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28 June 2008, Volume 15 Issue 2 Previous Issue    Next Issue
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Review or Special Topic

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Progress on Transferring Elite Genes from Non-AA Genome Wild Rice into Oryza sativa through Interspecific Hybridization FU Xue-lin, LU Yong-gen, LIU Xiang-dong, LI Jin-quan 2008, 15(2): 79-87 .  Abstract ( )   PDF   The progress of research on transferring elite genes from non-AA genome wild rice into Oryza sativa through interspecific hybridization are in three respects, that is, breeding monosomic alien addition lines (MAALs), constructing introgression lines (ILs) and analyzing the heredity of the characters and mapping the related genes. There are serious reproductive barriers, mainly incrossability and hybrid sterility, in the interspecific hybridization of O. sativa with non-AA genome wild rice. These are the ‘bottleneck’ for transferring elite genes from wild rice to O. sativa. Combining traditional crossing method with biotechnique is a reliable way to overcome the reproductive barriers and to improve the utilizing efficiency of non-AA genome wild rice.

Research Paper

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Prokaryotic Expression, Purification and Characterization of a Novel Rice Seed Lipoxygenase Gene OsLOX1 WANG Ren, SHEN Wen-biao, LIU Ling-long, JIANG Ling, ZHAI Hu-qu, WAN Jian-min, 2008, 15(2): 88-94 .  Abstract ( )   PDF   Lipoxygenase (LOX, EC1.13.11.12) is a key enzyme during the degradation of lipids in animals and even plants, and also the first key enzyme responsible for the biosynthesis of jasmonate. To purify and characterize the OsLOX1 gene from rice seeds, the entire coding region of the OsLOX1 gene was inserted into an expression vector pET30a(+) and transformed into Escherichia coli BL21 (DE3). Expression of the fusion protein was successfully induced by isopropyl-β-D- thiogalactopyranoside (IPTG) and the purified recombinant protein was obtained by His·Bind® Kits. Further assay showed that the purified recombinant protein exhibited the LOX activity. The optimum pH was 4.8 (acetate buffer) and the optimum temperature was 30°C for the above enzyme. Thus, the recombinant might confer an available usage for the synthesis of jasmonate in vitro, and also provides a possibility for elucidating the inter-relationship between the primary structure of the plant seed lipoxygenase protein and its physiological functions.

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Optimization of a Reaction System of Sequence Related Amplified Polymorphism and Segregation of Polymorphic Loci in an F2 Population of Rice JIANG Shu-kun, ZHONG Ming, ZHANG Xi-juan, ZHANG Li, XU Zheng-jin 2008, 15(2): 95-100 .  Abstract ( )   PDF   An effective PCR protocol for detecting the sequence related amplified polymorphism (SRAP) in rice was developed. One hundred and ten pairs of SRAP primers were used for segregation analysis in an F2 population derived from a cross between Shennong 606 and Lijiangxintuanheigu. Among the 110 primer pairs, 35 pairs generated 143 polymorphic bands with an average of 4.09 polymorphic bands per primer pair, and 24 pairs (16.78%) showed the genetic distortion (P<0.05). Of the 24 primer pairs, 12 pairs deviated toward the male parent Shennong 606 and 11 pairs toward the female parent Lijiangxintuanheigu, only one toward heterozygote. It was found that the segregation distortion might be caused by the joint gametic and zygotic effects.

