The indica-japonica classification of Asian rice ecotypes and Japanese lowland and upland rice (Oryza sativa L.)

Summary Rice cultivars (Oryza sativa L.) belonging to five ecotypes (aus, aman, boro, bulu and tjereh) and to two groups of Japanese rice (lowland and upland) are examined with respect to KClO₃ resistance, phenol reaction and apiculus hair length. These characters have been used as available criteria to classify rice into two types indica and japonica, for the last thirty years.The findings of this study are that the aman, boro and tjereh ecotypes should be classified as typical indica; and that the Japanese lowland rice cultivars are mainly typical japonica. Some of the aus, bulu and Japanese upland rice cultivars differ from typical indica and typical japonica, so the respective terms aus type, bulu type and J.u.r. type, are proposed. Aman, boro tjereh and Japanese lowland rice are cultivated in lowland. Some of the aus, bulu and Japanese upland rice cultivars have the characteristics of upland rice. In general, lowland rice cultivars can be clearly classified into indica or japonica, while upland cultivars cannot.Abbreviations Aph dominant gene for apiculus hair length > 0.7 mm - aph recessive gene for apiculus hair length < 0.7 mm - J.u.r. type Japanese upland rice type     

Analysis of Vietnamese rice germplasm provides an insight into Japonica rice differentiation

Genetic differentiation among landraces of rice in northern Vietnam that lie in the centre of genetic diversity of Asian cultivated rice was analysed using DNA markers, and morphological and physiological traits to obtain an insight into the genetic differentiation of Asian rice. Principle coordinate analysis, based on nuclear RFLP data, divided Vietnamese rice varieties into three groups, designated A, B and C. Chloroplast DNA variation discriminated group A, which corresponded to the Indica rice varieties, from both groups B and C, which corresponded to the Japonica rice varieties. Physiological characteristics for Indica‐Japonica and tropical‐temperate Japonica discrimination suggested groups A and B consisted of typical Indica and Japonica varieties, respectively, while the characteristics of group C were distinct from those of the other two groups. This suggests that the genetic differences between groups B and C represent a new aspect of genetic variation that has not been previously reported in Japonica rice. Groups C and B corresponded with upland and lowland rice, respectively. Eight marker loci were associated with upland‐lowland differentiation in Japonica rice. Highlighted chromosomal regions might have been selected during the history of cultivation under different cultural conditions, and thus contain genes related to adaptation.     

水稻,陆稻根系蛋白质含量和同工酶研究

对10个水稻栽培种和10个陆稻栽培种的研究结果表明,水稻和陆稻根系发育过程中蛋白质含量、POD和COD同工酶都有较明显的差异,陆稻根系中蛋白质含量高于水稻的含量,陆稻的POD同工酶谱带数虽少于水稻,但苗期和分蘖期酶谱带总面积却高于水稻.在不同发育时期,陆稻中POD同工酶谱型变化较水稻稳定.陆稻根系中COD同工酶谱带数多于水稻,但苗期和分蘖期大部分COD同工酶的相对酶活性低于水稻,陆稻根系发育过程中,在开花期尚能检测到COD_7酶带.与水稻相比,陆稻根系发育过程中COD同工酶谱型的变化较小.     

云南栽培稻生态型矿质元素含量的多样性

用ICP-AES测定了新平县相同生态条件下种植653份云南稻资源糙米8种矿质元素含量，并按丁颖的栽培稻生态型对其遗传多样性进行了研究。结果表明，云南水稻改良品种糙米P、Fe和Zn含量比地方稻种分别下降10.53%、14.76%和35.16%，但改良品种特别是粳稻Ca含量比地方种高, 8种矿质元素以Ca的多样性指数最大；糙米P、Ca、Mg、Fe、Zu、Cu和Mn平均含量以粳稻的Mg、Fe和Zn，水稻的P、K和Mg，陆稻的Fe和Zn，糯稻的K和Fe，早稻的Mg和Fe相对较高。8种矿质元素平均遗传多样性指数依次为粳>籼,陆>水,粘>糯,早中稻>晚稻和地方种>改良种,且P>K>Mn>Mg>Cu>Zn>Fe>Ca；其变异系数依次为Fe>Ca>Cu>Zn>Mn>K>Mg >P。     

