Endosperm Weight Research Articles

Physiological mechanism of heterosis in seedling growth of indica F1 rice hybrids.

To determine the possible cause of higher seedling vigor in F1 rice (Oryza sativa L.) hybrids, embryo weight, endosperm weight, leaf area, and seedling growth performance of 16 F1 indica crosses and their parental lines were evaluated. The embryos of 16 F1 rice hybrids showed midparent heterosis and those of 11 F1 rice hybrids showed better parent heterosis (heterobeltiosis). Lower heterosis in the F2 embryos was also observed. Midparent heterosis in endosperm weight did not always appear. Seedling growth of F1 rice hybrids grown in standard nutrient solution for 16 days showed midparent heterosis and relative growth rate in each four-day interval had little heterosis. Heterosis in embryo weight and leaf area were closely related with that in seedling weight. Higher leaf area expansion related with bigger embryo was considered the primary factor for heterosis in seedling growth of indica-indica F1 rice hybrids.

Effect of Zn on Electrical Conductivity (EC), Endosperm Weight, Germination, and Vigor of Three Rices

Effect of Zn on Electrical Conductivity (EC), Endosperm Weight, Germination, and Vigor of Three Rices

Genetic variations in embryo and endosperm weights, seedling growth parameters and alpha-amylase activity of the germinated grains in rice (Oryza sativa L.).

This paper describes the relationships between embryo and endosperm weights and seedling growth parameters, the characteristics of seedling growth and the relationships of the seedling growth parameters with alpha-amylase activity in 36 rice cultivars belonging to three ecospecies, japonica, indica and javanica. The embryo weight was positively and significantly correlated with the endosperm weight in the javanicas, but not in the japonicas and indicas. The entries with the heavier embryo and endosperm weights developed larger top dry weights (TDWs) and leaf areas (LAs) in the javanicas, but not in the japonicas and indicas. Four cultivar groups were classified on a plane defined by the first and second principal components for the seedling growth parameters at different growth or sampling stages of the three ecospecies. The factor loadings of the growth parameters, i. e. top dry weight (TDW), leaf area (LA), relative growth rate (RGR), net assimilation rate (NAR) and top dry weight : leaf area ratio (TLR) varied with the growth or sampling stages of the three ecospecies. The first and second principal components included the different growth parameters depending on the growth or samplin* stages of the three ecospecies. However, the parent-offspring cultivars and the brewer's cultivars were found to belong to the same cultivar groups throughout the sampling or growth stages. Furthermore, some of the cultivar groups or cultivars developed high TDWs through the increase of RGRS and NARS together with the increase of LAS and TLRS at the different sampling or growth stages in the three ecospecies except for the japonicas at the second sampling or growth stage. In the laboratory experiments, the alpha-amylase activity was positively and significantly correlated with the shoot and root fresh weights 3 and 6 days after seed incubation in the japonicas and javanicas, and only nine days after seed incubation in the indicas. However, the laboratory performance of integrated alpha-amylase activity during nine days was not correlated with the glasshouse performance of the TDW and RGR in the three ecospecies. Instead, the principal component analyses indicated that one cultivar group displayed a high integrated alpha-amylase activity together with a high TDW 10 days after sowing and a high RGR at this stage in the japonicas and indicas. However, the cultivar groups with a high integrated alpha-amylase activity and RGR exhibited a low TDW in the javanicas.

Influence of Growth Regulators and Nitrogen on the Number of Endosperm Cells in Wheat Grains from Different Positions on the Ear

The course of development of the endosperm in wheat grains from pot experiments after application of growth regulators and a varied N-supply was followed by an endosperm cell count. The maximum number of endosperm cells was reached within the third week after anthesis and remained constant at two further checking times for more than 30 days after anthesis. There was no effect of application of CCC and Ancymidol at the end of tillering on the maximum number of endosperm cells although the single grain weight was smaller than in the control. The number of endosperm cells and single grain weight had not been altered by the varied N-supply. Within the ear, there is a distinct relation between the maximum number of endosperm cells and single grain weight. During the course of grain development, the differences in the number of cells, appeared earlier than the differences in the grain weight.

