缘管浒苔的单性生殖

发现缘管浒苔生活史中，配子体进行单性生殖有两种方式：一种是配子体放散的配子不经结合，固着后直接发育成新个体，完成单性生殖；另一种是配子体配子囊中最后一个或几个配子不放散直接在原藻体上发育成新个体。放散出去的配子进行单性生殖时，第一次分裂分别产生顶端细胞和基部细胞，其发育呈顶基极性。两个细胞分别成为叶片和假根的祖细胞。末放散的配子在原藻体上进行单性生殖发育成叶状体，形成的新个体可聚生成簇。后一种单性生殖发育方式为首次报道。     

Ploidy manipulation in guinea grass (Panicum maximum Jacq., Poaceae) utilizing a Hybridization-supplemented Apomixis-components Partitioning Approach (HAPA)

Ploidy manipulations are achieved by utilizing unreduced gametes, somatic chromosome doubling or haploidization. Apomixis, the asexual mode of reproduction through seeds, involves two of these phenomena viz., apomeiosis (unreduced embryo-sac formation) and parthenogenesis (fertilization-independent embryogenesis). The two components when partitioned may yield high frequencies of triploids and haploids, and thus, serve as a tool to manipulate ploidy levels when appropriately supplemented with hybridization schemes. Utilizing this H ybridization-supplemented A pomixis-components P artitioning A pproach (HAPA), the largest ploidy series in a crop plant was generated in guinea grass ( Panicum maximum Jacq.). Eighty-nine diverse guinea grass accessions were characterized for their reproductive capacities to identify tetraploid (2 n  = 4 x  = 32) accession(s) with high apospory but reduced parthenogenetic capacity, thereby producing a high frequency of hexaploid seeds. Seeds from accession IG 04-164 were utilized to produce a ploidy series by appropriately combining partitioned apomixis components and hybridizations in two seasonal cycles. We successfully obtained plants representing ploidies 3 x, 4 x , 5 x , 6 x , 8 x and 9 x , all derived from a single 4 x progenitor. Production methodology, reproducibility and utilization of HAPA in cytogenetic and molecular studies are discussed.     

极端温度处理白杨雌花培育三倍体植株的研究

采用极端温度的物理方法处理毛新杨、银腺杨、银毛杨雌花芽,均可获得三倍体。结果表明：①雌花枝水倍１－５ｄ期间是处理雌花芽的有效时期;②高温处理化芽检测出１０株三倍体,处理温以４０,４４℃有效,分别获得８株、２株三倍体,其中４０℃高温处理效果最佳;③低温处理雌花芽检测出３株三倍体,４,－２℃低温处理均有效果,分别获得１株、２株三倍体,－２℃处理效果较好;④处理时间分别为：４０℃高温处理水倍１－５ｄ的花     

Second meiotic division restitution (SDR) 2n pollen formation in diploid and hexaploid species of Asparagus

Summary Plants of two cultivars of 2x A. officinalis L. and two related ornamental species, 2x A. plumosus Baker and 6x A. densiflorus (Kunth) Jessop cv. Sprengeri were screened for production of pollen of heterogeneous size. Twenty four plants out of thirty-one studied produced this type of pollen, with frequencies of 3% or more large pollen. Some of these plants also produced giant grains. The numerically unreduced pollen arose by the lack of chromosome migration at Anaphase II in either one or both cells of a meiocyte, followed by the absence of cytokinesis in cells with abnormal chromosome behavior, a Second Meiotic Division Restitution (SDR) cytological mechanism. Double unreduced pollen resulted from a similar mechanism acting at both Anaphase I and Anaphase II stages. The high frequency of plants which produced 2n pollen in significant amounts is taken as an indication that the modified meiosis observed is under genetic control.     

Breeding behavior of yield components and hollow heart in tetraploid-diploid vs. conventionally derived potato hybrids

Summary A factorial mating design with six 4x cultivars as stylar parents mated to three groups of pollen parents (4x cultivars, 4x high protein selections, and 2x S. phureja) was used to study breeding behavior of yield, tuber set, marketable yield and hollow heart in potatoes. Mean yield for the 4x-2x hybrids was equivalent to that of their cultivar parents although yield components, tuber set and average tuber size, were greater and less, respectively, than the cultivar parents. High estimates of general combining ability were found in both pollen and stylar parents for yield, tuber set, marketable yield, number of marketable tubers and hollow heart in all three hybrid populations. Specific combining ability estimates were significant only for yield and hollow heart. Frequency of white-fleshed 4x-2x progeny of five heterozygous yellow-fleshed 2x phureja genotypes was used to confirm cytological identification of a first division restitution mechanism operative in the 2x parents. Although three of these phureja genotypes generated high-yielding progeny, two others produced 4x-2x progeny with mean yield similar to that of hybrids among 4x cultivars.Scientific journal series article 11,601 of the Minnesota Agricultural Experiment Station.     

