28 July 2013, Volume 20 Issue 4 Previous Issue    Next Issue

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    Research Paper
    Positive Regulation of Phytochrome B on Chlorophyll Biosynthesis and Chloroplast Development in Rice
    ZHAO Jie 1, 2, ZHOU Jin-jun 1, GU Jian-wei 1, WANG ying-ying 1, XIE Xian-zhi1, 2
    2013, 20(4): 243-248.  DOI: DOI: 10.1016/S1672-6308(13)60133-X
    Abstract ( )   PDF (330KB) ( )  

    Phytochromes in rice are encoded by a gene family composed of three members, PHYA, PHYB, and PHYC. Through characterizing the phytochrome mutants and wild type (WT) in terms of photomorphogenesis, roles of individual phytochromes have been preliminarily explored in regulating rice de-etiolation, flowering time and fertility. However, little information has been reported about whether or how phytochromes affect chlorophyll biosynthesis and chloroplast development in rice. In this study, we compared the chlorophyll contents of wild type and the phyA, phyB and phyAphyB mutants grown under either white light (WL) or red light (R). The results suggest that phyB perceives R to positively regulate chlorophyll biosynthesis, while the role of phyA can be detected only in the phyB-deficient mutant. Analyses of the expression levels of genes involved in chlorophyll biosynthesis revealed that phytochromes affected the chlorophyll biosynthesis by regulating protochlorophyll oxidoreductase A (PORA) expression. The role of phyB in chloroplast development was also analyzed, and the results suggest that phyB perceives R to regulate chloroplast development by affecting the numbers of chloroplasts and grana, as well as the chloroplast membrane system.

    Molecular Variation and Application from Aerospace Mutagenesis in Upland Rice Huhan 3 and Huhan 7
    YU Shun-wu, LUO Hua-cheng, LI Jia-jia, YU Xin-qiao
    2013, 20(4): 249-258.  DOI: 10.1016/S1672-6308(13)60144-4
    Abstract ( )   PDF (964KB) ( )  

    To further improve upland rice varieties Huhan 3 and Huhan 7, seed samples were sent to outer space with two recoverable spaceships for approximately 1 and 5 d and were propagated for 7 and 5 generations, respectively. Phenotypic analysis revealed that the morphological traits and the protein and amylose contents of grains changed. Characterization of genomic mutations by the gene-associated simple sequence repeat (SSR) and insertion-delete (InDel) markers indicated that the mutation pattern was very complex. Most of the mutations occurred at the 3′- or 5′-end of the fragments in the simple sequence repeat fragment. Reverse transcription-polymerase chain reaction (RT-PCR) assay showed that mutations in those parts of the SSR affected their gene expression, indicating that gene associated markers would be helpful to isolate functional genes. Field survey for breeding also revealed that more lines with high yield, high quality and drought-tolerance could be selected through aerospace breeding. The results indicate that aerospace mutagenesis resulted in molecular variation, as well as physiological and morphological changes for rice breeding.

    Genetic Diversity of Rice Landraces from Lowland and Upland Accessions of China
    ZHANG Li-na, CAO Gui-lan, HAN Long-zhi
    2013, 20(4): 259-266.  DOI: 10.1016/S1672-6308(13)60139-0
    Abstract ( )   PDF (239KB) ( )  

    Genetic diversity of rice landraces from lowland and upland accessions of China was investigated using 66 polymorphic simple sequence repeat (SSR) markers. The total number of alleles detected from all 324 tested accessions was 555 with an average allele number (Na) of 8.409 per locus, the average effective number of alleles (Ne) of 3.574 and the average Shannon's information index (I) of 1.378. The genetic diversity was higher for the indica landraces compared to the japonica landraces, and the upland landraces were more genetically diverse than the lowland landraces. The SSR markers, RM72, RM232, RM219, RM241, RM224 and RM3 showed the highest rates of polymorphism and these SSR markers were suitable to assess the genetic diversity of rice germplasm resources. A dendrogram of 324 accessions of lowland and upland landraces showed that all rice accessions were mainly subdivided into two groups, japonica and indica, with some being intermediate. The distribution of lowland and upland landraces among the japonica and indica rice groups was distinct, with obvious differentiation between the lowland and upland landraces in japonica rice, but no such clear distinction in indica rice.

