分子标记用于赤眼蜂分子监测的研究

通过对松毛虫赤眼蜂（Trichogramma dedrolimi Matsumura）以及玉米螟赤眼蜂（Trichogramma ostriniae Pang et Chen）rDNA-ITS2基因的克隆测序，并联机检索GenBank核酸序列库中其它赤眼蜂的相关序列，利用核酸分析软件找到松毛虫赤眼蜂和玉米螟赤眼蜂ITS2序列中一段有鉴别意义的标志，并据此设计出蜂种的特异PCR引物，实现了松毛虫赤眼蜂和玉米螟赤眼蜂rDNA特异区带的PCR扩增。研究表明该特异区带具有种的特异性。我们认为该分子标记技术可用于目前我国生防中常用的松毛虫赤眼蜂和玉米螟蒌眼蜂的分子监测，如田间种群动态监控和寄生效果评估。     

Morphological and genetic diversity of Momordica cochinchinenesis (Cucurbitaceae) in Vietnam and Thailand

Momordica cochinchinensis (Cucurbitaceae) is native to South East Asia and is important for its nutritional and medicinal properties. There is little information available on morphological and genetic diversity, crop selection and strategic germplasm collection for M. cochinchinensis. In this study, 42 accessions of M. cochinchinensis collected from Vietnam, Thailand and Australia were analysed for diversity study both at a morphological and molecular level. Both morphological and molecular analyses were in agreement and clustered the accessions based on the country of origin. The markers investigated in this study could be used for future applications with samples from unknown origins or for gene tracking for important cultivars. The Momordica accessions were highly polymorphic based on the markers suggesting high genetic diversity. Therefore the results from this study will be important in future strategic germplasm collection, conservation, horticultural development and commercial propagation of M. cochinchinensis.     

Genetic diversity among a collection of bitter gourd (Momordica charantia L.) cultivars

Genetic Resources and Crop Evolution - Bitter gourd, Momordica charantia L., is a vegetable with one of the highest nutrition values in the world. Despite this, limited research has been conducted...     

Influence of N fertilisation on the isolation of Acetobacter diazotrophicus and Herbaspirillum spp. from Indian sugarcane varieties

 Observations of newer diazotrophs like Acetobacter diazotrophicus and Herbaspirillum spp. in Indian sugarcane varieties is reported here for the first time. A. diazotrophicus was isolated from sugarcane plants where N fertilisation was nil, and numbers in the Indian cultivars were estimated to be up to 10⁶–10⁷ colony forming units g¹ fresh weight. N fertilisation was the limiting factor for the isolation of A. diazotrophicus, as evidenced by selective growth patterns in different concentrations of N sources, but Herbaspirillum spp. were found to occur both in N fertilised and unfertilised samples. The fact that N is not the limiting factor for Herbaspirillum spp. was evidenced in a similar study of its growth pattern in different N sources. Received: 14 May 1998     

基于石蒜属转录组序列的SSR分子标记开发应用

为开发石蒜属简单重复序列(SSR)分子标记,并研究SSR引物在石蒜属内的通用性,本研究对石蒜属石蒜、忽地笑、中国石蒜、长筒石蒜、换锦花、香石蒜6个种质转录组测序,检测SSR位点并设计引物,通过PCR扩增和毛细管电泳判断引物的有效性和多态性,绘制石蒜属17个种质资源的指纹图谱并对杂交后代的真实性进行早期检测。结果表明,共获得404 481条Unigenes,利用数据库进行同源比对和功能注释,并对Unigene进行SSR位点挖掘和分析,共检测到59 612个SSR位点。其中,单核苷酸重复>二核苷酸重复>三核苷酸重复,分别占SSR总数的62.88%、20.06%和14.66%,四核苷酸及以上重复单元相对较少。选取并合成8对荧光引物进行PCR扩增,通过毛细管电泳检测发现,8对荧光引物共检测到60个多态位点,多态位点数平均为7.50,多态性信息含量(PIC)值变化范围为0.148 0~0.940 8,平均值为0.593 0。利用引物扩增带型组合法构建了石蒜属17个种资源的指纹图谱,其中引物QZ209可区分所有供试材料,并可用于杂交后代鉴定。本研究开发的SSR标记具有丰富的多态性,在石蒜属植物的资源多样性分析、杂交种鉴定及遗传图谱的构建应用中具有重要意义。     

Molecular diversity, genetic structure and mating system of Calopogonium mucunoides Desv.

