Effects of chilling tolerance induced by spermidine pretreatment on antioxidative activity,endogenous hormones and ultrastructure of indica-japonica hybrid rice seedlings

Spermidine（Spd） is known to be involved in the regulation of plant responses to chilling stress and counteract the adverse effect of stress conditions.Antioxidant activities,endogenous hormones and ultrastructure change under chilling stress were investigated in indica-japonica hybrid rice seedlings.12-d-old seedlings were subjected to exogenous Spd（1 mmol L^（-1）） and then a chilling stress（6℃,4 d） was induced,followed by a subsequent recovery（25℃,4 d）.Results showed that malondialdehyde（MDA） and proline content were enhanced significantly,whereas shoot fresh and dry weights decreased during chilling stress and after recovery;chlorophyll content of chilling-stressed seedlings increased slightly but declined after recovery;additionally,total soluble sugar,sucrose,fructose and starch contents increased significantly during chilling stress,and only soluble sugar and fructose contents were observed in increase after recovery;chilling stress-induced increases in superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） activities,but declined after recovery,and the level of ascorbate peroxidase was lower during chilling stress and after recovery;however,endogenous indole-3-acetic acid（IAA）,zeatin riboside（ZR）,gibberellic acid（GA_3）,and abscisic acid（ABA） levels were induced decreased compared with Spd pretreatment.The microscopic analysis revealed that chilling stress-induced destruction of the chloroplast envelope during chilling stress and increased the number of plastoglobuli along with aberrations in thylakoid membranes after recovery.In contrast,exogenous Spd protected rice seedlings from chilling-induced injuries in terms of lower malondialdehyde,proline and carbohydrates accumulation coupled with increased endogenous hormones metabolism.After recovery,Spd pretreatment chilling-exposed seedlings showed higher activities of antioxidant enzymes and normal physiological function of chloroplasts.These results suggest that Spd could promote effectively chilling tolerance which might be largely attributable to the integrity of cell structure and normal metabolism of endogenous hormones in indica-japonica hybrid rice seedlings.

Analysis of the Conditional Correlations from Different Genetic Systems Between the Protein Content and the Appearance Quality Traits of Indica Rice

A factorial mating design in two environments was conducted using 7 cytoplasmic male sterile lines （A） and 5 restorer lines （R） along with their F1 （A × R） and F2 populations. The unconditional and conditional analyses of genetic models and the corresponding statistic methods, including endospermic, cytoplasmic, and maternal plant genetic systems, were used to analyze the genetic relationships between protein content （PC） and the appearance quality traits of indica rice （Oryza sativa L.）. The results from unconditional analysis indicated that PC was significantly correlated with the appearance quality traits of rice, except for the brown rice thickness （BRT）. Only the genetic covariance between PC and the brown rice width （BRW） was positively correlative, whereas all the other pairwise traits were negatively correlative. The results from conditional analysis revealed that the weight of brown rice （WBR） or the amylose content （AC） could significantly affect the relationships between PC and the appearance quality traits of indica rice. The conditional analysis showed that WBR might negatively affect the relationships between PC and the brown rice length （BRL）, BRW, or BRT through the geuotype x environmental （GE） interaction effects, but positively affected the relationships between PC and the ratio of brown rice length to width （RLW） or the ratio of brown rice length to thickness （RLT）. The amylase content could positively affect the relationships between PC and BRL, RLW, RLT through the cytoplasmic effects and maternal additive effects, but negatively affected the relationships between PC and BRW.

Physiological traits of hybrid rice (Oryza sativa L.) associated with iron toxicity

Iron toxicity,a physiological disorder of rice,is widelyspread in tropical and subtropical areas and causes severerice yield reduction.Although there has been a consider-able amount of research on flee growth,nutrient uptaking,

Plant regeneration from mesophyll protoplast of indica rice Qiugui’ai 11 (Oryza sativa L.)

