中国疣粒野生稻的分布、濒危现状和保护前景

继1978-1982年全国野生稻普查后,又一次对中国疣粒野生稻（Oryza granulata (Nees et Arn.Ex Watt.））主要分布点的居群特征、濒危现状和破坏情况进行了野外生态学研究。由于行政区划的改变,目前疣粒野生稻在中国分布的市（县）达30个。它在群落盖度为90%-210%下生长良好,具有抗旱和适应中度干扰的能力。聚集参数分析表明在群落中居群以集群分布为主。该物种主要通过重力和动物传播种子,居群间的基因流有限,形成了典型的集合种群（metapoulation）结构。生境丧失对疣粒野生稻的生长造成非常严重的后果,巳有12.9%的疣粒野生稻居群灭绝,83.9%的居群处于中度和重度的干扰之下。由于各地区的破坏程度不平衡,目前疣粒野生稻的分布被压缩到海南省的西南部山区和云南省和澜沧江中下游、南汀河流域,面临热区开发的巨大威胁。研究中建立了中国疣粒野生稻的总DNA库,作为易位保护的手段之一和开展保护遗传学研究的基础;并讨论了居群遗传结构与居群分布格局之间的相互关系和保护中需注意的问题。     

六个核基因片段在中国颗粒野生稻中的单核苷酸多态性及其在群体遗传学研究中的应用

为了筛选可用于亚洲栽培稻的重要野生近缘物种颗粒野生稻群体遗传结构研究的有效SNPs标记,本研究共选取Osgstf3、OsNAC6、BADH、XCP2、EMF2和ERCC4 6个重要水稻功能基因,检测了来自中国云南和海南12份颗粒野生稻代表样品中的单核苷酸多态性,结果发现Osgstf3、OsNAC6、BADH和XCP2的单核苷酸多态性接近于零,但在EMF2和ERCC4内含子区中检测到较低的核苷酸变异。利用EMF2和ERCC4片段对来自云南的3个天然群体和来自海南的2个天然群体共52个个体进行了群体遗传学研究,发现该物种具有高水平的遗传分化和低水平的遗传变异的独特群体遗传结构;这种剧烈的遗传分化不仅来自云南和海南两个地区之间,而且还来自地区内居群间,说明该野生稻生长的热带、亚热带森林生境的破坏导致了碎裂的居群间基因流强烈受阻。     

Analysis of genetic variability of South American wild rice populations (Oryza glumaepatula) with isozymes and RAPD markers

The knowledge of population structure and genetic diversity of wild relatives of rice is needed to investigate their evolutionary history and potential use in breeding programs. Very little is known about the wild rice species ( Oryza spp.), particularly those that are native to South America. A study using isozyme and RAPD markers was conducted to estimate the level of genetic diversity of four South American wild rice populations ( Oryza glumaepatula ) recently collected in the Amazon forest and western Brazil rivers. F -statistics and genetic diversity parameters calculated from isozyme and RAPD markers indicated high values for inbreeding coefficients and differentiation among the four populations. In agreement with this, a pattern of greater variation between than within populations was observed with both types of markers. These findings were corroborated by an AMOVA analysis, which indicated that a large portion of the total genetic variation was attributed to regional divergence. The partition of the AMOVA analysis among populations showed that most of the genetic diversity was due to differences among populations. This distribution pattern of genetic variation of O. glumaepatula populations is in agreement with the expectation for an autogamous species and provides important baseline data for conservation and collection strategies for this species.     

中国野生稻的现状调查

中国有三种野生稻。野生稻是栽培水稻的野生近缘种,已被列为濒危植物^[7],它们分布于中国南方８个省（区）的热带、亚热带湿热生境中。 近年来人为的干扰和生境的破坏已导致它们的居群大量绝灭,其中濒危程度最高的是普通野生稻。本文阐述了它们的生物学、生态学特性,研究了它们的群落学特征,初步报道了它们的濒危状况,探讨了致濒原因。     

