Progenies Of Interspecific Crosses Research Articles

Maternal inheritance of plastids and mitochondria in Cycas L. (Cycadaceae)

Cycas is often considered a living fossil, thereby providing a unique model for revealing the evolution of spermatophytes. To date, the genetic inheritance of these archaic plants is not fully understood. The present study seeks to document the process of organelle inheritance in an interspecific cross of Cycas species. Extranuclear organelle DNA from chloroplasts and mitochondria was analyzed using both polymerase chain reaction-restriction fragment length polymorphism analysis and microscopy. Here, we show that the chloroplasts and mitochondria in the progeny of interspecific crosses between Cycas taitungensis and Cycas ferruginea were exclusively inherited from the female parent. Epifluorescence microscopic analyses of the pollen cells from Cycas elongata indicated that there was a significant degradation of organelle DNA in male reproductive cells following maturation; the DNA fluorescent signals were only seen after pollen mitosis two, but not detectable at mature stage. Lack of organelle DNA fluorescent signal in prothallial cells was confirmed by the absence of plastids and mitochondria in electronic microscopic images. In conclusion, these data suggest that the maternal plastid and mitochondrial inheritance in Cycas, native to the old world, are the same as seen in seed plants.

Segregation of Fall-flowering Progenies Derived from Interspecific Crosses between Rhododendron kiusianum Makino and Related Evergreen Azaleas

Inheritance of fall-flowering character was investigated among progenies of interspecific crosses between evergreen azaleas. The frequency of fall-flowering seedlings was high in the crosses with Rhododendron kiusianum Makino, irrespective of cross direction. R. kiusianum is a valuable parent to give crossing opportunity twice a year.

Identification of RAPD, SCAR, and RFLP markers tightly linked to nematode resistance genes introgressed from Arachis cardenasii into Arachis hypogaea.

Two dominant genes conditioning resistance to the root-knot nematode Meloidogyne arenaria were identified in a segregating F2 population derived from the cross of 4x (Arachis hypogaea x Arachis cardenasii)-GA 6 and PI 261942. Mae is proposed as the designation for the dominant gene restricting egg number and Mag is proposed as the designation for the dominant gene restricting galling. The high levels of resistance in GA 6 were introgressed from A. cardenasii and, therefore, a search to identify A. cardenasii specific RAPD markers that are tightly linked to these resistance genes was conducted utilizing bulked segregant analysis. One RAPD marker (Z3/265) was linked at 10 +/- 2.5 (SE) and 14 +/- 2.9 cM from Mag and Mae, respectively. The marker was mapped to linkage group 1 at 5 cM from Xuga.cr239 in the backcross map in an area where introgression from A. cardenasii had previously been reported. This fragment was cloned and used to generate a pair of primers that specifically amplified this locus (sequence characterized amplified region, SCAR) and as a RFLP probe. Their close linkage with the resistance genes will be useful in marker-based selection while transferring nematode resistance from introgression lines into elite breeding lines and cultivars. The Z3/265 marker associated with the genes Mae or Mag was not found in other highly resistant Arachis species (Arachis batizocoi or Arachis stenosperma), in progenies of interspecific crosses with A. cardenasii that were moderately resistant, or in the resistant A. hypogaea lines PI 259634 and PI 259572. These represent the first molecular markers linked with a resistant gene in peanut and the first report of two physiological responses to nematode attack associated with two genetic factors.

452 PB 297 COTYLEDON POSITION AS A SPECIES CHARACTER IN PHASEOLUS

The methods of Wall and York (1957) were used to measure cotyledon position in two populations of three species interspecific Phaseolus hybrids and in the single species cultivars and accessions of P. coccineus, P. acutifolius, and P. vulgaris used as parents. Cotyledon position was represented by the length of the epicotyl as a percentage of the total length of the seedling's stem from the first root initial to the base of the primary node. Progeny of interspecific crosses between P. coccineus and P. vulgaris have been shown to inherit the cotyledon position of the cytoplasmic parent. The objectives of this study were to determine if three species hybrids also inherited the cotyledon position of the cytoplasmic parent, and to determine if P. acutifolius could be distinguished from P. vulgaris by its cotyledon position. Results indicated that the cotyledon positions of the three species hybrids did not differ significantly from the cotyledon positions of cultivars of the species used as the cytoplasmic parent for both P. vulguris cytoplasm and P. coccineus cytoplasm. Further, the cotyledon position of the P. acutifolius accessions did differ significantly from the cotyledon positions of both the P. vulgaris cultivars and the three species hybrid with P. vulgaris cytoplasm. These results suggest that cotyledon position may indeed be a species-specific trait for Phaseolus in Lamprecht's sense of the term.

Inheritance of zingiberene in Lycopersicon

The inheritance of the sesquiterpene zingiberene was analyzed in segregating progeny of interspecific crosses among Lycopersicon hirsutum f. hirsutum Humb. and Bonpl. (hir), L. esculentum Mill. cv 'Nova' (esc), and L. hirsutum f. glabratum C.H. Mull (gla). The presence of zingiberene was inherited as a single dominant gene from hir in F2 and BC progeny of esc x hir, and as a single recessive gene in F2 and BC progeny of gla x hir. The segregation of esc x hir, gla x hir, and esc x gla progeny supported a single locus allelomorphic model in which the presence of zingiberene is controlled at a single locus, Z, where the allele from hir confers presence of zingiberene and is dominant to the allele from esc but recessive to that from gla. The presence of zingiberene in esc x hir progeny was not linked to the ability to set fruit or to several fruit characters, and progeny with zingiberene levels comparable to hir were recovered.