Genetic Studies on Improvement of Protein Content in Rice Grain

Relation of protein content to weight of grain components, viz. embryo, rice bran and endosperm was examined using thirty-one varieties which belong to the different ecospecies(japonica, indica, indica-japonica hybrids and large grain varieties)and thirty lines of F5 (Daikoku 1×Arborio) and F5 (Daikoku 1×Fuurenbozu) generations. Endosperm weight was positively correlated with embryo and rice bran weight, respectively(Figs.1 and 2). Embryo weight of japonica varieties was more widely distributed than other ecospecies. Excluding large grain varieties and F5 (Daikoku 1×Arborio), endosperm weight showed a negative correlation with its protein content in the population consisting of indica, japonica, indica-japonica hybrids and F5 (Daikoku 1×Fuurenbozu) (Fig.3). Any correlation was not observed between embryo weight and its protein content (Fig.4). However, indica varietaies and indica-japonica hybrids had larger embryo protein content than japonica varieties. Embryo protein content of Mao-zu-tao of indica varieties was higher about 50% than other indica varieties. This indicates that Mao-zu-tao is a gene source of rising embryo protein content.

Mucronate, Mc, a dominant gene of maize which interacts with opaque-2 to suppress zein synthesis

This paper describes a new dominant mutation of maize, Mc, which interferes in the endosperm with the synthesis of storage proteins. The mutant is characterized by an opaque phenotype; it reduces the deposition of zein and it increases the level of methionine. The mutation is specifically related to storage protein synthesis since soluble and insoluble carbohydrates are present at normal levels. The main interest of this mutant lies in its synergistic interaction with opaque-2 in repressing zein synthesis. In the double mutant o2Mc the accumulation of zein is reduced to less than 10% of that of the normal endosperm. The control on zein synthesis exerted by the double mutant is at the level of production or stability of translatable zein mRNAs. The double mutant o2Mc germinates well offering the opportunity of using it in biochemical and molecular studies related to storage protein synthesis; the reduced endosperm weight of o2Mc negates its practical utilization in breeding maize for quality.

Action of the opaque-7 mutation on the accumulation of storage products in maize endorsperm

The recessive allele at the regulatory locus opaque-7 induces a drastic reduction in endosperm weight and starch and total protein content. All the protein fractions are affected but no qualitative changes have been observed regarding their electrophoretic patterns. The high content of non protein nitrogen in the endosperm suggests the existence, in o7, of an early block in the synthetic route leading to proteins; this is particularly evident for zeins, the maize alcohol soluble storage proteins. The o7 mediated zein repression is more severe on the 19 Kd SDS-zein molecular component. Starch decrease in o7 does not lead to an accumulation of its precursors such as sucrose, glucose and fructose.

Modified Milling Procedure for Separating Endosperm and Nonendosperm Portions of the Wheat Kernel for Protein and Lysine Analysis1

AbstractConventional milling does not uniformly separate endosperm and nonendosperm components of wheats (Triticum aestivum L.). Uniform separation of bran and endosperm is required for protein and lysine analyses because of a protein gradient in wheat endosperm. A modified milling procedure for separating endosperm and nonendosperm components of the wheat kernel was evaluated for its utility in processing small breeder lots of seed for protein and lysine analyses. After conventional milling and sifting, the endosperm adhering to the bran was removed by washing with a 80:20 (vol/vol) ethanol:acetone solution, filtered from the washing solution, dried, and added to the mill flour to reconstitute the endosperm. Reconstituted endosperm weight was used to calculate percent endosperm. Reasonably complete and uniform separations of the endosperm and nonendosperm components were obtained without any appreciable loss of components. Endosperm percentages of the wheats tested ranged from 72.8 to 85.5%. Endosperm protein percentages ranged from 10.8 to 21.0%. Bran protein percentages ranged from 13.1 to 25.1%. Endosperm lysine (percent of protein) percentages ranged from 2.1 to 3.1%. Bran lysine (percent protein) percentages ranged from 3.2 5.0%.