原、异位保存东乡野生稻主要农艺性状的比较研究

为了解原、异位保存东乡野生稻主要农艺性状的变化,对庵家山普通野生稻原、异位群体进行了考察和比较分析。结果表明,原、异位保存的东乡野生稻在每穗总粒数、每穗实粒数、结实率等方面存在较大的差异,如异位保存的东乡野生稻每穗总粒数平均为58.28粒,比原位多11.44粒,但其每穗实粒数却较少,为9.89粒,结实率降低了45.43%。从种植环境可以发现,异位保存圃的环境不适宜东乡野生稻的生长,应该选择与原生境相类似的种植环境,以便于东乡野生稻的保存、研究与利用。     

Diversity in the Content of Some Nutritional Components in Husked Seeds of Three Wild Rice Species and Rice Varieties in Yunnan Province of China

In addition to rice (Oryza sativa L.) cultivars, there are three wild rice species, namely O.rufipogon Griff, O. officinalis Wall and O. granulata Baill, in Yunnan Province, China. Each species has different subtypes and ecological distributions. Yunnan wild rice species are excellent genetic resources for developing new rice cultivars. The nutritional components of the husked seeds of wild rice have not been investigated thus far. Herein, we report on the contents of total protein, starch, amylose, 17 amino acids, and five macro and five trace mineral elements in husked seeds from three wild rice species and six O. sativa cultivars. The mean (± SD) protein content in the husked rice of O. rufipogon, O. officinalis, and O. granulata was (14.5 ± 0.6)%, (16.3 ± 1. 1)%, and (15.3 ± 0.5)%, respectively. O. officinalis Ⅲ originating from Gengma had the highest protein content (19.3%). In contrast, the average protein content of six O. sativa cultivars was only 9.15%. The total content of 17 amino acids of three wild rice species was 30%-50% higher than that of the six cultivars. Tyrosine, lysine, and valine content in the three wild rice species was 34%-209% higher than that of the cultivars. However, the difference in total starch content among different O. sativa varieties or types of wild rice species was very small. The average amylose content of O. rufipogon, O. officinalis,and O. granulata was 12.0%, 9.7%, and 11.3%, respectively, much lower than that of the indica and japonica varieties (14.37%-17.17%) but much higher than that of the glutinous rice cultivars (3.89%). The sulfur, phosphorus, magnesium, zinc, and ferrite content in the three wild rice species was 30%-158% higher than that of the six cultivars. The considerable difference in some nutritional components among wild rice species and O. sativa cultivars represents a wide biodiversity of Yunnan Oryza species. Based on the results of the present study, it is predicted that some good genetic traits, especially high protein and ideal amylose content, of Yunnan wild rice species may be useful in improving the nutritional value of rice. This is the first report regarding the amino acid, mineral element, protein and amylose content of husked seeds of some Yunnan wild rice species that have important genetic characteristics for rice quality and nutritional value.     

ITS1 Sequences of Nuclear Ribosomal DNA in Wild Rices and Cultivated Rices of China and Their Phylogenetic Implications

he first internal transcribed spacer (ITS1) of nuclear ribosomal DNA of three wild rice species and two subspecies of cultivated rice, which are distributed in China, was amplified using PCR technique and sequenced with automated fluorescent sequencing. The sequences of ITS1 ranged from 193 bp to 218 bp in size and G/C content varied from 69.3%to 72.7%. In pairwise comparison among the five taxa, sequence site divergence ranged from 1.5 % to 10.6%. Phylogenetic analysis of ITS1 sequences using Wagner parsimony generated a single well-resolved tree, which revealed that Oryza rufipogon was much more closely related to cultivated rice species than to the other two wild species. Oryza granulata was less closely related to either cultivated rice species or the other two wild species, and might be a unique and isolated taxon in the genus Oryza. The phylogenetic relationships of the three wild rice species and two cultivated rice subspecies inferred from ITS1 sequences is highly concordant with those based on the molecular evidence from isozyme, chloroplast DNA (cpDNA), mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) of the genus Oryza.     

