SEED PROTEIN PROFILES IN THE NARROW-LEAVED SPECIES OF CHENOPODIUM OF THE WESTERN UNITED STATES: TAXONOMIC VALUE AND COMPARISON WITH DISTRIBUTION OF FLAVONOID COMPOUNDS

Water soluble seed proteins from 69 populations representing seven species of Chenopodium were separated electrophoretically. Very little or no intraspecific variation was detected. The use of seed proteins as taxonomic characters was evaluated and compared to data from flavonoid chemistry. Seed proteins are of value in distinguishing C. atrovirens and C. leptophyllum, something which could not be done with flavonoids. Proteins and flavonoid data demonstrated that C. hians and C. leptophyllum are distinct. An analysis of storage proteins failed to differentiate C. desiccatum from C. atrovirens and C. pratericola even though the species are distinct in flavonoids and other characters. Chenopodium atrovirens and C. pratericola produce similar or identical seed proteins, just as they are identical in flavonoids. Seed proteins indicated that plants referable to C. incognitum represent two biological entities, one apparently a minor morphological variant of C. atrovirens and the other conspecific with C. hians. The same interpretation had been given on the basis of flavonoid chemistry. The protein data suggest a close relationship between C. subglabrum on the one hand and C. atrovirens and/or C. desiccatum on the other.     

THERMAL SENSITIVITIES OF MALATE DEHYDROGENASE ISOZYMES IN TYPHA

Two species of cattail. Typha latifolia L. and T. domingensis Pers., occur naturally along the shoreline of Par Pond, an 1,128 ha impoundment subjected to intermittent thermal stress at the Savannah River Plant in South Carolina. T. domingensis is not tolerant of the stresses imposed at the hottest section of this lake. Typha latifolia is established throughout the lake but at the hottest section displays an altered morphology compared with stands from ambient areas. Both T. latifolia and T. domingensis are electrophoretically monomorphic, and no variation in isozyme expression in ten enzyme systems was recorded in populations from Par Pond. The malate dehydrogenase (MDH) isozyme patterns for T. latifolia and T. domingensis are identical, but their thermal sensitivities differ sharply. All six major T. domingensis MDH isozymes are denatured by heating at 50 C; whereas, T. latifolia has three isozymes which are stable at 50 C and three isozymes which are denatured at this temperature. Tests of thermal stability are more useful than measurements of electrophoretic mobility in detecting enzyme differences and a possible biochemical basis for differences in thermal tolerance in these natural populations.     

ALLOZYME VARIATION IN SEVERAL CLOSELY RELATED DIPLOID SPECIES OF CHENOPODIUM OF THE WESTERN UNITED STATES

Twelve allozyme loci were examined in a complex of closely related diploid (2n = 18) members of the genus Chenopodium occurring in the western United States. These plants are generally treated taxonomically as belonging to C. atrovirens, C. desiccatum, C. hians, C. leptophyllum, and C. pratericola. Also included were populations referable to C. incognitum. The enzymes examined and the allelic designations are given as follows: leucine aminopeptidase, Lap; phosphoglucoisomerase, Pgi-1, Pgi-2; glutamate-oxaloacetate transaminase, Got-1, Got-2, Got-3; glutamate dehydrogenase, Gdh; phosphoglucomutase, Pgm-1, Pgm-2; malate dehydrogenase, Mdh-1, Mdh-2; and malic enzyme, Me. All populations were fixed for the same allele at Gdh, Pgi-2, and Mdh-1. Chenopodium hians was fixed for a unique allele at Got-3 and contained two alleles at the Lap locus and two at Pgi-1 which were not detected elsewhere. Chenopodium leptophyllum likewise has unique alleles at Lap and Pgi-1. The other three taxa, C. atrovirens, C. desiccatum and C. pratericola, have alleles at Lap and Pgi-1 which were not found in C. hians or C. leptophyllum. The former three species have the same alleles in highest frequency at all polymorphic loci except Me, where C. desiccatum is consistently separable from C. atrovirens and C. pratericola. Allozyme data are concordant with information from morphology, flavonoid chemistry and seed protein profiles in suggesting that: (1) Chenopodium hians and C. leptophyllum are best regarded as distinct species; (2) C. atrovirens and C. pratericola are very similar and perhaps should not be recognized at the specific level; (3) C. desiccatum appears most closely allied to C. pratericola; (4) plants referable to C. incognitum represent two biological entities, one the same as C. atrovirens, and the other conspecific with C. hians; (5) little genetic variation is detectable in any taxon of these weedy annuals; (6) interspecific hybridization is not a cause of taxonomic difficulties in these plants.     

