晚实核桃新品种‘芹泉1号’

 ‘芹泉1号’为晚实核桃新品种, 果实较大, 壳薄, 光滑, 种仁饱满、色泽浅。单果质量10.3 g, 种壳厚1.18 mm, 内隔膜不发达, 取仁易, 出仁率55.20%。生长势健壮, 具有稳定的无融合生殖特性, 丰产优质, 抗逆性强, 适宜华北核桃产区及其相似土壤气候条件地区栽培。     

甜菜无融合生殖单体附加系M14大孢子发生期间细胞壁胼胝质的变化

应用脱色苯胺蓝诱导荧光法观察了甜菜单体附加系M14（Beta vulgaris L., VV+1C、2n=18+1）正常有性生殖与二倍体孢子生殖时，大孢子发生期间细胞壁内胼胝质的变化，结果如下。韭型（Allium odorum-type）胚囊大孢子发生时，自大孢子母细胞的珠孔端细胞壁内出现胼胝质荧光，并逐渐扩展到整个细胞壁，中期Ⅰ至末期Ⅰ细胞壁呈现胼胝质荧光。二分体时，珠孔端大孢子细胞壁内胼胝质荧光消失，二分体之间的横壁以及合点端功能大孢子的侧壁上荧光明显。二倍体功能大孢子的合点端细胞壁内的胼胝质荧光消失。单核胚囊形成后，其细胞壁内无胼胝质荧光，而退化的大孢子细胞壁胼胝质荧光显著。蝶须型（Antennaria-type）胚囊大孢子发生时，大孢子母细胞、二倍体功能大孢子的细胞壁均无胼胝质荧光。蓼型（Polygonum-type）胚囊大孢子母细胞减数分裂时，其珠孔端细胞壁出现胼胝质荧光，并逐渐扩展到整个细胞壁。二分体、三分体、四分体时期，胼胝质荧光主要存在于大孢子之间的横壁上，侧壁内胼胝质荧光较弱。退化的大孢子细胞壁胼胝质荧光明显，功能大孢子细胞壁上缺少胼胝质荧光。此外，本文还讨论了大孢子母细胞减数分裂与细胞壁内沉积胼胝质之间的相关性。     

Histological analysis of embryo-sac formation and detection of meiotic diplospory in cassava (Manihot esculenta Crantz)

Summary Embryo-sac formation in six cultivated Asian cassava clones and one unknown wild type, was histologically investigated to determine apomictic potential in the genus Manihot. All the 6 clones were found to possess one single sexual embryo-sac containing 6–8 nuclei at maturity. However, one clone, Rayong 3 possessed two functional embryo-sacs at 12 hours after controlled pollination (HACP). The larger embryo-sac was 6-nucleate (all 3 nuclei of the egg apparatus, 1 polar and 2 antipodal cells) and located towards the false micropylar or the nucellar beak region. The smaller embryo-sac also contained a total of 6 nuclei and approximately 10 m³ or 1/2 the volume of the former and located towards the chalazal pole. Percentage sexuality estimates indicated a 100% sexual reproduction in embryo-sacs of all the clones analysed. However, apomeiotic relationships indicate a low (0.3%) degree of meiotic diplosporous embryo-sac formation, thus suggesting facultative apomixis in cv. Rayong 3. This is the first embryological identification and evidence of apomeiosis and apomictic potential in cassava.Contribution from Plant Breeding Laboratory, Applied Genetics & Biotechnology Division, Faculty of Agriculture, Miyazaki University, No. 91.     

栽培甜菜（Beta vulgaris L．）和白花甜菜（B．corollifloraZoss．）种间杂交的研究Ⅱ．种间杂种回交后代染色体分布及形态变异

栽培甜菜（Ｂ．ｖｕｌｇａｒｉｓＬ．，ＰＴ６、２ｎ＝１９）与白花甜菜（Ｂ．ｃｏｒｏｌｌｉｆｌｏｒａＺｏｓｓ．，２ｎ＝３６）杂交获得ＶＣ８８～１杂种Ｆ＿１，其染色体组为ＶＶＣＣ，２ｎ＝３６．ＶＣ８８─１类似于异源多倍体，减数分裂基本正常，以其为母本与栽培甜菜（２ｎ＝１８）回交，或与其它物种如Ｂ．ｍａｒｉｔｉｎａＬ．杂交，皆获大量后代（Ｂ１０，Ｂ１４等），其染色体组为ＶＭＣ、ＶＶＣ等，２ｎ＝２７．以Ｂ１０～Ｂ１４（Ｂ＿１Ｆ＿２）为母本与栽培甜菜（２ｎ＝１８）回交，产生许多形态变异及各种染色体分布的后代（Ｂ＿２Ｆ＿３），其中以２ｎ＝１８染色体的植株最多达４１．５８％，推测它们当中可能含有代换系及易位系；２ｎ＝２７的个体出现频率高达３０．１９％，预示存在着无融合生殖现象；２ｎ＝１８＋１的植株以１０．３９％的频率出现，它们是带有白花甜菜染色体的单体附加系；附加２～８个染色体的植株频率为５．的％，低于前人报道数字；嵌合体频率达８．９３％，表现不稳定；极少数为２ｎ＝３６、２ｎ＝４５个体．     

