Japonica Rice Seeds Research Articles

Foliar application of molybdenum reduces yield loss and preharvest sprouting in Japonica rice seeds subjected to simulated flooding during seed development and maturation

Flooding damages rice crops and its incidence is increasing. Foliar spray applications of molybdenum (100, 600 or 3000 mg Mo L-1), abscisic acid (ABA, 50 μM), or deionised water (control) were made to pot-grown plants of the Japonica rice cv. Gleva at flag leaf appearance to determine their effects on seed yield and pre-harvest sprouting after flooding. Plants were submerged , to simulate flooding, for four days from 20 or 30 days after anthesis (DAA). Seed yield per plant, seed weight, and pre-harvest sprouting were determined after harvest at 37 DAA. Seed yield and weight were substantially reduced and pre-harvest sprouting promoted by submergence, with greater sprouting after the later treatment. Prior treatment with molybdenum or ABA reduced pre-harvest sprouting (P P > 0.05), compared with deionised water. The molybdenum concentration in both sprouted and non-sprouted seeds harvested at 37 DAA responded positively to molybdenum application rate. Molybdenum application rate had no consistent effect on seed ABA concentration. Foliar application of 100 mg Mo L-1 at 200 L ha-1 provided the most promising mitigation of flood damage, but benefits were minor in the context of seed damage from submergence.

Han River culture’s the first Cultivation of Japonica (Danrip) Rice and Beans in the Go-joseon Civilization

Go-Joseon civilization was the first ancient East Asian civilization established on the Korean peninsula and Manchuria in 3,000 BC by integrating the Han River culture, the Taedong River culture, and Hongshan culture.<BR> As a preceding foundation of Go-joseon civilization, Han River culture’s contribution to the cultivation of japonica (danrip) rice in 12,500 BP is the start of what is now widely known as “rice farming.” There is evidence of this when japonica rice seeds dating back 12,500 BP ± 150 years were found during excavations near the South Han River and Geum River basin. Additionally, Jodongri-based japonica (danrip) rice seeds (from 4,250~4,290 BC), Dacheonri-based japonica (danrip) rice seeds, wheat, barley, beans, foxtail millet and proso millet (from 3,500 BC) found in close proximity to the South Han River and the Geum River basin, Gawaji rice seeds found near Goyang city (3,360 BC ± 80 years) all provide support for such cultivation. The farming of japonica rice, beans, millet, wheat, and barley also spread to other parts of the Korean peninsula including areas near the Yeongsan River, Seomjin River, Nakdong River, Imjin River, Ryesong (Yeseong) River, Chongchon River, and the Amrok (Yalu) River. Moreover, the Han River culture’s method of rice cultivation traveled to the Liaodong peninsula and was used by the Dongyi (東夷) tribes living near the north of the Yangtze River on the eastern coast of China, and also to Kyushu, Japan. <BR> Although there is evidence of conventional rice cultivation near the Yangtze River, excavation of the Oksumam (玉蟾岩) cave revealed two grains of indica (jangrip) rice dating back to 11,000 bp. When directly comparing japonica rice to indica rice, the former derives from the Neolithic Han River culture, originating from the central region of the Korean peninsula. Following the establishment of the Go-joseon state and civilization, japonica rice cultivation traveled and became prevalent throughout East Asia. <BR> As one of the earliest human independent civilizations, Go-joseon civilization contributed the cultivation of japonica (danrip) rice, and beans and served as a basis for a unique pattern of food culture of rice and soy sauce(and soybean paste) in Korean and East Asian Civilizations.

Deficiencies in both starch synthase IIIa and branching enzyme IIb lead to a significant increase in amylose in SSIIa-inactive japonica rice seeds.

Starch synthase (SS) IIIa has the second highest activity of the total soluble SS activity in developing rice endosperm. Branching enzyme (BE) IIb is the major BE isozyme, and is strongly expressed in developing rice endosperm. A mutant (ss3a/be2b) was generated from wild-type japonica rice which lacks SSIIa activity. The seed weight of ss3a/be2b was 74-94% of that of the wild type, whereas the be2b seed weight was 59-73% of that of the wild type. There were significantly fewer amylopectin short chains [degree of polymerization (DP) ≤13] in ss3a/be2b compared with the wild type. In contrast, the amount of long chains (DP ≥25) connecting clusters of amylopectin in ss3a/be2b was higher than in the wild type and lower than in be2b. The apparent amylose content of ss3a/be2b was 45%, which was >1.5 times greater than that of either ss3a or be2b. Both SSIIIa and BEIIb deficiencies led to higher activity of ADP-glucose pyrophosphorylase (AGPase) and granule-bound starch synthase I (GBSSI), which partly explains the high amylose content in the ss3a/be2b endosperm. The percentage apparent amylose content of ss3a and ss3a/be2b at 10 days after flowering (DAF) was higher than that of the wild type and be2b. At 20 DAF, amylopectin biosynthesis in be2b and ss3a/be2b was not observed, whereas amylose biosynthesis in these lines was accelerated at 30 DAF. These data suggest that the high amylose content in the ss3a/be2b mutant results from higher amylose biosynthesis at two stages, up to 20 DAF and from 30 DAF to maturity.

