大麦核质互作型雄性不育系花粉败育过程的细胞学研究(简报)

雄性不育系在作物的杂种优势利用中具有重要的价值。研究其花粉败育过程有利于了解败育机理,并为化学杀雄和化学保雄提供理论     

沙冬青属的细胞学研究

沙冬青属(Ammopiptanthus)植物仅两个种,即蒙古沙冬青(A.mongolicus)和新疆沙冬青(A.nanus),为第三纪残遗种,是中亚荒漠唯一的常绿阔叶植物,因珍稀,临危而被列为国家重点保护植物”。国内外对该属两个种的染色体数目的记载存在着差异。本文对沙冬青属两种植物的染色体数目和核型进行了分析研究,旨在为探讨该属植物的发生和系统发育,以及开展植物多样性保护和合理开发利用积累资料。     

RING-POSITION AND FREQUENCY OF CHIASMA FAILURE IN RHOEO SPATHACEA

The mean chiasma number per cell was 11.44 ± 0.04 in 489 cells. Due to chiasma failures, the ring-of-twelve chromosomes may be broken into two or three chains. Cells with four or more chains were not observed. All six possible two-chain situations and eight different threechain situations were found. All possible lengths of chains from one to all twelve chromosomes were found, with “chain”-of-one inordinately frequent. The overall mean number of chromosomes in 273 chains in 188 cells is 8.26 ± 0.31 and 5.38 ± 0.31 among 154 chains in the 69 cells that had two or more chains. The mean number of chains per cell among these 188 was 1.45 ± 0.13. In 73 cells, 113 chiasma failures were found to be distributed at random among the twelve chromosome arm positions. The absence of association either between length of arm or between presence-absence of secondary constriction and frequency of chiasma failure support the generally accepted theory that, in Rhoeo, synapsis and crossing over are restricted to small terminal segments on all chromosomes.     

A CYTOLOGICAL STUDY OF BLACK GRAMAGRASS BOUTELOUA ERIOPODA

Streetman , L. J., and Neal Wright . (U.S.D.A., U. Arizona, Tucson.) A cytological study of black gramagrass, Bouteloua eriopoda. Amer, Jour. Bot. 47 (9) : 786–793. Illus. 1960. The chromosome number, microsporogenesis, embryo-sac development and embryogeny of Bouteloua eriopoda (Torr.) Torr. were investigated. Thirty-four of the 35 accessions had a diploid chromosome complement of 2n=20. One accession had a chromosome number of 2n=28. Meiotic behavior of the 20-chromosome plants was normal, and pollen quality approached 100%. However, metaphase-I and anaphase-I cells of the 28-chromosome plants had up to 8 lagging chromosomes. Pollen quality was approximately 67%; however, the plants were highly sterile. These results furnished evidence of a basic number of x = 10 for the genus Bouteloua. Megagametophyte development was normal, which resulted in an 8-nucleate embryo sac of the “Polygonum” type. Abnormal development of nucellar tissue was not detected, and embryo development did not begin until 12–18 hr. after anthesis. The development of the female gametophyte indicated sexual reproduction. A high degree of morphological variability among and within accessions afforded further evidence for sexual reproduction and suggested that the species was largely cross-fertilized. The proembryo, which began development 12–18 hr. after pollination, lacked a discernible arrangement of cells and sequence of division. The endosperm was free nuclear until 4 days after pollination, when it changed to a cellular form. Differentiation of the proembryo into various embryo structures began 4–5 days after pollination. The embryo matured anatomically 12 days after pollination. Black gramagrass, a perennial range grass native to the desert grasslands of the southwestern United States, is a major species in Arizona, New Mexico, and adjacent parts of Mexico. In many areas of low rainfall this species is the only desirable grass.     

CYTOLOGICAL INVESTIGATIONS OF KABATIELLA CAULIVORA

Cole , Herbert , Jr ., and Houston B. Couch . (Penn. State U., University Park.) Cytological investigations of Kabatiella caulivora. Amer. Jour. Bot. 46(1) : 12-16. Illus. 1959.—Initial growth of K. caulivora on artificial media is characterized by budding, yeast-like, conidia, exclusive of mycelia. After 14 days growth, at 20°C., mycelial growth becomes macroscopically evident. A study of the germination behavior of a total of 5500 conidia from the initial yeast-like growth stage showed 59 to germinate by the production of mycelia, while the balance germinated by budding. Five thousand conidia of the mycelial growth type were studied in a successive, single-spore transfer series, and, in all cases, conidial germination continued to be by means of germ tubes. Conidia of both growth forms were studied by means of bright field and phase contrast microscopy, and found to be multinucleate—possessing variable nuclear numbers, ranging from 1-8 per cell. Mean nuclear number for both the mycelial and conidial types was 2.8. All nuclei of both growth types appeared to contain the same chromosome complement. The cultural variability exhibited by K. caulivora cannot be reconciled with the concept of dual phenomenon. It is suggested, rather, that the mycelial homotype probably arises as the result of a unidirectional mutation within the conidial growth form.     

