GENOME RELATIONSHIPS IN INTERSPECIFIC AND INTERGENERIC HYBRIDS OF RENANTHERA

Kamemoto , H., and K. Shindo . (U. Hawaii, Honolulu.) Genome relationships in interspecific and intergeneric hybrids of Renanthera. Amer. Jour. Bot. 49(7): 737–748. Illus. 1962.—Chromosome numbers and meiotic behavior of species and hybrids of Renanthera (Orchidaceae) were investigated. Renanthera elongata, R. histrionica, R. matutina, R. monachica, and R. storiei were diploid (2n = 38). The race of R. coccinea commonly grown in Hawaii was found to be hexaploid (2n = 114), while a recently introduced clone from Thailand was diploid (2n = 38). Diploid interspecific hybrids formed about 18 bivalents at M-I, indicating a relatively strong homology of parental chromosomes. The tetraploid hybrid of diploid R. monachica and hexaploid R. coccinea showed predominantly 37 or 38 bivalents, indicating good homology of genomes of the 2 parental species, and autosyndetic pairing in the 2 additional genomes of R. coccinea. Intergeneric hybrids involving Renanthera spp. could be classified into 2 distinct groups: those with 14–11 bivalents that are generally oriented at the metaphase plate and eventually lead to a preponderance of tetrads or tetrads with microcytes, and those with fewer bivalents (9–5) many of which are unoriented pseudobivalents and which ultimately give rise to dyads and dyads with microcytes. Relationships of parental species on a taxonomic basis are closer in the former than the latter group.     

ANALYSIS OF GENOME AND SPECIES RELATIONSHIPS IN THE POLYPLOID WHEATS BY PROTEIN ELECTROPHORESIS

Protein spectra from 4n and 6n species of Triticum were obtained by electrophoresis of seed extracts on polyacrylamide gels. Homologies among the species with regard to protein bands were tested by comparing each species with the standard T. dicoccum in a protein mixture spectrum. By reference to two pairs of homologous bands, each spectrum was then adjusted to the migration velocity of the standard by photographic enlargement. The homologies were found to be consistent with evidence from conventional methods regarding genome relationships among the Triticum polyploids. T. dicoccoides and other known AABB tetraploids showed nine fast-moving albumin homologues, while T. timopheevi and other known AAGG tetraploids showed seven. The two genomic groups had five albumin bands in common. The hexaploid (AABBDD) subspecies showed 12 albumin homologues, 9 of which were also homologous with the 9 of the AABB tetraploids and 3 of which were attributed to the D-genome donor. Differences among species within each of the tetraploid genomic groups and among the hexaploid subspecies were largely confined to the slow-moving bands of the gliadin series.     

FLAVONOIDS OF THE MENYANTHACEAE: INTRA- AND INTERFAMILIAL RELATIONSHIPS

This paper describes our study of the flavonoid chemistry of the Menyanthaceae, which included Menyanthes, Fauria (= Nephrophyllidium), Liparophyllum (all monotypic), nine species of Nymphoides, and 11 species of Villarsia. The flavonoid profiles are based upon kaempferol, 7-O-methylkaempferol, quercetin, 7-O-methylquercetin, isorhamnetin, 3,7-di-O-methylquercetin, and 7,3′-di-O-methylquercetin, although not all taxa exhibit all of these aglycones. These compounds occur as a complex mixture of 3-O-mono- and 3-O-diglycosides; 4′-O-glucosides were restricted to four species of Nymphoides. Some acylated glycosides were also observed. The presence of flavonols and absence of both C-glycosylflavones and xanthones set the Menyanthaceae apart from the Gentianaceae, the family with which it is most often allied. Flavonoid data do not allow assignment of the Menyanthaceae with surety to either the Gentianales or Solanales. The flavonoid profiles of Liparophyllum and Fauria are unique within the family and do not support a close affinity of the latter genus to Menyanthes. A close relationship between Nymphoides and Villarsia, suggested on morphological grounds, is supported by the flavonoid data. Flavonoids support the view, based upon morphology, that the South African Villarsia capensis is more closely related to eastern Australian Villarsia species than to Western Australian ones that are geographically closer. Segregation of Nymphoides fallax from other Meso-American and Caribbean taxa is supported by the flavonoid data. Flavonoid data also support the view that N. indica is a circumtropical taxon not deserving separate species status in the New World.     

CHROMATOGRAPHIC COMPARISON OF DICENTRA SPECIES AND HYBRIDS

Ten species of Dicentra were examined by two-dimensional descending paper chromatography. The flavonoid components, including anthocyanins, formed patterns which were specific to a species or a group of closely related species, and these confirmed certain natural relationships within the genus. Some of the components were hydrolyzed and close structural relationships among them were revealed. They were further characterized by spray reactions and R_F measurements in a variety of solvent systems. The inheritance of the components, especially of the anthocyanins, was studied in the hybrids. All parental substances appeared in some hybrids, but in others some parental components were missing. “Hybrid substances” which had not been present in either parent were found in certain hybrids. This is thought to represent either reconstruction of ancestral biosynthetic pathways, probably through genic complementation, or extension of existing synthetic routes through some type of interaction between parental genomes.     