Development of Ribulose 1,5-Diphosphate Carboxylase in Nonphotosynthetic Endosperms of Germinating Castor Beans

Ribulose 1,5-diphosphate (RuDP) carboxylase has been partially purified from dark-grown nonphotosynthetic endosperms of germinating castor beans (Ricinus communis var. Hale). The Km values for RuDP, HCO(3) (-), and Mg(2+) are 0.51, 33, and 1.78 mm, respectively. The pH optimum for the carboxylation reaction is pH 7.5. Germination is required for the development of the carboxylase in the endosperms. The enzyme reaches a maximal activity in 4- to 5-day-old dark-grown seedlings (which have an endosperm weight of approximately 0.75 g fresh weight/bean) and then declines. Total endosperm carboxylase activity is 1230 nmoles/min.g fresh weight which is 25 and 50% of the total activity developed in soybean and maize leaves, respectively. Specific activity of the carboxylase in crude soluble endosperm preparations (which contain enzymic and storage protein) is 0.05 mumole/min.mg protein. This is 5 times greater than the specific activity of RuDP carboxylase in soluble preparations from etiolated leaves. During germination the V(max) of the endosperm carboxylase for RuDP increases 10-fold. Development of the enzyme is inhibited 90% by the exposure of the endosperm to 2 mug/ml cycloheximide or 50 mug/ml chloramphenicol. Light (or phytochrome Pfr) is not required for the synthesis of the enzyme. Electron photomicrographs of dark-grown endosperm cells (with peak RuDP carboxylase activity) show proplastids with several invaginations of the inner membrane but no prolamellar-like structures.

Weight, Oil, and Fatty Acid Composition of Components of Normal, Opaque‐2 and Floury‐2 Maize Kernels1

Normal and opaque‐2 kernels from segregating maize (Zea mays L.) ears were examined for kernel components, oil content, and fatty acid composition. Normal kernels were higher in kernel and endosperm weight and embryo oil concentration, and lower in embryo weight than opaque‐2 kernels. Compared to normal, the oil from opaque‐2 kernels was slightly but significantly higher in oleic acid and lower in linoleic acid composition. Comparison of normal and floury‐2 kernels from segregating ears showed kernel and endosperm weights of the normal kernels were greater than for floury‐2, and embryo weight was similar. In a comparison of near‐isogenic floury‐2 and normal single‐cross hybrids, the kernel components were heavier in normal, while percent oil was greater for floury‐2 owing largely to a greater proportion of embryo. Percent oil in embryo was less in floury‐2 hybrids.

Protein Distribution in the Oat (Avena sterilis L.) Kernel1

Kernels of 25 selections of Avena sterilis were dehulled, and the groats were hand‐dissected into the embryonic axis, scutellum, bran, and starchy endosperm. All fractions were weighed, analyzed for protein, and compared with one cultivar of Avena sativa L., Markton. Groat yield and groat size were lower for A. sterilis L. than for Markton. Protein concentration (%) was higher in the A. sterilis selections, but protein content per groat was lower, due to smaller groats. A. sterilis groats were mostly starchy endosperm (58.0%) and bran (39.1%), with scutellum and embryonic‐axis fractions contributing little to the total groat weight. These values were similar to those of Markton. Both bran weight and endosperm weight were positively correlated with groat size, although the proportion of endosperm was higher in larger groats. Protein concentration was lowest in the starchy endosperm. Except for a few selections, protein concentration of all fractions was higher in A. sterilis than in Markton. Selections with high protein showed higher protein concentrations in both the bran and starchy endosperm. As a single fraction, bran contained the greatest amount of the total groat protein in all but three of the selections.