In the recent decade,plant regeneration fromprotoplast has been obtained through embryo-genic cell suspension cultures of rice.Howev-er,not only the establishment of embryogeniccell suspension cultures of rice was difficult,but also the protoplasts became less and lessregenerable and the genetic change was gradu-ally accumulated during the prolonged culture.Since 1976(Deka.),extensive efforts have

Distinguishing male sterile and fertile cytoplasms in indica rice(Oryza sativa L.) by OPA 12

The majority of off-type plants in in-dica hybrid rice were CMS and itsmaintainer lines.Discrimination ofmaintainer and CMS could only beconducted at heading stage.If main-tainer and CMS line could be distin-guished earlier,it would be useful toavoid yield losses caused by usingcontaminated seeds.In this study,three pairs of A and B,Minghui 63,and Fand Fplants of Zhenshan97A/Minghui 63 were used to find

Genetic expression and effects of the rolled leaf gene Rl(t) in hybrid rice (Oryza sativa L.)

We constructed a nearisogenic line of rolled leaf gene Rl(t), which ex-pressed incompletely dondnance for the character of rolled leaf(RL), with ge-netic background of Zhenshan 97B. Using RL Zhenshan 97B and the originalZhenshan 97B as the female parents, and Minghui 63 and Yanhui 559 as themale parents, crosses of RL Shanyu 63 (RS63) and Shanyu 63(S63), RLShanyou 559 (RS559) and Shanyou 559 (S559) were made. Inheritance andeffects of Rl(t) in hybrid rice were studied at the flowering and at the 20 d afterflowering, respectively. Results were as follow:

Gametic selection in a doubled haploid population derived from anther culture of indica/japonica hybrid of Oryza Sativa L.

It is one of the key problems for application ofanther culture in hybrid breeding, geneticanalysis, and molecular mapping whether thedoubled haploid (DH) population derived fromanther culture of rice crosses represents a ran-dom array of the microspore population, i.e.whether gametic selection occurs in androgene-sis. A DH population including 132 lines de-

Quantitative Trait Loci for Grain Chalkiness and Endosperm Transparency Detected in Three Recombinant Inbred Line Populations of Indica Rice

Quantitative trait loci（QTL） for percentage of chalky grain,degree of chalkiness,and endosperm transparency were detected using 3 recombinant inbred line populations derived from crosses between parental lines of commercial three-line hybrids of indica rice.Two of the populations showed great variations on heading date,and the other had a short range of heading date variation.A total of 40 QTLs were detected and fell into 15 regions of 10 chromosomes,of which 5 regions were detected for 1 or more same traits over different populations,2 were detected for different traits in different populations,3 were detected for 2 or all the 3 traits in a single population,and 5 were detected for a single trait in a single population.Most of these QTLs have been reported previously,but a region located on the long arm of chromosome 10 showing significant effects in all the 3 populations has not been reported before.It was shown that a number of gene cloned,including the Wx and Alk for the physiochemical property of rice grain,and GW2,GS3 and GW5 for grain weight and grain size,could have played important roles for the genetic control of grain chalkiness in rice,but there are many more QTLs exerting stable effects for rice chalkiness over different genetic backgrounds.It is worth paying more attentions to these regions which harbor QTL such as the qPCG5.2/qDC5.2/qET5.2 and qPCG10/qDC10/qET10 detected in our study.Our results also showed that the use of segregating populations having high-uniform heading date could greatly increase the efficiency of the identification of QTL responsible for traits that are subjected to great environmental influence.

Production of bacterial blight resistant lines from somatic hybridization between Oryza sativa L. and Oryza meyeriana L.