Calopogonium mucunoides Desv. is a species native of South and Central America that is used as green manure and a pasture crop. The molecular genetic diversity was characterized in 195 C. mucunoides accessions from a germplasm collection using 17 microsatellite markers. Outcrossing rate was estimated after the evaluation of six microsatellite loci in 200 genotypes originated from 10 open-pollinated progenies (20 genotypes per progeny). Six genetic clusters were identified in the germplasm collection by the STRUCTURE software analysis, neighbor-joining tree comparisons and principal component analysis, which highly correlated with the geographic locations where these accessions were originated or collected. These results were confirmed using AMOVA. The largest portion of the genetic variation was observed among clusters (64.38%). The results indicated that: multilocus outcrossing rate (t _m ) was 16.3%, suggesting a mixed mating system with a predominance of autogamy; single locus outcrossing rate (t _s ) was 11%; difference (t _m ?t _s ) was 0.054, indicating that only 5.4% of outcrossing occurred among related individuals; paternity correlation (r _p ) was 33% suggesting a low probability of finding full sibs among the progeny; parental coefficient of inbreeding (F _m ) was 5.0%, indicating a low degree of inbreeding in each parent. A core collection for C. mucunoides was assembled to capture the allelic diversity found in this study. The complete allelic diversity was represented by only 15 accessions. These results should be useful for exploiting the genetic resources of C. mucunoides and could influence future conservation efforts and breeding programs.     

Castanea spp. biodiversity conservation: collection and characterization of the genetic diversity of an endangered species

Centuries of co-evolution between Castanea spp. biodiversity and human populations has resulted in the spread of rich and varied chestnut genetic diversity throughout most of the world, especially in mountainous and forested regions. Its plasticity and adaptability to different pedoclimates and the wide genetic variability of the species determined the spread of many different ecotypes and varieties in the wild. Throughout the centuries, man has used, selected and preserved these different genotypes, vegetatively propagating them by grafting, for many applications: fresh consumption, production of flour, animal nutrition, timber production, thereby actively contributing to the maintenance of the natural biodiversity of the species, and providing an excellent example of conservation horticulture. Nonetheless, currently the genetic variability of the species is critically endangered and hundreds of ecotypes and varieties are at risk of being lost due to a number of phytosanitary problems (canker blight, Chryphonectria parasitica; ink disease, Phytophthora spp.; gall wasp, Dryocosmus kuriphilus), and because of the many years of decline and abandonment of chestnut cultivation, which resulted in the loss of the binomial male chestnut. Recently, several research and experimentation programmes have attempted to develop strategies for the conservation of chestnut biodiversity. The purpose of this paper is to give an overview of the status of biodiversity conservation of the species and to present the results of a 7?year project aimed at the individuation and study of genetic diversity and conservation of Castanea spp. germplasm.     

Genetic relationship and diversity of Mangifera indica L.: revealed through SCoT analysis

Mango (Mangifera indica L.) is one of the most economically grown fruits in the tropical and subtropical areas around the world. In the present study, start codon targeted (SCoT) markers were employed to investigate the genetic diversity of 73 mango accessions obtained from Guangxi province, China. A total of 275 bands were amplified by thirty-four SCoT primers, of which 203 (73.82%) were polymorphic. Genetic similarity between accessions was in the range of 66.2–94.2% with an average of 78.8%. The observed highest genetic similarity value (94.2%) was found between ‘Ren Mian Mango’ and ‘Hong Hua Mango’, the observed lowest genetic similarity value (66.2%) was found between‘Xia Mao Xiang Mango’ and ‘India No. 15’. These coefficients were utilized to construct a dendrogram using the unweighted pair group of arithmetic means. All the accessions were grouped into four (A, B, C, D) clusters and correspond well with their geographical origin and their known history. These results have an important implication for mango’s rue germplasm characterization, improvement, management and conservation.     

Effect of Aelia spp. and Eurygaster spp. Damage on Wheat Proteins

The effect of Aelia spp. and Eurygaster spp. wheat bugs on the protein fractions of different wheat cultivars has been studied by size‐exclusion high‐performance liquid chromatography (SE‐HPLC) and free‐zone capillary electrophoresis (FZCE). Those methods were used to quantify and characterize the extent of protein modification. A decrease in the amount of alcohol‐insoluble polymeric proteins along with an increase in the alcohol‐soluble polymeric proteins and gliadins were observed in damaged wheat. The high molecular weight (HMW) and low molecular weight (LMW) glutenin fractions were barely detected in the incubated damaged wheat from some cultivars, which indicated hydrolysis of those proteins by the bug proteinases. In damaged wheats, both incubated and unincubated, gliadin electrophoregrams revealed the presence of some new peaks with mobilities similar to the ω gliadins. The overall results suggest that the bug proteinases are potent enzymes that appear to be nonspecific because they hydrolyze all gluten proteins.     

