Vermicompost Leachate as a Promising Agent for Priming and Rejuvenation of Salt-Treated Germinating Seeds in Brassica Napus

Salinity is a major constraint hampering germination and early seedling growth, especially in aged seed lots. Any rejuvenation treatment improving salt resistance at these crucial developmental stages will be of special interest. Two sets of experiments were performed in Brassica napus to precise the impact of vermicompost leachate (VCL) on seed germination in the presence of NaCl and to analyze its putative interest as seed priming agent before NaCl exposure. Two seed lots were used: one old seed lot (cv. Libomir) and a recent one (cv. Harry). VCL increased the germination percentage of aged seeds in the absence of NaCl and increased seedling length in both cultivars. VCL had only a minor impact when directly added to the NaCl-containing germinating solution. In contrast, priming with VCL strongly improved subsequent germination in the presence of NaCl in relation to a more efficient management of oxidative stress in both cultivars. The improvement of salinity resistance provided by VCL priming was not due to modification in ion or proline content. It is concluded that VCL may act as a rejuvenation agent invigoring old seed lots and as an efficient priming agent for improvement of salinity resistance at the germination stage. Valuable properties of VCL are discussed in relation to the simultaneous presence of several protecting compounds.     

Plant growth-promoting rhizobacteria: strategies to improve abiotic stresses under sustainable agriculture

The abiotic stresses like drought, heavy metal and salts directly or indirectly influence the global environmental pollution and decrease the agricultural productivity. The stress tolerant plant growth promoting rhizobacteria (PGPR) play an important role against the abiotic stresses in terms of enhancing the efficacy of soil, plant growth promotion (PGP). Stress tolerance PGPRs have certain specific PGP properties such as hormones synthesis, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, Indole-3-acetic acid (IAA) production, Abscisic acid (ABA) synthesis, enzymes production, nitrogen fixation, phosphorus (P) and Potassium (K) solubilization, as results which protect various crops during such stress conditions and consequently enhance crop sustainability. Efficient PGPRs isolated from various stress conditions have certainly, more useful against that particular stress. This article highlighted the isolation of various stresses tolerant PGPRs from varieties of crops under different stress conditions and their effect on varieties of crops to enhance their plant growth promotion.     

龙眼体细胞胚胎发生过程中的内源激素变化

采用HPLC法测定了龙眼“红核子”品种胚性愈伤组织胚胎发生过程中各个不同发育阶段的内源激素含量变化。结果表明,龙眼胚性愈伤组织中内源激素含量比非胚性愈伤组织高;除GA3外,体胚发生过程中内源激素变化趋势大致呈“M”状:胚性愈伤组织Ⅱ和球形胚为变化的2个明显转折点;内源激素的变化先于形态学的变化。      

Effect of rhizobacteria and cytokinins application on wheat growth and yield under normal vs drought conditions

ABSTRACT

Drought is a major constraint for agricultural productivity worldwide, and it is likely to further increase. Different strategies are required to mitigate drought stress in plants. In a two-year study that conducted at agronomic research area of the Islamia University of Bahawalpur, we investigated the role of rhizobacteria (RB) and cytokinins (Ck) on drought tolerance, nutrient uptake, yield, and physiological parameters in wheat under drought stress at different developmental stages (tillering, anthesis, and grain filling). Thirteen treatments used were well-watered control plants without RB or Ck, drought at tillering, anthesis, or grain filling without or with RB alone, Ck alone, or combination of both (RB+Ck). In both years, and at the different stages, measured parameters were highest in the well-watered plants but lowest in drought-stressed plants. Application of RB and Ck to drought-stressed plants increased these parameters in the order RB+Ck > RB > Ck. In some cases, under drought stress, there was no difference between inoculation with RB and application of Ck. It was concluded that the combined application of RB and Ck could play a significant role in improving wheat yield and also alleviation of stress under drought condition.     

Plant responses to drought and phosphorus deficiency: contribution of phytohormones in root‐related processes

Environmental stresses are one of the most limiting factors in agricultural productivity. A large portion of the annual crop yield is lost to pathogens (biotic stress) or the detrimental effects of abiotic‐stress conditions. There are numerous reports about chemical characterization of quantitatively significant substrate fluxes in plant responses to stress factors in the root‐rhizosphere system, e.g., nutrient mobilization, heavy‐metal and aluminum immobilization, or establishment of plant‐growth‐promoting rhizobacteria (PGPR) by exudation of organic anions, phytosiderophores, or carbohydrates into the soil, respectively. The hormonal regulation of these responses is not well understood. This paper highlights this complex process, stressing the involvement of phytohormones in plant responses to drought and phosphorus deficiency as examples. Beside ethylene, abscisic acid (ABA) plays an important role in drought‐stress adaptation of plants. This hormone causes morphological and chemical changes in plants, ensuring plant survival under water‐limited conditions. For example, ABA induces stomata closure, reduction in leaf surface, and increase in root : shoot ratio and, thus, reduction in transpiration and increase in soil volume for water uptake. Furthermore, it supports water uptake in soil with decreasing water potential by osmotic adjustment. Suitability of hormonal parameters in the selection for improving stress resistance is discussed. Auxins, ethylene, and cytokinins are involved in morphological adaption processes to phosphorus (P) deficiency (increase in root surface, e.g., by the formation of more dense root hairs or cluster roots). Furthermore, indole‐3‐acetic acid increases root exudation for direct and indirect phosphorus mobilization in soil. Nevertheless, the direct use of the trait “hormone content” of a particular plant organ or tissue, for example the use of the drought‐stress‐induced ABA content of detached leaves in plant breeding for drought‐stress‐resistant crops, seems to be questionable, because this procedure does not consider the systemic principle of hormonal regulation in plants.     

