Molecular cytogenetic characterization of Thinopyrum genomes conferring perennial growth habit in wheat- Thinopyrum amphiploids

Seven wheat‐Thinopyrum amphiploids, AT 3425, AgCs, PI 550710, PI 550711, PI 550712, PI 550713 and PI 550714, were evaluated for perennial growth habit in the field. Three of them, AgCs, AT 3425, and PI 550713, were identified as perennials. Fluorescent genomic in situ hybridization (FGISH) patterns of mitotic chromosomes indicated that AgCs had seven pairs of Thinopyrum chromosomes and 21 pairs of wheat chromosomes. PI 550713 and AT 3425 showed similar FGISH patterns of mitotic chromosomes with three pairs of wheat‐Thinopyrum translocated chromosomes, seven pairs of Thinopyrum chromosomes, and 18 pairs of wheat chromosomes. Thinopyrum chromosome pairing in the Fi hybrid of AT 3425 with AgCs demonstrated differences between Thinopyrum genomes in these two amphiploids. Based on chromosome constitutions, pairing and reported pedigrees, AgCs and AT 3425 were identified as a wheat‐Thinopyrum elongatum amphiploid and partial wheat‐Thinopyrum ponticum amphiploid, respectively. Chromosome pairing in the F₁ hybrid between AT 3425 and PI 550713 revealed that these two amphiploids contained the same Thinopyrum genome. Two different Thinopyrum genomes conferring perennial growth habit were identified from the perennial amphiploids and characterized cytogenetically.     

太谷核不育小麦籽粒标记蓝色性状的初步研究

利用太谷核不育小麦和4D-4E 二体代换系杂交,通过中国春 phlb 突变体诱导部分同源配对,试图给太谷核不育小麦籽粒作出蓝色标记。观察到在 phlb 基因作用下,多价体频率加大,有可能使部分同源染色体4D 和4E 配对、交换,使太谷核不育基因(Tal)和4E 染色体上的蓝色胚乳基因连锁。从中得到少量中蓝色的全不育株行,其中 Tal 基因和     

Nearly Total Absence of Homoeologous Pairing in a Hybrid between Tetraploid Hordeum chilense and Triticum aestivum

A hybrid between an induced tetraploid of Hordeum chilense (2n = 28 = H^chH^chH^chH^ch) and Triticum aestivum var. ‘Chinese Spring’ (2n = 42 = AABBDD) has been produced to test gene effects of this wild barley on homoeologous pairing in wheat. Cytological investigations in metaphase I have shown that the hybrid, which is perennial like H. chilense but morphologically more similar to the wheat parent, possesses the expected genome composition H^chH^ch ABD and a stable euploid chromosome number of 2n = 35. Pairing among the homologous H. chilense chromosomes was almost complete. The level of non-homologous chromosome association proved to be lower than the range of pairing known from euhaploids of ‘Chinese Spring’.     

The controlled introgression of Festuca arundinacea genes into Lolium multiflorum

Summary Using phosphoglucoisomerase (PGI/2) as a genetic marker, it has been shown to be possible to transfer genes from Festuca arundinacea into diploid Lolium multiflorum using the pentaploid hybrid L. multiflorum (4x) x F. arundinacea (6x). The pentaploid hybrid was sufficiently fertile to be used in reciprocal crosses with diploid. L. multiflorum. When used as the male parent, only two backcross generations were then required to reconstitute the diploid genotype. Intergeneric recombinants including a F. arundinacea PGI/2 allele were found among the diploid BC₂. Cytological data indicates that although the majority of chromosome associations involve only homologous Lolium chromosomes, associations involving Lolium and Festuca chromosomes also occur.Interpollinating the pentaploid hybrids prior to commencing a backcrossing programme increases the number of cycles of recombination and improves the chance of recovering intergeneric recombinants. The crossing programme described is proposed to be an effective method of introducing F. arundinacea genes into L. multiflorum.     

Meiotic behavior in interspecific hybrids between Brachiaria ruziziensis and Brachiaria brizantha (Poaceae)

The meiotic behavior of two half-sib interspecific tetraploid (2n = 4x = 36) promising hybrids, a sexual and an apomictic one, from crosses B. ruziziensis and B. brizantha, was evaluated. Although chromosome paired predominantly as bivalents, a few tri- and quadrivalents were recorded. Results suggest that B. brizantha and B. ruziziensis are closely related and genetic recombination is expected in hybrids. Introgression of specific target genes from B. ruziziensis into B. brizantha and vice-versa may be foreseen. However, abnormalities such as irregular chromosome segregation, chromosome stickiness and abnormal cytokinesis reported in these hybrids affect pollen fertility. More than 65% of pollen grains are sterile. Since the distinctive cytological feature of these hybrids is abnormal cytokinesis, this fact suggests that both parental genomes are unable to coordinate their activities with regard to this cytological phenomenon. Deployment of such hybrids in the process of developing varieties is discussed.     

The influence of Elymus sibiricus L. genome on the diploidization system of wheat

Summary The meiotic behaviour of five tetraploid wheat strains x Elytricum fertile (2n=42 chromosomes, AABBD(SH) genomes) F₁ hybrids has been analysed. Multivalent associations were observed in the hybrids which could be attributed to Elymus sibiricus L. gene (s) somewhat suppressing the activity of the wheat homoelogous pairing control system. This interaction depends on the wheat genotype. The effect was particularly notable when Triticum turgidum var. salomonis was the wheat parent. The possibility of gene transfer from Elymus to wheat is discussed.     

利用诱导部分同源配对向小麦转移异源染色体节段

从比较几种向小麦转移异源遗传物质的方法出发,讨论了利用诱导部分同源配对转移异源基因的优越性。对国内外诱导部分同源配对所采用的4种方法的具体步骤、研究成果及其优缺点进行了综述,并对进一步提高人工诱导异源易位系的水平提出了改进意见。     

双季杂交稻高产技术经验分析

作者总结各地高产经验认为，穗数和粒数是杂交水稻高产的关键。为了增穗增粒必须培育带大蘖的壮秧，使本田前期分蘖早发，以建立中、后期的合理群体结构和良好的冠层结构。品种搭配上双杂能显著高产，应突破杂交早稻。     

Meiosis in Two New Intergeneric Hybrids between Hordeum and Secale

The diploid hybrid Hordeum californicum×Secale vavilovii and the tetraploid hybrid H. parodii× S. anatolicum, were obtained through embryo rescue techniques at relative frequencies of 0.70 and 5.3 % of pollinated florets, respectively. Means of 11.741 + 1.1311 per cell at metaphase I of meiosis were obtained in the diploid hybrid and 14.74¹+ 6.3l¹¹+ 0.22¹¹¹+ 0.02^IV in the tetraploid hybrid with a maximum of 6.0¹+ 4.0¹¹ and 9.0¹¹+2.0¹¹¹+ 1.0^IV respectively. In the diploid hybrid there was preponderance of intragenomic pairing (86.7 %). Increased pairing in the tetraploid hybrid was attributed to autosyndesis among Hordeum chromosomes.     

福建农业电子商务发展模式研究

介绍了农业电子商务的两种基本的发展模式;进而说明福建当前实施农业电子商务的主要运营模式,并通过对福建农业信息网上农产品的供求信息配对率和点击率统计分析得出两个结论,即福建农业电子商务发展相对滞后和农产品的供求信息配对率跟点击率之间是不相关的关系;最后,文章根据统计分析的结果对福建农业电子商务的发展前景进行预测。