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1.
Summary Genetic analyses were conducted on peroxidase of the embryo and endosperm of seeds of one open pollinated and six inbred lines of cultivated rye (Secale cereale L.), and one line of Secale vavilovii Grossh. The analyses of the individual parts of the S. cereale seed yield a total of 14 peroxidase isozymes. Isozymes m, a, b, c, d, e, f and g (in order from faster to slower migration) were found in the embryo plus scutellum, while isozymes 1, 2, 3, 4, 5 and 6 (also from faster to slower migration) were peculiar of the endosperm. S. vavilovii has isozymes m, c1, d, e, f and g in its embryo plus scutellum, and isozyme 2 in the endosperm. Segregation data indicated that at least 13 different loci would be controlling the peroxidase of S. cereale. Isozymes a and b are controlled by alleles of the same locus, all the other loci have one active and dominant allele coding for one isozyme, and other null and recessive allele. The estimation of linkage relationships shows that five endosperm loci are linked, and tentative maps are shown. A possible dosage effect and the existence of controlling gene(s) for endosperm isozyme 4 is reported. All these data and the high frequency of null alleles found are discussed in relation to recent reports.  相似文献   

2.
Is the wild oat embryo monocotylous?   总被引:1,自引:0,他引:1  
The embryogeny of the wild oat (Avena fatua L.) was studied in detail. The pattern of embryo development was observed to be similar to the other investigated grass taxa, conforming to thePoa variation of the Asterad type. The embryogeny and anatomy of young seedlings showed that the embryo of the wild oat was not monocotylous, but dicotylous. The scutellum of the embryo, as reported for other grasses, was regarded as the first cotyledon, and the first leaf primordium, which developed later into a photosynthesizing leaf and situated opposite the scutellum, was interpreted as the second cotyledon. Observations indicated that the cotyledons of the embryo were placed lateral to the shoot apical meristem, which was terminal in position. The cotyledons were found to be dimorphic in structure and function. The scutellum, a modified cotyledon, functioned as a suctorial organ, transporting nutrients from the endosperm to the embryo axis. The second cotyledon or the first true leaf supplied nutrients directly to the embryo axis through the process of photosynthesis.  相似文献   

3.
The embryo development conforms to the Asterad type or Megarchetype II. A single cotyledon called scutellum is derived from the entire tierl. The shoot apex, lateral in position, and the coleoptile, originate from the tierl. The remaining parts of the mature embryo are derived from the tiers situated belowl. The short suspensor takes its origin from the lowermost tierp. The endospermab initio is free nuclear in development. It becomes cellular first around the proembryo. Physiologically, the ripe endosperm represents a dead tissue.  相似文献   

4.
Summary Peroxidase isozymes were studied in the Triticum aestivum L. kernel and in nullisomic-tetrasomic and ditelocentric combinations of Chinese Spring wheat. Analyses were carried out on different parts of dry kernels (embryo plus scutellum and endosperm) using polyacrylamide and starch gel electrophoresis, different electrophoretic buffer systems and various staining methods. The peroxidase isozymes showed a low substrate-specificity and a high tissue-specificity. The embryo plus scutellum and the endosperm always presented different peroxidase patterns. Endosperm peroxidases were associated with chromosome arms 7DS, 4BL and 7AS; whereas the embryo plus scutellum isozymes were related to chromosome arms 3AL, 3BL and 3DS. The different results obtained using various electrophoretic techniques are due to the buffer system used. All staining procedures employed revealed the same peroxidase isozymes.  相似文献   

5.
The taxonomy of Bambusoideae is in a state of flux and phylogenetic studies are required to help resolve systematic issues. Over 60 taxa, representing all subtribes of Bambuseae and related non-bambusoid grasses were sampled. A combined analysis of five plastid DNA regions, trnL intron, trnL-F intergenic spacer, atpB-rbcL intergenic spacer, rps16 intron, and matK, was used to study the phylogenetic relationships among the bamboos in general and the woody bamboos in particular. Within the BEP clade (Bambusoideae s.s., Ehrhartoideae, Pooideae), Pooideae were resolved as sister to Bambusoideae s.s. Tribe Bambuseae, the woody bamboos, as currently recognized were not monophyletic because Olyreae, the herbaceous bamboos, were sister to tropical Bambuseae. Temperate Bambuseae were sister to the group consisting of tropical Bambuseae and Olyreae. Thus, the temperate Bambuseae would be better treated as their own tribe Arundinarieae than as a subgroup of Bambuseae. Within the tropical Bambuseae, neotropical Bambuseae were sister to the palaeotropical and Austral Bambuseae. In addition, Melocanninae were found to be sister to the remaining palaeotropical and Austral Bambuseae. We discuss phylogenetic and morphological patterns of diversification and interpret them in a biogeographic context.  相似文献   

