Relationships among <Emphasis Type="Italic">Avena</Emphasis> species as revealed by consensus chloroplast simple sequence repeat (ccSSR) markers

Consensus chloroplast simple sequence repeat (ccSSR) makers were used to assess the genetic variation and genetic relationships of 80 accessions from 25 taxa of the genus Avena. Fifteen out of 16 ccSSR markers (93.75%) were polymorphic. A total of 51 alleles were detected at the 16 ccSSR loci. The number of alleles per locus ranged from 1 to 6, with an average of 3.2 alleles. Among these ccSSR loci, the highest polymorphism information content (PIC) value was 0.754, while the lowest PIC value was 0. The mean genetic similarity index among the 80 Avena accessions was 0.545, ranging from 0.188 to 1.000. To assess the usefulness of ccSSRs in separating and distinguishing between haplome (genome) groups, we used ordination by canonical discriminant analysis and classificatory discriminant analysis. Although discriminant analysis separated the haplome groups unequivocally, it was up to 69% predictive of correctly classifying an individual plant whose haplome(s) is unknown in the case where it belonged to the A haplome group, 75% where it belonged in the AC group, and almost 80% where it belonged in the ACD group. The analysis of genetic similarity showed that diploid species with the A haplome were more diverse than other species, and that the species with the As haplome were more divergent than other diploid species with the A haplome. Among the species with the C haplome, A. clauda was more diverse than A. eriantha and A. ventricosa. In the cluster analysis, we found that the Avena accessions with the same genomes and/or belonging to the same species had the tendency to cluster together. As for the maternal donors of polyploid species based on this maternally inherited marker, A. strigosa served as the maternal donor of some Avena polyploidy species such as A. sativa, A. sterilis and A. occidentalis from Morocco. A. fatua is genetically distinct from other hexaploid Avena species, and A. damascena might be the A genome donor of A. fatua. Avena lusitanica served as the maternal parents during the polyploid formation of the AACC tetraploids and some AACCDD hexaploids. These results suggested that different diploid species were the putative A haplome donors of the tetraploid and hexaploid species. The C genome species A. eriantha and A. ventricosa are largely differentiated from the Avena species containing the A, or B, or D haplomes, whereas A. clauda from different accessions were found to be scattered within different groups. Wei-Tao Li and Yuan-Ying Peng have contributed equally to this paper.     

Genetic Diversity in AA and CC Genome Oryza Species in Southern South Asia

The CC genome of Oryza is found in nine species of Oryza that are distributed on all continents having a tropical climate. Three diploid Oryza species with CC genome are found in Africa and Asia to Papua New Guinea. In southern South Asia these three CC genome diploid species can be found, O. eichingeri and O. rhizomatis in Sri Lanka and O. officinalis in India. AA genome wild relatives of rice are also found in the same geographic region. Germplasm of both diploid CC and AA genome Oryza germplasm has recently been collected from Sri Lanka. AFLP analysis was used to compare the genetic diversity of the two Oryza genomes from a similar geographic region in southern South Asia. In addition, the diploid CC Oryza germplasm was also analyzed by RAPD and SSR methodologies and the combined results were analyzed. The results show that in southern South Asia the diploid CC genome species have a high level of genetic diversity compared to the diploid AA genome species. Molecular marker analysis revealed that populations of O. rhizomatis from northern and southeastern Sri Lanka are genetically differentiated. One accession of O. rhizomatis was aligned with O. eichingeri. This accession was collected from the site of O. rhizomatis that is the closest to a population of O. eichingeri. O. eichingeri showed lower genetic diversity than the other two diploid Oryza CC genome species. O. officinalis accessions from Assam, India, and China were genetically less diverged from O. eichingeri and O. rhizomatis than two accessions of O. officinalis from Kerala state, India. The first two authors contributed equally to this research     

Genomic Evolution of Brassica Allopolyploids Revealed by ISSR Marker

Polyploidization has been viewed as a highly dynamic process and a major force in the evolution of higher plants, including many important crops. To better understand the genomic evolution of Brassica polyploids, we used the Brassica triangle, including three allopolyploids and three diploids, to study genomic evolution after the formation of polyploids. Based on the inter-simple sequence repeat (ISSR) analysis, the different degree of A, B or C genomic modifications were observed in the three Brassica allopolyploids. In B-contained allopolyploids, B genome always altered less than the other genome (A or C), showing that B genome was relatively conserved in the evolution of Brassica allopolyploids. ISSR data supported that a higher degree of ancestral genomic divergence gave rise to a greater frequency of genomic change of polyploids. The possible mechanisms for the genomic changes and the reason for the relatively conserved B genome were discussed.     