Microsatellite marker based analysis of genetic diversity in short day tropical Indian onion and cross amplification in related <Emphasis Type="Italic">Allium</Emphasis> spp.

This paper deals with the diversity assessment of tropical Indian onion and cross amplification of genomic and EST-SSR markers in distantly related native wild species. Out of 60 SSRs, 10% genomic SSRs were able to amplify as compared to EST-SSR where 53.3% primers were able to reveal amplicons. Clustering revealed five groups and indigenous short day onion formed separate cluster from the exotic short day and long day onions. A. roylei accessions exhibited a dissimilarity index of 35.5% between themselves whereas ‘Pran’ and A. × proliferum grouped together at a genetic distance of 0.4. A. fistulosum accessions formed a tight cluster and distantly related wild species A. carolinianum, A. chinense and A. hookeri formed neutral nodes. Present results are important to aid in analyzing the diversity present in short day onion and its utilization in breeding programs. Further, this is the first time that three accessions of A. roylei Stearn were used and rare alleles amplified in wild species will aid in detecting population structure and molecular marker aided selection for interspecific hybrid development.     

Molecular diversity of Omani wheat revealed by microsatellites: I. Tetraploid landraces

Results of archaeological studies indicate a millennia-old cultivation history for wheat (Triticum spp.) in Oman. However, in spite of numerous collection surveys and efforts for phenotypic characterization of Omani wheat landraces, no attempts have been made using molecular tools to characterize this germplasm. To fill this gap, 29 microsatellite markers revealing 30 loci were used to study the genetic diversity of 38 tetraploid wheat landrace accessions comprising the species T. dicoccon, T. durum and T. aethiopicum. A total of 219 alleles were detected whereby the number of alleles per locus ranged from 2 to 16 with an average number of 7.1 alleles per locus. The highest number of alleles occurred in the B genome with on average 7.9 alleles per locus as compared to the A genome with 6.5 alleles per locus. Heterogeneity was detected for all microsatellites except for GWM 312, GWM 601 and GWM 192B with an average heterogeneity over all primers and lines of 14.4%. Approximately 10% of the accessions contained rare alleles with an average allele frequency <4%. Gene diversity across microsatellite loci ranged from 0.26 to 0.85. The pairwise comparison of genetic similarity ranged from 0.03 to 0.91 with an average of 0.2. Cluster analysis revealed a clear separation of the two species groups T. dicoccon versus T. durum and T. aethiopicum. Within the species clusters regional patterns of subclustering were observed. Overall, this study confirmed the existence of a surprisingly high amount of genetic diversity in Omani wheat landraces as already concluded from previous morphological analyses and showed that SSR markers can be used for landraces’ analysis and a more detailed diversity evaluation.     

Molecular diversity of Omani wheat revealed by microsatellites: II. Hexaploid landraces

For millennia, wheat (Triticum spp.) has been grown in traditional aflaj-irrigation systems of remote mountain oases in Oman. However, little is known about the diversity of the ancient landraces used. Given recent reports about the occurrence of novel germplasm in such material, the objective of this study was to evaluate the genetic diversity of hexaploid wheat (Triticum aestivum L.) landraces in relation to their geographic origin using microsatellites. The collection covered most of the cultivation areas in northern Oman where wheat landraces are growing. Total genomic DNA was extracted from six pooled plants representing each accession. A total of 161 wheat accessions were assayed using 35 microsatellite loci in which a total of 305 polymorphic bands were recorded for the 35 microsatellites. The polymorphic information content (PIC) across the 35 microsatellite loci ranged from 0.02 to 0.89 with an average of 0.50. A heterozygosity percentage value of 9.09 was determined and the highest level recorded for accessions from the Batinah district. Rare alleles averaged 1.85 with the highest value being from the Dakhilia district. The results indicated a significant correlation between gene diversity and number of alleles across districts. The correlation coefficient between these two variables over the 35 loci was 0.657, whereby correlation coefficients of 0.718, 0.706, 0.657 and 0.651, respectively, were found for the Batinah, Dhahira, Dakhilia and Sharqia materials. Genetic distances indicated that all landraces were closely related. The cluster analysis discriminated most of the landraces accessions. However, it failed to achieve region-specific groupings of landraces. The present study demonstrated the presence of high diversity in Omani landraces and also indicated the effectiveness of microsatellites to describe it.     