Novel bacterial blight (BB) resistance gene(s) for rice was (were) introduced into a cultivated japonica rice variety Oryza sativa (cv. 8411), via somatic hybridization using the wild rice Oryza meyeriana as the donor of the resistance gene(s). Twenty-nine progenies of somatically hybridized plants were obtained. Seven somatically hybridized plants and their parents were used for AFLP (amplified fragment length polymorphism) analysis using 8 primer pairs. Results confirmed that these plants were somatic hybrids containing the characteristic bands of both parents. The morphology of the regenerated rice showed characters of both O.sativa and O.meyeriana. Two somatic hybrids showed highest BB resistance and the other 8 plants showed moderate resistance. The new germplasms with highest resistance have been used in the rice breeding program for the improvement of bacterial blight resistance.

Isozyme analysis on progenes of somatic hybrids of Oryza sativa L.and O.officinalis

Some wild species of Oryza possess agronomi-cally useful traits such as disease/insect resis-tance and salt tolerance.However,the use ofwild Oryza species for rice improvement hasbeen hampered by the sexual incompatibility orsterility of hybrids obtained by conventionalmethods.We have used protoplast fusion as amethod to incorporate useful trait of wild O-ryza species into cultivated rice and~ obtainedsomatic hybrid plants between O.sativa and

水稻(Oryza sativa L.)亚种间杂交穗部性状的双列分析

采用6×6没有反交的完全双列杂交,对亚种间杂交穗部性状的遗传和基因作用以及配合力进行了研究。结果表明,粒长、粒宽、长宽比和粒重为不完全显性,遗传方差中以加性效应为主;穗长、二次支梗数、穗粒数为超显性,显性效应大于加性效应;一次支梗数表现有明显的上位性效应。狭义遗传力的排列顺序为粒宽>长宽比>千粒重>粒长>穗长>穗粒数>二次支梗数。二次支梗数和穗粒数具有相似的遗传基础,其余性状的基因系统具有相对的独立性。8EC1936对所有考察性状皆含有较多显性基因,而02428隐性基因偏多。约有1组显示显性的基因控制籽粒长宽比。穗长、千粒重、一次支梗数、二次支梗数和穗粒数的一般配合力和特殊配合力皆达极显著水平,粒长、粒宽、长宽比仅一般配合力达极显著。Lemont和02428对穗粒数及其相关性状的一般和特殊配合力俱佳;而对增加粒重和获得理想的籽粒形状8EC1936.CA529和矮64、Lemont是可供选择的亲源。

水稻(Oryza sativa L.)温敏核不育系在有利于遗传型鉴别环境下的遗传改良(英文)

低不育起点温度(CSP)、高自繁育性和高的异交结实率对于水稻温敏核雄性不育系配制纯合的杂交种子和获得经济的自繁种子有重要意义。本研究分析了不同环境对这些性状选择效率的影响,结果表明,温敏核雄性不育系的雄性不育起点温度、自繁雄性可育性、柱头外露率和穗伸出率、生长势和适应性的选择效应受环境影响。在某种环境下遗传材料的这些性状过高的表达并没有导致高的区分度,因为在这种情况下性状在株间表现较整齐一致,温敏核雄性不育基因(tms)在高温下雄性不育性也表现相似的结果,因此认为有必要在适当有利于区分遗传型的环境下进行选择。在相对较低的温度条件下选择低的CSP和高的自繁雄性可育性有较高的选择效率;在较高的湿度条件下选择柱头外露较有效,而高的温度下选择穗的抽出率效率高,在相对低的土壤肥力环境下改良不育系的生长活力和适应性效率高。

Effects of soilless substrates on seedling quality and the growth of transplanted super japonica rice