水、旱稻根基粗和抗旱系数QTL的标记辅助选择及验证

利用水、旱稻杂交、回交所产生的4个分离群体对RIL群体定位到的抗旱相关的根基粗、抗旱系数2个QTL进行了选择验证。结果表明，根基粗、抗旱系数QTL的两侧标记在不同群体、不同的遗传背景中遗传稳定。在旱田种植条件下，YIBC1、JIBC1、JIF2 3个分离群体携带有根基粗QTL brt4.1两侧标记有利等位基因的个体与没有携带brt4.1两侧     

旱稻渗入系抽穗期根系性状定位

摘 要：[目的]研究稻作抗旱的根系特征及其遗传机理,发掘旱稻有利基因,从水旱稻杂交中选育高产耐旱的稻作品种提供理论基础和研究材料。[方法]以旱稻豪格劳为供体亲本,水稻沈农265为受体亲本,利用187个SSR标记构建了一套具有180个家系的旱稻渗入系群体,并采用单标记分析法,对拔节期根系6个性状：最长根长、粗根数、总根数、平均最粗根粗、根干重、总干重进行QTL定位。[结果]抽穗期共检测到QTL38个,其中影响上述六个性状的QTL数目分别是6、6、4、6、4和12,它们的总贡献率分别为29%、27%、21%、33%、23%和61%。除此,在粗根数和总根数中分别检测到3个和1个来自豪格劳的等位基因的加性效应为负,其余均为正。除平均根粗外,其它5个性状的加性效应都较大。[结论]89.5%的渗入位点对以沈农265为遗传背景的渗入系的6个性状根系有促进作用;定位到的影响不同根系性状的QTL多数成簇、集中分布;RM3853附近定位到影响四个性状的QTL,推测是一个在抽穗期与根系性状和抗旱密切相关的基因簇。     

Localization of QTL for basal root thickness in <Emphasis Type="Italic">japonica</Emphasis> rice and effect of marker-assisted selection for a major QTL

Root traits are key components of plant adaptation to drought environment. By using a 120 recombined inbred lines (RILs) rice population derived from a cross between IRAT109, a japonica upland rice cultivar and Yuefu, a japonica lowland rice cultivar, a complete genetic linkage map with 201 molecular markers covering 1,833.8 cM was constructed and quantitative trait loci (QTLs) associated with basal root thickness (BRT) were identified. A major QTL, conferring thicker BRT, located on chromosome 4, designated brt4, explained phenotypic variance of 20.6%, was selected as target QTL to study the effects of marker-assisted selection (MAS) using two early segregating populations derived from crosses between IRAT109 and two lowland rice cultivars. The results showed that the flanking markers of brt4 were genetically stable in populations with different genetic backgrounds. In the two populations under upland conditions, the difference between the means of BRT of plants carrying positive and negative favorable alleles at brt4 flanking markers loci was significant. Phenotypic effects of BRT QTL brt4 were 5.05–8.16%. When selected plants for two generations were planted at Beijing and Hainan locations under upland conditions, MAS effects for BRT QTL brt4 were 4.56–18.56% and 15.46–26.52% respectively. The means of BRT for the homozygous plants were greater than that of heterozygous plants. This major QTL might be useful for rice drought tolerance breeding. L. Liu and P. Mu are contributed equally to this work.     

