Hybridization barriers among the species of Arachis L., namely of the sections Arachis (including the groundnut) and Erectoides

Some members of section Erectoides have been found resistant to early leaf spot disease, a serious constraint to groundnut productivity. These accessions do not cross with cultivated species. Crossing between one such diploid species, A. paraguariensis (ICGs 8130 and 8973) of section Erectoides, and the diploids, A. batizocoi and A. duranensis, and the tetraploid A. hypogaea (groundnut) of section Arachis has helped understand barriers to hybridization between sections. These crosses result in the development of normal pegs and pods, but with of ovule and embryo development restricted or non-existent. Such restricted growth and embryo abortion is found to be due to cessation of early endosperm development in A. duranensis (2x) times A. paraguariensis (2x), the non-development of endosperm beyond the coenocytic stage in A. batizocoi (2x) times A. paraguariensis (2x), and the overgrowth of nucellar tissue into the embryo sac in case of A. hypogaea (4x) times A. paraguariensis (2x).The weak cross-compatibility between the species of two sections suggest relatively closer phylogenetic relationship between them, than with the other incompatible sections of the genus Arachis.     

Development of new sources of tetraploid <Emphasis Type="Italic">Arachis</Emphasis> to broaden the genetic base of cultivated groundnut (<Emphasis Type="Italic">Arachis hypogaea</Emphasis> L.)

Groundnut, an important crop of many countries of the world, is susceptible to a range of diseases and pests. High levels of resistances are not available in the cultivated gene pool as the crop is said to have a narrow genetic base. Narrow genetic base is attributed to the evolution of the crop which took place by the combination of A and B genome species, and later doubling their chromosome number, giving rise to tetraploid cultivated groundnut. Direct utilization of cross-compatible wild relatives, which are diploids, to broaden the genetic base and introduction of useful traits, is not a straight-forward process due to ploidy differences between the cultivated species and wild relatives. Hence amphiploids and autotetraploids were created by not only combining the putative genomes, but many other A and B genome species, thus producing a highly variable population of tetraploid groundnuts also called new sources of Arachis hypogaea. This study describes the development and characterization of newly generated tetraploid groundnuts and the level of molecular diversity as assessed by DArT markers.     

Resistance to Meloidogyne javanica in wild Arachis species*

The root-knot nematode, Meloidogyne javanica Race 3 is an important nematode parasite of groundnut. Greenhouse evaluation of 184 accessions of 33 wild Arachis spp. five interspecific derivatives, 18 groundnut cultivars for root damage (galls formed by nematode) and nematode reproduction demonstrated that resistance to the nematode is available in the genepool of wild Arachis spp. Seven accessions, ICG 8952 (Arachis helodes), ICC 13211 (A. sylvestris), ICG 13224 (A. kretscmeri), ICG 13231 (Arachis sp.), ICG 14862 (A. kuhlmannii), ICG 14868 (A. stenosperma), and ICG 14915 (A. sylvestris) were highly resistant to nematode reproduction and root damage. There was no gall and eggmass formation on any plant of these accessions. Thirty-three accessions were resistant and 14 were moderately resistant. All the tested accessions of A. monticola, A. benensis, A. ipaensis, A. hoehnei, A. kempff-mercadoi, A. valida, A. chiquitana, A. rigonii, A. vallsii, A. dardani, A. paraguariensis, A. triseminata, interspecific derivatives, and groundnut cultivars were susceptible. The possible use of resistance sources in the breeding program is discussed.     

Genetic variation vis-à-vis molecular polymorphism in groundnut, Arachis hypogaea L.

Recent studies on the genus Arachis using molecular markers have revealed very little demonstrable polymorphism in the cultivated groundnut, A. hypogaea. This has led to the hasty generalization that the groundnut lacks genetic variation. However, this is in complete contradiction to the results of other lines of investigations into the origin and evolution of A. hypogaea. Further, a characterization of the world collection for various traits also shows significant levels of variation for almost all genetic traits. The literature review in this article suggests that the lack of genetic variation was inferred because of an inadequacy in the material studied, and the range of techniques used to study molecular polymorphism. A comprehensive and rigorous examination of the material available in the groundnut world collection, either by improving current techniques, or by using such advanced techniques as SSRs and AFLP could well reveal polymorphism at the molecular level.     