    Genetic Analysis of Streaked and Abnormal Floret Mutant st-fon
    CHEN De-xi, LI Ting, QU Guang-lin, HUANG Wen-juan, HE Zhong-quan, LI Shi-gui
    2013, 20(4): 267-275.  DOI: 10.1016/S1672-6308(13)60132-8
    Abstract ( )   PDF (569KB) ( )  

    A double mutant with streaked leaf and abnormal floret was found and temporarily named streaked leaf and floral organ number mutant (st-fon). For this mutant, besides white streak appeared on culm, leaves and panicles, the number of floral organs increased and florets cracked. The extreme phenotype was that several small florets grew from one floret or branch rachis in small florets extended and developed into panicles. By using transmission electron microscope to observe the ultrastructure of white histocytes of leaves at the seedling stage, the white tissues which showed abnormal plastids, lamellas and thylakoids could not develop into normal chloroplast, and the development of chloroplast was blocked at the early growth stage of plastid. Scanning electron microscope and paraffin section were also used to observe the development of floral organs, and the results indicated that the development of floral meristem was out of order and unlimited, whereas in the twisty leaves, vascular bundle sheath cells grew excessively, or some bubbly cells increased. Genetic analyses carried out by means of cross and backcross with four normal-leaf-color materials revealed that the mutant is of cytoplasm inheritance.

    Response of Osmotic Regulation Substance Content and Protective Enzyme Activities to Shading in Leaves of Different Rice Genotypes
    LIU Li1, WANG Li1, DENG Fei1, HUANG Yun1, LIU Dai-yin2, REN Wan-jun1, YANG Wen-yu1
    2013, 20(4): 276-283.  DOI: 10.1016/S1672-6308(13)60137-7
    Abstract ( )   PDF (437KB) ( )  

    Effects of shading at the flowering and grain filling stages on osmotic regulation substance content and protective enzyme activities in the leaves of different rice genotypes (e.g., IIyou 498, Gangyou 188, Dexiang 4103, Gangyou 527 and Chuanxiang 9838) were investigated. The results showed that the malondialdehyde content of Gangyou 188 significantly increased under shading, whereas those of IIyou 498, Dexiang 4103, Gangyou 527 and Chuanxiang 9838 showed no significant differences compared to the control. The soluble sugar content significantly decreased in IIyou 498, Gangyou 188, Dexiang 4103 and Chuanxiang 9838, whereas it did not significantly increase in Gangyou 527 under the weak light conditions (shading). Moreover, the soluble protein content in the leaves of different genotypes tended to decrease under shading. Further, the protective enzyme activities in the leaves varied in different rice genotypes under the shading treatment. Based on the osmotic regulation substance content and the protective enzyme activities in the leaves of different rice genotypes, it was concluded that Gangyou 188 and Gangyou 527 had strong abilities to adapt to the low light conditions. In addition, the mechanism of damage to rice leaves in different genotypes under shading was discussed.

    Effect of Soil Salinity and Alkalinity on Grain Quality of Tolerant, Semi-Tolerant and Sensitive Rice Genotypes
    2013, 20(4): 284-291.  DOI: 10.1016/S1672-6308(13)60136-5
    Abstract ( )   PDF (374KB) ( )  

    Soil salinity and alkalinity adversely affects the productivity and grain quality of rice. The grain quality of 19 rice genotypes characterized as salt tolerant (T), semi-tolerant (ST) and sensitive (S) was assessed in lysimeters containing saline and highly alkaline soils. Head rice recovery was reduced by salinity stress whereas it was not affected by alkalinity stress. The ratio of length to width (grain dimensions) was significantly reduced in the T genotype even at low electrical conductivity (EC, 4 mS/cm) and alkalinity (pH 9.5), whereas in the ST genotype, it was significantly reduced at high salinity (EC 8 mS/cm). There was no significant effect of any levels of salinity or alkalinity on grain dimensions in the S genotype. Amylose content was significantly reduced in T and ST groups even at low EC (4 mS/cm) and alkalinity (pH 9.5) and the effect in the S genotype was only at high salinity. Starch content showed significant reduction at high salinity and alkalinity (EC 8 mS/cm and pH 9.8) in the T and ST genotypes and no significant effect was observed in the S genotype. The effect of both levels of salinity (EC 4 and 8 mS/cm) and high alkalinity (pH 9.8) on gel consistency was observed only in the S genotype. The tolerant genotypes IR36 under high salinity, and CSR10 and CSR11 under alkali stress showed less reduction in amylose content. The T genotype BR4-10, and ST genotypes CSR30, CSR29 and CSR13 showed better gel consistency under saline and alkali stress. Amylose content was affected even at low salinity stress and thus important to be considered in breeding rice for salt tolerance. Overall, the grain quality of T and ST genotypes was less affected by saline and alkali stress compared to S ones.

