Rice Pollen Research Articles

イネ科花粉について，とくにイネ（?EＯｒｙｚａ Ｓａｔｉｖａ?F）を中心として

In order to examine the possibility of distinguishing rice pollen from other grasses, the sculptural details of 68 species including wild and cultivate type were studied based on the transmission electron (TEM) and phase contrast microphotographs (PCM).It was found that TEM of surface replicas might help the interpretation of phase contrast observations and might clarify the appreciation of differences in cases where a discrimination of the various types was difficult.Three types of grass pollen could be distinguished based on PCM.1. Punctate type: Grains have single spinules occurring one by one on the surface based on TEM. In this type each spinule appears as a distinct dark dot with phase contrast. Zea, Coix, Secale and sometimes Hordeum.2. Areolate (negative reticulate) type: More than three spinules appear grouped on small islands or clumps which are isolated by incised grooves based on TEM. Each spinule clump is seen as an irregularly delimited dark dot and their sculpture is areolate. Most wild grasses were studied.3. Maculate type: Mixed type of single spinules and clumps of two or three spinules. According to PCM, grains of this type are seen as indistinct punctate in lower focus but more or less indistinct areolate in upper focus. Oryza, Hordeum, Triticum and some Agropyron. Some of Bambusoidae such as Arundinaria, Chinobambusa and Sasa have grains of spinule clump type, but each clump is so small that it is seen as a indistinct dot and their sculpture is maculate.From this fact Oryza pollen can be distinguished from those of punctate and areolate types, but it is difficult to distinguish Oryza from other maculate pollen except for Hordeum and Triticum which have larger pollen than that of Oryza.

Genotypic Differences in the In Vitro Formation of Embryoids from Rice Pollen

Twenty varieties of rice were assessed for the ability of their pollen to give rise to ombryoids and haploid plantlets in anther culture. There were wide differences in response between the varieties, a primitive cultivar from Assam being the most responsive. Only anthers containing uninucleate microspores showed differentiation of pollen embryoids. It appeared that during the initial stages of development the embryoids were attached to the wall of the anthors by a suspensor-like attachment. Genotypic differences, besides several other factors, have a definite role in shifting the normal course of development of the pollen.

Studies on the Developmental Physiology in Rice Pollen : I. The metabolic patterns connected with the structural changes in developing pollen

Several investigations have been carried out on the male sterility in rice plants, especially referring to the damage in pollen by cold weather. So far results obtained, however, seem to be unsatisfactory in the developmental physiology of rice pollen which is one of the most important field. The work reported here is a part of the study to elucidate the metabolic patterns connected with the developmental phases in rice pollen. The results obtained were summarized as follows; 1. The occurrence of the unfruitfulness spikelets on the panicles in rice varieties, Kamenoo and Akaho, was encouraged by top-dressing of excessive nitrogen at the early stage of panicle formation. 2. The increment of the pollen grains in diameter was rapid at one nuclear Period (I period), but slow at binuclear period (II period) and again vigorous at trinuclear period (III period). The change in water content of anther was similar to that in the pollen diameter above mentioned. 3. The length of anther closely correlated with the developmental stages in pollen. 4. Total nitrogen content per dry weight of anther at I and II period was higher than at III period. Insoluble nitrogen (IN) content per anther increased at I period. The increment of IN at II period was slow, while the soluble nitrogen (SN) per anther began to increase since this stage. At III period, both IN and SN contents per anther increased conspicuously. On the basis of such results, it was assumed that there are three patterns of nitrogen metabolism in pollen development; the first is active protein synthesis at I period, the second is active amino -acid synthesis at II period and the third is active synthesis of both protein and amino-acid at III period. 5. Soluble and insoluble organic phosphorous contents per anther gradually increased to II period, but they decreased at III period. On the contrary, inorganic phosphorous (Pi) content per anther at III period was over three times than at II period. As a result, Pi content in anther at III period was about 60% of total phosphorous content. 6. Although there was just a trace of starch content in anther at I and II period, it increased remarkably at III period. High synthetic activity of starch at III period showed a sharp contrast to those of other periods. 7. The top-dressing of excess-nitrogen caused the high occurrence of the fruitfulness spikelets following the decrease of SN content at II period and Pi and starch content at III period in anther. 8. On the morphorogical observation in developing pollens, it was recognized that the generative nucleus was surrounded by membrane-like substance at the time of division. The characteristics of rice pollens seem to be represented by the metabolic patterns proper to one-, bi- and tri- nuclear period, and also by the presence of the membrane-like substance surrounding the generative nucleus. The morphological and physiological knowledges of rice pollens will be enriched through the elucidation of these properties of them and this effort will contribute to throw light on the mechanism of the occurrence in male sterility of rice plants.