Du3, a mRNA cap-binding protein gene, regulates amylose content in Japonica rice seeds

Five non-allelic dull (du) mutants have been isolated and characterized as low amylose mutants in rice (Oryza sativa) endosperm. Synthesis of amylose is controlled by Waxy the gene that encodes granule-bound starch synthase. We previously showed that the du1 and du2 proteins may encode general splicing regulators which affect the expression level and splicing efficiency of Waxy b (Wx b ), an allele that has a single-base mutation in the 5� splice site of intron 1. Here we report that the du3 mutant has also reduced the splicing efficiency of Wx b pre-mRNA. Furthermore, map-based cloning revealed that Du3 encodes the rice homolog of a cap-binding protein 20 kD subunit (CBP20), a component of the heterodimeric nuclear cap-binding complex (CBC) playing a role in pre-mRNA splicing, RNA nuclear export, and nonsense-mediated decay. Transient expression of green fluorescent protein (GFP)-tagged Du3 proteins in rice protoplasts resulted in localization to the nucleus showing a speckled pattern similar to the pattern displayed by other splicing factors.

Difference of optimum germination temperature of seeds of intact and dehusked japonica rice during seed development

The effects of incubation temperature on germination of intact and dehusked japonica rice that had been harvested every 5 days from 10 days after anthesis (DAA) to 70 DAA were surveyed. At 30 °C incubation, the germination percentage of intact seeds at 25 DAA exceeded that of dehusked seeds. This tendency persisted until 65 DAA, when around 95% of both intact and dehusked seeds germinated. Germination percentages of intact seeds incubated at 20 °C were lower than seeds incubated at 30 °C for all DAA. However, germination percentages of dehusked seeds incubated at 20 °C were consistently higher than at 30 °C. Germination percentages of intact and dehusked seeds were similar at 20 °C incubation. Germination of intact seeds under 34/11 °C (16/8 h) was higher than at 30 °C. In contrast, germination of dehusked seeds under 34/11 °C (16/8 h) was lower than at 30°C. Inhibitory effects of removing husk on germination were observed from 15 to 70 DAA. Almost all of the intact seeds at 45 DAA germinated when imbibed 35, 30 and 25 °C, and germination percentages decreased with decreasing incubation temperatures from 20 to 15 °C. By contrast, germination percentage of dehusked seeds was highest in 20 °C incubation temperature; further increase or decrease of incubation temperature reduced germination percentage. The optimum germination temperature of intact and dehusked seeds of japonica rice differs during seed formation, such that the extent of germination inhibition by husk removal depends on the incubation temperature.

English

Rapidly growing embryogenic calli of different ages derived from the scutellum of mature seed embryos of indica rice (Rasi) and mature seeds of japonica rice (Taipei 309) was biolistically transformed. Plasmid pUCGUS containing the uidA gene encoding �-glucuronidase was used to optimize transformation conditions using various combinations of helium pressure, target distance and gap distance. Plasmid pHX4 carrying hygromycin phosphotransferase (hph) gene and pUCGUS was used for co bombardment. Resistant calli were selected in the presence of hygromycin B. Successful co-transfer of DNAs to cells was monitored by analyzing transient gus expression 24 h after bombardment and 24 days after selection. Maximum level of gus expression was observed if calli were selected for transformation after 44 days in maintenance medium. Maximum callus transformation frequency of 37.5 was observed for Taipei 309 as compared to 24.2 for indica rice cv. Rasi.

Transgenic expression of trypsin inhibitor CMe from barley in indica and japonica rice, confers resistance to the rice weevil Sitophilus oryzae.

