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30 June 2004, Volume 11 Issue 4 Previous Issue    Next Issue
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Research Paper

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Phenotypic Expression of Whitebacked Planthopper Resistance in the Newly Established japonica / indica Doubled Haploid Rice Population Kazushige SOGAWA , SUN Zong-xiu , QIAN Qian , ZENG Da-li 2004, 11(4): 155-160 .  Abstract ( )   PDF (237KB) ( )   A new doubled haploid (DH) rice population was established from a cross between WBPH-resistant japonica Chunjiang 06 (CJ-06) and susceptible indica TN1. Sucking inhibitory and ovicidal resistance of the DH rice lines were evaluated on the basis of non-preference response of WBPH immigrants and honeydew excretion by WBPH females, and appearance of watery lesions in the necrotic discoloration of leaf sheaths ovipositied by WBPH,respectively. Both the major gene resistance to WBPH, sucking inhibitory and ovicidal resistance, showed 1 (resistant): 1 (susceptible) segregation ratio in the DH population. Relative density of WBPH populations and damage scores in the DH population indicated combined functions of both the major resistance genes as well as QTLs affecting the host plant response to WBPH infestations. Thus, the newly developed CJ-06/TN1 DH population could be a useful material to analyze major genes and QTLs for WBPH resistance in japonica rice.

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Clustering of Major Genes Conferring Blast Resistance in a Durable Resistance Rice Cultivar Gumei 2 WU Jian-li , CHAI Rong-yao , FAN Ye-yang , LI De-bao , ZHENG Kang-le , Hei LEUNG , ZHUANG Jie-yun 2004, 11(4): 161-164 .  Abstract ( )   PDF (90KB) ( )   By using 304 recombinant inbred lines derived from indica rice cross Zhong 156/Gumei 2, a linkage map consisting of 177 marker loci and covering 12 rice chromosomes was constructed and employed for mapping genes conferring blast resistance in rice. Genomic location of gene Pi25(t) conferring neck blast resistance to the Chinese isolate 92-183 (race ZC15) was verified to be located between markers A7 and RG456 on chromosome 6, with genetic distances of 1.7 cM and 1.5 cM to A7 and RG456, respectively. Leaf blast resistance of Gumei 2 to the Philippine isolate Ca89 (lineage 4) was found to be controlled by a single gene. The gene tentatively designated as Pi26(t) was located between makers B10 and R674 on chromosome 6, with genetic distances of 5.7 cM and 25.8 cM to B10 and R674 respectively. Resistant alleles at both gene loci were derived from Gumei 2, indicating an existence of resistance gene cluster in Gumei 2.

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Grain Quality and Genetic Analysis of Hybrids Derived from Different Ecological Types in Japonica Rice (Oryza sativa) LENG Yan, HONG De-lin 2004, 11(4): 165-170 .  Abstract ( )   PDF (448KB) ( )   The performance and inheritance of 7 quality traits were studied using F2 rice grain derived from 8×8 diallel crossing made by employing 8 parents of different ecological japonica rice types. Differences in each trait among 8 parents were not obvious, but in F2 generation, transgressive phenomena were found in all the traits studied, indicating that the genes controlling these traits among parents were segregated. The inheritance of grain width, grain weight, chalkiness score (CS), gelatinization temperature (GT) and gel consistency (GC) were suitable to additive-dominant model, and dominant effect contributed mainly for the 5 traits. The inheritance of grain length (GL) and amylose content (AC) did not fit into additive-dominant model, existing epistatic interactions. Dominant genes for grain width and grain weight had the efficiency of decreasing effect, and dominant genes for CS, GT and GC had the efficiency of enhancing effect. Koshihikari contained more recessive genes for gelatinization temperature than other varieties. Zhendao 88 had more dominant genes in grain width and grain weight than other varieties. Xiushui 04 possessed more dominant genes for GL and GC, and more recessive genes for CS than other varieties.

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Inheritance of the Male Sterility in a New Photo/Thermo-Sensitive Genic Male Sterile Line B06S of Rice HE Hao-hua, HUANG Wen-xin, PENG Xiao-song, ZHU Chang-lan, LIU Yi-bai 2004, 11(4): 171-176 .  Abstract ( )   PDF (303KB) ( )   The major male sterile genes in a new photo/thermo-sensitive genic male sterile (PTGMS) line B06S of rice were analyzed by the manipulation of mixture distribution theory. The results indicated that a pair of major male sterile nuclear genes with large effects were responsible for controlling the male sterility of B06S.

