A revised classification of the tribe Phaseoleae (Leguminosae: Papilionoideae), and its relation to canavanine distribution

The subtribal classification of the tribe Phaseoleae has drifted into disorder since Bentham's (1865) scheme in the Genera Plantarum. A revised classification is here proposed, which for the first time accounts for all of the currently recognized genera. This classification has seven subtribes: Cajaninae, Diocleinae, Kennediinae, Phaseolinae, Glycininae, Ophrestiinae, and Erythrininae, of which the Ophrestiinae is new. A survey for the free amino acid, canavanine, shows that it is most often present in the Diocleinae and Kennediinae and frequently absent in the rest of the tribe.     

The occurrence of polyprenols in seeds and leaves of woody plants

The contents of the heterogenous group of polyisoprenoids was found about two orders of magnitude lower in seeds than the amount of polyprenols and/or their carboxylic esters accumulated during vegetation season in leaves. In contrast to leaves, no seeds were found containing more than 0.5 mg of these lipids per gram of dry tissue. Almost 50% had less than 0.01 mg/g - the amount which is the limit of detection by the procedure used in this work. In gymnosperms (10 representatives of Cupressaceae, Pinaceae and Taxaceae) the polyprenol spectra in seeds and in needles were similar. In angiosperms (25 representatives of 13 botanical families) the polyisoprenoid mixture in seeds resembled the minor, additional subfamily found in leaves.     

The occurrence and activity of epithiospecifier protein in some cruciferae seeds

Epithiospecifier protein (ESP) activity was determined in the seeds of two cultivars of Brassica napus, in B. campestris and in Lepidium sativum. All four types of seeds contained susceptible substrates for ESP (that is, glucosinolates with terminal unsaturation in their side-chain), although L. sativum contained only a very small amount of one. Results suggest that Fe²⁺ is essential for ESP activity, but its presence certainly promoted the effects of ESP to a considerable extent, and even at a very low level (e.g. 6 × 10^?11 mol Fe²⁺. Further evidence was gained for the intramolecular nature of the reaction which results in cyanoepithioalkane formation.     

Seed-coat anatomy of the non-pleurogrammic seeds in the tribe Ingeae (Leguminosae,Mimosoideae)

An anatomically complex structure of the seed-coat is a general characteristic of all members of the Leguminosae. Nonetheless, certain genera exhibit a particular type of seed, the “overgrown” seen that has been defined by a developmental criterion and by more simple anatomical features of the seed-coat. Only the last criterion seems suitable for unambiguously distinguishing this type of seed, which is here referred to as “overgrown-like.” This type appears to be apomorphic in the Ingeae (and probably in all the Leguminosae) and likely results from a heterochronic loss of tissue differentiation. Variations in this character may be useful at the generic level, and detailed anatomical observations reveal the occurrence of three distinct patterns. The high degree of correlation with other characters suggests that overgrown-like seeds have evolved separately at least three times in the Ingeae and thatPithecellobium s.s. may be polyphyletic. The overgrown-like seeds are likely to be an adaptive response to wet tropical climates.     

Combinational dormancy in seeds of Sicyos angulatus (Cucurbitaceae,tribe Sicyeae)

Seeds with a water‐impermeable seed coat and a physiologically dormant embryo are classified as having combinational dormancy. Seeds of Sicyos angulatus (burcucumber) have been clearly shown to have a water‐impermeable seed coat (physical dormancy [PY]). The primary aim of the present study was to confirm (or not) that physiological dormancy (PD) is also present in seeds of S. angulatus. The highest germination of scarified fresh (38%) and 3‐month dry‐stored (36%) seeds occurred at 35/20°C. The rate (speed) of germination was faster in scarified dry‐stored seeds than in scarified fresh seeds. Removal of the seed coat, but leaving the membrane surrounding the embryo intact, increased germination of both fresh and dry‐stored seeds to > 85% at 35/20°C. Germination (80–100%) of excised embryos (both seed coat and membrane removed) occurred at 15/6, 25/15 and 35/20°C and reached 95–100% after 4 days of incubation at 25/15 and 35/20°C. Dry storage (after‐ripening) caused an increase in the germination percentage of scarified and of decoated seeds at 25/15°C and in both germination percentage and rate of excised embryos at 15/6°C. Eight weeks of cold stratification resulted in a significant increase in the germination of scarified seeds at 25/15 and 35/20°C and of decoated seeds at 15/6 and 25/15°C. Based on the results of our study and on information reported in the literature, we conclude that seeds of S. angulatus not only have PY, but also non‐deep PD, that is, combinational dormancy (PY + PD).     