水分胁迫对云南陆稻主要农艺性状的影响

为了揭示水分胁迫对陆稻主要农艺性状的影响,以21 个云南陆稻品种为材料,对其9 个主要农艺性状在旱作和水培2 种水分管理模式下的变化规律以及与旱作产量的相关关系进行分析。结果表明：陆稻旱作较水作生育期延长、有效穂数降低、实粒数减少、结实率下降、千粒重降低。水分胁迫下陆稻各主要农艺性状与抗旱系数的通径分析表明：陆稻的多种农艺性状均与其抗旱能力有着不同程度的依存关系,但是与旱作产量关系最密切、影响最大、最直接的还是有效穗数、实粒数、千粒重这3 个指标。因此在陆稻栽培过程中,宜采用“稳穗、增粒、增重”的高产生产措施。通过采取适宜的措施,在适当增加穗数的前提下,通过提高陆稻的结实率和千粒重实现高产。     

Phenological responses of Oryza sativa, O. glaberrima and inter-specific rice cultivars on a toposquence in West Africa

Phenological properties of rice cultivars, particularly crop duration, determine their yield potential, local agronomic suitability and ability to escape from drought. Crop duration of a given cultivar depends mainly on photoperiod (PP) and temperature, but is also affected by the crop establishment practice and environmental stresses. A sample of 84 ecologically and genetically diverse rice cultivars was sown on five dates between May and September 1997 on the flooded-lowland (transplant), hydromorphic and upland levels of a toposequence at 7^° 52′ N in Cote d'Ivoire, in order to characterize the cultivars' phenological responses. In the upland, life-saving sprinkler irrigation was applied when drought symptoms were visible. A non-replicated design augmented with four replicated checks (four replications per ecosystem) was used. Phenology was characterized by date of emergence, first heading, 50% flowering and maturity. The period from emergence to flowering was subdivided into three phases following a simple model used at IRRI to characterize germplasm for photoperiodism. For each ecosystem and cultivar, the basic vegetative period (BVP) was estimated by subtracting 30 d from the duration to flowering at the sowing date associated with the shortest duration, and expressed in degree-days (dd), assuming a base temperature of 10 ^°C. The PP-sensitive phase (PSP) was estimated by subtracting BVP+30 d from the time to flowering. PP-sensitivity (PS) was calculated from the apparent change in PSP between 12.0 and 12.5 h mean astronomic daylength during the PSP, by regression across dates. Cultivars differed strongly in BVP (300 to 1200 dd) and PS (0 to 1000 dd). The BVP was generally longer in the lowland than in the hydromorph, and mostly longer in the upland than in the hydromorph, possibly due to transplanting shock (lowland) and drought (upland). Many cultivars, particularly upland-adapted japonicas, had a greater PS in the lowland than in the upland. Principal-component and cluster analyses based on BVP and PS in each of the three ecosystems established three large and three small groups of cultivars having common phenological responses. The linkage groups were associated with ecotypes (lowland vs upland, traditional vs improved) and genetic groups (O. sativa japonica and indica, O. glaberrima, inter-specific progenies). The groups were seen to represent past selection strategies by farmers and recent breeding strategies, with respect to achieving yield stability in the various ecosystems. For example, indigenous selection strategies for O. sativa upland rices seem to have favored a long BVP, whereas from O. glaberrima, which generally has a superior initial vigor, cultivars with a short BVP have been selected. The authors conclude that the modern upland rice breeding strategy for the region on the basis O. sativa, which aims at drought escape using a short BVP, is paralleled by existing indigenous O. glaberrima materials. Efforts to utilize these materials for breeding are ongoing. This revised version was published online in August 2006 with corrections to the Cover Date.     