6.
Embryogenic callus was obtained from bulb segments of Iris pseudacorus on Murashige and Skoog (MS) medium with 2,4-dichlorophenoxyacetic acid (2,4-D) alone or in combination with kinetin. When early globular somatic embryos were subcultured onto MS medium with 4.52 μM 2,4-D, high frequency of somatic embryogenesis was obtained. Deprivation of 2,4-D was required for maturation. Mature somatic embryos had an elongated scutellum with a notch on the base of scutellum. Separation of embryos from embryo clusters was necessary to enhance the frequency of germination. Germination was stimulated by separation of embryos from embryo clusters and transfer onto fresh half-strength MS medium with 3% sucrose. After acclimation in artificial soil in greenhouse for 2 months, 96.4% of plantlets survived.  相似文献   

7.
以澳洲杨的胚珠及其种子为材料,运用光学显微镜和电镜扫描的方法对其从胚珠发生直到种子成熟的个体发育过程和结构进行观察,同时与鸭脚西番莲的种子附属结构的发育过程进行对比研究。结果表明:(1)澳洲杨的珠孔类型为外珠孔类型,种子附属结构起源于珠孔而非珠柄,其为种阜,而非假种皮。(2)鸭脚西番莲的珠孔类型为内珠孔类型,种子附属结构起源于珠柄,并且最终将珠孔包被,其为真正的假种皮结构。通过种阜与假种皮的不同个体发育过程,建立了大戟科种阜与假种皮的不同发育模式,并对种子附属结构的生物学功能及其暗示的不同植物进化路径进行了讨论。  相似文献   

8.
Laccopetalum giganteum (Ranunculaceae) is a rare endemic buttercup from the montane regions of the Peruvian Andes. The systematic position of this monotypic genus within Ranunculaceae was investigated using cpDNA matK sequence data. Our findings indicate that L. giganteum forms a highly supported clade together with Krapfia. Several morphological characters are shared by these genera; large subglobose and fleshy flowers, presence of androgynophore with a separated staminal and carpellate region and many tiny achenes. The Laccopetalum-Krapfia clade is sister to the core Ranunculus group with a high bootstrap support. The number of sepals and similar characteristics of achene morphology support an affinity of Laccopetalum with Ranunculus s.s tr.  相似文献   

9.
Fruit Development and Structure in Some Indian Bamboos   总被引:2,自引:0,他引:2  
Fruit structure and development of seven species belonging tofive genera of Indian bamboos are described. The fruit in fourspecies is a caryopsis typical of the family Poaceae. The ovuleis bitegmic; the outer surface of the cells of nucellar epidermisbecomes cutinized and forms the seed coat. Three species beara fleshy fruit with a unitegmic ovule. In a mature fruit theendosperm is either completely absorbed by the embryo or ispresent only in small quantity. The developing embryo comesin direct contact with the fruit wall due to the disintegrationof the nucellus and integument. The embryo is covered by a thickbrown mat from the disorganized cells of the inner layers ofthe fruit wall. Poaceae, Bambusoideae, Bambusa, Dendrocalamus, Melocalamus, Ochlandra, Pseudostachyum (fleshy fruits), fruit wall  相似文献   

10.
Summary Tissue cultures ofTriticum aestivum L. (wheat) initiated from young inflorescences and immature embryos possessed the potential for regeneration of whole plants. Both a friable and a compact type of callus were produced on Murashige and Skoog's medium with 2 mg/l 2,4-dichlorophenoxyacetic acid. The friable callus contained meristematic centers in which the peripheral cells ceased dividing, elongated, and could be easily separated. Roots were frequently formed in this type of callus. The compact, yellowish, and nodular callus arose from the epithelial and sub-epithelial cells of the embryo scutellum, and the rachis and glumes of the young inflorescence. Such callus had a smooth surface and characteristic chlorophyllous areas. Plants were regenerated only from the compact callus. The first sign of differentiation in the compact callus was the formation of a cleft or notch on the smooth surface, followed by the appearance of trichomes and the direct development of leafy structures which were not associated initially with any shoot meristems. Multiple shoots subsequently arose at the bases of the leafy structures, which are considered modifications of the scutellum, a definitive part of the cereal embryo. Accordingly, we suggest that while typical bipolar embryos are generally not formed, plant regeneration nevertheless takes place through embryogenesis and the precocious germination of the embryoids. Plants regenerated from immature embryo and inflorescence cultures were grown to maturity in soil, and were shown to have the normal chromosome number of 2n=6x=42.  相似文献   

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