Study of the genetic variability and similarity among and within Arachis villosulicarpa, A. pietrarellii and A. hypogaea through isoenzyme analysis

Arachis villosulicarpa is a perennial species cultivated for its soft and tasty seeds by indigenous inhabitants of the Mato Grosso State, Brazil. Besides A. hypogaea, this species is considered as the only species of Arachis which represents a valuable food source for human consumption. Due to the lack of knowledge concerning the genetic diversity of A. villosulicarpa, this study was conducted to evaluate the genetic variability of the accessions from the Germplasm Collection of CENARGEN/EMBRAPA (Brasília, DF, Brazil) and Instituto Agrono^mico (IAC, Campinas, SP, Brazil). In addition, the genetic similarity between A. villosulicarpa, the related wild species A. pietrarellii, and the cultivated peanut A. hypogaea cv. Tatu was evaluated. From the entire sample analyzed of A. villosulicarpa, the accession from Instituto Agrono^mico showed the highest indices of diversity for both enzymatic systems analyzed, pointing this accession as a promising source of genetic variabil ity that must be preserved in the Germplasm Bank. A high level of genetic similarity was observed between A. pietrarellii and A. villosulicarpa, supporting previous suggestions that A. pietrarellii could be the ancestral progenitor species of A. villosulicarpa or that both species originated from a common ancestor.     

Groundnut (Arachis hypogaea L.) improvement in sub-Saharan Africa: a review

Groundnut (Arachis hypogaea L.) is a multi-purpose legume crop widely cultivated in sub-Saharan Africa (SSA). However, yield levels of the crop has remained relatively low in SSA owing to a range of biotic, abiotic and socio-economic constraints. A dedicated groundnut improvement programme integrating new tools and methodologies to breed varieties suitable for current and emerging agro-ecologies and market needs is essential for enhanced and sustainable groundnut production in SSA. The objective of this review is to highlight breeding progress, opportunities and challenges on groundnut improvement with regard to cultivar development and deployment in SSA in order to guide future improvement of the crop. The review analysed the role of new tools in breeding such as, high-throughput and automated phenotyping techniques, rapid generation advancement, single seed descent approach, marker-assisted selection, genomic selection, next-generation sequencing, genetic engineering and genome editing for accelerated breeding and cultivar development of groundnut.     

Chemical composition and biological activities of Arachis species

Arachis hypogaea , known as the peanut, is native to South America. Peanut contains several active components including flavonoids, phenolic acids, phytosterols, alkaloids, and stilbenes. Some therapeutic effects have been reported for peanut seed extracts, such as antioxidative, antibacterial, antifungal, and anti-inflammatory activities. This paper aims to give an overview of the chemical composition, focusing on secondary metabolites, and of the biological activity of A. hypogaea, to stimulate new studies about species of the Arachis genus.     

沂蒙山区坡耕花生地垄间植草对土壤理化性质的影响

以沂蒙山区坡耕花生地为研究对象,建立野外原位观测小区,将花生+狗牙根(处理Ⅰ)、花生+草木犀(处理Ⅱ)、花生+黑麦草(处理Ⅲ)、花生+三叶草(处理Ⅳ)、花生+空白对照(处理Ⅴ)5种植草方式进行对比,研究垄间不同植草方式对坡耕花生地土壤理化性质的影响,并运用灰色关联分析法对多个土壤理化性质指标进行综合判定。结果表明:垄间植草方式中土壤粗化指数、砂粒含量、总孔隙度、毛管孔隙度、毛管持水量、有机质及全氮含量出现了不同程度的升高,而容重、黏粒与粉粒、全磷含量呈现下降趋势;与空白对照相比,垄间植草明显改良了土壤理化性质,其中以花生+黑麦草处理效果最优,灰色关联度达到0.931 9,其余依次为花生+三叶草(0.929 6)、花生+草木犀(0.747 6)及花生+狗牙根(0.731 1),空白对照效果最差,灰色关联度仅为0.548 7。     