カンキツのフラバノン・ネオヘスペリドシドの遺伝

カンキツのフラバノン•グリコシド系の苦味成分 (フラバノン•ネオヘスペリドシド) の遺伝を明らかにするため, 著者ら (5) はカンキツ実生の果実 (果汁) のフラバノン•グリコシド組成の定性分析を高速液体クロマドグラフィー法 (HPLC法) により行った. その結果,フラバノン•ネオヘスペリドシドは優性に発現し, 無味のフラバノン•ルチノシドは劣性ホモの発現であること, ヘテロ品種と劣性ホモとの品種の交雑では, ネオヘスペリドシドを含有する個体とルチノシドのみを含有する個体が3:1ないし, 1:1に分離することも見出した. しかし, 結実までに長年月を要する果樹では調査個体数が限られており, 既報 (5) では完全な遺伝解析をするまでには至らなかった. 果実のフラバノン•ネオヘスペリドシドの遺伝解析を完全に行うためには,フラバノン•グリコシド組成の解析を果実で行うのではなく, 栄養体である葉を用いた早期検定による解析法を確立する必要がある. 著者らは前報 (6) において葉抽出液のネオヘスペリドシドの有無から果実のそれの有無を推定できることを明らかにするとともに, 酵素免疫測定法 (ELISA法) によるフラバノン•ネオヘスペリドシドの高感度•簡易分析法を確立した. そこで本報告では交配実生集団の葉を用い, ELISA法によるカンキツのフラバノン•ネオヘスペリドシドの分析結果からその有無の遺伝を解明したので報告する.

Selection for early flowering in progenies of interspecific crosses of ten species in the genus Dianthus

Twenty-seven progenies of interspecific crosses, involving ten Dianthus spieces (D. caryophyllus, D. chinensis, D. superbus, D. barbatus, D. japonicus, D. brachyzonus, D. versicolor, D. trifasciculatus, D. serotinus and D. knappii) and some complex interspecific hybrids (Diantini genotypes and D. ‘Allwoodii’ selections) were grown from seed under 8 hr days at two light intensities: 12 W/m2 and 22 W/m2. Observations on individual plants were made on vegetative development and date of flowering. After six months, 178 plants were selected from 23 seedling progenies and the resulting clones were compared under 22 W/m2 and two photoperiods: 8 hrs and 24 hrs per day for a period of nearly six months. In the seedling stage, large differences were observed between progenies, e.g. in percentage generative plants (0–100%), plant length (3–78 cm) and plant fresh weight (0.5–68 g). Effects of light intensity were most pronounced in plant fresh weight (0.2–18 g in 12 W/m2 and 0.5–68 g in 22 W/m2). Progenies of D. chinensis were the earliest to flower. Most progenies of crosses between D. superbus and D. barbatus segregated into flowering and non-flowering (rosetting) plants. In the clonal stage, most clones originating from non-flowering seedlings remained vegetative (rosetting), while all clones from flowering seedlings were either in flower or in bud within six months. Average dates of flowering of seedling progenies and of their clones were highly correlated, suggesting that selection on flowering date at the seedling stage is effective. High correlations were also found between the average flowering date of seedling progenies and the number and total weight of flowers harvested per plant in their clones within six months from planting. Overall effects of LD in the clonal stage were much less spectacular than the effects of light intensity in the seedling stage.

Linkage Maps for 20 Enzyme Loci in Aedes triseriatus

Twenty enzyme loci were mapped on the three linkage groups of Aedes triseriatus using intraspecific and interspecific matings. Large numbers of single-pair forced matings were made among field-collected A. triseriatus. Parents with appropriate isozyme linkage genotypes were identified and the progeny analyzed using standard electrophoretic procedures. Interspecific data were obtained by performing single-pair forced matings between A. triseriatus and either A. hendersoni or A. brelandi and then backcrossing to one of the parental species. Interspecific recombination values were adjusted to compensate for reduced chiasmata (and crossovers) in progeny of interspecific crosses. Four loci--Aat2, Me, Idh 1, and Mpi-- were associated with sex on linkage group (LG)I. The LG I map was about 24% longer than the predicted length of 62 map units. Eleven loci--Gpi, Hk4, Odh, Est2, Pgm, Sod1, Gpd, Had, Aco2, Idh2, and Est5--were assigned to LG II and spanned approximately 60 map units. Five loci--Mdh2, Pgd, Aat1, Gapd, and Fum--were assigned to LG III, but exact positions and distances of loci were not definitely established. The linkage relationships of enzyme loci of A. triseriatus were compared to maps of five other Aedes species in four subgenera. Map differences indicated several major inversions and translocations that separated the subgenera. In addition, several linkage groups appeared to have been conserved during Aedes subgeneric divergence.

Further cytological studies of Antipodean Teleogryllus species and their hybrids (Orthoptera: Gryllidae)

Three additional populations of T. oceanicus and six intra- and inter-specific hybrids of Teleogryllus species have been studied. Some abnormal chromosome conditions, such as variation in number, occurrence of numerous univalents, chromosomal bridges, and polyploid cells, were found in the intraspecific hybrids of T. commodus and in interspecific hybrids.The low fertility of intraspecific hybrids of T. commodus and the production of sterile progeny of interspecific crosses may be due to the unequal segregation and chromosomal incompatibility.