of these hormones was able to promote adventitious rooting in mature cuttings. DR5:GUS expression was observed to increase in juvenile cuttings with increasing auxin treatment but not in the mature cuttings. Therefore, it seems the vegetative to floral ontogenetic switch involves an alteration in the tissue’s auxin homeostasis that significantly reduces the indole-3-acetic acid pool and ultimately results in a decline in adventitious root formation