黄土丘陵区撂荒草地不同生态位物种非结构性碳水化合物对氮添加的响应

为研究氮添加对不同生态位物种非结构性碳水化合物的影响。通过对黄土丘陵区典型撂荒草地进行3年的氮添加试验N0(0 g/(N·m²·a))、N3(3 g/(N·m²·a))、N6(6 g/(N·m²·a))和N9(9 g/(N·m²·a)),[JP]分析了不同生态位物种可溶性糖、淀粉和非结构性碳含量。结果表明:氮添加主要影响占据较高生态位的白羊草(Bothriochloa ischaemum)和长芒草(Stipa bungeana)的非结构性碳水化合物的储存,而对铁杆蒿(Artemisia sacrorum)和杂草影响较小。N6和N9处理对白羊草和长芒草非结构性碳、可溶性糖和淀粉的储存表现出明显的促进作用,这种作用在地上部分表现尤为明显。同时,植物相对重要值与植物地下非结构性碳和淀粉含量显著正相关,而与地上可溶性糖含量和可溶性糖/淀粉显著负相关。研究结果有利于加强对氮沉降背景下不同生态位物种碳储存及分配特征的认识。     

Phylogenetic relationships among natural populations of perennial buckwheat, Fagopyrum cymosum Meisn., revealed by allozyme variation

Twenty natural populations of F. cymosum, an insect-pollinated allogamous wild species of Fagopyrum, were investigated for their chromosome number and allozyme variation at 10 Ioci encoding 8 enzymes. Diploid populations were obtained in Sichuan, Yunnan and Tibet in China, whereas tetraploid populations were obtained in Tibet, the Himalayan hills, Thailand and southern China. Both diploid and tetraploid populations maintained a large amount of allozyme variation. The average heterozygosity, H_e, ranged from 0.045 to 0.389 (0.213 on average). Tetraploid populations showed higher H_e values than diploid populations. Natural populations of F. cymosum were locally well differentiated (G_ST = 0.322), probably due to reproductive isolation between the two ploidy levels and to distribution over wide areas from southern China to the Himalayan hills. The phylogenetic tree constructed by the neighbor-joining method based on allozyme variation clarified two distinct groups of diploid populations, the Sichuan and Yunnan groups. As for the tetraploid populations, polyploidization occurred twice independently, once in Yunnan and once in eastern Tibet. Tetraploid F. cymosum diffused to warmer areas such as southern Yunnan and Thailand as well as to cooler areas of Tibet and the high Himalayan hills and became the most widely distributed of the Fagopyrum species.     

Identification of genomic constitutions of <Emphasis Type="Italic">Oryza</Emphasis> species with the B and C genomes by the PCR-RFLP method

Oryza officinalis complex is the largest and the most complicated group in the genus Oryza L., consisting of about ten species with the B, C, BC, CD, and E genomes. Taxonomy and identification of the species, particularly those with the B, C and BC genomes, are difficult due to the similar morphology and overlapping distribution of some species. The difference in ploidy levels of some species adds more complexity. In the present study, we surveyed 64 accessions of rice germplasm in the O. officinalis complex using RFLP analysis of PCR-amplified Adh genes in addition to chromosome counting. The results confirmed that all O. rhizomatis accessions are diploids with the C genome, whereas all O. minuta accessions are tetraploids having the BC genome. However, both diploid and tetraploid forms were found for the accessions identified in the genebank as O. officinalis, O. punctata and O. eichingeri. The tetraploid form of O. officinalis with the BC genome is exclusively distributed in India and has been described as O. malampuzhaensis. The tetraploid form of O. punctata which has been called O. schweinfurthiana by some workers was found to be as widely distributed as its diploid form in Africa. It is noteworthy that two accessions that had been determined as tetraploid O. officinalis were actually belonging to a species with the CD genome (O. latifolia). Our results promote a better understanding of the genomic constitutions of many accessions in the O. officinalis complex and correct determination of the genebank material, which serves as an important basis of germplasm cataloguing for further research and utilization.     