普通野生稻小种群的交配系统与遗传多样性

小种群的遗传动态是保育遗传学关注的核心问题之一,而种群遗传动态又与交配系统密切相关.普通野生稻(Oryza rufipogon Griff.)是具有重要经济价值的濒危物种,目前其种群规模都较小,研究其小种群交配系统与遗传变异性对普通野生稻的保护具有重要意义.运用7对SSR引物,对采自江西东乡普通野生稻小种群的36份种茎和其中20个家系共计601份子代进行了分析.结果显示:该种群的表观异交率为0.318,多位点法估计(MLTR)的多位点异交率为0.481;50%以上的子代共享亲本,非随机交配明显;东乡普通野生稻种群交配系统属于混合交配类型.比较亲本和子代种群的遗传变异性显示:子代种群比亲本种群遗传变异性更丰富;子代种群的杂合子不足与种群变小自交比例上升有关;而亲本种群杂合子过剩可能与杂合基因型的选择优势有关.这些结果说明创造条件扩大种群规模对普通野生稻的原生境保护显得尤为重要.     

中国野生稻及栽培稻核糖体DNA第一转录间隔区序列分析及其系统学意义

用 PCR技术从产于我国的 3种野生稻和亚洲栽培稻的 2个亚种中特异地扩增和测序了 r DNA的第一转录间隔区。普通野生稻 (Oryza rufipogon)、药用野生稻 (O.officinalis)、疣粒野生稻 (O.granu-lata)和栽培稻的两个亚种 (O.sativa ssp.indica,O.sativa ssp.japonica)的 ITS1序列为 1 93bp、1 94bp、2 1 8bp、1 94bp和 1 94bp,它们的 G/ C含量为 69.3%～ 72 .7% ,序列中位点趋异率为 1 .5%～ 1 0 .6%。序列的相似性比较和简约性分支分析的结果表明 ,普通野生稻与栽培稻的两个亚种之间的亲缘关系最为密切 ;药用野生稻与普通野生稻和与栽培稻的两个亚种的相似性都为 82 % ,说明它与 AA基因组有一定的亲缘关系 ;疣粒野生稻与普通野生稻、药用野生稻和栽培稻两个亚种的亲缘关系相对较远 ,它在稻属中可能是一个系统地位较独特的类群。以 ITS1序列构建的 3种野生稻和 2个栽培稻亚种的系统发育关系与前人用同工酶、叶绿体 DNA、线粒体 DNA和核 DNA资料重建的稻属的系统发育关系基本一致     

采用RAPD和ISSR标记探讨中国疣粒野生稻的遗传多样性

Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) methods were applied to detect genetic variation of 20 bulking samples and two individually sampled populations of Oryza granulata (Nees et Arn. ex Watt.) from China (M5 from Hainan Province and M27 from Yunnan Province). For the bulking sampled populations, 20 RAPD and 12 ISSR primers generated 209 and 122 bands, of which 134 (64.11%) and 89 (72.95%) were polymorphic respectively. For population M5, 146 and 95 bands were generated with 21.48% and 34.78% being polymorphic (PPB). For population M27, 151 (PPB = 17.22%) and 94 (PPB = 19.15%) bands of RAPD and ISSR were obtained. The results indicated that the level of genetic variation of O． granulata was lower than other species detected in the genus Oryza. UPGMA cluster based on genetic similarity and principle component analyses (PCA) based on band patterns divided the populations into two groups corresponding to their sources, which revealed that the majority of genetic variation of O. granulata occurred between Hainan and Yunnan. Consequently, more populations of the species should be considered for a reasonable conservation management. Comparison between the two marker systems showed that ISSR was better than RAPD in terms of reproducibility and ability of detecting genetic polymorphism. Mantel test revealed that the goodness of fit between them was significant (r=0.917, t=12.718) when detecting genetic diversity at species level, but was poor at population level (r<0.200). The discrepancy was considered as the facts that different fragments were targeted by RAPD and ISSR, and that evolutionary process of O. granulata varied at different hierarchical levels.     