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Characteristics of Resistance to Rice Sheath Blight of Zhongda 2, a Transgenic Rice Line as Modified by Gene “RC24” YUAN Hong-xu , XU Xin-ping , ZHANG Jian-zhong , GUO Jian-fu , LI Bao-jian 2004, 11(4): 177-180 .  Abstract ( )   PDF (185KB) ( )   The transgenic rice, Zhongda 2, which was genetically modified from an indica rice line Zhuxian B by rice chitinase gene (RC24), had high resistance to rice sheath blight (Rhizoctonia solani) in laboratory and a two-year field experiment. The pathogen could invade sheath of Zhongda 2 and induce symptoms of the disease. No difference was noted in time of penetration or incubation period between Zhongda 2 and non-transgenic rice control, Zhuxian B, but the hyphae lysate could be observed earlier than control. Its resistance expressed as to inhibit the growth of mycelium in host tissue. F1s from Zhongda 2 (♂) crossed with other five non-transgenic rice lines showed higher resistance than donor non-transgenic parents, but the resistance was different along with the different maternal parents.

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Factors Affecting Agrobacterium-Mediated Transformation Efficiency in Rice CHEN En-hui , ZHANG Ping , ZUO Shi-min , LI Ai-hong , ZHANG Ya-fang , CHEN Zong-xiang , PAN Xue-biao 2004, 11(4): 181-185 .  Abstract ( )   PDF (235KB) ( )   Several important factors affecting the efficiency of Agrobacterium-mediated rice transformation were studied with several predominant commercial indica and japonica rice cultivars. As far as indica rice callus was concerned, CC medium was the best and the quality of callus was improved with the addition of 1.0 to 2.0 mg/L ABA. It decreased the percentage of browning calli and improved the callus growing state by addition of a certain amount of sorbitol to the subculture medium. NB medium was the best for callus initiation of japonica rice, but the improvement in the quality of callus of japonica subspecies was not obvious by adding ABA. During the period of subculture, to a certain degree, increasing the sucrose concentration could improve the proportion of hygromycin resistant calli. Furthermore, the transformation efficiency would be higher by applying selection pressure in the selection stage, removing selection pressure during the plantlet differentiation period and applying selection pressure again during seedling hardening period. Besides, suitable combination of plant hormones was beneficial for callus differentiation. An efficient Agrobacterium-mediated rice transformation system had been established for several rice cultivars and a lot of transgenic rice plants had been obtained.

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Resistance to Bacterial Leaf Blight in a Somaclonal Rice Mutant HX-3 at Cellular Level GAO Dong-ying , ZHOU Yi-hong , HUANG Xue-qing , SUN Li-hua , LIU Ai-min 2004, 11(4): 186-190 .  Abstract ( )   PDF (119KB) ( )   The interaction between rice host and its pathogen Xanthomonas oryzae pv. oryzae (Xoo) at cellular level was studied by using a resistant somaclonal mutant HX-3 and its susceptable donor Minghui 63. After inoculation with Xoo strain Zhe 173 (Chinese pathotype Ⅳ), the activity of superoxide dismutase (SOD) and peroxidase (POD) in the callus of Minghui 63 was increased dramatically, and the active oxygen(O2 ) was produced at a higher rate; Meanwhile, the callus grew slowly with the reduction of protein content. Compared to the activity of SOD and POD, the production rate of O2 and the fresh weight in HX-3 callus varied little after the inoculation. It could be proposed that there were great differences between the resistance of HX-3 and Mighui 63 at cellular level. There was no difference detected concerning resistance to bacterial leaf blight in HX-3 between the plant and the callus.