Molecular characterization of emmer (Triticum dicoccon Schrank) Italian landraces

Emmer (Triticum dicoccon Schrank,2n = 4x = 28) is a hulled wheatspecies [more] widely spread in the Mediterranean basin. In Italy it survives as acrop in a few marginal areas and peculiar ecological niches in different regionsof central and southern Italy. A renewed interest has occurred during the lastdecade toward local varieties belonging to this species. As a matter of fact,local varieties have the highest genetic variation and adaptation to the naturaland anthropological environment from where they originated. Results on thegenetic diversity within and relationships among 11 Italian local varieties ofemmer as assessed with 17 RAPD marker loci are here reported. The proportion ofthe among-local variety genetic diversity was as high as 48% (G_ST =0.479). Thus, about 52% of the total variation was within population. Localvarieties of emmer proved to be formed by a variable number of lines geneticallydistinguishable from each other, and the vast majority of individuals overpopulations proved to be different multilocus genotypes. Landraces of emmer fromcentral and southern Italy showed distinctive molecular traits. In particular,local varieties classified as «Central Italy» types were characterized by a common set of RAPD marker alleles and proved to bedistinguishable from both the «Southern Italy» and the«Garfagnana» accessions. The overall results confirm the highvariability that can be found within landrace populations, underlining thevalues of landraces as an irreplaceable bank of genetically diversified andhighly co-adapted genotypes. Information for an appropriate insitu conservation and management of this valuable source of emmergermplasm is discussed.     

Characterization of the missing diploid progenitors of the common oat

Summary The genomic formula ACD of the hexaploid oat,Avena saliva, AC for the tetraploid speciesA. magna andA. murphyi, and the hypothesis that the A genome was contributed byA. strigosa group and C genome byA. ventricosa—A. eriantha group, have derived from karyotype studies. Cytogenetic evidence, however, does not support any of the known diploid oats as possible progenitors of the hexaploid oats.A. magna, and to a lesser extent,A. murphyi, are closer to the hexaploids than other tetraploids. Morphologically, these tetraploids resemble thesterilis type, which is apparently the genuine form of the hexaploid oats, with a few important differences. Spikelet morphology of these three wild oats indicates some features that must also occur in one or more of their diploid progenitors: 1. Ventricose diaspore containing the entire spikelet, 2. Long and broad callus with blunt tip, 3. Awn insertion at the lower one quarter of the lemma, 4. Close proximity of lemma tips of the two lower florets.A. magna andA. murphyi have narrow ecological ranges and are restricted to heavy alluvial soils which are now mostly under cultivation. It is likely that on similar soil type the diploid progenitors would grow as well and a search for them should be attempted there. Morocco is the most promising area for finding the missing diploids. Not onlyA. magna andA. murphyi grow there, but except one, all other annual oat species as well.     

Genetic Diversity of Asian Cotton (Gossypium arboreum L.) in China Evaluated by Microsatellite Analysis

Asian cotton (Gossypium arboreum L.) was once widely cultivated in China. It has also been a valuable source of genetic variation in modern cotton improvement. In this study, the genetic diversity of selected G. arboreum accessions collected from different regions of China was evaluated by microsatellite (simple sequence repeats, SSRs) analysis. Of the 358 microsatellite markers analyzed, 74 primer pairs detected 165 polymorphic DNA fragments among 39 G. arboreum accessions examined. Twelve accessions could be fingerprinted with one or more SSR markers. With the exception of two accessions, DaZiJie and DaZiMian, genetic similarity coefficients among all accessions ranged from 0.58 to 0.87 suggesting high level of genetic variation in the G. arboreum collections. The UPGMA dendrogram constructed from genetic similarity coefficients revealed positive correlation between cluster groupings and geographic distances. In addition, comparison of the microsatellite amplification profiles of the diploid G. arboreum and tetraploid Gossypium hirsutum L. found that size distribution of amplified products in G. arboreum was dispersive and that of G. hirsutum was relatively concentrated. The information on the genetic diversity and SSR fingerprinting from this study is useful for developing mapping populations for constructing diploid cotton genetic linkage map and tagging economically important traits.Diqiu Liu, Xiaoping Guo: These two authors contributed equally to this work.     