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Influence of Genetic Drift of Restoring Gene (Rf) on Seed Purity of Yuetai A, a Honglian-Type Cytoplasmic Male Sterile Line in Hybrid Rice WANG Ji-feng, LU Zuo-mei 2008, 15(2): 101-109 .  Abstract ( )   PDF   The seed samples of Yuetai A, a Honglian (HL) type cytoplasmic male sterile (CMS) line in hybrid rice were investigated to assess the seed purity and to analyze the cause of off-type plants by imitating the biological contaminant to Yuetai A in Nanjing, Jiangsu Province and Lingshui, Hainan Province during 2004–2006. The seed impurity of Yuetai A mainly resulted from the genetic drift of restoring fertility gene (Rf) after biological contamination but not from its sterility unstability. All of the ten maintainer lines, five restorer lines and three thermo-sensitive genic male sterile lines used in the study could pollinate Yuetai A and Yuetai B to produce F1 plants, directly or indirectly resulting in Rf-gene drifting into Yuetai A and generating ‘iso-cytoplasm restoring-generations’. Furthermore, high outcrossing rate and similar heading date of Yuetai A with many varieties used in rice production might easily result in the biological contamination. After removing all plants with Rf-gene mixed in Yuetai A and preventing Rf-gene drifting into Yuetai A, the seed purity of Yuetai A and Yuetai B had been raised to 100%.

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Analysis on Dry Matter Production Characteristics of Super Hybrid Rice WU Wen-ge, ZHANG Hong-cheng, QIAN Ying-fei, CHENG Ye,WU Gui-cheng, ZHAI Chao-qun, DAI Qi-gen 2008, 15(2): 110-118 .  Abstract ( )   PDF   Six middle-season indica hybrid rice combinations, including five super hybrid rice combinations with the high yield about 10.5 t/ha and a check hybrid rice combination Shanyou 63 with a yield potential about 9.5 t/ha, were used as materials to study the dry matter production characteristics. The super hybrid rice showed a high ability in dry matter production and accumulation and its yield enhanced with the increase of dry matter accumulation. The advantage period of dry matter production in the super hybrid rice was mainly at the middle and late growth stages compared with the check. The grain yield had no significant correlation with the dry matter accumulation before the elongation stage while had a significantly positive correlation with the dry matter accumulation from the elongation to maturity stages in super hybrid rice. There were more dry matter in vegetative organs at the heading stage in the super hybrid rice but its contribution to yield (apparent conversion percentage) was averagely 4.3 percent points lower than that in the check. For crop growth rate (CGR), the comparative advantage of super hybrid rice was at the middle and late stages, especially after flowering. Moreover, as the rising of leaf area index (LAI) and leaf area duration (LAD), CGR enhanced. The total LAD and the mean of LAD per day of super hybrid rice was about 14.79% and 10.31% higher than those of the check, respectively. The results indicate that the high yield of super hybrid rice mostly comes from the products of photosynthesis after heading, which is shown by the increased CGR at middle and later stages. It is suggested that LAD character might be used to better explain the advantage in the dry matter production of super hybrid rice than LAI.

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Relationship Between Diurnal Changes of Net Photosynthetic Rate and Influencing Factors in Rice under Saline Sodic Stress YANG Fu, LIANG Zheng-wei, WANG Zhi-chun, CHEN Yuan, 2008, 15(2): 119-124 .  Abstract ( )   PDF   The net photosynthetic rate of flag leaves and influencing factors under saline sodic soil conditions were investigated at the full heading stage of rice. The net photosynthetic rate of rice leaves showed a double-peak curve in a day in both non-saline sodic and saline sodic soil treatments. The first peak of the net photosynthetic rate appeared at 9:00–10:00 and 9:00 in the saline sodic and non-saline sodic soil treatments, respectively, whereas the second peak both at 14:00. The midday depression of the net photosynthetic rate always appeared regardless of non-saline sodic or saline sodic soil conditions. In addition, the net photosynthetic rate significantly decreased in all day under saline sodic conditions compared with that under non-saline sodic conditions. Some differences were observed in correlation characters between the net photosynthetic rate and all influencing factors during 9:00–13:00. Under non-saline sodic conditions, the diurnal changes of the net photosynthetic rate in a day were mainly caused by stomatal conductance, and the limitation value and the stomatal factors served as determinants; whereas under saline sodic stress, the diurnal changes of the net photosynthetic rate in a day were mainly caused by non stomatal factors including light intensity and air temperature.