黑龙江省杂草稻与栽培稻的生物学多样性及遗传关系研究

为评价杂草稻与栽培稻的遗传多样性及其变异关系,用9个农艺性状研究了50份杂草稻和18份栽培稻的生物学多样性及遗传关系。结果表明,杂草稻株高、穗长、平均穗粒数、结实率、芒长、芒色、粒色等植物学特性均较栽培稻变异大。Nei’s遗传多样性值（h）明显高于栽培稻,表明杂草稻比亚洲栽培稻具有更丰富的遗传多样性。UPGMA聚类为明显的杂草稻与栽培稻两个类群,且关系密切,但在遗传上存在明显的分化。杂草稻较栽培稻植物学特性变异大,遗传多样性丰富,在遗传上存在明显的分化,支持将其视为不同亚种的观点。     

杂交粳稻不同穗位垩白性状的差异与遗传率分析

以辽宁省近年审定的2个杂交粳稻组合9946与1052及其对应亲本为材料,对稻米垩白品质性状在穗上不同部位和不同枝梗上的分布特点和遗传差异进行研究。结果表明:垩白米率、垩白面积和垩白度表现了下部穗位最大,中部和上部穗位次之,二级枝梗大于一级枝梗。差异大的组合(9946)遗传率大,一级枝梗的遗传率大于二级枝梗的遗传率。垩白性状受遗传、栽培条件以及穗位与遗传互作的影响。因此,选择垩白性状差异小,而其他性状优良的亲本进行组配,结合合理的株型育种,有可能育出低垩白的优质组合。     

水、旱栽培条件下稻米主要品质性状的比较研究

以旱稻品种IRAT109的116个株系与水稻品种越富杂交构建的DH群体及其亲本，在水、旱2种栽培条件下种植，研究了稻米加工、外观、蒸煮和营养等品质性状的变化规律及其各品质性状间的相关性。结果表明，在11个稻米品质性状中，蛋白质含量、整精米率、胶稠度和碱消值等4个性状水、旱2种不同栽培条件下差异较大，说明这些性状受水分条件影响较大；粒长、粒宽、直链淀粉含量和垩白率也有一定的差异，一定程度受土壤水分环境影响。旱栽条件下稻米蛋白质含量、整精米率、胶稠度、碱消值等均有不同程度的升高，其中蛋白质含量平均提高37.9%，平均增加3.02个含量百分点，而垩白率下降，稻米米粒变小，总体上旱栽稻米品质有变优趋势。糙米率、精米率和长宽比在2种栽培条件下没有差异，基本上不受土壤水分环境影响。此外，对同一品质性状在水、旱2种不同栽培条件下相关性分析，表明加工品质性状的基因与环境互作较大，外观、蒸煮和营养等品质性状比较稳定。因此，通过水稻和旱稻相互杂交，可将旱稻的抗旱基因导入外观品质、蒸煮、食用品质以及营养品质优良的目标水稻亲本中，选育出抗旱、优质的水稻或旱稻品种。     

Identification of two types of differentiation in cultivated rice (Oryza sativa L.) detected by polymorphism of isozymes and hybrid sterility

Magnitudes of genetic variation within each of major varietal groups of cultivated rice were surveyed in terms of isozyme polymorphism and allelic differentiation of hybrid sterility loci, both of which are considered to have litt le selective value. Allelic differences for 20 isozyme loci were examined in a total of 337 accessions, including Indica and Japonica rices. Aus cultivars from India, Javanica cultivars and both landraces and cultivars from China. Eleven out of the 20 isozyme loci were polymorphic. The Aus cultivars contained more alleles per locus than others. The hybrid sterilities in the crosses among Chinese cultivars, Indica and Japonica cultivars were mainly controlled by locus S-5, whereas the hybrid sterilities of Aus cultivars, when they were crossed to Indica, Japonica or Javanica cultivars, were found to be controlled by allelic interaction at hybrid sterility loci S-5, S-7, S-9 and S-15. Also in terms of the number of alleles at S-5 and S-7, Aus cultivars contained more alleles than others. While the Aus group showed an extreme diversity for both hybrid sterility alleles and isozymes, modern cultivars from the south of YangZi River in China were classified into Indica type and those from the north were into Japonica, which were almost the same as those in Japan. On the basis of the measured polymorphism the Indica-Japonica differentiation was explained by founder effects, i.e., through selection and distribution of two original sources each with a unique set of markers. Contrastingly, the continuous and pronounced diversity in the Aus group was attributed to the absence of such a process. The intermediate groups in Yunnan province and Tai-hu Lake region of China are considered to be isolated from such founder effects, retaining an intermediate diversity in terms of isozymes and hybrid sterility genes. Since hybrid sterility hampers the exchange of genes between cultivars of different groups, the understanding of its genetic basis will be important in rice breeding, particularly in hybrid rice breeding. This revised version was published online in July 2006 with corrections to the Cover Date.     