Phenotypic Characterization of <i>Oryza nivara</i> (Sharma <i>et</i> Shastry) Collected from Different Ecological Niches of Sri Lanka

Information on the genetic diversity of wild rice species in Sri Lanka is relatively meagre, though it plays a key role in crop improvement programs of cultivated rice (Oryza sativa L.). The present study was carried out to identify the morphological variation pattern of the wild populations of O. nivara in Sri Lanka. Seven populations (P1 to P7) collected from different agro-ecological regions were characterized in a common garden based on nine morphological traits. The findings revealed a high level of phenotypic variation between populations when compared to within a population. The most variable traits were the flag leaf panicle neck length (FLPNL) and flag leaf angle (FLA), whereas the least variable trait was the flag leaf length (FLL). Box plots clearly illustrated the large differentiation of phenotypic traits in the entire distribution of wild rice populations. The cumulative values of the two principal components, i.e., FLPNL and FLA, explained 58.7% of the total variance. Populations from similar natural habitats clustered together. The P7 was adapted to intercept more sunlight by increasing flag leaf width (FLW) and FLA to compete with weeds and other shrubs. P2 and P5 were the most closely related populations representing approximately similar ecological conditions of the dry zone. The P3 population from the intermediate zone showed a vigorous plant growth with the highest plant height, culm girth and awn length (P < 0.05). Knowledge of such morphological diversity would facilitate designing conservation strategies and basic information for the proper utilization of wild resources in rice genetic improvement.     

海南省万宁市野生荔枝资源种群特征研究

野生荔枝是荔枝(Litchi chinensis Sonn.)进行品种改良与创新的重要基因库,该研究通过对海南万宁自然保护区内、外野生荔枝资源进行实地调查,并用空间分布格局、种群径级结构、静态生命表、存活曲线等方法进行比较分析,以揭示野生荔枝种群在保护区内、外的分布规律及其种群动态趋势,为野生荔枝资源的保护提供依据。结果表明:(1)海南万宁自然保护区内、外野生荔枝种群均为聚集分布,且非自然保护区聚集程度比自然保护区的聚集程度更为明显。(2)径级结构分析发现,自然保护区内野生荔枝种群结构为增长型,种群生命期望值整体上基本随径级增加呈递减趋势,存活曲线呈近直线型,说明自然保护区内的野生荔枝种群处于相对稳定的状态;而自然保护区外的野生荔枝种群为衰退型。(3)群动态预测结果也显示,自然保护区内外的野生荔枝种群的动态变化指数(Vpi′)以及随机干扰风险极大值均趋于零,但自然保护区外的值均大于区内,说明保护区外受到的敏感性比自然保护区内更强,即保护区外野生荔枝种群的生存环境已受到严重的人为干扰威胁。研究认为,在自然保护区外,野生荔枝种群幼树的严重缺失不仅与野生荔枝种群自身的更新机制有关,更重要的是生存环境的破坏和人为砍伐导致野生荔枝种群结构发生变化,野生荔枝林面积下降。     

Population Ecological Characteristics of the Rare and Endangered Plant Camellia rhytidophylla from Guizhou

Camellia rhytidophylla is endemic and endangered and with important economic species, from the ⅢD10d in eastern Asia, which distributed at 573-920m in evergreen broad leaved deciduous mixed forest in Luowang river valley of Kaiyang county. So, it is significant to study the population characteristics, conservation and utilization. We took general survey in suspected distribution area about 6 square kilometers, set up plots in dense area, and analyzed the population structure, development and spatial distribution pattern. The results showed that the structure of Crhytidophylla populations were increasing and the proportion of young tree in population was 4638%. The size of population density was young shrubs＞middle aged shrubs＞adult shrubs. The survival curve of population was Deevey Ⅲ model. There were 2 peaks in the Ⅰand Ⅳ age classes on the mortality rate curve and disappearance rate curve respectively, then there are 2 troughs in the Ⅲ and Ⅵ age classed at the same time. The spatial distribution pattern of Crhytidophylla significantly differentiated at different stages of development, the young individuals were aggregated at all spatial scales while the middle aged individuals were aggregated at small spatial scales and randomly distributed at larger scales. Differences in the distribution of adult individuals could be attributed to artificial disturbance and habitat heterogeneity. The spatial pattern was not close in different stages of development, which all showed negative or no correlation. The spatial distribution pattern of Crhytidophylla was the interaction of the factors, such as its biological characteristics,habitat heterogeneity, and artificial disturbance, etc.. The key factor limiting population development was low natural reproduction rate; the primary factors causing its endemic distribution mainly included habitat heterogeneity, topographical constraints on seed dispersal and artificial disturbance.     