Indica and japonica rice (Oryza sativa L.) plants were transformed by particle bombardment with the Itr1 gene encoding the barley trypsin inhibitor BTI-CMe, under the control of its own promoter that confers endosperm specificity, and the maize ubiquitin promoter. From 38 independent transgenic lines of indica (breeding line IR58) and 15 of the japonica (cv Senia) selected, 22 and 11, respectively, expressed the barley inhibitor at detectable levels. The transgene was correctly translated as indicated by western blot analysis with a level of expression in R3 seeds up to 0.31% (IR58) and 0.43% (Senia) of the total extracted protein. The functional integrity of BTI-CMe was confirmed by trypsin activity assays in liquid media and by activity staining gels, performed with seed extracts. The significant reduction of the survival rate of the rice weevil (Sitophilus oryzae, Coleoptera: Curculionidae) reared on homozygous transgenic indica and japonica rice seeds expressing the BTI-CMe, compared to non-transformed controls, and the decrease in the trypsin-like activity of insect crude midgut extracts, confirmed the utility of this proteinase inhibitor gene for the control of important storage pests.

Parameters influencing the regeneration capacity of calluses derived from mature indica and japonica rice seeds after microprojectile bombardment

The microprojectile bombardment procedure has allowed the stable transformation of indica and japonica rice varieties, although at different frequencies of transformation depending mainly on their regeneration capacity and on the specific parameters of the transformation protocol. A study of the process of regeneration to whole plants from primary calli derived from mature indica and japonica rice seeds, via embryogenesis, has shown that somatic embryos are produced by division and differentiation of the external cell layers of callus tissues. Adjusting the bombardment conditions to optimize gene delivery to those regenerable cells, we have evaluated the influence of parameters such as the target distance, particle penetration and the effect of osmotic treatment on the regeneration capacity of bombarded cells.

The Effects of Kinetin and Gibberellin on the Germination of Dehusked Seeds of Indica and Japonica Rice (Oryza sativaL.) under Anaerobic and Aerobic Conditions

The effects of kinetin and gibberellin were examined under anaerobic conditions (0% oxygen) and aerobic conditions (20% oxygen) on the germination of dehusked seeds of indica and japonica rice cultivars that had been harvested at different times during the formation of seeds. Surjamkhi was used as a representative of deep dormant indica cultivars and Assam IV as a less dormant indica cultivar. Sasanishiki was used as the japonica rice cultivar. Both phytohormones were applied at a concentration of 10−3mwhich proved to have the greatest stimulatory effect in preliminary work at concentrations of 10−3–10−5m. Under aerobic conditions, inhibition of germination by dehusking of Sasanishiki seeds that had been harvested either 30 or 60 d after anthesis was overcome by kinetin and all seeds germinated. Complete germination induced by kinetin under aerobic conditions was also achieved with the dehusked seeds of the indica rice cultivar Assam IV that had been harvested on two occasions and of Surjamkhi that had been harvested 28 d after anthesis. In contrast, germination of dehusked japonica seeds stimulated by anaerobiosis was inhibited by kinetin. The stimulatory effects of gibberellin on the germination of indica and japonica rice seeds were observed under aerobic and anaerobic conditions. Under anaerobic conditions, the responses of dehusked indica and japonica rice seeds to kinetin and gibberellin differed, being negative with kinetin and positive with gibberellin. Under aerobic conditions, the stimulatory effects of kinetin on germination of dehusked seeds were greater than those of gibberellin. Thus, treatment with kinetin appears to be useful for breaking the considerable dormancy commonly observed in the dehusked seeds of indica rice. Mechanisms are proposed to explain the stimulatory effects of these phytohormones on the germination of dehusked seeds of indica and japonica rice under aerobic and anaerobic conditions.

Differences in the Effects of Dehusking during Formation of Seeds on the Germination of Seeds of Indica and Japonica Rice (Oryza sativa L.)

Abstract Differences in germination of intact and dehusked seeds of two japonica and two indica cultivars of rice ( Oryza sativa L.) were examined during the development and maturation of seeds both under high-temperature (30/23°C) and low-temperature (20/13°C) regimes and a 14-h photoperiod in growth cabinets. As described previously for seeds grown in the paddy fields, germination of freshly harvested japonica rice seeds that developed and matured in growth cabinets was inhibited by dehusking. We observed a roughly consistent triphasic pattern with respect to the germination of intact and dehusked seeds during the development and maturation of seeds of indica and japonica rice. The triphasic pattern consisted of: ( a ) an initial phase, during which germination was stimulated by dehusking both in indica and japonica rice; ( b ) a second phase during which almost no dehusked seeds of indica or japonica rice germinated; and ( c ) a third phase during which intrinsic differences between indica and japonica rice were observed, with dehusking stimulating germination of indica rice but inhibiting that of japonica. Temperature regimes did not affect this triphasic pattern, but the time from the day of anthesis to mass maturity was affected by temperature regimes, and the effect was more pronounced in indica than in japonica rice.