Effect of Outcrossing on Protein Quality, Kernel Weight, and Related Characters in Opaque‐2 and Floury‐2 Maize (Zea mays L.)1

Outcrossing of opaque‐2 and floury‐2 single crosses of corn, Zea mays L., to the same mutant but unrelated genotype, significantly increased kernel weight and weight of grain per ear of opaque‐2 and floury‐2 single crosses, and this increase was greater than in the normal counterparts. When sibbed, opaque‐2 and floury‐2 kernels had heavier germs than the normal kernels. Outcrossing also increased weight of endosperm in opaque‐2, floury‐2, and normal kernels; and germ weight in opaque‐2 and normal kernels. Protein and lysine content were apparently not affected by outcrossing.

Energetics of Early Seedling Growth in Corn (Zea mays L.)1

Early growth of the corn seedling was studied in relation to its dependence on energy from endosperm and early photosynthetic tissue. Measurements were made of (1) endosperm utilization rate of seedlings grown in light and dark; (2) growth and leaf area of seedlings as affected by partial endosperm removal; and (3) photosynthesis (P), respiration (R), and 14CO2 uptake of seedlings as affected by endosperm excision at different ages. Endosperm utilization and growth rates were similar in light and dark until the two‐leaf stage l0 days after germination. Regression of root and shoot growth on age was 15.4 mg/day and of root and shoot growth on endosperm weight loss was .65 mg/mg. Partial removal of the endosperm at seeding resulted in decreased growth of roots and shoots and indecreased leaf area per seedling. Apparent P was negative at 9 days of age and was greatest for seedlings with endosperm excised. Apparent P was positive and similar at days 11, 12, and 13 for seedlings with endosperm excised and was positive, and increased from day 11 to day 13 for seedlings with endosperm. Energy obtained from CO2 fixation was not equivalent to that supplied by the endosperm until the 10th day. At this time seedlings had two fully emerged leaves. Absorption of 14CO2 was similar for seedlings with and without endosperm, and increased with age as a result of increased leaf area and increased absorption per unit of leaf area. Endosperm removal resulted in greater translocation of 14CO2 to seedling roots.

Physiology of Cereal Grain II. Starch Granule Formation in the Developing Barley Kernel

Types, numbers, volumes, and weights of starch granules in the barley endosperm were measured at different times from anthesis to maturity. The formation of two types of granule was confirmed: the first (type A) was initiated until 15 days after anthesis; the second (type B) between 18 and 30 days. At maturity there were approximately 10 times as many type B granules as type A, although the latter made up 90 per cent. of the total granule volume. There was a linear relationship between starch granule and endosperm volume throughout kernel development, while the rate of increase in volume per unit granule volume was the same, irrespective of granule size, at anyone time. Starch weight increased as endosperm dry weight increased although the precise form of this relationship is in doubt. The interrelationships between starch granule weight and volume, and also endosperm dry weight and volume, suggest that both starch granules and endosperm increase in density during development.