CYTOHISTOLOGICAL STUDIES OF CYTOCHIMERIC AND TETRAPLOID GRAPES

Thompson, M. M., and H. P. Olmo. (U. California, Davis.) Cytohistological studies of cytochimeric and tetraploid grapes. Amer. Jour. Bot. 50(9): 901–906. Illus. 1963.—Cytohistological studies were made on 62 different grape clones suspected to be tetraploids to determine if they were chimeras, and if so, what type. The chromosomal constitution of the apical layers in the shoot was determined on the basis of cell and nucleus size, size of chromosome mass, and chromosome estimates or counts. Three cytological types were observed; 2–4,² 4–2, and 4–4. The possible types of chimeras and their stability depend upon the organization of the shoot apex. In most buds there appeared to be a biseriate tunica covering a corpus. However, the number of tunica layers fluctuated from 1 to 3, and there were occasional periclinal divisions in L-II. This lack of discreteness of the second layer probably accounts for the homogeneity of all tissue beneath the superficial layer. The rarity of periclinal divisions in L-I explains the stability of 2–4 types, but reversions are not impossible. The relative frequency of the different types of sports is discussed in relation to their possible origin. The theory of intraclonal variability developed in grapes by Reichardt (1955) and Rives (1961) on the basis of a multilayered shoot apex is re-evaluated under the concept of a functionally uniseriate tunica.     

RING-POSITION AND FREQUENCY OF ADJACENT DISTRIBUTION OF MEIOTIC CHROMOSOMES IN RHOEO SPATHACEA

The morphological sequence of the twelve chromosomes around the ring as worked out by Sax is reaffirmed with slight corrections of the centromere position on three chromosomes: Aa, fA, and Dd. Adjacent distribution was found in 53/120 MI PMC (44.2%). Ring-position analysis was achieved in 34 of the 53. There were 127 chromosomes and 66 arm-pairs involved in adjacent distribution in these 34 MI PMC. Adjacent distributions occurred at random among the twelve chromosome positions and among the twelve arm-pair positions. There were eleven instances among the 66 arm-pairs (16.7%) of adjacent distribution despite free ends due to chiasma failure. Up to four consecutive chromosomes may pass to the same pole. Not all cells with 6–6 distribution are genetically balanced. Distribution of 7–5 occurred in 24/120 AI PMC (20.0%). Another nine (7.5%) in the same sample had one or more lagging chromosomes. At MI, three PMC had 8–4 distribution, but none such were seen at AI.     

CYTOLOGICAL EXPRESSIONS OF A CYTOPLASMIC MALE STERILITY IN SOLANUM

Anther contents of plants expressing the cytoplasm-gene interaction that results in anther indehiscence were studied under the light microscope. Plants could be classified in four groups on the basis of anther content: (1) A blockage resulted from cessation of development principally during the stages of meiosis of apparently normal sporocytes. This produced anthers in open flowers that usually contained monads or dyads. (2) Disorganization of sporocytes during first meiotic prophase resulted in irregularity of disjunction during the two meiotic divisions. Sporocytes produced quartet-stage clumps having more than four cells. Microspores failed to grow beyond early stages of exine development. (3) Abnormal small pollen having a very thick exine. (4) Normal pollen present in anthers that lacked terminal pores. The variety of anther content types resulted from presence of modifying genes rather than from differing actions of genes that conditioned indehiscence itself. Expression was not modified by environmental fluctuations, and plants did not show chimeral sectors having changed anther contents or dehiscent anthers.     

青藏高原一些种子植物的核型研究

本文对产于青藏高原地区的１１个属１２个种植物进行了核型分析。大部份种为首次报道。它们的核型公式和核型不对称性如下：云雾雀儿豆Ｃｈｅｓｎｅｙａ ｎｕｂｉｇｅｎａ（Ｄ．Ｄｏｎ）Ａｌｉ,为２ｎ＝１６＝１０ｍ＋６ｓｍ,属２Ｂ型;变色锦鸡儿Ｃａｒａｇａｎａ ｖｅｒｓｉｃｏｌｏｒ Ｂｅｎｔｈ．,为２ｎ＝１８＝１４ｍ＋４ｓｍ,２Ｂ型;异叶青兰Ｄｒａｃｏｃｅｐｈａｌｕｍ ｈｅｔｅｒｏｐｈｙｌｌｕｍ Ｂｅｎｔｈ．,