外源激素和糖类对玉米zSs1表达的影响

为明确外源激素和糖类对叶片zSs1表达的影响,本文以玉米优良自交系18-599叶片为材料,在分别含有甘露醇、蔗糖、葡萄糖的培养基中处理,然后分别添加ABA、GA,提取总RNA,通过Real-time PCR检测zSs1基因mRNA表达量变化.结果表明:与只含基础盐处理相比,单独用甘露醇和葡萄糖处理玉米叶片,zSs1基因...     

铅胁迫与黄瓜幼苗生长及内源激素关系的研究

通过试验利用高效液相色谱(HPLC)对黄瓜幼苗内源激素进行了测定探索,并研究了铅胁迫对黄瓜幼苗生长及内源激素的影响.结果表明(1)HPLC法测定黄瓜幼苗内源激素的最佳条件为以甲醇、水和2%醋酸为流动相,采用浓度梯度洗脱;(2)低于200mg·L-1铅处理促进黄瓜幼苗生长;300～900 mg·L-1铅处理抑制黄瓜幼苗生长,其抑制作用随铅质量浓度增加而强化,高质量浓度铅处理能诱导不定根形成;(3)根中的脱落酸含量随铅质量浓度的增加而增加,叶和根中玉米素含量随铅质量浓度增加而下降;(4)生长素脱落酸(IAA/ABA)比值高于对照值对幼苗生长具有激活效应,IAA/ABA比值低于对照值则抑制幼苗生长,表现为毒害效应,此比值可以作为抗重金属毒害的指标之一.     

外源化学物质对小麦温光敏核不育两用系C49S育性的影响

本文探讨了外施赤霉素（GA3）、吸哚乙酸（IAA）、萘乙酸（NAA）、乙烯释放剂乙烯利（CEPA）、乙烯生物合成抑制剂氨基乙氧基乙烯基甘氨酸（AVG）、植物生长调节剂受多收（有效成分单硝化愈创木酚钠）、氯化钙（CaCl2）等化学物质对小麦温光敏核不育两用系C49S育性的影响。结果表明，IAA、NAA、GA3对早播不育（重庆10月30日播种）和晚播可育（重庆12月10日播种）的C49S的结实率均有不同程度的提高。乙烯利对C49S的育性表现很强的抑制作用，而AVG则对育性有明显的促进作用。爱多收和CaCl2对C49S的结实率有一定程度的提高。因此认为，C49S育性转换与激素的综合平衡关系有密切关系。乙烯利或其它化学杀雄剂可以用来控制异常高温下C49S不育系可能出现的微量可育花粉，以提高制种纯度；GA3、AVG、IAA、NAA、爱多收等可以用来提高C49S自交繁殖时的结实率和种饱满度。     

不同植物激素诱导拟南芥SDG8的表达模式

与植物激素在植物整个生命周期中起着多重作用类似,基因SDG8对植物生长、发育、代谢、抗性等多个方面也具多效性。对拟南芥Col-0和转p SDG8::GUS植株分别进行KT、ABA、GA3、IAA、Me JA和Me SA喷洒处理24h后,用GUS试剂和RT-q PCR研究SDG8基因的表达模式。结果显示,在植物营养生长阶段和使用的激素浓度范围内,这6种激素对SDG8基因的表达调控有4种模式:KT高低浓度都抑制表达;ABA低浓度促进表达,高浓度表达量下降;GA3低浓度与高浓度促进表达的水平相同;随IAA、Me JA和Me SA浓度增加表达水平提高。这些结果从总体上揭示了植物激素对SDG8的表达趋势的影响,对进一步研究植物激素与SDG8基因相互作用有一定的参考价值。     

激素在植物冷胁迫应答中的角色

寒冷是限制植物生长发育的非生物胁迫因子之一。冷胁迫应答过程中,植物内源激素在生理水平和基因表达调控中起重要作用。本文综述了水杨酸、脱落酸、乙烯、茉莉酸、赤霉素和细胞分裂素等激素在植物抵御冷胁迫过程中的作用机制,并对这些激素在植物冷胁迫应答研究中存在的问题进行了讨论,以期为今后通过激素调节提高植物的抗寒性研究提供参考。