STUDIES ON COLCHICINE‐INDUCED AUTOTETRAPLOID BARLEY.: III. PHYSIOLOGICAL STUDIES

THE MORPHOLOGICAL and cytological characteristics of some colchicine-induced autotetraploid barley plants have been given in the previous paper of this series. The present account reports some physiological characteristics of these tetraploid plants. RESPIRATION.-Oxygen consumption and carbon dioxide production by the germinating seeds of 2n and 4n barley were measured by means of the microrespirometers of Warburg as used by one of us in previous measurements of respiration in germinating seeds (Tang, 1931). Seven dehulled seeds which had been germinating at 240C. for 36 hours were placed in the main portion of the respirometer vessel. The inset contained 0.2 ml. 10 per cent NaOH when oxygen consumption was to be measured, and water when cazrbon dioxide production was to be measured. Two respirometers were run at a time beside the thermobarometer, one for the 2n seeds and the other for the 4n seeds. The experiments were performed at 180, 240 and 280C. At the end of the experiments the seeds were ground and dried to constant weight and their nitrogen contents were estimated by micro-Kjeldahl. Table 1 gives the rates of 02-consumption and C02-production of the germinating seeds of the 2n and 4n barley plants used. It is seen from this table that both the rates of 02-consumption and C02-production of the 4n seeds were lower than those of the 2n seeds, whether expressed in terms of dry-weight or of nitrogen content. Taken as a whole, the respiratory quotients of the 4n seeds were found to be lower than those of the 2n seeds. 1 Received for publication September 14, 1944. Manuscript received through the Department of State, Washington, D. C., and published under a special ruling of the Editorial Board. The R.Q. values for both kinds of seeds, however, changed with temperature, agreeing with a previous observation to this effect in Lupinus albus(Tang, 1932). The values of the temperature quotients for 02-consumption were different in the two cases, being 3.4 for the 2n seeds and 2.8 for the 4n seeds. That the lower rate of respiration in the 4n seeds is an inherent characteristic of the cells, and not due to the fact that they may contain less living matter in proportion to the reserve materials is shown by the following experiment. The embryo and endosperm were separated from each other in one hundred 2n and one hundred 4n seeds. The two portions were dried and weighed separately. No difference was found in the ratio of weight of embryo to weight of endosperm in the two types of seeds. TRANSPIRATION.-The rates of transpiration of 55-day-old 2n and 4n barley plants were measured by means of simple potometers. Seven 2n and an equal number of 4n plants, all at the 4-leaf stage, were used, each placed in a separate potometer. The experiment lasted from noon to 10 P.M., at the end of which the leaf area and dry weight of the seedlings were ascertained. The average amount of water transpired by the seven 2n seedlings during the 10 hours of exposure was 0.38 ml. per square centimeter of leaf area. That for the seven 4n seedlings was 0.26 ml. per square centimeter. This difference becomes more apparent when the rate is expressed in terms of ml. transpired per unit dry-weight. In that case, the respective values become 78.3 ml. per gm. and 38.8 ml. per gm. OSMOTIC, CONCENTRATION AND SUCTION PRESSURE.

On the Relation between Vitamin-B Content and the Form and Quality of Rice Kernels.(resume)

The relation between Vitamin-B content and the form and quality of hulled rice was investigated in the following manner: 13 varieties of hulled rice which are different in size and weight were taken and fed the fowls to determine the latent period of beri beri illness. Subsequently the correlation coefficient between Vitamin-B content and the form and quality of rice kernels was calculated. The results obtained are summarized below. 1. Correlation between length×width×thickness and Vitamin-B content of rice kernels in a volume. r=-0.76±0.08 2. Correlation between weight per 1, 000 kernels and Vitamin-B content of rice kernels in a volume. r=-0.78±0.07 3.Correlation between (length)/(width) and Vitamin-B content of rice kernels in a volume. r=-0.02±0.19 4. Correlation between the weight of embryo and Vitamin-B content of rice kernels in a volume. r=-0.36±0.16 5. Correlation between the volume of embryo and Vitamin-B content of rice kernels in a volume. r=-0.55±0.13 6. Correlation between the weight of endosperm and Vitamin-B content of rice kernels in a volume. r=-0.78±0.07 7. Correlation between the volume of endosperm and Vitamin-B content of rice kernels in a volume. r=-0.78±0.07 8. Correlation between the all bran layer and Vitamin-B content of a rice kernel. r=+0.56±0.13 9. Correlation between the thickness of outer bran layer and Vitamin-B content of a rice kernel. r=-0.08±0.19 10. Correlation between the thickness of inner bran layer and Vitamin-B content of a rice kernel. r=+0.74±0.08 The correlation coefficient noted above seems to indicate that the magnitude of weight per 1.000 kernels, length×width×thickness, weight and volume of endosperm, thickness of inner bran layer is closely to Vitamin-B content of rice kernels. Very slight correlation was found between the magnitude of (length)/(wedth), weight of embryo and Vitamin-B content of rice. Again no marked correlation between Vitamin-B content and the magnitude of the volume of embryo and the thickness of all bran layers was found. From these results, it is advisable to choose the small rice kernels with thickened inner bran layer for better supply of Vitamin-B. Also it is recommended to determine the thickness of inner bran layer as an easy method of Vitamin-B content of the rice kernels.