Biological control of Pythium damping‐off by seed‐treatment with pseudomonas putida: Relationship with ethanol production by pea and soybean seeds

The relationship between biocontrol activity of Pseudomonas putida strain N1R against Pythium ultimum on pea and soybean seeds and the reduction in ethanol evolution by imbibed seeds was investigated under different treatment conditions, including temperature and numbers of seed‐applied cells of the bacterium. Treatment with strain N1R increased emergence at all temperatures, except for soybean at 12 °C and reduced ethanol concentration in the spermosphere of imbibed seeds at several temperatures. The concentration of bacterial cells in the seed treatment suspension also significantly affected biocontrol efficiency and reduced ethanol production, especially in pea seeds. In contrast, the duration (0–7 h) of submergence of seeds in bacterial suspension had little effect on biocontrol activity of N1R, although submergence of soybean seeds reduced their emergence even in the absence of the pathogen or biocontrol agent. Competition for seed‐derived compounds, including ethanol, is suggested to be one possible mechanism of biocontrol of Pythium by strain N1R, which is not known to produce antifungal antibiotics.     

羊蹄甲属植物种子的裂解色谱鉴定法研究

本文探索了裂解气相色谱法作为植物种子分类表征方法的可能性。对豆科植物中不同属、不同亚属及相同亚属的共10种种子的裂解色谱图,用分区编码法进行区别,分析结果表明,不同种子最少有一个编码不同,方法简易快速,可为高等植物种子的区分提供一种佐证手段。     

休眠与萌发过程中苹果种子的呼吸代谢

“秦冠”苹果种子的总呼吸强度和EMP途径的呼吸强度在2℃条件下层积之后逐渐增加,解除休眠临界期大体在层积后第30天发生,此后增长速度较快。HMP途径和TCAC在临界期之前变化极慢,而后急剧增加。种子萌发后子叶和胚轴的总呼吸强度、EMP和TCAC初期呈急剧上升趋势,大约当胚轴长度达2cm时迅速下降,HMP在萌发过程中始终呈上升趋势。细胞透性层积之后逐渐降低,解除休眠至萌发阶段呈上升趋势。用不同浓度呼吸抑制剂处理解除休眠种子的试验结果表明,除1mM碘乙酸能明显刺激萌发和生长外,NaCN、SHAM和丙酮酸都表现为抑制作用。     

Seed size,pollination costs and angiosperm success

Summary Seed plants capture pollen before seeds are dispersed and abort unpollinated ovules. As a result, each seed is associated with an accessory cost that represents the costs of pollen capture and the costs of aborted ovules. Accessory costs may explain the minimum seed size among species, because these costs are likely to comprise a greater proportion of total reproductive allocation in species with smaller seeds. For very small propagules, the costs of pollination may not be worth the benefits, perhaps explaining the persistence of pteridophytic reproduction at small propagule sizes. The smallest angiosperm seeds are much smaller than the smallest gymnosperm seeds, both in the fossil record and in the modern flora. This suggests that angiosperms can produce pollinated ovules more cheaply than gymnosperms. Pollination becomes less efficient as a species decreases in abundance, and this loss of efficiency is greater for species with a higher accessory cost per seed. We propose that the greater reproductive efficiency of angiosperms when rare can explain why angiosperm-dominated floras were more speciose than the gymnosperm-dominated floras they replaced.     

Polymorphism at the Hor 1 locus of barley (Hordeum vulgare L.)

The Hor 1 locus of barley encodes a group of seed storage polypeptides called C hordein. Two-dimensional electrophoretic analysis of C-hordein fractions from six cultivars with different alleles at the Hor 1 locus showed extensive polymorphism. A total of 34 major polypeptides was mapped, with between 4 and 18 present in each cultivar. There was less variation among the same cultivars in the numbers (6 to 10) of restriction fragments of genomic DNA which hybridized to a cDNA clone related to C hordein. The total number of restriction fragments was also lower (22), and most pairs of cultivars had more restriction fragments than polypeptides in common. A total number of about 20–30 C-hordein genes per haploid genome was estimated. The results indicate that cultivars differ mainly in the extent of gene and polypeptide divergence, rather than in the degree of gene reiteration. They are consistent with the proposed origin of the multiple structural genes at the Hor 1 locus by the duplication and divergence of a single ancestral gene.NACB was supported by a grant from the Home Grown Cereals Authority.     