水、旱栽培条件下稻谷粒型和粒重的相关分析及其QTL定位

为了解水、旱栽培条件下水稻粒形和粒重的表型及QTL变化,以陆稻品种IRAT109和水稻品种越富构建的双单倍体群体为材料,系统分析了稻谷粒长、粒宽、粒重及长宽比在水、旱栽培条件下的相关性,并进行了数量性状基因位点的比较定位。结果表明,水、旱条件下,粒长与长宽比和粒重均呈极显著正相关;粒宽与长宽比呈极显著负相关,与粒重极显著正相关,4个性状在水、旱条件间相关性都达极显著正相关。其中粒长的相关系数最高,达0.817,粒宽的相关系数最低,为0.457。表明粒长受水分影响最小而粒宽受水分影响较大。粒重、长宽比介于二者之间。两种条件下共检测到14个QTLs,分布于水稻1、5、6、7、10和12染色体上,其中控制粒长的5个,LOD值为1.93~5.11,贡献率为5.97%~28.85%;控制粒宽的1个,LOD值为2.39,贡献率为12.76%;控制长宽比的3个,LOD值为2.08~4.6,贡献率为7.78%~21.89%;控制粒重的5个,LOD值为2.68~9.45,贡献率为4.1%~14.8%。其中控制粒长的qGL-5及控制粒重的qGWt-1a和qGWt-1b在水、旱条件下均能检测到,在抗旱育种中可用于分子标记辅助选择籽粒性状。QTL分析的结果进一步验证了表型分析结果,粒宽相对易受土壤水分影响,粒长、粒重和长宽比,受水分胁迫影响较小,遗传比较稳定。     

Inheritance of isozymes in peach x Prunus kansuensis and peach x Prunus davidiana hybrids

Summary Isozyme variation and inheritance were investigated with starch gel electrophoresis in peach (Prunus persica L. Batsch) x P. kansuensis Rehd. and peach x P. davidiana (Carr.) Franch. interspecific hybrids. Of five enzyme systems surveyed for polymorphism, four systems were identified as polymorphic [isocitrate dehydrogenase (IDH, EC 1.1.1.41), phosphoglucomutase (PGM, EC 2.7.5.1), aspartate aminotransferase (AAT, EC 2.6.1.1), and 6 phosphogluconate dehydrogenase (PGD, EC 1.1.1.44)] and may be useful as genetic markers in future cultivar and rootstock development. Analysis of progenies segregating for pairs of loci suggests a possible linkage between the loci coding for Aat-1 and Pgd-2. Independent assortment was observed for isozyme loci Idh/Pgm-2, Idh/Aat-1, Idh/Pgd-2, Pgm-2/Aat-1, Pgm-2/Pgd-2, and Aat-2/Aat-1. The red leaf locus, Gr, assorted independently of the isozyme loci: Idh, Pgm-2, Aat-1, and Pgd-2.     

旱稻种质的遗传差异和配合力分析

用52个RAPD随机引物和53对SSR引物，分析了来自国内外的14个旱稻品种和4个杂交稻亲本的遗传差异。结果表明，供试旱稻品种可清楚地区分为籼、粳2个亚种。以4个旱稻品种和4个水稻品种为材料，按完全双列杂交设计，探讨了在旱种和水种条件下供试材料的配合力和反交效应特点。资料显示，在水、旱2种条件下，旱稻品种的产量和品质性状的一般配合力效应多数均未达显著水平，且明显低于水稻品种；株高、结实率、千粒重、整精米率、长宽比和直链淀粉含量的特殊配合力效应呈现旱稻/旱稻〉旱稻/水稻〉水稻/水稻的趋势。在旱种条件下，多数旱稻/水稻组合的糙米率、精米率和整精米率的反交效应达极显著水平。     