RFLP analysis of Aegilops species belonging to the Sitopsis section

The phylogenetic relationships among theAegilops species belonging to the Sitopsis section were investigated using RFLP (restriction-fragment-length polymorphism) analysis. Twenty-five probes, each of which hybridised to oneor more restriction fragments located in the B-genomechromosomes of cultivated wheats, were used. At least one and in most cases two fragments were located in every B genome chromosome arm. Adendrogram derived from a cluster analysis of the complete RFLP dataset showed a subdivision of the species belonging to the Sitopsis section into one group comprising the species of the Truncata subsection and another group comprised of the species of theEmarginata subsection. Dendrograms also were produced using RFLP data from loci located in different combinations of only three chromosomes, and some of these showed different subdivisions of the species. This demonstrates the importance in obtaining reliable classification data of using probes that detect loci evenly distributed in the genome and located in each chromosomearm.     

晋西黄土区幼龄苹果+花生间作地土壤水分的时空分布特征

选取晋西黄土区具有典型代表性的幼龄苹果(Malus pumila)+花生(Arachis hypogaea)间作地作为研究对象,在花生生长季的不同时间对苹果+花生间作地和对照花生单作地的土壤水分进行定位监测,研究苹果+花生间作系统间作界面上土壤水分的时空分布特征和水分效应,及其对花生生长状况和产量的影响。结果表明:1)间作地土壤平均水分含量生长季逐月变化显著,水分耗用最大的时间为7月;2)在垂直方向上,土壤含水量随着土壤深度的增加而增加,在水平方向上,土壤含水量最低值出现在距离果树行最近的区域,并随着与树行距离的增加而增加;3)间作地种间土壤水分耗用量最大的区域为靠近苹果树的表层土壤;4)在当前树龄下,苹果+花生间作系统相对于花生单作土壤水分在整体上表现为负效应,对花生的产量产生了不利的影响,并限制了果农间作系统生态效益和经济效益的进一步提高。建议采取适当的调控和管理措施缓解种间水分竞争并提高花生的产量。     

合成六倍体小麦与其亲本在合成后小麦A/B染色体组微卫星位点的比较

构建人工合成六倍体小麦是利用小麦近缘材料优异基因的很有效的方法。但是目前在人工合成异源六倍小麦的过程中对微卫星位点的影响研究尚不完善。本研究直接比较了亲本四倍体小麦PS5与4个不同粗山羊草进行远缘杂交并经染色体自然加倍后获得4个人工合成六倍体小麦前后,位于普通小麦A/B染色体组不同染色体臂上的104对引物的变化。结果表明,104对微卫星引物的扩增产物在4个合成六倍体小麦中具有与普通小麦相同的带型;但在22对引物的扩增产物上存在差异,其中Am4与其它3个六倍体小麦Am1,Am2,Am3在15对引物扩增的条带存在差异;另外发现有45对特异与AB染色体的引物能够在粗山羊草中扩增出产物,其中特异于B染色体组的引物47.54%的可以在粗山羊草中扩增出产物,而A染色体组的引物占38.24%。因此,基于普通小麦开发的微卫星引物可以用于合成六倍体小麦的研究,而Am4材料与其它3个合成二倍体小麦的差异尚需进一步研究,另外我们推测普通小麦的B染色体组与A染色体组相比与粗山羊草存在较近的亲缘关系。     

New peanut (Arachis hypogaea) phytoalexin with prenylated benzenoid and but-2-enolide moieties

A new pigmented, optically active, low molecular weight metabolite has been isolated from peanut (Arachis hypogaea) kernels challenged by four species of Aspergillus. The structure of the new compound, termed SB-1, was elucidated by analysis of 1H NMR, 13C NMR, and mass spectrometric data. The SB-1 molecule bears prenylated benzenoid and but-2-enolide moieties and represents an unusual class of compounds. The closest known analogue to SB-1 was isolated from heartwood of Pericopsis elata. Both A. hypogaea and P. elata belong to the family Leguminosae. The new metabolite was accumulated in different peanut genotypes challenged by five Aspergillus species and may be an important representative of a new class of peanut phytoalexins. SB-1 production often exceeds production of major known stilbenes.     