A comparison of androgenetic doubled-haploid,and single seed descent lines in Triticale

Summary Sixty single seed descent (SSD) lines and about 25 anther-derived doubled-haploid (DH) lines were obtained from two triticale crosses. The frequency distributions of 10 quantitative agronomic traits were compared using parametric and non-parametric tests. A multivariate discriminant analysis was subsequently carried out. Gliadin patterns obtained from each line by polyacrylamide gel electrophoresis were used to calculate intra- and inter-population diversities from relative dissimilarity indices. It was found that DH and SSD lines show significant differences in frequency distributions of 1000 grain weight in both crosses, of heading date for one cross, and of lodging susceptibility for the other cross. The results of intra- and inter-population gliadin diversity indicate that although the SSD method theoretically provides more opportunity for recombination to occur than the DH method, it did not produce a greater range of recombinants. Since there is no significant difference between SSD- and DH-line distributions for grain yield, anther culture appears to be an efficient method for producing high yielding homozygous lines from F₁ hybrids of triticale in a relatively short time.     

Seed germination in Chenopodium album L.: further evidence for the dependence of the effects of growth regulators on nitrate availability

Abstract Chenopodium album L. plants, grown under controlled environmental conditions on different levels of soil nitrate, produced seeds with proportionately different NO^?₃ contents. Regardless of the endogenous NO^?₃ content, few seeds germinated in water or upon treatment with KNO₃. Ethylene promoted germination, and the extent of germination was positively correlated with the endogenous seed NO^?₃ content. Combined application of ethylene and KNO₃ in the dark had a synergistic effect on NO^?₃ -deficient seed. The synergism between ethylene and KNO₃ was attributable to the NO^?₃ moiety of the nitrate salt. Ethylene and light showed moderate synergism in seeds with low or high endogenous nitrate. Addition of nitrate, however, masked the interaction between ethylene and light. Gibberellic acid₄₊₇ (GA₄₊₇) or red light, each alone or combined with KNO₃, had little effect on germination. When applied together in the dark, ethylene and GA₄₊₇ synergistically enhanced the germination of NO^?₃-deficient seed. The combined effects of the two hormones on this seed were further enhanced by the addition of KNO₃. There was no synergism between ethylene and GA₄₊₇ in NO^?₃-rich seed. These interactions among GA₄₊₇, ethylene and KNO₃ were not affected by light. The results confirm and further elaborate our earlier finding that the sensitivity of C. album seeds to ethylene may depend on nitrate availability.     

Pollenfertility and seed formation in theOrnithogalum umbellatum/angustifolium complex (Liliaceae/Scilloideae)

The pollen fertility and seed formation of six species of theOrnithogalum umbellatum/angustifolium complex and of seven related species were studied. Four types of pollen grains could be recognized. The pollen fertility varied greatly in this complex and is not related to the ploidy level. The seed formation ofO. umbellatum showed an adaptation to a subcontinental-Mediterranean climate, that ofO. angustifolium to an Atlantic climate. In both cases raindrops seem to be important for pollination, in view of the absence of insect pollinators. After open pollination 113 seedlings were obtained in four species. Their chromosome numbers were determined. Nearly all the cultivated seedlings were aneuploid, which points to a positive selection of euploids in nature, because aneuploid individuals are rare in the wild.Biosystematic Studies on theOrnithogalum umbellatum/angustifolium Complex III.—Previous parts of this series are Part I: Taxonomy. Proceeding Kon. Ned. Acad. Wet. series C,85 (4), 563–574 (1982) andvan Raamsdonk (1984).     

Temperature control of germination and its possible role in the survival of a non-dormant population of Avena fatua

Germination of freshly harvested seeds of a non-dormant (ND) line (Stonehouse 319) of wild oats ( Avena fatua L.) was inhibited by incubation of the seeds at relatively high temperatures of 25 and 30°C. The germination inhibition in these seeds appeared to be a case of thermo-inhibition which was the direct effect of hightemperature treatment (HIT), since it did not persist after transferring the seeds to an optimum germination temperature of 20°C. Even a prolonged HTT of 30°C for over 5 weeks did not prevent germination of about 80% of the seeds transferred to 20°C. However, in a significant proportion of the seeds, thermo-dormancy was induced by 10 days of HTT at 30°C if the seeds were then incubated at sub-optimal temperatures of 5 to 15°C. This thermo-dormancy would appear to be 'restrictive' in form, since its expression was restricted to very specific conditions. Relatively low inclubation temperaturs of 5 and 10°C markedly slowed germination whether HTT was applied or not. The results suggest that thermo-inhibition and thermo-dormancy, induced during seasonal temperature fluctuations, may provide a survival mechanism for seeds of such ND lines as Stonehouse 319.