Differences in the Effects of Dehusking during Formation of Seeds on the Germination of Seeds of Indica and Japonica Rice ( Oryza sativaL.)

Differences in germination of intact and dehusked seeds of two japonica and two indica cultivars of rice ( Oryza sativaL.) were examined during the development and maturation of seeds both under high-temperature (30/23°C) and low-temperature (20/13°C) regimes and a 14-h photoperiod in growth cabinets. As described previously for seeds grown in the paddy fields, germination of freshly harvested japonica rice seeds that developed and matured in growth cabinets was inhibited by dehusking. We observed a roughly consistent triphasic pattern with respect to the germination of intact and dehusked seeds during the development and maturation of seeds of indica and japonica rice. The triphasic pattern consisted of: ( a) an initial phase, during which germination was stimulated by dehusking both in indica and japonica rice; ( b) a second phase during which almost no dehusked seeds of indica or japonica rice germinated; and ( c) a third phase during which intrinsic differences between indica and japonica rice were observed, with dehusking stimulating germination of indica rice but inhibiting that of japonica. Temperature regimes did not affect this triphasic pattern, but the time from the day of anthesis to mass maturity was affected by temperature regimes, and the effect was more pronounced in indica than in japonica rice.

Studies on changes in fatty acid composition and content of endogenous antioxidants during γ irradiation of rice seeds

AbstractAccelerated aging effects, induced by y irradiation, were investigated on the fatty acid composition of lipids and on the content of endogenous antioxidants of four Indica and four Japonica rice seeds with and without intact hull. While the linoleic acid content of the phospholipids decreased gradually with the increase in irradiation doses, there was a corresponding increase in the linoleic acid content of the free fatty acids. Such changes were drastic, especially in the case of Japonica rice seeds irradiated without intact hull. However, the neutral lipids were found to be resistant to γ irradiation.The α‐tocopherol content was found to decrease (markedly) in rice seeds irradiated with or without hull, especially in the Japonica rice seeds. At a dose of 15 kGy only traces of a‐tocopherol could be detected in Japonica and Indica rice seeds irradiated with and without intact hull. Oryzanol, a relatively weaker anti‐oxidant, was found to be more resistant to oxidative damage than a‐tocopherol. At 15 kGy, the oryzanol content ranged from 59 μg to 170 μg/g lipid in rice seeds irradiated with intact hull, while the corresponding value for rice seeds irradiated without hull was 52 μg to 153 μg/g lipid.The overall susceptibility to oxidative damage was less in Indica rice seeds, indicating that the antioxidative defense system offered better protection in overcoming oxidative stress in Indica rice hull than in Japonica rice hull.

High Temperature Storage Effect on Longevity of Rice Seeds

ABSTRACTStorage of Indica (Oryza sativa L. cv. Katakutara) and Japonica (Oryza sativa L. cv. Kusabue) rice seeds at 30° and 40°C for 2 months in the dark did not result in the loss of viability in both cultivars. Storage at 60°C, however, resulted in a complete loss of germination after 45 days in the case of Kusabue while the Katakutara rice seeds retained the germination potential well above 95%. Corresponding increases in the linoleic acid content of the free fatty acid fraction and TBA values of the extracted lipid fraction were also observed in Kusabue rice seeds. The investigation indicated that the Indica rice seeds were better protected than the Japonica rice seeds by the enclosing rice hull during the storage period.

Inhibitory effects of oxygen on seed germination as a specific trait of Japonica rice, Oryza sativa L.

Dormancy in cereal seeds of oat, barley and rice is usually broken by a higher oxygen tension. In this experiment, however, the inhibitory effect of high oxygen tension on seed germination was observed in the seeds of japonica rice, unlike in those of indica and wild type rices. Standard dehusking, which increases the supply of oxygen to the embryo of a seed and the increment of the oxygen tension in the atmosphere surrounding an intact seed strongly inhibited germination of rice for a certain period of time after harvest. This inhibition was not observed under anaerobic conditions, such as in water and at a low oxygen tension. The inhibitory effect was especially recognizable in japonica rice seeds with a high water content irrespective of whether they were dormant or non-dormant cultivars, but not in indica or in wild rice (O. perennis MOENCH and O.sativa f.spontanea ROSCHEY).