花生油体蛋白家族基因的克隆和表达分析

油体蛋白是一类覆盖在油体表面的碱性小分子蛋白.油体蛋白的存在对于维护油体的稳定性非常重要,油体蛋白也是种子作为生物反应器表达重组外源蛋白的重要载体.本研究通过构建花生(A rac his hypogaea L.)未成熟种子的全长cDNA文库,测序得到284条编码油体蛋白的EST.根据编码蛋白分子量的大小可将花生油体蛋白基因分为6个亚族:AhOLE O- 16.9、AhOLEO- 17.7、AhOLEO- 18.6、AhOLEO-22、AhOLEO- 18.4和AhOLEO- 14.3 (GenBank登录号分别为:EG372527、EG373122、EG373716、EG372719、EE125019和EE124234),其中AhOLEO- 16.9,AhOLEO- 17.7和AhOLEO- 14.3分别有2个成员,其它家族的各只有1个成员.本研究首次从花生中克隆了分子较大的AhOLEO-22.cDNA芯片和半定量PCR结果表明6个亚族的油体蛋白基因在花生的不同器官和在种子不同发育时期表达模式相似,在根、茎、叶、花中几乎检测不到油体蛋白基因的表达,在种子中表达量高,在果针入土15d内几乎检测不到油体蛋白基因的表达,随着种子发育成熟油体蛋白基因的表达量逐步提高.本研究为研究花生油体蛋白基因的家族构成和利用花生油体蛋白基因提高花生含油量、生产外源蛋白等提供了有用的信息.     

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.     

Variation in a wild groundnut species, Arachis duranensis Krapov. & W.C. Gregory

Forty-two accessions of Arachis duranensis, a wild groundnut species that has been reported as a source of resistance to several groundnut diseases, were studied for 30 quantitative traits including total protein content, oil content, and reaction to groundnut rust. Protein profiles were also investigated for variation at the molecular level. Principal component analysis was applied to 28 traits that showed significant variation. Of these, only five characters, namely, height of the main stem, length of apical leaflet on the main stem, length of isthmus between pods, width of seed, and reaction to groundnut rust, accounted for more than 61.4% of the total variation. Protein profiles of these accessions were broadly similar, except some accessions which differed in few bands. The importance of these variations in strategies for germplasm collection and breeding is discussed.Submitted as Journal Article No. 1507 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru P.O. 502 324 A.P. India.     

我国花生根瘤菌技术应用与研究进展

花生根瘤菌技术应用与研究在我国已有30多年的历史,1949—1955年的资料已有总结。本文是总结1956—1985年的资料,30年来接种面积累积达3425.2万亩。1256次试验,增产5%以上的占试验总数90.9%;每亩增产花生10—35公斤的占试验总数81.8%。选育出一批优良菌株,其中以009、97-1和C₁菌株应用面积最大,达300万亩以上。菌剂生产有固体或液体培养,用草炭吸附,每克菌剂含活菌数1—2亿。接种技术普遍采用直接拌种,也有再用石膏等球化技术,一般球化比直接拌种增产。深施接种或幼苗接种也有增产效果。细沙壤土接种效果最好。接种后用地膜覆盖可获良好增产。亩施2—3公斤氮素不影响结瘤固氮,可提高花生产量。缺磷条件下增施磷肥,能提高接种效果。用钼酸铵和根瘤菌拌种可促进菌剂的增产作用。     

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.     

