Effect of a free radical scavenger, 3,4,5-trichlorophenol, on ethylene production and on changes in lipids and membrane integrity during senescence of petals of cut carnations (Dianthus caryophyllus)

Three free radical scavengers were tested: sodium benzoate, propyl gallate and 3,4,5-trichlorophenol. One of the compounds, namely 3,4,5-trichlorophenol, was capable of prolonging the vase-life of carnations ( Dianthus caryophylius L. cv. Ember). A delay in the appearance and a much lower intensity of the ethylene peak were associated with this positive effect on the morphology. Also the loss of membrane integrity, the breakdown of fatty acids of polar lipids and the massive production of peroxides occurred much later after treatment with 3,4,5-trichlorophenol than in the controls. Free radicals thus appear involved in the process of ageing in carnation petals, where they affect ethylene synthesis and where their action on lipids leads to the loss of membrane integrity. It is suggested that the peroxidation plays a fundamental role and that ethylene appears as a by-product of the senescence process rather than an initiating factor.     

Why are most organelle genomes transmitted maternally?

Why the DNA‐containing organelles, chloroplasts, and mitochondria, are inherited maternally is a long standing and unsolved question. However, recent years have seen a paradigm shift, in that the absoluteness of uniparental inheritance is increasingly questioned. Here, we review the field and propose a unifying model for organelle inheritance. We argue that the predominance of the maternal mode is a result of higher mutational load in the paternal gamete. Uniparental inheritance evolved from relaxed organelle inheritance patterns because it avoids the spread of selfish cytoplasmic elements. However, on evolutionary timescales, uniparentally inherited organelles are susceptible to mutational meltdown (Muller's ratchet). To prevent this, fall‐back to relaxed inheritance patterns occurs, allowing low levels of sexual organelle recombination. Since sexual organelle recombination is insufficient to mitigate the effects of selfish cytoplasmic elements, various mechanisms for uniparental inheritance then evolve again independently. Organelle inheritance must therefore be seen as an evolutionary unstable trait, with a strong general bias to the uniparental, maternal, mode.     

The electrolyte leakage method can be misleading for assessing the frost hardiness of roots

Abstract

The relative electrolyte leakage (REL) method is often used to assess the frost hardiness of plant organs. However, testing the frost hardiness of roots with REL yields different results when the roots are frozen while remaining in the soil or in some other substrate than when REL follows a freezing test made on excised root segments. In this study, we show that the electrolytes may already leak out of injured roots during freeze/thaw treatment and during washing of the roots after the treatment. In this case, the conductivities measured after the freezing test and killing of the tissue both give lower readings than expected for injured samples, and hence the results of the REL are incorrect. We suggest that roots should be washed free of soil and placed in test tubes prior to the freezing test. The leakage of electrolytes from injured roots to soil may also limit the use of the REL method for measuring root viability.     

Una Iscrizione Commeaiorativa Già Esistente All'Orto Botanico di Padova

Abstract

The use of the mini-plug system for the production of container seedlings is relatively new, so there is little information on the potential impact of method on the quality of planting stock. The objective in this study was to evaluate the impact of mini-plug growing method on quality of Pinus brutia seedlings, and compare the performance of this stock type with that of standard container nursery stock. Seedling survival, growth and physiological status (root growth potential, shoot electrolyte leakage) were measured after pre-cultivation in mini-plugs, at the end of the first growing season in standard containers and after field transplanting. Our results showed that mini-plug transplants of P. brutia seedlings performed as well as the standard planting stock currently used in nursery operation in Greece. For the pre-cultivation of P. brutia seedlings in mini-plugs, the use of peat and a density of 2000 mini-plugs m^?2 are recommended.     