    Efficiencies of Chemical Techniques for Rice Grain Freshness Analysis
    Khongsak SRIKAEO, Uttaphon PANYA
    2013, 20(4): 292-297.  DOI: 10.1016/S1672-6308(13)60144-4
    Abstract ( )   PDF (364KB) ( )  

    Two chemical methods which are commonly used for rice grain freshness determination were investigated for their efficiencies. Method 1 is made of bromothymol blue indicator, and the principle is based on indicator’s color which is changed in according to pH of the stored rice grains. Method 2 is based on peroxidase activity which deteriorates during storage of rice grains. Both methods were used for determination of fresh-aged rice index of six Thai-rice cultivars, four from non-waxy rice cultivars (KDML 105, Chai Nat 1, Chai Nat 2 and Phitsanulok 2) and two from waxy rice cultivars (San-pah-tawng and RD6). Rice samples were kept in the forms of paddy and polished rice. Fresh-aged rice indices were determined using both methods every two weeks over the storage period of 24 weeks (six months). It was found that both methods were capable of detecting fresh-aged rice indices. The color of chemical solutions changed with regards to the age of rice grains and it could be detected spectrophotometrically. Rice grains which have been kept as paddy provided more consistent results. Method 1 is recommended for industrial application as it is simple, efficient and inexpensive.

    Soil Physico-Chemical Properties and Microflora as Influenced by Bispyribac Sodium 10% SC in Transplanted Kharif Rice
    S. BERA, R. K. GHOSH
    2013, 20(4): 298-302.  DOI: 10.1016/S1672-6308(13)60148-1
    Abstract ( )   PDF (263KB) ( )  

    The effects of bispyribac sodium 10% SC and butachlor 50% SC on soil physico-chemical properties and microflora in transplanted kharif rice were investigated over two seasons (2010 and 2011). Effects of the herbicide on bulk density, water holding capacity, moisture content, soil pH, organic matter content, electrical conductivity, as well as total nitrogen, available phosphorus and available potassium contents were analyzed along with microflora population (total bacteria, actinomycetes and fungi). No significant changes in soil physico-chemical properties were observed. Herbicide treatments resulted in decreases in microbial counts initially. With the degradation of applied herbicides within a considerable time, the microflora populations even exceeded the initial count at 60 d after application of the herbicide.

    Mycoflora and Mycotoxicological Quality of Four Freshly Harvested Paddy Rice Cultivars and Relation with Harvest to Industry Reception Timing
    Menithen BEBER-RODRIGUES, Vildes Maria SCUSSEL
    2013, 20(4): 303-308.  DOI: 10.1016/S1672-6308(13)60151-1
    Abstract ( )   PDF (195KB) ( )  

    Grain quality and safety of four freshly harvested paddy rice (Oryza sativa L.) cultivars (Epagri 109, SCS 114 Andosan, Tio Taka 113 and Epagri 115 CL) grown under irrigation system in the north of Santa Catarina State, Brazil were studied. The quality parameters evaluated were mycoflora, mycotoxins (aflatoxins, ochratoxin A and zearalenone), water distribution (moisture content and water activity) apart from environmental conditions (relative humidity and temperature) and the relation between harvest and the industry reception timing. All cultivars presented an average waiting time of 8.6 h (ranged from 0.3 to 24.9 h), a total fungi load of 8.6×104 cfu/mL (ranged from 1.8×103 to 9.4×105 cfu/mL) with a rather high humidity condition of 19.0% moisture content (varied from 14.9% to 24.5%) and 0.92 water activity (varied from 0.78 to 0.99) under the average environmental conditions of 87.3% relative humidity (varied from 80.0% to 96.8%) and 25.4 °C (varied from 22.5 to 27.5 °C), respectively. The conditions to which the samples were submitted allowed fungal growth, but no mycotoxins were detected. Regarding the rice cultivars fungal genera isolated, Aspergillus and Penicillium were the most often isolated among all the cultivars and variation on fungi distribution among them was not observed. Moreover, it was not found a correlation of the grain loading & unloading time with the humidity conditions and the total fungi load. Furthermore, all results and the importance of monitoring the rice mycotoxicological quality and safety were discussed.

    Short Communication
    Effects of Continuous Steaming on Milling Characteristics of Two Indica Rice Varieties
    2013, 20(4): 309-312.  DOI: 10.1016/S1672-6308(13)60141-9
    Abstract ( )   PDF (123KB) ( )  

    Parboiling improves milling characteristics of rice in a positive manner, which has been found to influence consumers demand and acceptability. A laboratory model of continuous steaming unit was fabricated and tested with two indica rice varieties, fine (ADT39) and coarse (CO43) rice, at three different soaking temperatures (50, 60 and 70 ?C) for 4 h and five residence times of steaming (1.0, 1.5, 2.0, 2.5 and 3.0 min). The effects of continuous steaming on milling characteristics of rice were studied and compared with the values obtained from the control experiment (open steaming process under laboratory conditions). The favourable conditions for continuous parboiling of the fine variety ADT39 were identified as soaking at 70 ?C for 4 h and 3.0 min residence time of steaming. These conditions showed head rice outturn of 74.0%. The favourable processing conditions for the coarse variety CO43 were found to be 4 h of soaking at 60 ?C and steaming of 3.0 min residence time, and at these conditions the head rice outturn was 73.9%.