五节芒等植物水土保持效果试验研究

选取香根草、象草和五节芒3种植物在中国南方红壤丘陵区山坡进行水土保持成效试验。对不同试验小区的土壤理化性状、径流量与水土流失量等指标进行了近3a的观测,结果表明,3种植物均有较好的水土保持效果。与香根草和象草相比,五节芒在增加地表覆盖,改善土壤理化性质,拦蓄径流泥沙,改良微地貌,防治水土流失,改善生态环境等方面具有明显优势,且分布广,种源多,种植成本低,是一种优良的水土保持草种。在南方红壤丘陵区水土流失治理生物措施中,可以优先选用五节芒。     

Durum wheat cultivation associated with Aegilops tauschii in northern Iran

Hexaploid bread wheat (Triticum aestivum L. ssp. aestivum) is assumed to have originated by natural hybridization between cultivated tetraploid Triticum turgidum L. and wild diploid Aegilops tauschii Coss. This scenario is broadly accepted, but very little is known about the ecological aspects of bread wheat evolution. In this study, we examined whether T. turgidum cultivation still is associated with weedy Ae. tauschii in today’s Middle Eastern agroecosystems. We surveyed current distributions of T. turgidum and Ae. tauschii in northern Iran and searched for sites where these two species coexist. Ae. tauschii occurred widely in the study area, whereas cultivated T. turgidum had a narrow distribution range. Traditional durum wheat (T. turgidum ssp. durum (Desf.) Husn.) cultivation associated with weedy Ae. tauschii was observed in the Alamut and Deylaman-Barrehsar districts of the central Alborz Mountain region. The results of our field survey showed that the T. turgidum–Ae. tauschii association hypothesized in the theory of bread wheat evolution still exists in the area where bread wheat probably evolved.     

Variability and Genetic Diversity for Gliadins in Natural Populations of Hordeum Chilense Roem. et Schult.

Hordeum chilense Roem. et Schult. is wild diploid barley that has been used for the synthesis of the new cereal, tritordeum (× Tritordeum Ascherson et Graebner). This species is distributed in Chile and Argentina where it is possible to find in natural populations. In this work, the gliadin fraction of the seed storage protein have been used for evaluating the genetic diversity in nine natural populations of H. chilense. The total diversity (Ht) in the nine populations was 0.879 (ranging from 0.926 for the ω-gliadins to 0.795 for the β-gliadins). Data showed that the 71.3% of this genetic diversity was between populations, whereas the 28.7% was within populations. This species is considered as self-pollinating, where gene flow within populations was mainly attributed to seed dispersal because of these materials appear distributed in cattle zones where the pasturing could be an efficient mechanism of dispersion.     

Speciation in Chenopodium in West Bengal, India

Two diploid cytotypes of Chenopodiumalbum have earlier been proposed as the probable ancestors ofhexaploid C. album in Gangetic Plainof West Bengal on the basis of cytomorphological data. The present study withthe diploid cytotypes of C. album (onebroad leaved, another narrow leaved), one wild species, C.murale and the hexaploid C.album utilizing parameters like seed protein, isozyme,RAPD, tissue culture along with conventional cytomorphological data supports ourearlier hypothesis of allopolyploid origin of hexaploid C.album. The results indicate that all the three diploidprogenitors have contributed for the evolution of present day semi-cultivatedhexaploid C. album. This study furthersuggests that the diploid cytotypes had been evolved sympatrically.     