This study was conducted to investigate the effects of soilless substrates of hydroponically grown long-mat seedlings （HLMS） on seedling quality and field growth characteristics of transplanted super japonica rice. A widely grown conventional super japonica rice cultivar （Wuyunjing 23） was selected as the test material. The effect of HLMS on seedling quality, mechanical transplantation quality, field growth characteristics, yield, and benefit-cost ratio were compared with seedlings grown in organic substrates and traditional nutritive soil, whJch was selected as the control. Root number, root twJstJng power and root activity of seedlings cultivated by HLMS were decreased compared to that of the organic substrates andcontrol. However, seedling root length as well as aboveground growth were increased compared to the organic substrates and control seed- lings. In the HLMS, the content of gibberellin acid （GA3） decreased while abscisic acid （ABA） content increased compared to that of the organic substrates and control seedlings. During the early stages after transplanting, the re-greening of HLMS was delayed compared to that of the organic substrates and control seedlings. Nevertheless, there were no significant differences in tiller dynamics and crop yield among the HLMS, organic substrates and control treatments. The effects of HLMS on seedling production were similar to those of the organic substrates and traditional nutritive soil in the present study, suggesting that HLMS have the potential to replace traditional nutritive soil in seedling production without decreasing crop yield. Finally, it is important to reduce organic substrates and topsoil dependence during rice seedling production and worthwhile to consider HLMS popularization and its application on a larger scale.

Effects of exogenous salicylic acid on growth and H_2O_2-metabolizing enzymes in rice seedlings under lead stress

Salicylic acid （SA） was an essential component of the plant resistance to pathogens and also plays an important role in mediating plant response to some abiotic stress. The possible effects of SA on the growth and H2O2-metabolizing enzymes in rice seedlings under lead stress were studied. When rice seedlings grown in nutrient solution containing Pb^2＋ （0, 0.05, 0.15, 0.25 mmol/L） for 18 d, the plant biomass as well as the chlorophyll content of leaves decreased with increasing Pb concentration. The pre-treatment with SA （treated with 0.1 mmol/L SA for 48 h before Pb stress） partially protected seedlings from Pb toxicity. The chlorophyll contents were significant higher in leaves of Pb-exposed with SA pre-treatment seedlings than in Pb-exposed plants at the same Pb intensity. SA pre-treated alone could significantly increase the length of shoot and root of seedlings but the vigour difference was not marked under long-term exposure to Pb toxicity. SA pre-treated influence the H2O2 level in leaves of seedlings by up-regulating the activity of superoxide dismutase （SOD）, repressing the activity of catalase （CAT） and ascorbate peroxidase （APX） depending on the concentrations of Pb^2＋ in the growth medium. The results supported the conclusion that SA played a positive role in rice seedlings against Pb toxicity.

Why are There Indica Type and Japonica Type in Rice?——History of the Studies and a View for Origin of Two Types

On the bases of archaeological discoveries, the earliest domestication of rice has been confirmed in the middle and lower Changjiang River basin, while in the region wild rice populations are found in shallow swamps under a climate with freezing winter cold. These findings lead us to-examine the past ideas about domestication and differentiation of rice. Historically, in 1930s two sub-species, indica and japonica, were proposed on the basis of sterility in F1 hybrids between them. Soon after that, the two types were classified by the associations of a number of genetically independent traits. The characteristic associations of traits have been explained by the hybrid sterility or reproductive barriers which were assumed to comprise a set of duplicate recessive lethal genes and to be an inner genetic mechanism to lead to the varietal differentiations In 1980s, the hybrid sterility between Indica and Japonica types was analyzed, and Indica, Japonica, and wide-compatibility type which gives fertile hybrids when cross to Indica and Japonica types, are proved to contain an allele, S5＇, S5＇ and S5^n, respectively at a locus on chromosome 6. And those gametes having Sj allele are found to be partially aborted in the hybrid genotypes of S5＇/S5＇ while no gamete abortion occurs in S5＇/S5^n and S5＇/S5^n genotypes. Since then, the gene S5^n has been used in hybrid rice breeding to obtain fertile and vigorous hybrids between subspecies, and the long-disputed problem of hybrid sterility has been solved. Also in such studies the characteristic association of traits found in each of vadetal groups is better explained by founder effects. On the other hand, a large number of native cultivars of rice were surveyed with enzyme polymorphism in 1980s and later with molecular markers. As a result, profound genetic diversity is found in cultivated rice as well as in wild rice. These findings seem to lead us to the idea of multiple independent domestications of rice. However, before reaching such a conclusion, at least two factors, i.e., long-distance-dissemination of some genotypes and the possibilities of introgression by local wild rice to primitive cultivars need to be examined. Taking the two factors as well as the historical events into consideration, it is considered here that the perennial japonica cultivars which are close to wild rice in the Changjiang River basin were disseminated to East India through Assam or along the Bengal Bay, where they were transformed under the introgressions of local wild rice and formed a secondary center, from which some genotypes seem to be disseminated to colonies in Southeast Asia under the influence of Hinduism. Later some of the genotypes were introduced into China and constituted so called Indica type. This may be a reasonable picture for the varietal differentiation.