Studies on the Longevity of Pollen Grains of Rice, <i>Oriza sativa</i> L

1. Conspicuous morphological change was observed in rice pollen grains when they were left in the air after shedding.2. Within a few minutes, a lot of vacuoles appeared around each pollen grain. Inclusion of the vacuoles was exuded from inside of pollen grains, but chemical analysis has not been carried out in the present study.3. However, a rapid alteration in the physiological condition might have occurred to result in a decrease of germinability of pollen grains. And in part, this has been proved by TTC test.4. Above described transformation of the pollen grains was characteristically occurred when they were shed sparsely on the slide glass. But when they were scattered densely, there were also observed a few pollen grains which kept the viability for longer time.5. It was concluded that the rice pollen grains rapidly lost their viability by losing inner substances when they were left in the drought condition in the air. Further study on the physiological and metabolic disturbances in the course of losing viability, will throw light on the problem of longevity in rice pollen grains.

Rice pollen asthma.

Asthmatic attacks are most frequent and severe in autumn in Japan. There is much argument as to their cause. Recently, the authors have seen a severe attack of bronchial asthma which began suddenly in the beginning of September, after the patient had been almost free from asthma for a period of ten months after being desensitized with house dust. It came to our mind that this was just the season that rice (oryxa sative) came into flower. Skin tests with rice pollen extract were strongly positive, and an inhalation test was also positive, suggesting that he was hypcrsensitive to rice pollen. The same results were obtained on thirtccn asthmatic children. From these results it might be concluded that rice pollen asthma indeed exists in Japan where rice is widely cultivated. As to the antigenicity of pollens of cereal grains in producing pollinosis, those of rye, barley, oat, wheat and corn received attention,l while little is known about that of rice.2 Grass pollens similar to rice pollen are included in the groups Elasine indica, Gigitalia adscendens, and Miscanthus sinensis (pampas grass) , all of which, like rice, belong to the Graminae family and grow wild in autumn in Japan. There still remain unknown facts concerning cross-allergenicity among the above-described species of the Graminae family. Anyway, rice pollen is the most abundant in this family, and its pollen has a size of 4347 microns in diameter. The methods for pollen-counting were essentially the same as recommended by the Pollen Survey Committee of the American Academy of except that an area of 10 sq. cm. instead of 1 sq. cm. was used. Two peaks of marked increase in the amount of pollen were found in the 7-months period from May to September, 1967. The first peak lasted a month from the beginning of AZay to the beginning of .June, and the second peak was from the middle of July to the end of October. Almost all the pollen grains which made up the second peak were identified as belonging to the species Graminae by direct microscopic examination and comparison with pollen directly collected from the oryxa sativa stamen. Efflorescence of the rice plant in the district studied was found to occur from the middle of July to the end of September in 1967, just matching the second peak of Graminae pollen. In 34 of 41 asthmatic children, the asthmatic attacks occurred mostly in autumn, closely corresponding to the pollination of the rice plant (Fig. l),

Studies on Rice Pollen Asthma : II. Studies on cross antigenicity between Rice Pollen and other Grass Pollens

Studies on Rice Pollen Asthma : II. Studies on cross antigenicity between Rice Pollen and other Grass Pollens

On the Artificial Germination of Pollen of Rice : VI. Protoplasmic streaming in pollen tube. : VII. The relation between temperature and protoplasmic streaming.

The movement of the protoplasm in pollen tube is generally streaming accompanied with rotation. The movement was able to be observed at first when pollen tube reached 30YAMADA∼35μ in length for 5 minutes after setting of pollen on the media. The rate of protoplasmic streaming (μ/sec.) was measured under microscope from that time. It was found that the initial rate of streaming (5∼10 minutes after pollen setting) was very high in Japanese varieties, but it became low as the time went on. In foreign varieties, on the contrary, the rate was very low during the whole course. These results are shown in Figure 1. The results obtained under various temperature conditions are given in Figure 2. According to those, the rate of streaming increased as the temperature rose to some extent. The maximum streaming rate was recognized only at 30°C among all plots for 5∼10 minutes after pollen setting. The rotating movement of the protoplasm ceased at 40°∼45°C, and the streaming also at nearly 10°C. Changes of the streaming rate with time under different temperature conditions were examined by using two Japanese varieties (Figure 3). At 30°C the initial rate of streaming was very high, but it was then slowed down and ceased. Under 15°and 20°C conditions, the rate were always low during the whole period of the experiment. However when the temperature rose to 38°C, the rate fell between those of 30°and 15°C. In the case of 25°C condition, the intermediate values between 30°and 38°C were obtained.

Note on the detection of segregation by examination of the pollen of rice

Note on the detection of segregation by examination of the pollen of rice