Genetic diversity in cucumber (cucumis sativus L.): Iii. An evaluation of Indian germplasm

Genetic variation in cucumber (Cucumis sativus L. var. sativus) accessions from India was assessed by examining variation at 21 polymorphic isozyme loci. Forty-six accessions acquired by the U.S. National Plant Germplasm System (NPGS) before 1972 were compared with 146 accessions collected during a 1992 U.S.–India expedition to the states of Rajasthan, Madhya Pradesh and Uttar Pradesh, India. Isozymic profiles of these Indian accessions were also compared with 707 previously examined U.S. NPGS cucumber accessions. Two distinct groups (Group 1 and Group 2) were identified within accessions collected in 1992 (0.025 > P > 0.01). Variation at Ak-2, Fdp-2, Gr, Mdh-2, Mpi-1, Per, Pgm and Skdh was important in the detection of this difference. A previously unreported Pgm allele [Pgm (3) – 105] was detected in accessions collected in a market in Pali, Rajasthan. Group 1 contained 37 (27 Madhya Pradesh + 10 Uttar Pradesh) accessions and Group 2 contains 102 (84 Rajasthan + 18 Madhya Pradesh) accessions. Seven accessions (5 Madhya Pradesh + 2 Rajasthan) were not associated with either group. The accessions 20664 (Tonk, Rahjasthan), 20666 (Jaipur, Rahjasthan), 20872 (Sehore, Madhya Pradesh), 20881 (Ashtok, Sehore, Madhya Pradesh) and 21026 (Bhatta, Dehra Dun, Uttar Pradesh) were heterozygous for at least nine loci and represent the genetic diversity within this collection. Isozymic variation in U.S. NPGS accessions acquired before 1972 differed significantly (P > 0.005) from those collected during 1992. All loci were important in the detection of this difference, except Ak-2, Pep-pap, and Pgd-2. When Indian accessions taken collectively (i.e., those acquired before 1972 and during 1992) were compared with an array of 707 C. sativus accessions examined previously, relationships between accessions grouped by country or subcontinent differed from those found in previous work.     

Sesbania spp., Aeschynomene indica and Crotalaria spp. are amide-exporters

Abstract

Extract

Leguminous plants consist of two groups, amide-exporting and ureide-exporting plants. The former legumes export a large fraction of fixed-N in the form of amides (asparagine and glutamine), and the latter legumes in the form of ureides (allantoic acid and allantoin). Another characteristic of the nodules is the enrichment in ¹⁵N. There are two types of legumes: one characterized by the enrichment with ¹⁵N in N₂-fixing nodules, in contrast to the other where the enrichment does not occur. The first investigation by Shearer et al. (1982) suggested that the nodules exporting fixed-N in the form of ureides were enriched in ¹⁵N unlike those exporting it in the form of amides. Soybeans, mungbean, and cowpea belong to the former group and groundnut, alfalfa, white clover to the latter. Although pea and faba bean were first classified into the latter group (Shearer et al. 1982), a recent investigation (Yoneyama 1988) showed that these nodules were also enriched in ¹⁵N.     

Diversity in Indian sesame collection and stratification of germplasm accessions in different diversity groups

Sesame (Sesamum indicum L.) is one of the ancient oil crops, grown in India since over 5,000 years ago. Diversity in the Indian sesame collection (3,129 accessions), representing all eco-geographical regions, for a range of morphological and agronomic characters was studied. Wide variation in plant habit (plant height and branching pattern), pubescence of various plant parts (stem, leaf, corolla and capsule), flower colour and number of flowers per leaf axil, capsule characteristics (shape, size, number in the axil of a leaf and number of locules in a capsule), number of capsules per plant, number of seeds per capsule, mean seed weight, and yield per plant was recorded. A detailed multivariate analysis was performed on a set of 100 selected accessions representing different agro-ecological zones. The accessions were classified into 7 discrete clusters. The principal components analysis described the spatial relationship among the entities and confirmed groupings obtained through clustering. Based on the clustering pattern of 100 accessions, the entire collection was allocated to different clusters. Representation of various zones in 7 clusters gives us the opportunity to form distinct diversity groups making combined use of passport and characterisation data. These diversity groups would subsequently be used for sampling the accessions for building up a core collection of sesame, a project already operative at the NBPGR.     