栽培稻与4种野生稻的原生质体融合

野生稻具有许多优良性状,是水稻遗传改良的重要物质基础。为了探讨应用原生质体融合技术转移野生稻有利基因的途径,进行了栽培用与4种野生稻融合试验。总计6·28×107个野生稻原生质体与栽培稻原生质体进行了电激融合。获得了4364块愈伤组织,再生了490个植株。试验了Y射线处理野生稻原生质体的有效剂量和碘代乙酰胺抑制栽培稻原生质体生长的浓度。探讨了原生质体来源对融合效果的影响,讨论了融合亲和性问题。     

Genetic Evaluation of in situ Conserved and Reintroduced Populations of Wild Rice (Oryza rufipogon: Poaceae) in China

We evaluated the genetic consequences and efficiency of conservation practices in Oryza rufipogon using microsatellite DNA markers. Spatial autocorrelation analysis from 12 microsatellite loci revealed that microsatellite alleles were exclusively distributed in patches within the population, indicating that large populations were unlikely to be homogeneous. An in situ conserved stand of O. rufipogon, which has been protected by a concrete wall from a large population, captured only 67.9% of the total genetic variation of the previous large population. The concrete wall was built to protect the wild rice, but it acted more as a physical barrier to gene exchanges between the two sides. An assignment test revealed only 11.1% putative seed exchanges across the wall. A reintroduced population was found to be genetically very diverse. About 76.3% of the total genetic variation detected in other populations was captured in this reintroduced population, and 24.8% of the total genetic variation in this population was not found in other populations. These results display two important findings for conservation of O. rufipogon. First, conserving one part of a large population of O. rufipogon will not preserve an adequate sample of the genetic variability, since populations are not homogeneous, and genotype distribution varies among localities. Second, a reintroduced population is not genetically depauperate, but it is too early to assess its long-term survival.     

居群遗传结构研究中显性标记数据方法初探

为对比显性标记应用于居群遗传结构研究时不同统计参数的适用性,利用RAPD技术对中国5个居群的100个疣粒野生稻个体进行了遗传结构分析。在衡量居群遗传多样性水平时,多态位点比率（PPB）会低估遗传变异的量,其价值不如Shannon多样性指数和Nei基因多样性指数,而采用Nei指数时不必进行Lynch-Milligan矫正。对个体间遗传关系进行分析时,17种遗传相似性指数矩阵两两之间的Mantel检测都表现出极显著的相关性（r＞0.95,t＞t     

中国野生稻遗传资源的保护及其在育种中的利用

我国有三种野生稻,即普通野生稻(Oryza rufipogon)、药用野生稻(O.officinalis)和瘤粒野生稻(O.meyeriana)。这三种野生稻均被列为国家二级保护植物(渐危种)。调查结果表明,野生稻由于其自然群落大量丧失而濒危,濒危程度为普通野生稻>药用野生稻>瘤粒野生稻。造成濒危的主要原因是人为的破坏活动。人类的经济活动导致了野生稻生境丧失、生境质量不断恶化、栖息地越来越少;人类的活动也导致了外来种的入侵。目前,对野生稻的保护措施主要有就地保护(原地保护或原位保护)和迁地保护(易地保护或异位保护)。易地保护包括以种子保存的种质厍、以种茎保存的种质圃和以器官培养物作为材料的超低温保存。野生稻具有许多优良特性,如特强的耐寒性、高的抗病虫性、优质蛋白质含量高、功能叶片耐衰老的特异性、特强的再生性、良好的繁茂性及生长优势等等,这些优良特性已被广泛用于水稻常规育种和杂交育种中,并取得了巨大的社会效益和经济效益。有关野生稻生物技术方面的研究,如花药培养、原生质培养、体细胞杂交和基因工程等方面已取得了较大的进展。野生稻将在水稻育种中发挥越来越重要的作用。     

