Chromosomal location of adenylate kinase isozymes in Triticeae species

Summary One system of monomeric adenylate kinase isozymes, designated ADK, was observed in Triticum aestivum and in five diploid Triticeae species. The gene loci Adk-a, Adk-b and Adk-d were located on 7AL, 7BL and 7DL Triticum aestivum cv Chinese Spring chromosomal arms, respectively. Adk gene loci were also located on the 7RL chromosomal arm of Secale cereale cv Ailés, the 7H chromosome of Hordeum vulgare cv Betzes, 7X of Agropyron intermedium, 7E of Elytrigia elongata and CSU-E of Aegilops umbellulata. The results suport the notion of the conservation of gene synteny groups within Triticeae species.     

小麦族鹅观草属三种植物的生物系统学研究

本文研究了禾本科小麦族鹅观草属的3个种:缘毛鹅观草(Roegneria pendulina Neuski 2n=4x=28),纤毛鹅观草(R. ciliaris (Trin.) Nevski 2n=4x=28)和鹅观草(R. kamoji Ohwi 2n=6x=42)及其种间杂种的形态变异和染色体配对行为。各杂种F_1的减数分裂染色体配对数较高,但杂种高度不育。在杂种减数分裂中还观察到一定频率的多价体形成。以上结果充分表明该3种植物享有两个共同的基本染色体组,在S和Y染色体组之间发生过染色体相互易位,缘毛鹅观草的染色体组可拟定为S~PY~P。     

新疆、青海和四川等地区小麦族植物的细胞学观察

本文对采集于新疆、青海和四川等地的小麦族(Triticeae Dumortier)10属、52种、370份种子材料进行了细胞学观察。该地区小麦族各属种的染色体数目变化范围是从2n=14到2n=84,前者主要存在于大麦属(Hordeum)、新麦草属(Psathyrostachys)和黑麦属(Secale),而后者全部集中于赖草属(Leymus)。其中染色体数目为2n=28和2n=42的类型出现的频率很高,大多存在于鹅观草属(Roegneria)和披碱草属(Elymus)。除个别种内存在不同倍性的细胞型外,绝大多数种的染色体数目非常稳定。在所有的样本中均没有观察到具非整倍体和B-染色体的材料。     

Presence and organization of an osmotic stress response domain in wild Triticeae species

Sixteen Triticeae species of the genera Aegilops L., Pseudoroegneria (Nevski) Löve, Taeniatherum Nevski and Thinopyrum Löve were investigated by PCR amplification for the presence of a wheat germin gene internal domain involved in osmotic stress resistance. In all of the species studied a single band of identical or very similar size was detected, After cloning and sequencing of these fragments, different degrees of homology were found with the original wheat domain, which suggested that in these species there are functional differences in the osmotic response involving the germin core.     

Pollen size in Hordeum L.: correlation between size,ploidy level,and breeding system

The size of pollen in the genus Hordeum (Poaceae) is correlated with ploidy level and breeding system. Generally, the pollen size increases with the ploidy level, and outbreeding species possess significantly larger pollen than inbreeders. In H. roshevitzii (2x), H. pusilplum (2x), H. murinum subsp. murinum (4x), and H. parodii (6x) pollen, heteromorphisms occur between the central and the lateral florets of the triplet. In all four taxa, pollen from florets in which the anthers are exserted is larger than pollen from florets where the anthers remain inside the floret. The biological consequences of heteromorphic pollen are discussed, and a model for the evolution of breeding strategies in Hordeum is suggested.     