Assessment of genetic diversity and relationships among <Emphasis Type="Italic">Triticum urartu</Emphasis> and <Emphasis Type="Italic">Triticum boeoticum</Emphasis> populations from Iran using IRAP and REMAP markers

Einkorn wheat is known as the donor of ‘A’ genome to cultivated wheat and source of many important genes. Therefore, genetic erosion in cultivated wheat provides a good reason to investigate genetic diversity in these species. In the present study, genetic diversity of 14 populations of Triticum urartu and Triticum boeoticum collected from west and north-west of Iran was examined by IRAP and REMAP markers. In total, 26 out of 36 IRAP and 41 out of 88 REMAP combinations amplified polymorphic and scorable banding patterns. IRAP and REMAP combinations produced 6.53 and 5.21 polymorphic bands per assay, respectively. Mean of polymorphism information content for IRAPs and REMAPs were 0.38 and 0.40 and marker index values for them were 2.60 and 2.09, respectively. Analysis of molecular variance based on IRAP and REMAP data revealed significant within and among population variances, although within population variance was higher than that of among population. Primer combinations based on Sukkula and Nikita retrotransposons produced the highest number of markers in the whole population. Cluster and principal coordinate analyses using REMAP data grouped the populations based on the species and geographical origin, but grouping based on IRAP could not separate the two species. However, based on both marker systems considerable diversity was observed among and within the studied populations.     

Genetic diversity and origin of cultivated potatoes based on plastid microsatellite polymorphism

The origin of cultivated potatoes has remaining questions. In this study, 237 accessions of all cultivated species and 155 accessions of wild species closely related to cultivated potatoes, including their putative ancestors, were analyzed using 15 plastid microsatellites (SSRs) to investigate genetic diversity and their relationships with the wild species. We here used polymorphic plastid SSRs we developed from potato plastid genome sequences as well as already known plastid SSR markers. All 15 loci were polymorphic and identified a total of 127 haplotypes. Dramatic decreases in levels of genetic diversity were revealed in landraces in comparison with wild ancestor species. The plastid SSR results showed a decrease in haplotype number and diversity from Peru to both north and south. Phylogenetic analysis revealed two distinct groups. One of them, group A, contained the majority of accessions of cultivated species of the Solanum tuberosum Andigenum group including all accessions of cultivated diploid and triploid cytotypes of this group (S. chaucha, S. phureja, and S. stenotomum by a former taxonomic system) and most of tetraploid accessions of the S. tuberosum Andigenum group (S. tuberosum subsp. andigenum), and the majority of accessions of wild ancestors from the northern members of the S. brevicaule complex. Another group B comprised most of the wild species accessions and almost exclusively hybrid cultivated species which have introgressed plastid genomes from the other wild gene pools. Lack of clustering of traditional cultivated species (as used above) support a revised group classification of S. tuberosum.     

花生二氢黄酮醇还原酶基因(DFR)的克隆及表达分析

二氢黄酮醇还原酶(dihydroflavonol 4-reductase,DFR)是植物花青素合成过程中的关键酶,催化二氢黄酮醇生成无色花青素。本研究利用花生(Arachis hypogae a L.)未成熟种子cDNA文库,通过大规模EST测序,从花生中克隆了DFR基因的全长cDNA序列。序列分析表明,花生DFR蛋白氨基酸序列与其他植物来源的DFR有很高的同源性。利用花生cDNA芯片和半定量RT-PCR方法对花生DFR基因表达模式的研究发现,DFR基因在果针中表达水平最高,其次是花,在根和叶中有微量表达;不同种皮颜色花生品种的种子中表达差异明显,随种皮颜色的加深,DFR基因表达增强,在中花9号黑色种子中表达量最高。对茎叶紫色花生种质材料的研究表明,在紫色组织中DFR基因表达较强。结果表明DFR表达量与花青素积累量呈正相关,说明DFR催化反应是花青素合成途径的关键步骤。