Status and Prospects of Hybrid Rice Breeding in Jiangsu, China

Research on hybrid rice in Jiangsu Province, China began in 1970. Great progress has been made since then, which can be divided into three stages according to the development of hybrid rice breeding and production in Jiangsu Province. The first stage was beginning stage from 1970 to 1980, when progress was mainly made in cytoplasmic male sterile line breeding. The second stage could be described as developing stage, from 1980 to 1995, when indica hybrid rice was rapidly popularized, and japonica hybrid rice became popular later. From 1996, hybrid rice breeding in Jiangsu Province entered the third stage, when both indica and japonica hybrid rice breeding in the three-line system or intersubspecific hybrid rice breeding in the two-line system made a great breakthrough with the successful breeding of the hybrids Feyou 559, 9 You 138 and Liangyoupeijiu. The developing trend of hybrid rice breeding in Jiangsu Province is also discussed.

Agronomic Performance of Cultivars of Upland Rice in the Southern of the Region of Rondonia,Brazil

The upland rice is grown in most Brazilian states. However, in many of them the yield obtained is low. The choice of cultivar more suited to a particular environment can contribute to increased productivity of this crop. This research aimed to evaluate the performance of a hybrid cultivar of upland rice (Ecco) and five conventional cultivars (BRS Monarca, BRS Primavera, AN Cambará, BRS Sertaneja and BRS MG Curinga) in two environments (Vilhena and Cerejeiras). The tests were conducted in the agricultural year 2010/2011. We evaluated the following characteristics: tillering, panicle number per unit area, number of filled grains per panicle sterile, mass of grains per panicle, 1000 grain weight, grain yield (kg·ha-1) and whole grain yield. There was no cultivar x environment interaction for all traits. Greater tillering, higher panicle number per area, higher productivity and yield of whole grains in the municipality of Cerejeiras were observed, while the highest number of sterile grains per panicle was obtained in Vilhena. The hybrid Ecco highlighted in relation to all other cultivars is in relation to tillering, panicle number per area and grain yield. The municipality of Cerejeiras is the most suitable for the cultivation of upland rice.