Genetic diversity and population structure assessed through simple sequence repeat markers in Saccharum spp. hybrids from Pakistan and Sri Lanka

Genetic Resources and Crop Evolution - The Saccharum species members are extremely complex allopolyploids. In this study, sixty Saccharum spp. hybrids were analyzed using simple sequence repeat...     

碱性肥料对土壤微生物多样性及香蕉枯萎病发生的影响

【目的】 研究碱性肥料对土壤微生物活性及多样性的影响,探究防控香蕉枯萎病的有效途径。 【方法】 采用两因素裂区设计进行了盆栽试验。主处理是施肥量相等、pH值分别为5.5、7.0、8.0的3个氮磷钾复合肥 (22-8-15);副处理为接种香蕉枯萎病尖孢镰刀菌 [Fusarium oxysporum f. sp. cubensce (E.F.Smith) Snyder et Hasen],包括不接种尖孢镰刀菌 (FOC)、接种FOC×106 cfu/g两个水平,共6个处理。 【结果】 1) 施用pH为7和8的两种肥料处理显著降低了香蕉枯萎病的染病率及病情指数,pH 8.0的碱性肥料较pH 5.5的酸性肥料分别降低了38和16个百分点。2) 接种FOC后,碱性肥料相比中性和酸性肥料显著增加了香蕉整株生物量,增加量分别为15%和23%,而对香蕉根部生物量影响不显著。3) 肥料的酸碱性对土壤微生物群落数量有显著影响,碱性肥料处理土壤中的FOC和真菌数量显著少于酸性肥料处理的,分别减少了60%和51%,而放线菌和细菌数量却都明显多于酸性肥料处理的,分别是酸性肥料的1.22和2.25倍。4) 碱性肥料较酸性肥料提高了土壤微生物的总碳源利用率及活性;在接种FOC的情况下,碱性肥料较酸性肥料可以显著地提高土壤微生物多样性。 【结论】 施用碱性肥料能明显减少土壤中FOC和真菌数量,增加细菌、放线菌数量,显著优化土壤微生物种群结构,提高土壤微生物活性及多样性,有效抑制FOC的萌发和致病,从而有效防控香蕉枯萎病的发生。      

High and low nodulation in relation to molecular diversity of chickpea mesorhizobia in Indian soils

Chickpea (Cicer arietinum L.) nodulation variants of two cultivars ICC 4948 and ICC 5003 were used as trap plants to isolate 385 native rhizobia from CCS Haryana Agricultural University, Hisar farm soil. After authentication and considering growth characteristics, selected 110 rhizobia revealed immense molecular diversity using the profiles of DNA fragments generated by Polymerase chain reaction (PCR) with enterobacterial repetitive intergeneric consensus (ERIC) sequences. Low nodulating variants of cvs ICC 4948 and ICC 5003 were able to trap more numbers of rhizobial genotypes, namely seven as compared four to five by high nodulating variants of these cultivars. Overall eight rhizobial genotypes were trapped by the chickpea cultivars. Rhizobial isolates from same nodule or same plants were present in the same or different clusters and few isolates showed 100% similarity also. Based on nodules from a plant, nodulation variant or cultivar, rhizobia could not be differentiated and no exclusive cluster was formed by either rhizobial isolates from low or high nodulating variants of both the cultivars. Two most efficient rhizobial isolates LN 707b and LN 7007 were characterized by amplification and sequencing of 16S rRNA gene. Rhizobial isolate LN 707b showed more than 98% similarity with Mesorhizobium sp SH 2851 and Mesorhizobium mediterraneum. Another isolate LN 7007 showed more than 99% similarity with the sequence of 16S r RNA gene of Mesorhizobium sp STM 398, and M. mediterraneum. So the chickpea rhizobia from Northern Indian subcontinent are proposed to be kept under M. mediterraneum strain LN707b and LN 7007.     

A phenetic analysis and lateral key of the genus Lolium (Gramineae)

88 herbarium specimens of the genus Lolium were scored for 22 characters, comprising 7 vegetative, 8 inflorescence and 7 seed characters. The aim was to review the species relationship and to produce a lateral key to the genus. The data were analysed using principal components analysis, discriminant function analysis and cluster analysis. All analyses separated L. perenne, L. multiflorum and L. temulentum from each other. The 2 varieties of L. rigidum showed varying degrees of separation from each other and from L. multiflorum. Their distinction as a species and as 2 varieties is discussed. L. perenne and L. rigidum were shown to contain the greatest similarity between species and L. temulentum was found to be the most distinct. A lateral key is proposed that separates the species on the basis of 11 morphological characters that are easily scored in the field.