Inheritance of photoperiod sensitive genic male sterility and breeding of photoperiod sensitive genic male-sterile lines in rice (Oryza sativa L.) through anther culture

The fertility segregations of F₁, F₂, BCF₁ descended from crosses between PSGMR and japonica varieties, and F₁'s anther cultured homozygous diploid pollen plant populations (H₂) were studied to reveal the genetic mechanism of photoperiod sensitive genic male sterility in PSGMR under natural daylight length at Shanghai. Rate of bagged seed-setting was used as an indicator of fertility. Fifteen F₁ showed complete fertility similar to their parents. The ratio of completely sterile plants to fertile plants in fifteen F₂ and four BCF₁ was 1:15 and 1:3, respectively. The ratio of completely sterile to fertile diploid pollen plants in nine diploid populations (H₂) was 1:3. These results demonstrated that the photoperiod sensitive genic male sterility in PSGMR was governed by two pairs of independent major recessive genes. There were no significant fertility segregations in hybrids F₁ and selfed F₂ between Nongken 58S and its derivatives 7001S, 5088S, 5047S and M105-9S, indicating that the photoperiod sensitive genic male-sterile genes in Nongken 58S were allelic to those in its derivatives. Several photoperiod sensitive genic male-sterile diploid pollen lines were bred from anther cultured homozygous diploid populations (H₂) in about a three-year period. Most of these diploid lines showed significant fertility transformation and stable complete sterility from 5 August to 5 September, excellent agronomic traits and high resistance to blast and bacterial leaf blight. This revised version was published online in July 2006 with corrections to the Cover Date.     

The crossing of common wheat (Triticum aestivum L.) with cultivated rye (Secale cereale L.). I. crossability,pollen grain germination and pollen tube growth

Summary The crossing of common wheat (Triticum aestivum L.) with rye (Secale cereale L.), and especially the action of the crossability genes of wheat, was studied using the readily crossable wheat cv Chinese Spring (genotype kr ₁ kr ₁ kr ₂ kr ₂ >), the poorly crossable wheat cv Hope (genotype Kr ₁ Kr ₁ Kr ₂ Kr ₂ ), as well as the disomic substitution line of chromosome 5B of Hope into Chinese Spring (CS/Hope 5B, genotype Kr ₁ Kr ₁ kr ₂ kr ₂ ). By comparing crossability and actual fertilization, the poor crossability with rye of both cv Hope and the CS/Hope 5B substitution line was shown to result from absence of fertilization. Studies of pollen grain germination and pollen tube growth showed that the dominant alleles of the crossability genes manifested themselves through retardation and eventually inhibition of pollen tube growth at the style base and in the ovary wall. In Hope the growth of all pollen tubes was inhibited, whereas in CS/Hope 5B rarely fertilization was achieved. The recessive alleles of the crossability genes do not seem to have an influence on the growth of rye pollen tubes in wheat pistils.     

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.     

辐照花粉对小麦与中间偃麦草杂交及其胚胎发育的影响

用γ射线辐照中间偃麦草散粉期的穗,用其花粉授予普通小麦“J-11”和“中国春”,研究不同剂量辐照花粉对普通小麦与中间偃麦草杂交结实率、杂交种子含胚率、杂种幼胚培养和杂种幼苗获得率的影响。结果表明,5~9Gy低剂量γ射线略提高了中国春×中间偃麦草的结实率,表现出低剂量辐射的刺激效应,但对J-11×中间偃麦草却未表现出刺激效应。所有剂量的辐射对杂种幼胚均有伤害作用,杂交种子含胚率、杂种幼胚成苗率随剂量增加而下降。30Gy处理时有12.9%~14.5%的杂种幼胚发育成了植株,但该剂量应用到小麦中难以获得后代。在50~100Gy高剂量γ射线处理杂交种子胚发育不良,通过幼胚培养未能得到植株。将花粉辐照技术与幼胚拯救技术、花药培养技术有效结合,可以快速获得突变体,提高诱变育种效率。     

黄皮花粉萌发研究

采用 6种培养基对采自广西大学林学院内的无核黄皮和有核黄皮花粉进行萌发研究。结果表明 :不同品种 ( B)、不同培养基 ( A)、A× B对花粉萌发率的影响均达到极显著水平 ,无核黄皮和有核黄皮均以0 .75 %琼脂 1 0 %蔗糖 0 .0 0 1 %硼酸培养基的培养效果最好 ,其花粉萌发率分别为 3.0 7%、 84 .1 3%。不同品种花粉管长度的差异也达到极显著水平 ,有核黄皮花粉管平均长度为无核黄皮的 2 .2倍。不同品种、不同培养基对花粉管粗度的影响不显著     