Life‐history traits and geographical divergence in wild rice (Oryza rufipogon) gene pool in Indochina Peninsula region

Indochina Peninsula is the primary centre of diversity of rice and lies partly in the centre of origin of cultivated rice (Oryza sativa) where the wild ancestor (Oryza rufipogon) is still abundant. The wild gene pool is potentially endangered by urbanisation and the expansion of agriculture, and by introgression hybridisation with locally cultivated rice varieties. To determine genetic diversity and structure of the wild rice of the region we genotyped nearly 1000 individuals using 20 microsatellite loci. We found ecological differentiation in 48 populations, distinguishable by their life‐history traits and the country of origin. Geographical divergence was suggested by isolation of the perennial Myanmar populations from those of Cambodia, Laos and Thailand. The annual types would be most likely to have lost genetic variation because of genetic drift and inbreeding. The growing of cultivated and wild rice together, however, gives ample opportunities for hybridisation, which already shows signs of genetic mixing, and will ultimately lead to replacement of the original wild rice gene pool. For conservation we suggest that wild rice should be conserved ex situ in order to prevent introgression from cultivated rice, along with in situ conservation in individual countries for the recurrent evolutionary process through local adaptation, but with sufficient isolation from cultivated rice fields to preserve genetic integrity of the wild populations.     

Fitness estimation through performance comparison of F1 hybrids with their parental species Oryza rufipogon and O. sativa

BACKGROUND AND AIMS: Introgression of crop genes into populations of wild relatives has important implications for germplasm conservation as well as for the persistence of novel transgenes in wild populations. Studies of hybrid fitness can be used to evaluate the potential for introgression to occur following episodes of interspecific hybridization. METHODS: This study estimated relative fitness of interspecific hybrids through performance comparison of F(1) hybrids with their parental species, a cultivated rice (Oryza sativa) Minghui-63 and perennial common wild rice (O. rufipogon) under the cultivation conditions. KEY RESULTS: Compared with their parents, the hybrids had the lowest values of seedling survival ability, pollen viability and seed production; intermediate values of seed germination, spikelet production and flag leaf areas; and the highest values of plant height, number of tillers and panicles. The hybrids performed poorly at the stage of sexual reproduction, although they had a slightly higher hybrid vigour at the vegetative growth stage and better tillering ability than their wild parent. There were no significant differences in composite fitness across the whole life-history between the hybrids and their wild parental species. CONCLUSIONS: Rice genes, including transgenes, might persist in wild rice populations through vegetative and sexual reproduction. Further studies are needed to examine whether the extent of gene flow from rice is sufficiently significant to influence genetic diversity in wild populations of O. rufipogon, a species that has become endangered in some regions of south-east Asia.     

Microsatellite variation within and among populations of Oryza officinalis (Poaceae), an endangered wild rice from China

Oryza officinalis Wall. ex Watt. is an agriculturally important but seriously endangered species of wild rice. To obtain more accurate estimates of population structure for improved conservation planning of the species, genetic variability at 14 microsatellite DNA loci was examined in population samples covering most of the species' range in China. Considerable genetic variability (overall Na = 1.886, P = 62%, HO = 0.056, HE = 0.216, and HS = 0.277) was detected at the 14 loci in 442 individuals of the 18 natural populations. The evaluation of partitioning of genetic variability (FST = 0.442) suggested high genetic differentiation among the Chinese O. officinalis populations. An overall value of Nm = 0.316 suggested limited gene flow occurred among the sampled populations. Most of the populations showed heterozygote deficits in tests of Hardy-Weinberg equilibrium and significantly positive FIS values. This could be due to some inbreeding occurring in this predominantly outcrossing species. For effective in situ conservation and restoration genetics, maintenance of significant historical processes is particularly important, including high outbreeding, considerable gene flow, and large population effective sizes. The high FST values detected among populations in this study are instructive for adopting a conservation plan that includes representative populations with the greatest genetic variation for either in situ conservation management or germplasm collection expeditions.