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Pollen Grain Germination and Pollen Tube Growth in Pistil of Rice CHEN Shi-qiang, WANG Zhong, LIU Man-xi, XIE Zhao-wei, WANG Hui-hui 2008, 15(2): 125-130 .  Abstract ( )   PDF   The germination of pollen grain in vitro and the growth of pollen tube in the pistil of rice were observed with a microscope. The stigma was removed at different time points after pollination to study its effect on seed setting rate. The rice pollen grain started to germinate at 2 min after pollination and the pollen tube penetrated stigma into style in 5–10 min, 30 min later the end of pollen tube reached the bottom of ovary, and only some pollen tubes arrived at embryo sac at 40 min after pollination. Meanwhile, a small amount of callose began to deposit in the pollen tubes, a great deal of callose was observed at 50 min after pollination, whereas the pollen grain began to shrink. The growing rates of pollen tube in the rice stigma, style and ovary were 1500, 5000, and 5400 μm/h, respectively. The seed setting rate was quite low when the stigma was removed at about 10–15 min after pollination, gradually increased when it removed at 20 min to 50 min after pollination, and over 60% when it removed at 50 min after pollination and finally tended to be stable.

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Use of Linear Spectral Mixture Model to Estimate Rice Planted Area Based on MODIS Data WANG Lei, Satoshi UCHIDA 2008, 15(2): 131-136 .  Abstract ( )   PDF   MODIS (Moderate Resolution Imaging Spectroradiometer) is a key instrument aboard the Terra (EOS AM) and Aqua (EOS PM) satellites. Linear spectral mixture models are applied to MOIDS data for the sub-pixel classification of land covers. Shaoxing county of Zhejiang Province in China was chosen to be the study site and early rice was selected as the study crop. The derived proportions of land covers from MODIS pixel using linear spectral mixture models were compared with unsupervised classification derived from TM data acquired on the same day, which implies that MODIS data could be used as satellite data source for rice cultivation area estimation, possibly rice growth monitoring and yield forecasting on the regional scale.

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Genetic Diversity and Pathogenicity Variation in Rhizoctonia solani Isolates from Rice in Sichuan Province, China XIAO Yong, LIU Ming-wei, LI Gang, ZHOU Er-xun, WANG Ling-xia, TANG Jie, TAN Fu-rong, ZHENG Ai-ping, LI Ping 2008, 15(2): 137-144 .  Abstract ( )   PDF   Fifty-five representative samples of Rhizoctonia solani isolates, which were collected and isolated from five different ecological regions in Sichuan Province, China, were purified and analyzed for the pathogenicity and molecular genetic variation. The hyphal fusion test revealed that almost all the isolates belonged to the AG-IIA group except the isolate D42. In addition, some of the isolates were ‘bridging isolates’, which could fuse with several groups simultaneously. The pathogenicity analysis on in vitro leaves confirmed a significant pathogenicity variation in the tested isolates. The 55 isolates were then classified into 8 groups by further RAPD (randomly amplified polymorphic DNA) cluster analysis at the similarity coefficient of 0.941. The results suggest that under the certain ecological conditions in Sichuan Province, China, most of the R. solani strains were genetically stable, but a few changed drastically.

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Isolation and Identification of Burkholderia glumae from Symptomless Rice Seeds ZHU Bo, LOU Miao-miao, HUAI Yan, XIE Guan-lin, LUO Jin-yan, XU Li-hui 2008, 15(2): 145-149 .  Abstract ( )   PDF   A survey on isolation and detection of the casual organism of bacterial grain rot of rice was conducted during 1997–2006. In 2006, six pathogenic bacterial strains were isolated from two symptomless seed samples of rice (Oryza sativa L.) originally produced in Hainan Province and then planted in Zhejiang Province, China. They were identified as Burkholderia glumae which is the causal organism of bacterial grain rot of rice by physiological characteristics, colony morphology, pathogenicity test, Biolog, fatty acid methyl ester (FAME) analysis and RAPD-PCR compared with the four standard reference strains. It is confirmed that there is the infection of B. glumae in so-called ‘health looking seeds’.