Pollen-limited production of viable seeds in an endemic dwarf birch, Betula apoiensis, and incomplete reproductive barriers to a sympatric congener, B. ermanii

An endemic dwarf birch, Betula apoiensis, is critically endangered, and two populations of this species are restricted to the ridges of Mt. Apoi in Hokkaido, Japan. We observed the flowering phenology, pollen dispersal, and viable seed production and conducted pollination experiments in order to examine pollen limitation and hybridization with a sympatric congener, B. ermanii. B. apoiensis flowered earlier than B. ermanii but had a more variable flowering time among trees than B. ermanii. The female flowering of B. apoiensis temporally overlapped with the male flowering of B. ermanii as well as with that of B. apoiensis. Pollination experiments demonstrated that seed set and seed germination were higher in female flowers outcrossed than in those that were non-pollinated, selfed, hybridized with B. ermanii pollen, or pollinated naturally. A few selfed or hybrid seeds were filled and germinated, which indicates that self-incompatibility and reproductive barriers are not complete. Logistic regressions of local density of conspecific trees on natural seed set and seed germination were significantly positive. These results suggest that B. apoiensis is pollen-limited.     

Palynology of late Quaternary coastal sediments, Perak, Malaysia

Twenty eight samples of peat, clay and silty clay from a tin mine exposure near Pantai Remis, Perak, Malaysia, were palynologically analyzed. Six pollen zones and eight subzones were delineated based on the dominant floral components. Accelerator mass spectrometry (AMS) radiocarbon and thermoluminescence datings on selected samples indicate late Pleistocene and older age. The occurrence ofPodocarpus imbricatus pollen suggests that the deposit is no older than late Pliocene. The fluctuation of sea level during the late Pleistocene is believed to be the main factor that influenced the development of vegetation at the Pantai Remis area. The presence of mangrove peat at depths between 13.0 m and 14.0 m, which overlies a freshwaterPandanus peat, indicates the position of a former shoreline at Pantai Remis when the area was inundated sometime during the last interglacial marine incursion. During this period of high sea level, thePandanus swamp was probably being gradually replaced by mangrove vegetation. The mangrove sequence is regarded as equivalent to the Kempadang formation. A slight drop in sea level sometime during the last glacial interstadial stage probably caused a small, open alluvial swamp to be developed over the mangrove forest. This freshwater deposit may be the equivalent of the Simpang formation.     

编码日本梨树(Pyrus pyrifolia )花粉类β-1,3-葡聚糖酶蛋白的cDNA克隆与核苷酸序列

构建了日本梨树(Pyrus pyrifolia)花粉cDNA文库,发现了一个编码花粉管分泌的类β-1,3-葡聚糖酶蛋白(BGN-1)的cDNA(bgn-1)并测定了其序列.bgn-1由1408 bp组成,包括47 bp的5'-非翻译区,由1194bp组成并编码了397个氨基酸的ORF和167 bp的3'-非翻译区.3'-非翻译区含有1个NUE(AATTAA)和3个似FUE的基序,分别位于1369～1374(AATTAA)、1320～1325、1327～1332(TTTTTA)和1363～1368(TTTGGA).bgn-1编码的蛋白(BGN-1)与DDBJ中的植物β-1,3-葡聚糖酶的序列相似性范围为37%～59%,与3D结构已知的大麦β-1,3-葡聚糖酶(GⅡ)的序列相似性为39.7%.对GⅡ与BGN-1进行的疏水簇分析(HCA同源分为87.1%,＞75%的一般标准)和使用3D-PSSM软件进行的分析暗示,BGN-1的3D结构与大麦GⅡ同源性最大(≥95%的肯定度).BGN-1的信号肽长度为22 aa,成熟的BGN-1(375 aa)的理论分子量为4 0723 D,理论pI值为9.59,诊断氨基酸残基模式(D,L,S,L)与禾谷类的与生长相关的亚家族D的诊断氨基酸残基模式(D,L,S,Q)极相似.在BGN-1的C-端延伸区的位点352～367之间发现了1个功能不清,重复出现的ProXXPro结构.     

黄瓜单倍体育种的研究进展

综述了黄瓜作物单倍体育种的研究进展，包括花药培养、未授粉子房培养，辐射花粉诱导单倍体培养在黄瓜育种中的应用；总结了近年来所采用的黄瓜染色体倍性鉴定方法和加倍技术；讨论了目前这些领域存在的问题和今后的研究方向。     

辐照水稻花粉双受精行为的剂量效应

用＾６０Ｃｏγ射线辐照水稻保持系Ｖ２０Ｂ成熟花穗，在不育系Ｖ２０Ａ上授粉，观察雄配子体双受精行为的辐照剂量效应。结果表明，雄配子体双受精进程所需时间随辐照剂量增大而延长，且主要表现在雌雄配子体核仁融合时间延长。