血清AIb、PA、NLR水平在直肠癌术后发生吻合口瘘评估中的应用

摘要 目的：探讨血清白蛋白（AIb）、前白蛋白（PA）、中性粒细胞与淋巴细胞比值（NLR）水平在直肠癌术后发生吻合口瘘评估中的应用。方法：选择2018年6月至2019年12月于我院进行直肠癌手术患者90例患者进行研究,其中38例发生术后吻合口瘘,设为研究组, 52例未发生吻合口瘘作为对照组。分析患者术后血清AIb、PA、NLR水平变化情况,采用受试者工作特征曲线分析血清AIb、PA、NLR对术后发生吻合口瘘的评估作用。结果：研究组血清AIb、PA水平显著低于对照组,NLR水平显著高于对照组,差异显著（P＜0.05）;造口组术后血清AIb、PA水平显著高于未造口组,NLR水平显著低于未造口组,差异显著（P＜0.05）;ROC结果显示,血清AIb预测术后吻合口瘘的AUC为0.967,灵敏度为81.25%,特异度为90.14%,截断值为33.06 g/L;血清PA预测术后吻合口瘘的AUC为0.772,灵敏度为80.36%,特异度为89.56%,截断值为119.04 mg/L;血清NLR预测术后吻合口瘘的AUC为0.991,灵敏度为85.62%,特异度为93.23%,截断值为6.86。结论：监测血清AIb、PA、NLR水平有助早期发现直肠癌患者术后吻合口瘘。     

Nursery Culture Impacts Cold Hardiness in Longleaf Pine (Pinus palustris) Seedlings

Success in restoring longleaf pine ecosystems depends on outplanting high‐quality longleaf pine seedlings. One important and relatively understudied attribute of seedling quality is cold hardiness. A suite of trials was conducted to investigate the influence of common nursery cultural practices on longleaf pine cold hardiness. Cold hardiness was increased with higher rates of nitrogen, unaffected by copper coating containers, greater for foliage than for root‐collar tissue, and tended to increase with increases in container size.     

Funaria Rhizoids infected with Pleotrachelus wildermani

Abstract

The recolonisation of bryophytes on soil during 3½ years following fire in a mixed forest in south-west Tasmania is characterised by the presence of Marchantia berteroana, Funaria hygrometrica, Ceratodon purpureus and Polytrichum juniperinum, while limited cover is provided by Campy lop us introjlexus, Tortella calycina and Bryum sauteri. It has been verified that the protonemal growth of the early colonising mosses is more rapid than non-colonising specles. The preference for spores of Funaria hygrometrica, Ceratodon purpureus and Marchantia berteroana to germinate on burnt soil is confirmed. However, it has been shown that burnt substrates do not inhibit the germination of non-colonising species. Therefore, the rapid development of protonemata and gametophytes in the colonising species may be a critical factor for their success.     

Growth of tomato (Lycopersicon esculentum) in response to salicylic acid under water stress

Abstract

Plants of Lycopersicon esculentum L. cv. K-25 were subjected to water stress by withholding water for 10 days at 20 (WS I) and 30 (WS II) days after sowing (DAS). Seedlings were sprayed with double distilled water (DDW) or 10^?5M salicylic acid (SA) at 45 DAS. The water stress at earlier stage of growth (20 day stage) was more inhibitory as compared to the later stage (30 day stage). The plants exposed to water stress exhibited a significant (p<0.05) decline in photosynthetic parameters, membrane stability index (MSI), leaf water potential, activity of nitrate reductase (NR), carbonic anhydrase (CA), chlorophyll and relative water content (RWC). A follow-up treatment with SA protected against the stress generated by water and significantly improved the above parameters. However, proline content and antioxidant enzymes increased under drought as well as under SA treatments.     

Functional characterization of a sucrose:fructan 6-fructosyltransferase of the cold-resistant grass Bromus pictus by heterelogous expression in Pichia pastoris and Nicotiana tabacum and its involvement in freezing tolerance

We have previously reported the molecular characterization of a putative sucrose:fructan 6-fructosyltransferase (6-SFT) of Bromus pictus, a graminean species from Patagonia, tolerant to cold and drought. Here, this enzyme was functionally characterized by heterologous expression in Pichia pastoris and Nicotiana tabacum. Recombinant P. pastoris Bp6-SFT showed comparable characteristics to barley 6-SFT and an evident fructosyltransferase activity synthesizing bifurcose from sucrose and 1-kestotriose. Transgenic tobacco plants expressing Bp6-SFT, showed fructosyltransferase activity and fructan accumulation in leaves. Bp6-SFT plants exposed to freezing conditions showed a significantly lower electrolyte leakage in leaves compared to control plants, indicating less membrane damage. Concomitantly these transgenic plants resumed growth more rapidly than control ones. These results indicate that Bp6-SFT transgenic tobacco plants that accumulate fructan showed enhanced freezing tolerance compared to control plants.