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Studies on Seed Setting Stability in Associated with Temperature for a Two-Line Hybrid Rice, Liangyoupeijiu LU Chuan-gen, ZONG Shou-yu, ZOU Jiang-shi 2004, 11(4): 191-194 .  Abstract ( )   PDF (193KB) ( )   When being planted in wide areas in southern China (23°23′–33°23′ N, 98°35′–120°19′ E, sea level above 2.7–1285 m), Liangyoupeijiu (LYPJ), a two-line hybrid rice combination, showed a seed setting rate of 75.2–77.2%, which was lower by 4.3–7.5 percent point than that of an indica hybrid rice Shanyou 63 (CK), with similar values of grain yield and coefficients of variation to CK. Sowing during 5-25th of May in Nanjing (32°3′ N, 118 °48′ E), China, LYPJ headed before 4th September, and gave a seed setting rate of 75–90%, and grain yield over 1 kg/m2. If the sowing date was delayed to 14–15th, June, its heading date would be as late as 17th–21st September, and seed setting rate would be declined by 10–15% in comparison with that on a suitable sowing date. When flowering took place at an average daily temperature range of 13.7–28.5℃ for five days, the spikelet fertility (SF) would be increased by 1.9–10.7%, for each increment of 1℃. The suitable (SF≥90%) and safe (SF≥75%) temperatures for flowering stage were indicated to be 26.5℃ and 22.9℃, respectively. To get a high and stable seed set in cultivating LYPJ, it was recommended that LYPJ would be planted in the areas south of 34°N, and the favorable average daily temperature during flowering stage should be at 26–28℃.

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Effect of Temperature on Pollen Fertility in Inter-Subspecific Rice Hybrids YANG Jie, WAN Jian-min, * , ZHAI Hu-qu, WANG Cai-lin, ZHONG Wei-gong, ZOU Jiang-shi 2004, 11(4): 195-199 .  Abstract ( )   PDF (128KB) ( )   Seventeen rice varieties and hybrids of different types (indica, japonica, javanica, indica hybrid, japonica hybrid and inter-subspecific hybrid) were evaluated to determine the effect of temperature on pollen fertility in inter-subspecfic hybrids. The pollen fertility of inter-subspecific hybrids was greatly reduced when average daily temperature dropped to 22.0 － 23.0℃ at meiosis stage, and the extent of pollen fertility reduction varied greatly with respect to different hybrids. However, the pollen fertility reduction of indica and japonica hybrids and conventional varieties was not obvious under the same regime of temperature conditions. When the average daily temperature dropped to 20℃, the pollen development of conventional varieties and hybrids was also affected. Correlation analysis revealed that there existed a positive correlation between pollen fertility and average daily temperature. A significant difference (P<0.01) was also found between the two correlation coefficients i.e. inter-subspecific hybrids and conventional varieties. Temperature at meiosis stage of pollen mother cell was a key factor in pollen developing, and the pollen fertility of inter-subspecific hybrids was more sensitive to low temperature than that of traditional variety.

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Relationship Between Changes in Leaf Endogenous Hormone Contents and Senescence During Grain Filling Stage of a Rice Hybrid and its Parents FAN Jin-juan, LI Xue-mei , XU Zheng-jin, ZHANG Li-jun 2004, 11(4): 200-204 .  Abstract ( )   PDF (119KB) ( )   A major problem in hybrid rice production is the occurrence of leaf senescence during the grain filling stage that can result in reduction of yield. Changes in contents of several endogenous hormones are related to leaf senescence. The relationship between endogenous hormones and leaf senescence in the rice hybrid Tiyou 418 and its parents Tijin and C418, was undertaken for investigation. Indicators of leaf senescence, including superoxide dismutase (SOD) activity, malondialdehyde (MDA) accumulation and chlorophyll content, as well as the contents of abscisic acid (ABA), zeatin riboside (ZR), gibberellin (GA1/3) and auxin (IAA) in the leaves were determined. Different rates of leaf senescence were observed in the three materials. Senescence occurred earliest and fastest in Tijin, followed by Tiyou 418 and then C418. A similar trend was recorded in ABA, ZR, and IAA contents during the grain filling stage in the three materials. Changes in (GA1/3+ZR+IAA)/ABA ratios were also similar, being quite stable during the early stage of leaf senescence, and decreasing markedly during the late stage. The ratio declined more dramatically in Tijin, in accordance with its faster leaf senescence. The results suggest that the ratio of (GA1/3+ZR+IAA)/ABA regulates chlorophyll content, SOD activity, MDA content and membrane lipid peroxidation. It is postulated that endogenous hormones may play a role in the regulation of leaf senescence in a systematic way.