A novel genome of C and the first autotetraploid species in the <Emphasis Type="Italic">Setaria</Emphasis> genus identified by genomic <Emphasis Type="Italic">in situ</Emphasis> hybridization

Genomic in situ hybridization (GISH) was used to investigate the genomic relationships among some newly collected species of genus Setaria. Previous work identified that S. viridis and S. adhaerens carry genomes A and B, respectively. GISH patterns obtained in this report clearly distinguished the genome of S. grisebachii from the known genomes A and B, and indicated its new genomic constitution which we suggest to name genome C of the Setaria genus. The two sets of chromosomes of tetraploid S. queenslandica hybridized well with the A genome of S. viridis indicating its autotetraploid nature. This is the first autotetraploid identified in the Setaria genus, which should be classified into the primary A genome gene pool rather than the tertiary gene pool as previously classified. GISH patterns did not distinguish the genome of S. leucopila from the A genome of S. viridis and S. italica, suggesting its close relation with foxtail millet. Strong hybridization signals were observed when S. adhaerens genomic DNA was used as probe to hybridize the chromosomes of diploid S. verticillata, inferring its B genome nature. Combined with morphological observation and previous work, we deduce that diploid S. verticillata and S. adhaerens are probably taxonomically the same species with different names. Y. Wang and H. Zhi contributed equally to this article.     

Diversity of native rice (Oryza Poaceae:) species of Costa Rica

We found several populations of wild Oryza species in the lowlands of Costa Rica. The plants showed extensive morphological variation, suggesting the presence of several species. In the morphologic study, 33 traits were scored for plants of all the species. A principal component analysis revealed the significant morphological separation of the different species. The analyses indicated that there are three species, O. grandi­glumis, O. latifolia and O. glumaepatula. Two putative hybrid types were found, both significantly differing in their morphology from the known species and intermediate at several traits. O. grandi­glumis is a new record for Costa Rican flora. Its main population is located in Caño Negro Wildlife Refuge, Los Chiles, Alajuela. O. latifolia is distributed throughout the lowlands of the country and the plants of the Atlantic slope are significantly bigger in general habit than those of the Guanacaste area. During this study a population of O. glumaepatula of hundreds of thousands of plants was discovered in the Medio Queso River wetland, Los Chiles, Alajuela. This population is the most important source of genes for cultivar's improvement from the primary gene pool of rice in Costa Rica. The small ligule and the wide flag leaf characteristic of the two CCDD species separated them from the AA diploid O. glumaepatula. Seed size, ligule size, number of branches in the panicle, plant height and sterile lemma length are all bigger in O. grandi­glumis, and influenced the second factor that separated the CCDD species in two discrete clusters. The species found offer great possibilities for the improvement of rice cultivars and they should be thoroughly studied and appropriately protected.     

The genome biogeography of Hibiscus L. section Furcaria DC

Summary Hibiscus L. section Furcaria DC. (Malvaceae) is a natural group of more than 100 known species, many of which are handsome ornamentals with large, showy, delicate flowers. This group includes the fiber, food, and medicinal plants kenaf, H. cannabinus L., and roselle, H. sabdariffa L. The basic chromosome number is x = 18. In nature are found diploid, tetraploid, hexaploid, octoploid, and decaploid taxa. This group displays a remarkable amount of genome diversity, as shown by cytological analysis of 140 hybrid combinations from over 60,000 crosses. At least 13 genomes are present: A, B, C, D, E, G, H, J, P, R, V, X, and Y. Subsaharan Africa is the center of genome diversity; nine of the 13 genomes are represented in African taxa, and nine of the 10 confirmed diploid species occur in Africa. Five (possibly six) genomes reside in extant diploids. The G genome (or a modified G genome) is widely distributed. Found in only one diploid species in Africa, it is found also in African tetraploid and African and Indian octoploid species, in New World tetraploid and decaploid species, and in Australian hexaploid species. The G-genome apparently was widely dispersed and differentiated, followed by hybridization, subsequent chromosome doubling, and radiation. The A, B, X, and Y genomes, on the other hand, are confined mainly to Africa, with a few taxa in Asia, and apparently are the products of a later round of hybridization and allopolyploidy.     