Short Communication

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Social Factors Affecting Wetlands Utilization for Agriculture in Nigeria: A case study of sawah rice production OLADELE Oladimeji Idowu, Toshiyuki WAKATSUKI 2008, 15(2): 150-152 .  Abstract ( )   PDF   Wetlands have immense poverty-fighting potentials and in Nigeria, more and more people are dependent on wetlands for their livelihoods. To examine the social factors affecting the current status of the wetlands utilization for agriculture in Nigeria, a simple random sampling technique was used to select 200 farmers cultivating wetlands and a structured questionnaire was applied to elicit the information on the social factors. Data collected were described using frequency and percentage and a multiple regression analysis was used to identify significant variables that are determinants of wetland utilization. The results of the analysis showed that significant variables included crop preferences, farming system, culture, taste, land tenure, knowledge of wetland cultivation, perceived suitability, farmers’ tribe, location of wetland, and farmers’ age. It was concluded with suggestions for the right combination of policies, public awareness, and appropriate farming methods in order to improve wetland utilization in Nigeria.

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Genetic Analysis and Primary Mapping of pms4, a Photoperiod-Sensitive Genic Male Sterility Gene in Rice (Oryza sativa) HUANG Ting-you, WANG Zhi, HU Yun-gao, SHI Shou-pei, PENG Tao, CHU Xu-dong, SHI Jun, XIANG Zu-fen, LIU Ding-you 2008, 15(2): 153-156 .  Abstract ( )   PDF   To understand the genetic characteristics of a new photoperiod-sensitive genic male sterile line Mian 9S, some reciprocal crosses were made between Mian 9S and six indica rice materials, Yangdao 6, Luhui 602, Shuihui 527, Mianhui 725, Fuhui 838 and Yixiang 1B. Genetic analysis results suggested that the photoperiod-sensitive genic male sterility (PGMS) of Mian 9S was controlled by a single recessive nuclear gene. Thus, the F2 population derived from the cross of Yangdao 6/Mian 9S was used to map the PGMS gene in Mian 9S. By using SSR markers, the PGMS gene of Mian 9S was mapped on one side of the markers, RM6659 and RM1305, on rice chromosome 4, with the genetic distances of 3.0 cM and 3.5 cM, respectively. The gene was a novel PGMS gene and designated tentatively as pms4. In addition, the application of the pms4 gene was discussed.

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Mapping of Rice Fertility-Restoring Genes for ID-Type Cytoplasmic Male Sterility in a Restorer Line R68 LI Liang-jie, ZHOU Hai-peng, ZHAN Xiao-deng, CHENG Shi-hua, CAO Li-yong 2008, 15(2): 157-160 .  Abstract ( )   PDF   An F2 population derived from the cross Zhong 9A/R68 was used to map the fertility-restoring (Rf) gene for ID-type cytoplasmic male sterility (CMS). Two bulks (a fertile bulk and a sterile bulk) were constructed by pooling equal amount of ten highly fertile lines and ten highly sterile lines, respectively. Four hundred and thirteen pairs of simple sequence repeat (SSR) primers, which evenly distributed on 12 chromosomes of rice, were selected for analyzing polymorphisms between the parents and between the two bulks. The primer RM283 on chromosome 1 and the primers RM5756, RM258, RM6100 and RM171 on chromosome 10 were found to be polymorphic between the parents and between the two bulks. These five SSR markers were linked to fertility-restoring genes. A total of 82 excessive sterile lines were selected from Zhong 9A/R68 F2 population to estimate the genetic distance between five SSR markers and fertility-restoring genes respectively. The results indicated that one Rf gene was linked to RM283 located on chromosome 1 at a distance of 6.7 cM, and the other Rf gene was mapped to the long arm of chromosome 10 flanked by RM258 and RM6100 at the distances of 8.0 cM and 2.4 cM, respectively.