可生物降解PBAT微塑料对土壤理化性质及上海青生理指标的影响

伴随着传统塑料制品引发的“白色污染”问题日益严重,可生物降解塑料应运而生,同时引发了新的可生物降解微塑料污染,但有关可生物降解微塑料对土壤生态系统以及农作物生长的毒性效应尚未完全明确。该研究以可生物降解材料聚对苯二甲酸–己二酸丁二醇酯微塑料(PBAT-MPs)为研究对象,同时以不可降解聚丙烯微塑料(PP-MPs)为对照,通过发芽试验和盆栽试验探究了微塑料填埋前后的形态变化、对土壤理化性质及上海青(Brassica chinensis L.)生长过程中生理指标的影响。结果表明,PBAT-MPs在土壤中发生了降解,而PP-MPs表面形态几乎未发生变化;PP-MPs的添加会导致土壤中TN含量的下降,TP含量先降低后升高,而PBAT-MPs会增加土壤TN含量,TP含量先降低而后恢复;两种微塑料的添加整体会增加土壤中水稳性团聚体含量,影响团聚体粒径分布;MPs对上海青产生的影响会随着植物的自身调节作用减弱,对植物生理指标的影响呈动态变化;相关性分析结果表明,PBAT-MPs处理土壤总磷与植物发芽率、根系活力、根长和茎长呈现正相关,植物丙二醛含量与发芽率、根系活力和茎长呈现负相关。与不可降解微塑料相比,可生物降解微塑料PBAT未因其自身降解而对土壤、上海青产生显著的不良效应,有希望在农业生产中代替传统不可降解农膜以减轻白色污染问题。本研究结果对评价可生物降解微塑料对土壤-植物系统的毒性效应具有重要意义。

Genome-wide analysis of the phospholipase D family in Oryza sativa and functional characterization of PLDβ1 in seed germination

Phospholipase D （PLD） plays a critical role in plant growth and development, as well as in hormone and stress responses. PLD encoding genes constitute a large gene family that are present in higher plants. There are 12 members of the PLD family in Arabidopsis thaliana and several of them have been functionally characterized; however, the members of the PLD family in Oryza sativa remain to be fully described. Through genome-wide analysis, 17 PLD members found in different chromosomes have been identified in rice. Protein domain structural analysis reveals a novel subfamily, besides the C2-PLDs and PXPH-PLDs, that is present in rice - the SP-PLD. SP-PLD harbors a signal peptide instead of the C2 or PXPH domains at the N-terminus. Expression pattern analysis indicates that most PLD-encoding genes are differentially expressed in various tissues, or are induced by hormones or stress conditions, suggesting the involvement of PLD in multiple developmental processes. Transgenic studies have shown that the suppressed expression office PLDβ1 results in reduced sensitivity to exogenous ABA during seed germination. Further analysis of the expression of ABA signaling-related genes has revealed that PLDβ1 stimulates ABA signaling by activating SAPK, thus repressing GAmyb exoression and inhibiting seed germination.

Bioactivity of Four Plant Extracts on Coleopterous Pests of Stored Cereals and Grain Legumes in Nigeria

The efficacy of ethanol extracts from four plants, Dennettia tripetala Baker, Eugenia aromatica Baillon, Piper guineense Thonn et Schum and Anchomanes difformis P. Beauv. as bioinsecticides for control of adult Sitophilus zeamais Motschulsky, Tribolium castaneum Herbst, Callosobruchus maculatus Fabricius, Oryzaephilus mercator Fauvel and Lasioderma serricorne Fabricius were determined at two concentrations (0.5% and 2.0%) in the laboratory. All extracts were toxic to beetles with E. aromatica being the most potent of four plant materials tested and had the least LT 50 value. This was followed by A. difformis extract. At 2.0% v/w extract concentration, percentage grain damage by insects in treated grains stored for 90 days was nil. Grains protected with A. difformis had the least percentage seedgerminationof62.50%whilethoseprotectedwithP.guineensehadthehighestpercentagegermination(74.58%)at2.0% extract concentration. The mean percentage germination in the control was 72.72%. Treatment of grains with plant extracts had no significant (P>0.05) effect on its water absorption capacity.

Influences of Temperature Regime on Germination of Seed of Wild Soybean(Glycine soja)

As an important plant species with high protein contents,wild soybean(Glycine soja),has drawn much attention and appeared to be useful for the genetic improvement of soybean germplasms.Since temperature is one of the numerous environmental factors affecting the germination of most plants,an experimental study was carried out to determine the effect of temperature on germination of wild soybean(G.soja)seeds.Germination test was conducted by setting up thirty-six constant and alternating temperature regimes,ranging from 5 to 40 ℃(16 h night/8 h day).Responses in germination rate to these temperature regimes were then used to construct a quadratic response surface,giving estimated germination rates with confidence intervals at P ≤ 0.05.The results showed that germination capacity was significantly greater while exposed to constant temperatures of 25 ℃,and under the alternating temperature regime the optimum temperature occurred at the 20/25,25/25,25/30 ℃ regime(16 h/8 h)with the amplitude widened from 0 to 5 ℃.Together with regional monthly climate data,these results could be used to improve and promote the cultivation of wild soybean(G.soja),making it available to develop the location-specific optimum seeding time and to apply weed-control treatments.

The role of miR156 in developmental transitions in Nicotiana tabacum

Plants undergo a series of developmental transitions during their life cycle. After seed germination, plants pass through two distinct phases: the vegetative phase in which leaves are produced and the reproductive phase in which flowering occurs. Based on the reproductive competence and morphological changes, the vegetative phase can be further divided into juvenile and adult phases. Here, we demonstrate that the difference between juvenile and adult phase of Nicotiana tabacum is characterized by the changes in leaf size, leaf shape as well as the number of leaf epidermal hairs(trichomes). We further show that miR156, an age-regulated microR NA, regulates juvenile-to-adult phase transition in N. tabacum. Overexpression of miR156 results in delayed juvenile-to-adult transition and flowering. Together, our results support an evolutionarily conserved role of miR156 in plant developmental transitions.

Induction of seed germination in Orobanche spp.by extracts of traditional Chinese medicinal herbs

The co-evolution of Orobanche spp.and their hosts within the same environment has resulted in a high degree of adaptation and effective parasitism whereby the host releases parasite germination stimulants,which are likely to be unstable in the soil.Our objective was to investigate whether extracts from non-host plants,specifically,Chinese medicinal plants,could stimulate germination of Orobanche spp.Samples of 606 Chinese medicinal herb species were extracted with deionized water and methanol.The extracts were used to induce germination of three Orobanche species;Orobanche minor,Orobanche cumana,and Orobanche aegyptiaca.O.minor exhibited a wide range of germination responses to the various herbal extracts.O.cumana and O.aegyptiaca exhibited an intermediate germination response to the herbal extracts.O.minor,which has a narrow host spectrum,showed higher germination rates in response to different herbal extracts compared with those of O.cumana and O.aegyptiaca,which have a broader host spectrum.Methanolic extracts of many Chinese herbal species effectively stimulated seed germination among the Orobanche spp.,even though they were not the typical hosts.The effective herbs represent interesting examples of potential trap crops.Different countries can also screen extracts from indigenous herbaceous plants for their ability to induce germination of Orobanche spp.seeds.The use of such species as trap plants could diminish the global soil seed bank of Orobanche.