Inter Simple Sequence Repeat (ISSR) Analysis of Diploid Coffee Species and Cultivated Coffea arabica L. from Tanzania

Inter simple sequence repeat (ISSR) markers were used to evaluate levels of genetic similarity among Coffea arabica L. accessions from Tanzania and to estimate levels of genetic similarities in C. arabica and diploid coffee species. The six ISSR primers used generated a total of 82 fragments and the dissimilarity values ranged from 0.21 to 1. Mean dissimilarity values between provenances (0.56–0.85) were higher than within provenances (0.37–0.68). Cluster analysis based on Nei’s genetic distances showed C. arabica provenances grouping based on geographical origin. Two major clusters were formed that constituted of provenances from Kilimanjaro and Arusha in one sub-cluster; Tanga and Morogoro in the other; the second cluster had Mbeya provenances and diploid species, respectively. The implication is that Mbeya provenances are different from the rest of Tanzanian C. arabica. A principal coordinate analysis (PCA), whose first three coordinates explained 43% of the variation, showed similar groupings as in the cluster analysis. A separate cluster analysis of diploid species showed a distinct separation of the three species used. ISSR data gave results similar to previous findings from random amplified polymorphic DNA(RAPD) analysis. The results also confirm the limited diversity present in cultivated C. arabica in Tanzania     

Growth and survival of Eisenia fetida (Sav.) (Oligochaeta: Lumbricidae) in relation to temperature,moisture and presence of Enchytraeus albidus (Henle) (Enchytraeidae)

Summary The aim of this study was to investigate the environmental requirements of Eisenia fetida (Lumbricidae) and its relation to Enchytraeus albidus (Enchytraeidae). Specimens of Eisenia fetida were cultured at two different temperatures (15°C and 25°C) and moisture conditions (50% and 80%) in presence or absence of Enchytraeus albidus. Eisenia fetida grew best at the higher temperature and amount of moisture. Enchytraeus albidus impaired the growth of Eisenia fetida at the higher temperature. When Enchytraeus albidus was present, the mortality of Eisenia fetida increased.Interaction between Eisenia fetida and Enchytraeus albidus was shown, although the mechanisms remain unclear. These species, coexisting in the same habitat (compost), appear to have slightly different niches: Eisenia fetida favours warmer, moister conditions than Enchytraeus albidus.Dedicated to the late Prof.Dr. M.S. Ghilarov     

Studies on awns in polyploid rice (Oryza sativa L.) and preliminary cross experiments of a special awnless tetraploid rice

Awns are an important genetic character of rice (Oryza sativa L.) and almost all awnless diploid varieties will change into awned varieties after polyploidization. In order to increase the understanding of awns and promote the development of polyploid rice breeding, the effect of polyploidization on awns was investigated and the development and distribution characteristics have been summarized. Furthermore, cross experiments were made between a special awnless tetraploid rice and two awned tetraploid rice. The results showed that the awns of polyploid rice initially emerged at the pistil–stamina formation stage and there was a stable corresponding relationship between awn development and other organs or development characteristics. Polyploidization had a great effect on awns. Awn length was considerably affected when diploid rice was doubled to polyploid. However, the degree of change varied between varieties. The F₁ hybrids between awnless and awned tetraploid rice in this research were all partial awn types and showed that the larger the mean, maximum awn length and the percentage of awned spikelets (PAS) of their awned parents, then the larger these of their F₁ hybrids. But different cross combinations showed some variation. The F₂ generations were still all partially awned and awnless type was not found. And the awn length and PAS of the plants developing from awned grains were significantly greater than that of the plants developing from awnless ones. This showed that the awn character of a grain could affect the plants developing from this grain. The results laid the foundation of further research of awn inheritance.     

Microsatellite markers – a new tool for distinguishing diploid wheat species

Triticum baeoticum and T. urartu are very similar morphologically. By using microsatellite markers it was possible to distinguish between these two species. Microsatellite markers are, therefore, a powerful new tool to support the determination of critical races in diploid wild wheat species. They also allow the discussion of evolutionary pathways within Triticum.