利用InDel标记鉴定浙优系列杂交稻籼粳属性和预测杂种优势

【目的】准确鉴定水稻材料的籼粳属性及利用遗传距离预测杂种优势,为开展水稻超高产育种和籼粳亚种间杂种优势利用提供基础。【方法】利用19对籼粳稻特异插入/缺失(Ins6rtion/Deletion,InDe1)引物,对12个浙优系列杂交稻及其双亲的籼粳属性进行了InDe1分子标记鉴定,根据被检测水稻样品在多个InDe1位点上的籼型或粳型基因频率,参考卢宝荣的方法,将供试样品分别判定为"籼稻"、"偏籼"、"中间偏籼"、"中间偏粳"、"偏粳"和"粳稻"。采用Nei的方法求算1 3个亲本间(1个不育系和12个恢复系)的InDe1遗传距离,用UPGMA法进行遗传相似性聚类,用SPSS 17.0统计分析软件对InDe1条带赋值进行主成分分析,依据第一和第二主成分的特征向量的平均分量值作平面散点图。统计杂种F_1稻谷产量、每穗总粒数、每穴有效穗、结实率、千粒重及单穗重各产量性状的对照优势,以此分析InDe1遗传距离与杂种优势的相关性。【结果】(1)参试材料籼粳属性的判别:不育系浙04A被鉴定为"粳稻",8个恢复系被判定为"籼稻"或"偏籼",由其所配组的8个杂交组合被判定在"中间偏籼"到"偏粳"之间,证实了这8个组合为典型的籼粳交组合;另外4份恢复系被判定为"偏粳",所配组的4个杂交组合被判定为"粳稻"。(2)参试材料的聚类分析:当GS为0.350时,35份试验材料被分为"粳稻"和"籼稻"2个主群,GS为0.638时,粳稻主群又被划分为"粳稻/偏粳"和"中间偏粳"2个亚群。其中,粳稻/偏粳亚群包括不育系浙04A、4个粳粳交恢复系及粳粳交杂种F_1、3个粳稻对照种和粳稻秀水09;中间偏粳亚群包括8个籼粳交杂种F_1。籼稻主群则包括8个籼粳交组合的恢复系、3个籼稻对照种和籼杂组合汕优6 3。(3)InDe1遗传距离与杂种优势的相关性:在以粳粳交、籼粳交组合整体作为分析对象时,InDe1遗传距离与稻谷产量、每穗总粒数、单穗重呈极显著正相关,与结实率呈显著负相关;仅以籼粳交组合为研究对象时,InDe1遗传距离仅与单穗重和千粒重呈显著正相关。【结论】供试的12个浙优系列中的8个组合被证实为典型的粳不/籼恢型籼粳交组合,这些组合的双亲间具有较远的遗传距离;InDe1遗传距离在不同类型品种间具有较好的杂种优势预测能力,可用于单穗重的优势预测,即随着InDe1遗传距离的扩大,杂种优势主要体现在单穗重的增加上。

水稻第2染色体上细菌性条斑病抗性QTL的检测

用中抗和高抗细菌性条斑病(简称细条病)的两个籼稻品种明恢86和佳辐占为亲本构建了F2群体,应用SSR标记在水稻第2染色体的RM279～RM154之间检测到1个与水稻细条病抗性有关的QTL,其可解释遗传表型变异的13.7%,其加性效应为0.9576,来自抗病亲本佳辐占。

水、旱栽培条件下水稻叶片水势与抗旱性的相关分析及其QTL定位

为了揭示叶片水势在水稻抗旱中所起的作用及其遗传机制,以越富和IRAT109为亲本构建了120个重组自交系,开展叶片水势与抗旱相关性及QTL定位的研究。重组自交系及亲本群体在旱田和水田两种条件下种植,于始穗期测量叶片凌晨水势和中午水势;以抗旱系数作为抗旱鉴定指标。结果表明,叶片水势在重组自交系间变异显著。相关性分析表明旱田中午叶片水势与抗旱系数及旱田单株产量呈极显著正相关,旱田叶片水势变化与抗旱系数及旱田单株产量呈极显著负相关,说明旱田中午叶片水势高且能保持凌晨基础叶片水势的品种更具抗旱性。共检测到6个叶片水势加性QTL,其中旱田凌晨叶片水势2个,分别解释表型变异的5.4%和7.9%,旱田中午叶片水势1个,解释表型变异的10.0%,旱田叶片水势变化2个,分别解释表型变异的11.6%和9.5%,水田叶片水势变化1个。未检测到水田叶片水势加性QTL。共检测到5对上位性效应QTL,其中旱田中午和凌晨叶片水势各检测到1对上位性QTL,水田凌晨叶片水势上位性QTL1对,水田中午叶片水势上位性QTL2对。抗旱系数共检测到3个加性QTL和2对上位性QTL。叶片水势遗传力较低,田间直观选择效果差,利用分子标记辅助选择将会提高选择效率。