Evolution and adaptedness in a facultatively apomictic grass, Poa pratensis L.

Summary Facultative apomixis confers great adaptedness and evolutive potential on biotypes belonging to the Poa pratensis L. agamic complex. Pioneering and recent research have dealt with and sometimes elucidated different aspects of apomictic expression, such as cytological mechanisms, distribution patterns, genetic control and environmental effects, in this species. We carried out an investigation on the mode of reproduction expressed in Italian natural populations, cultivars and selected genotypes together with an extensive time (56 years) and space (six countries) review in order to obtain a comprehensive picture of apomixis expression in P. pratensis. Histograms of the estimations were prepared. They showed that, due to breeder and natural selection, both cultivars and natural populations very frequently expressed a high degree of apomixis. Variations in the degree of apomixis across generations, different pollen donors, environments and estimation levels were generally low. It would, therefore, seem that the tenet which holds that apomixis in P. pratensis is strongly influenced by external factors should be reconsidered. Despite the fact that little is known of the genetic, physiological and molecular control underlying apomixis, the overall picture that emerges from our study helps to explain how the balance between sexual and asexual reproduction confers extreme versatility, adaptedness and evolutive capacity on this remarkable grass.     

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.     

A test for obligate apomixis in grain sorghum R473

Summary Segregation patterns in progeny arrays of selfed plants, heterozygous for the Mdh 1 isozyme marker locus, were used in an attempt to confirm the presence of apomixis in the grain sorghum line R473. No evidence for obligate apomictic reproduction was obtained. However, our studies did not rule out the possibility of a low level of facultative apomixis in R473.     

草地早熟禾胚发育类型及无融合生殖特征

【目的】通过对草地早熟禾不同时期胚囊发育过程的观察,掌握其胚囊类型和无融合生殖胚囊发育特征,为更深入了解无融合生殖的机理、选育中国本土草地早熟禾新品种提供理论基础。【方法】采用改良的石蜡切片技术,即FAA固定材料,多梯度二甲苯透明,切片厚度8 µm,苏木精（30 min）伊红（5 min）双重染色,观察并分析草地早熟禾的胚囊发育类型和特征。【结果】在石蜡切片中,观察到草地早熟禾巴润生殖过程中的5种胚囊类型,有性生殖胚囊所占比例为21.44%、体细胞无孢子生殖胚囊为49.67%、孤雌生殖胚囊为10.72%、助细胞胚胎和反足细胞胚囊分别为4.82%和7.66%,其中,体细胞无孢子生殖胚囊为主控型胚囊;草地早熟禾有性生殖胚囊为典型的蓼型胚囊;草地早熟禾同一胚珠中存在有性生殖胚囊、体细胞无孢子生殖胚囊或无配子生殖胚囊共存于一体的多胚现象,多胚出现频率为5.69%,其中,卵细胞形成的有性生殖胚囊与助细胞形成的胚囊极性相同,反足细胞形成的胚囊与卵细胞有性生殖胚囊极性相反;无孢子胚囊发育极不规则,通常单个发生或2个以上发生而形成多胚,2个胚囊并存现象居多。【结论】草地早熟禾生殖方式多样,具备有性生殖和无融合生殖2种生殖方式,为兼性无融合生殖植物,其无融合生殖方式以体细胞无孢子生殖为主,此外还有少量孤雌生殖和极少量的无配子生殖。     

无融合生殖水稻HDAR002的胚胎学研究

对无融合生殖水稻材料ＨＤＡＲ００２六个株系的胚胎学研究结果表明，６个株系无融合生殖胚的发生具有多源性，未受精胚的发生具有多源性，未受精胚囊内胚的发生有两种方式：即卵细胞的孤雌生殖和助细胞的无配子生殖；此外珠心细胞可直接分裂形成不定胚。无融合生殖胚的启动分裂时期为开花前２－３ｄ，其胚胎发育过程基本同正常水稻，部分材料的胚在形态上与正常水稻有差异。同时还观察到ＨＤＡＲ００２胚胎发育中的多极核现象与无胚