鹅观草属三个种的染色体组分析与同工酶分析

本文通过对鹅观草属的三个种:鹅观草(Roegneria kamoji Ohwi)、纤毛鹅观草(R. ciliaris (Trin.) Nevski)和竖立鹅观草(R. japonensis (Honda)Keng)的染色体组分析和二种同工酶电泳酶谱的分析,研究了这三个种的系统关系。两个种均含有两个相同的染色体组。R. kamoji和R. ciliari、R. japonensis的杂种F_1减数分裂均不正常,不能结实;而R. ciliaris和R. japonensis的正反交杂种F_1减数分裂规则,结实正常,两个种之间无生殖隔离。R. kamoji的酯酶和酸性磷酸酯酶同工酶谱与R. ciliaris和R. japonensis有明显区别,而后二种的上述酶谱无明显差异。上述结果均一致地支持了将R. ciliaris和R. japonensis合并为一种的观点,将R. japonensis处理为R. ciliaris的变种。     

Analysis of phylogenetic relationships in the Triticeae tribe using RFLPs

The use of restriction fragment length polymorphisms in combination with other approaches is very useful for the reconstruction of evolutionary events revealing phylogenetic relationships. A set of 21 cDNA probes hybridizing to different chromosome arms in hexaploid wheat was used in a series of experiments designed to estimate the phylogenetic relationships among and within 16 species of the Triticeae tribe. A high degree of polymorphism was found both between and within the species examined. The RFLP data were used to generate a cladogram and a phenogram in order to compare the two different methods of constructing phylogenetic trees. The results of both methods were consistent with each other and with the general taxonomic information provided by earlier morphological studies, meiotic pairing analysis, isozyme tests, and sequence alignment in theTer,NOR, and5s DNA loci. In addition, several correlations were found between the geographical origin of accessions from the same species and their phylogenetic relationships as shown by the cladogram and phenogram.This paper reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by the USDA or the University of Missouri.This paper is a contribution of the U.S. Department of Agriculture, Agricultural Research Service, and Missouri Agricultural Experimental Station, Journal Series No. 11706.     

Meiotic pairing behaviour reveals differences in genomic constitution between Hystrix patula and other species of the genus Hystrix Moench (Poaceae, Triticeae)

Interspecific and intergeneric hybridizations were carried out to evaluate the genomic relationships among species of Hystrix Moench and to study the relationships between Hystrix species and Psathyrostachys huashanica Keng (2n=2x=14, Ns^h). Meiotic pairing in hybrids of Hystrix duthiei ssp. duthiei × P. huashanica (2n=3x=21), Hystrix duthiei ssp. longearistata × P. huashanica (2n=3x=21) and H. patula × P. huashanica (2n=3x=21) averaged 5.18, 5.11 and 0.29 bivalents per cell, while H. patula × H. duthiei ssp. longearistata (2n=4x=28) averaged 25.36 univalents and 1.32 bivalents per cell, respectively. The results indicate that (i) H. duthiei ssp. duthiei and H. duthiei ssp. longearistata have one set of Ns genome from Psathyrostachys; (ii) H. patula has no Ns genome; (iii) genomes of H. duthiei ssp. duthiei and H. duthiei ssp. longearistata are non-homologous to those of H. patula. The genomic relationships between H. patula and other Hystrix species are also discussed.     

Multiple intercontinental dispersals shaped the distribution area of Hordeum (Poaceae)

The grass genus Hordeum (Poaceae, Triticeae), comprising 31 species distributed in temperate and dry regions of the world, was analysed to determine the relative contributions of vicariance and long-distance dispersal to the extant distribution pattern of the genus. Sequences from three nuclear regions (DMC1, EF-G and ITS) were combined and analysed phylogenetically for all diploid (20 species) and two tetraploid Hordeum species and the outgroup Psathyrostachys. Ages of clades within Hordeum were estimated using a penalized likelihood analysis of sequence divergence. The sequence data resulted in an almost fully resolved phylogenetic tree that allowed the reconstruction of intrageneric migration routes. Hordeum evolved c. 12 million years ago in South-west Asia and spread into Europe and Central Asia. The colonization of the New World and South Africa involved at least six intercontinental exchanges during the last 4 million years (twice Eurasia-North America, North America-South America, twice South America-North America and Europe-South Africa). Repeated long-distance dispersal between the northern and southern hemisphere were important colonization mechanisms in Hordeum.