The degradation of canavanine by jack bean cotyledons

Summary Germinating jack bean cotyledons liberated ¹⁴CO₂ when fed ¹⁴C-guanidoxy-canavanine but did not accumulate any ¹⁴C-compounds other than the applied canavanine. This suggested that the canavanine was being degraded by the action of canavanase to canaline and urea, the urea then being converted to ammonia and carbon dioxide by the action of urease. Hydroxyurea and acetohydroxamic acid (both inhibitors of urease activity) strongly inhibited the liberation of ¹⁴CO₂ from ¹⁴C-guanidoxy-canavanine by the cotyledons but neither compound induced the accumulation of ¹⁴C-urea within the tissues. This inhibitory action of hydroxyurea on ¹⁴CO₂ output was thought to be due at least in part, to this inhibition of canavanase activity.     

Pathways of ultraviolet mutability in Saccharomyces Cerevisiae. IV. The relation between canavanine toxicity and ultraviolet mutability to canavanine resistance.

Seven umr mutants of Saccharomyces cerevisiae which had reduced capacity for ultraviolet light (UV)-induced forward mutation from CAN1 to can1 were tested for sensitivity to L-canavanine relative to one wild-type UMR strain and one slightly UV-sensitive but phenotypically umr⁺ strain (mutant 306). Relative UV mutation resistance was estimated by dividing the UV fluence needed to yeild a particular induced mutation frequency by that needed to reach the same frequency in the genotypic wild-type strain. The umr5 and umr6 strains were especially sensitive to canavanine growth inhibition, while umr1 was no more sensitive than either wild type; umr2, umr3, umr4, a umr7, and α umr7 were equally sensitive to an intermediate degree. Incubation at 30°C of wildtype cells plated on canavanine-selective agar for increasingly longer times before UV irradiation resulted in decreasing UV mutation frequencies (reduced to 50% in 1.6 h). All umr strains tested in this way lost UV mutability faster than wild type, including mutant 306, umr1 (not sensitive to growth inhibition), and umr6 (very sensitive to growth inhibition). Cells were grown to stationary phase in YEDP growth medium and assayed for arginine and tryptophan transport into the cell. The umr6 strain, which had weak UV mutation resistance but high sensitivity to canavanine growth inhibition, transported arginine and tryptophan at essentially wild-type levels. The umr1 strain, however, which had moderate UV mutation resistance and normal canavanine toxicity, transported both amino acids at rates tenfold higher than wild type. The data suggest that increased canavanine toxicity does not necessarily lead to defective mutability at CAN1, and that mutational deficiency cannot result solely from increased canavanine toxicity. Although exposure to canavanine was shown to block mutation fixation and/or expression, it is suggested that the degree of growth inhibition is not strictly correlated with the degree of mutation resistance.     

Diverse patterns of cell wall mannan/galactomannan occurrence in seeds of the Leguminosae

Endosperms from seeds of different subfamilies of Leguminosae were submitted to sequential aqueous and alkaline aqueous extractions. The extractions from species belonging to the Mimosoideae and Faboideae subfamilies yielded galactomannans with constant Man:Gal ratios, whereas the extractions from Caesalpinioideae seeds gave rise to galactomannans with increasing values of the Man:Gal ratio. The presence of a family of galactomannans within the same species may be a trait found only in Caesalpinioideae subfamily. The final insoluble residues that were obtained after the removal of galactomannans from the Caesalpinioideae and Faboideae subfamilies are composed of pure mannans and do not contain cellulose, while those from the Mimosoideae subfamily are composed of cellulose. A mannan was isolated from the unripe endosperm of Caesalpinia pulcherrima, suggesting no developmental relationship between galactomannan and mannan. These results are consistent with the presence of a distinctive cell wall pattern in the endosperms of Leguminosae species.     

Systematic significance of canavanine in the Papilionoideae (faboideae)

Canavanine is a nitrogen-rich non-protein amino acid, with a supposedly dual role of food storage and defence in seeds and seedlings. It seems to be unique to Leguminosae subfamily Papilionoideae although it does not occur in all species or genera. This report extends the previous surveys for canavanine to 1200 species in 240 genera (including first records for 70 genera) and assesses the systematic and ecological significance of its distribution.