Farmers' Perceptions on Rice Varieties in Sikasso Region of Mali and their Implications for Rice Breeding

Rice is an important staple food and cash crop. Although many varieties of rice have been developed to date, few are adopted possibly because researchers did not take into account farmers’ preferences and perceptions on varieties during the development process. Because farmers increasingly rely on low-yielding landraces, production fails to meet demand. To provide an understanding of farmers’ preferences for rice cultivars and perceptions on drought stress and management practices as inputs to rice breeding research, this study was conducted in the Sikasso region of Mali in September 2005 using participatory rural appraisal approach. A total number of 125 farmers were randomly selected from 10 villages in three ecologies and interviewed individually and in groups. Results showed that farmers’ preferences, crop management practices and ranking of production constraints differed significantly across ecologies. Whereas farmers in the irrigated ecologies preferred high-yielding, long duration rice varieties, those in the upland and lowland ecologies preferred tall plants of short duration. While upland and lowland farmers preferred red and white long grains, respectively, irrigated ecologies were indifferent about grain colour. Farmers appeared willing to trade-off yield for grain quality and plant height, inconsistent with traditional breeders’ selection criteria. The high preference for tall varieties among farmers in the upland and lowland ecologies also contrasted sharply with the model of dwarf rice varieties responsible for the green revolution in Asia. The implication of these findings for rice breeders is that different plant idiotypes complemented by effective drought management practices should target different ecologies to increase impact.     

栽培稻叶结构、水分生理与抗旱性关系研究

摘 要：增强栽培稻品种的抗旱性是稻作节水生产的重要途径。稻作种质资源抗旱相关指标的研究是改良稻作品种抗旱性的重要依据。选择抗旱性差异明显的四种类型稻作种质,采用三种干旱胁迫方式,对孕穗期植株叶片的叶肉厚、中脉粗、叶片相对含水量及叶片保水率进行了考察,分析稻作种质在三种处理下各性状相互之间的内在关联及其与品种抗旱性的关系;结果表明叶肉厚、中脉粗、叶片相对含水量及叶片保水率在干旱胁迫下均表现为旱稻类型高于水稻类型。轻度干旱下的叶肉厚与成熟期生物量抗旱指数DRIm2-B极显著相关,与孕穗期生物量抗旱指数DRIm2-H显著性相关。重度干旱下的中脉粗与DRIm2-B极显著相关,重度干旱下的叶片保水率与重度干旱产量抗旱指数DRIm2-Y显著相关,中脉粗和叶片相对含水量在四种种质类型中差异不明显;孕穗期叶肉厚和叶片保水率可分别作为稻作种质抗旱性研究和评价的两个指标。     

Genetic variation in root morphology and microsatellite DNA loci in upland rice (Oryza sativa L.) from Vietnam

Drought is a major constraint to the productivity of rice in upland ecosystems. The rice root system plays an important role in the regulation of water uptake and extraction from deep soil layers. The aim of this research was to study the variation in root morphology and the genetic diversity in upland rice accessions. Thirty-three upland rice accessions originated from Vietnam along with 13 selected upland rice lines from several other countries were used in this study. Variation in root morphology was observed in most of the investigated root traits such as maximum root length, total root dry weight, deep root to shoot ratio, and total root to shoot ratio. Most of the traits showed significant correlation and appeared interrelated. Genetic diversity among upland rice accessions was studied with microsatellite markers. Forty-one alleles were detected with 14 rice microsatellite primer pairs among all the rice accessions. Two dendrograms have been created based on 35 microsatellite alleles and 10 morphological traits data for 38 accessions and compared. These results provided useful information for the selection of suitable cross combinations for mapping quantitative trait loci (QTLs) related to drought resistance in upland rice.