无籽八月橘花粉育性观察

运用酸解及改良卡宝品红染色压片相结合的方法,对无籽八月橘及其有籽原种的花粉母细胞减数分裂过程、花粉粒形态、生活力、发芽率和畸形率等指标进行了观察.结果表明,无籽八月橘花粉母细胞减数分裂正常,能形成正常的四分孢子,且花粉的育性较强,与其有籽原种的育性无显著差异,表明无籽八月橘无籽与花粉育性无关.     

N2O induces mitotic polyploidization in anther somatic cells and restores fertility in sterile interspecific hybrid lilies

Fertile plants undergoing male gametogenesis can be treated with nitrous oxide (N₂O) gas to obtain 2n male gametes. N₂O treatment is also expected to restore the fertility of interspecific hybrids through meiotic restitution or mitotic amphidiploidization. However, this technique has few applications to date, and it is un-known how N₂O treatment restores fertility in sterile hybrids. To establish optimal N₂O treatment conditions and determine its cytological mechanism of action, we treated various sized floral buds with N₂O gas at different anther developmental stages from fertile and sterile hybrid lilies. N₂O treatment using the optimal 1–4 mm floral buds induced mitotic polyploidization of male archesporial cells to produce 2n pollen in fertile hybrid lilies. In sterile hybrid lilies, N₂O treatment doubled the chromosome number in male archesporial cells followed by homologous chromosome pairing and normal meiosis in pollen mother cells (PMC), resulting in restoration of pollen fertility. Backcrossing the resultant fertile pollen to Lilium × formolongi produced many triploid BC₁ plants. Thus N₂O treatment at the archesporial cell proliferating stage effectively overcame pollen sterility in hybrid lilies, resulting in fertile, 2n pollen grains that could produce progeny. The procedure presented here will promote interspecific or interploidy hybridization of lilies.     

大白菜2n配子发生的遗传分析

遗传分析表明,大白菜２ｎ配子发生受隐性单基因控制,遵循孟德尔遗传规律。在参与受精的２ｎ配子中,２ｎ雌配子较２ｎ雄配子具有较高的受精传递率。     

Chromosome Number Manipulation as Part of Potato Pre-breeding Programs

The cultivated potato(Solanum tuberosum L.) is a tetraploid(2n=4x=48) and can be improved with the incorporation of desirable traits from other Solanum species.Often the transfer of these traits is hindered by complex genetics and breeding barriers within potato.Parthenogenesis and microsporogenesis are used in chromosome number manipulation allowing breeders to reduce the potato's chromosome number to dihaploid(2n=2x=24)[diploid] or monohaploid(2n=x=12) from which a predictable transfer of traits can be made,in accordance with the endosperm balance number theory(EBN).Furthermore,the reproductive processes of first division restitution(FDR) and second division restitution(SDR) are utilized in order to increase the chromosome number for incorporation into the cultivated potato.     

K型温敏雄性不育小麦的遗传模式分析

【目的】明确K型温敏雄性不育小麦的配子传递方式及遗传模式。【方法】以K型1B/1R小麦雄性不育系K3314A,K型非1B/1R雄性不育系A731和A116,保持系116B、731B及恢复系KR783、桑榆3号和WM5-5为材料,构建了4个群体K3314A//KR783/731B、A731//KR783/731B、A116//A116/桑榆3号和A116//116B/WM5-5,分别调查其亲本及后代的自交结实率和单倍体发生的频率,结合植物数量性状主基因+多基因混合遗传模型进行遗传分析。【结果】1BS染色体片段代换了1RS染色体片段后,非1B/1R类型不育系及其后代不产生单倍体;不育系核内基因主要由雌配子传递,属配子体不育类型;育性受2对加性-显性-上位性主基因+加性-显性-上位性多基因共同控制,且2对主基因控制育性的作用相当,在B2群体中主基因的遗传率最高。【结论】杂合1B/1R核型要比纯合1B/1R核型产生的单倍体频率高;在K型不育系育性相关基因定位的群体选择中,只有组配不育系//保持系/恢复系的后代,才会出现不育和可育的分离;该类型小麦温敏雄性不育系中有2个主效基因的存在,同时受多基因的修饰作用。