CHROMATOGRAPHIC COMPARISON OF TRAGOPOGON SPECIES AND HYBRIDS

Approximately 1,700 plants representing five species of Tragopogon (Compositae) and their F₁ and F₂ hybrids were analyzed by two-dimensional descending paper chromatography. Each species, or population within a species, was chromatographically distinct. Often, however, the differences were more quantitative than qualitative. The chromatographic data generally supported the species relationships which had been determined from previous morphologic, hybridization, and fertility studies. Inheritance of the flavonoid compounds was usually additive in the F₁'s. Segregation and recombination of the genes controlling the synthesis of these compounds sometimes approximated 3:1 or 9:7 ratios in the F₂'s. Occasionally parental compounds were missing from some of the hybrids. “Hybrid” compounds which had not been found in either parent were absent from the F₁ but did occur in several F₂ populations. Two linkage groups were present. The first contains genes controlling the synthesis of three compounds and the second, four compounds.     

GENOME RELATIONS OF AGROPYRON SERICEUM,HORDEUM JUBATUM AND THEIR HYBRIDS

Cytogenetic investigation of microsporogenesis in Agropyron sericeum, Hordeum jubatum, their spontaneous hybrid, Agrohordeum pilosilemma, its amphiploid, and the backcross of the amphiploid to A. sericeum, B₁, elucidated the genome relationships of A. sericeum and H. jubatum. The tetraploid parental species share a partially homologous genome which affects the pairing relationships evidenced in their hybrids. The genome formulae assigned to these plants are: A. sericeum, A“A”BB; H. jubatum, AAA'A‘; Agrohordeum pilosilemma, AA'A“B; the amphiploid, AAA'A‘A”A“BB; and B₁, AA'A”A“BB. Observed pairing configurations were compatible with the expected maximum pairing configurations predicted under the assumption of genetic control of pairing with dosage effects. This is interpreted as further support for the hypothesis that pairing in the hybrids of H. jubatum is controlled by the A genome, one dose of A allowing homeologous pairing and two doses of A promoting homeologous association.     

MEIOTIC IRREGULARITY IN SPECIES AND INTERSPECIFIC HYBRIDS OF PINUS

This paper describes a comparative analysis of meiotic conditions in 61 individual trees representing 21 species and 22 interspecific hybrid combinations of the genus Pinus. Material was collected during three successive growing seasons at the Eddy Arboretum of the Institute of Forest Genetics at Placerville, California. Meiotic irregularity occurred in all species and hybrids examined; mean irregularity frequencies of individual trees ranged from 0 to 47.2 percent. Abnormalities in chromosome movement and their consequences, (1) precocious disjunction associated with the occurrence of univalents and (2) the failure of chiasma terminalization leading to lagging chromosomes and to chromosome breakage and fragments, account for most of the observed irregularity. The same kinds of irregularity occur both in the species and in the hybrids, but they were considerably more frequent in certain of the hybrids than in the related species. These abnormalities in chromosome movement seem to be characteristic of Pinus and are attributed primarily to rrechanical difficulties which attend the large pine chromosomes in meiosis. The most spectacular meiotic irregularities were the characteristic bridge-fragment configurations considered to be the result of crossing-over in heterozygous paracentric inversions. Inversion bridges were observed in 59 of the 61 trees and were as frequent in the species as in the hybrids. They apparently do not result from interspecific differentiation in chromosome structure but from spontaneous intra-specific rearrangements. The literature and work now in progress provide increasing evidence that introgression has been an important factor in the evolution of pine populations. The cytological study of pine chromosomes has failed to produce qualitative evidence of introgression, but the quantitative measurement of meiotic irregularity may serve as a useful criterion for recognizing the results of past hybridization.     

中国蜜环菌生物种与北美种的交配关系

将中国三个未知蜜环菌生物种A、C、D的38个代表菌株与北美蜜环菌A．sinopina、A．calvescens、A．nabsnona、A．gemina、A．ostoyae、NABSX等六个种的22个代表菌株进行了配对试验,结果表明中国生物种A与北美种A．sinopina互交可育,属于同一种。中国生物种C与任一北美种都互交不育,不存在部分可育现象,为亚洲特有种。中国生物种D与欧美的A．ostoyae的两个菌株互交可育,实验证实该种另外四个欧美菌株已经失去交配能力,因此确认中国生物种D与A．ostoyae属于同种。     

野生稻与栽培稻及种间杂种F1叶表面亚显微结构的研究

用扫描电镜对原产中国的３种野生稻、２个栽培稻品种及栽培稻与野生稻间的杂种Ｆ１,就气孔频度、气孔器乳突、大瘤状乳突及本栓细胞乳突等叶片表面亚显微结构作了比较观察研究。结果显示这些性状具有种的特性,发现种间杂种的亚星微性状与两个亲本 特性及亲缘关系远近有关。     

CHROMOSOME NUMBERS OF SOME SACCHARUM SPECIES HYBRIDS AND THEIR CELL SUSPENSION CULTURES

Chromosome numbers of five Saccharum species hybrids and their cell suspension cultures were determined. The chromosome number was stable in four parental clones (2n = 122, 114, 114, and 112), but was variable in another (2n = 108-128). The cell suspension cultures have been maintained in a yeast extract-enriched nutrient medium for more than 6 years. These cultures were variable in chromosome number for all clones, with a partial aneuploid series at the haploid and/or polyploid level. Each clone had different chromosomal population modes after 6 years of culture. The loss of chromosomes over a period of time would have an effect on the genetic makeup of a cell population. This has implications in the use and interpretation of data from pathological, cytogenetical, biochemical, and physiological studies using cell cultures and is probably a partial explanation for the loss of totipotency in 6-year-old sugarcane tissue and suspension cultures.