CHROMOSOME NUMBERS IN THE LEGUMINOSAE. III. SPECIES OF THE SOUTHWESTERN UNITED STATES AND MEXICO

Turner, B. L., and Olin S. Fearing. (U. Texas, Austin.) Chromosome numbers in the Leguminosae. III. Species of the Southwestern United States and Mexico. Amer. Jour. Bot. 47(7) : 603–608. Illus. 1960.—Chromosome counts for 43 species of the Leguminosae from the southwestern United States and Mexico have been reported. These include first reports for 42 taxa of which 16 are for the subfamily Mimosoideae. Olneya tesota (2n = 18) is the only new generic count listed. Chromosome reports of particular significance include a single polyploid count for a North American species of Acacia, as well as diploid and tetraploid counts for closely related taxa in this genus. Four species of the genus Schrankia were found to be diploid with In = 26, indicating a base of x = 13 instead of the x = 8 reported by some previous workers. Leucaena pulverulenta was found to have a diploid count of 2n = 56 indicating a base of x = 14.     

RACES OF PERONOSPORA MANSHURICA IN THE UNITED STATES

I propose a set of 11 soybean varieties for the differentiation of races of Peronospora manshurica: Pridesoy, Norchief, Mukden, Richland, Roanoke, Illini, S 100, Palmetto, Dorman, Kabott, and Ogden. When I employed these, I found fifteen new races of Peronospora manshurica, the casual agent of downy mildew of soybeans, described them, and assigned numbers 9 through 23. Race 8 was encountered most frequently and occurred at 40% of the locations from which seed samples were obtained. Races 1, 2, 10, 12, 18, and 23 occurred at 5–8% of the locations sampled. Race 10 was common in the southern U. S. Of 247 soybean seed lots sampled, 73% contained some oospore-encrusted seeds. These ranged from 12–26% lighter than healthy seeds. The percentage of oospore-encrusted seeds occurring in seed lots ranged from 0–25%.     

PROBLEMS IN THE IDENTITY AND ORIGIN OF THE APPALACHIAN VITTARIA GAMETOPHYTE,A SPOROPHYTELESS FERN OF THE EASTERN UNITED STATES

Populations of a fern gametophyte presumed to be of the genus Vittaria occur commonly in the uplands of the southeastern United States. The gametophytes occur on non-calcareous rock outcrops of various composition in areas which provide continuous moisture and protection from temperature extremes. Gametophytes in these habitats are robust and long lived, frequently forming the dominant vegetation in areas covering several square feet. Reproduction is exclusively vegetative by production of gemmae. Although sex organs are present in most populations, viable sporophytes are never produced. The gametophytes have previously been considered most likely to be V. lineata, which occurs in Florida, but morphological and physiological comparisons do not support that conclusion. Significant differences between Appalachian and Florida gametophytes occur in growth form, growth rate, cold hardiness, sporophyte production, and patterns of gemma production. The distribution of the Appalachian gametophytes correlates with old, unglaciated land masses suggesting antiquity rather than recent introduction. Present evidence favors the interpretation that the Appalachian Vittaria gametophytes either belong to a tropical American species from which they have long been separated, or that they represent a distinct species of which the sporophyte no longer exists.     

赖草属七个种同工酶研究

用聚丙酰胺凝胶电泳法对赖草属７个种的幼根、幼叶进行了酯酶、过氧化物酶同工酶分析,结果表明：无论从相同器官进行不同的同工酶分析,还是从不同器官进行相同的同工酶分析,这７个种的酶谱在各带区存在相似酶带,但更多的是相异酶带。从酯酶、过氧化物酶这两种酶分析结果来看,酯酶比过氧化物酶分离效果好些;从幼根和幼叶这两个器官的酶谱来看,幼根比幼叶酶带多些,分离效果也好些。同时也表明这７个种的酶谱变化与染色体倍性变化无关