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Traits Related to Chilling-Induced Photoinhibition in Leaves of 2004, 11(4): 205-212 .  Abstract ( )   PDF (404KB) ( )   Physiological indices related to PSⅡ photochemical efficiency (Fv/Fm) and membrane lipid peroxidation were measured in leaves of indica rice cv Shanyou 63 and japonica rice 9516 at different temperatures and light intensities for four days. No obvious changes in Fv/Fm and MDA were observed in both indica and japonica rice at moderate temperature and medium PFD, implying neither photoinhibition nor photooxidation happened in these cases. In indica rice either at medium temperature with higher PFD or at lower temperature with medium PFD Fv/Fm dropped obviously with no changes in MDA contents, and photoinhibition appeared while photooxidation did not occur. However, D1 protein, Fv/Fm, (A+Z)/(A+Z+V), and SOD activities dropped, and O2 production and MDA content increased accordingly, as well as both photoinhibition and photooxidation appeared in two rice varieties at lower temperature and higher PFD. Experiment with inhibitors at lower temperature and higher PFD showed that as compared with japonica rice the decrements appeared in D1 protein contents, SOD activities, and (A+Z)/(A+Z+V) ratios, the xanthophyll cycle and non-photochemical quench (qN) were inhibited in a more degree, as well as increments of MDA content were greater, thus exhibiting more distinct photoinhibition and photooxidation in indica rice. It is suggested that Fv/Fm and membrane lipid peroxidation product－MDA were the key indices to predict and diagnose photooxidation.

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Recovery and Biological Properties of Nitrate Non-utilizing Mutants of Rice Blast, Magnaporthe grisea ZHANG Chuan-qing, ZHOU Ming-guo 2004, 11(4): 214-218 .  Abstract ( )   PDF (173KB) ( )   Eleven nitrate non-utilizing (nit) mutants were recovered from six isolates of Magnaporthe grisea cultured on MM media amended with 60 g/L potassium chlorate, with a frequency of 1.42 %. Some biological properties, such as growth rate, growth biomass, cultural characters, conidial production, sexual reproduction ability, and pathogenicity were compared between nit mutants and their parent isolates. Results showed that all the nit mutants were resistant to chlorate. Some important biological properties such as the growth rate on YPSA, conidial production ability on TPSA, pathogenicity, had no significant differences between nit mutants and their parent isolates. Mating type didn’t change, but perithecia production ability of fertile isolates changed significantly as compared with that of their parent isolates. Therefore, the nit can be used as a genetic marker to study the genetics such as pathogenicity, fungicide resistance in Magnaporthe grisea.

Experimental Technique

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A New and Simple Method for Collecting Eggs of the Striped Stemborer, Chilo suppressalis SHEN Jun-hui, LIU Guang-jie 2004, 11(4): 219-221 .  Abstract ( )   PDF (232KB) ( )   The method for collecting eggs of the striped stem borer, Chilo suppressalis using plastic bags was studied in comparison with using caged rice plants. There was no significant difference in fecundity of C. suppressalis at 279 eggs/moth and in percentage of hatched eggs at 95% between in plastic bags and on rice plants. More egg masses were collected on plastic bags than on rice plants, whereas more smaller egg masses (less than 100 eggs per mass) in plastic bags than on rice plants. The advantages in collecting eggs of C. suppressalis and other insects by using plastic bags were also discussed.

Short Communication

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Mutagenic Improvement of Shattering Characteristic of the Restorer Line of a Hybrid Rice “Xieyou 9308” SHEN Sheng-quan , CHEN Sheng-guang , WU Dian-xing , XIA Ying-wu , SHU Qing-yao 2004, 11(4): 222-224 .  Abstract ( )   PDF (95KB) ( )   The newly developed hybrid rice combination “Xieyou 9308” (Xieqingzao A/T9308) has been regarded as a super-high-yielding rice variety, of which the yield potential reached as high as 12 t/ha. However, its high shattering characteristic (as high as 60%) has limited its wider application. In the current experiment, a non-shattering mutant line, M9308, was developed from T9308 by gamma irradiation. Comparisons were made but no marked differences were found between T9308 and M9308 as well as between their F1 hybrids crossed to Xieqingzao A for major agronomic and grain quality characters as well as resistance to diseases. Genetic analysis indicated that the non-shattering character of M9308 was governed by a single recessive gene.