Involvement of compatible solutes in chill hardening-induced chilling tolerance in Jatropha curcas seedlings

Low temperature is a major environmental factor that affects metabolism, growth, development, distribution and production of chilling-sensitive plant, and J. curcas L. is a sustainable energy plant with great potential for biodiesel production due to the fact that its seed contains high oil content, which has attracted much attention worldwide. Our previous work found that the chill hardening improved the chilling tolerance of J. curcas seedlings (Ao et al. in Acta Physiologiae Plantarum 35:153–160, 2013), but its mechanism still remains elusive. In present work, the mechanism of chill hardening-induced chilling tolerance was further investigated in J. curcas seedlings. The results showed that chill hardening at 12 °C for 2 days markedly lowered osmotic and water potentials, which, in turn, maintained relative higher pressure potential in leaves of J. curcas seedlings compared with the control seedlings without chill hardening. In addition, chill hardening gradually increased compatible solutes proline, betaine and total soluble sugar contents compared with the control. When the control and hardened seedlings were subjected to chilling stress at 1 °C for 1–7 days, the chill-hardened seedlings significantly accumulated higher proline, betaine and total soluble sugar contents, which decreased osmotic and water potentials, and maintained higher pressure potential. To further understand the pathways of accumulation of compatible solutes, measurement of activities of ?¹-pyrroline-5-carboxylate synthetase (P5CS), glutamate dehydrogenase (GDH), ornithine aminotransferase (OAT), arginase, proline dehydrogenase (ProDH) and betaine dehydrogenase (BADH) showed that the chill hardening at 12 °C for 2 days obviously increased the activities of P5CS, GDH, OAT, arginase and BADH, as well as lowered ProDH activity both in leaves and stems of J. curcas seedlings to some extent as compared with the control. When the control and hardened seedlings were exposed to chilling stress at 1 °C for 1–7 days, the chill-hardened seedlings generally maintained significantly higher activities of P5CS, GDH, OAT, arginase and BADH. All above-mentioned results illustrated that the chill hardening could induce an accumulation of compatible solutes in leaves of J. curcas seedlings and compatible solutes play important roles in chill hardening-induced chilling tolerance.     

Involvement of antioxidant defense system in chill hardening-induced chilling tolerance in Jatropha curcas seedlings

Jatropha curcas L. is a sustainable energy plant with great potential for biodiesel production, and low temperature is an important limiting factor for its distribution and production. In this present work, chill hardening-induced chilling tolerance and involvement of antioxidant defense system were investigated in J. curcas seedlings. The results showed that chill hardening at 10 or 12 °C for 1 and 2 days greatly lowered death rate and alleviated electrolyte leakage as well as accumulation of the lipid peroxidation product malondialdehyde (MDA) of J. curcas seedlings under severe chilling stress at 1 °C for 1–7 days, indicating that the chill hardening significantly improved chilling tolerance of J. curcas seedlings. Measurement of activities of the antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and glutathione reductase (GR), and the levels of the antioxidants ascorbic acid (AsA) and glutathione (GSH) showed the chill hardening at 12 °C for 2 days could obviously increase the activities of these antioxidant enzymes and AsA and GSH contents in the hardened seedlings. When the hardened and non-hardening (control) seedlings were subjected to severe chilling stress at 1 °C for 1–7 days, the chill-hardened seedlings generally maintained significantly higher activities of the antioxidant enzymes SOD, APX, CAT, POD, and GR, and content of the antioxidants AsA and GSH as well as ratio of the reduced antioxidants to total antioxidants [AsA/(AsA + DHA) and GSH/(GSH + GSSG)], when compared with the control without chill hardening. All above-mentioned results indicated that the chill hardening could enhance the chilling tolerance, and the antioxidant defense system plays an important role in the chill hardening-induced chilling tolerance in J. curcas seedlings.     

小桐子ISSR-PCR体系的优化

采用正交试验设计方法.建立了小桐子ISSR-PCR反应体系和扩增程序.结果表明,在20μl反应体系中含有1×PCR缓冲液、200μmol/L dNTP、0.5μmol/L引物、2.0mmol/L MgCl2、0.5U Tag DNA聚合酶和90ng模板DNA最适用于小桐子ISSR-PCK扩增.适宜的扩增程序为94℃ 7min;94℃ 1min,44℃～56℃(退火温度随引物不同而定)45s,72℃ 1min,35个循环;72℃7min;4℃保存.     

Agro-climatic zoning of Jatropha curcas as a subside for crop planning and implementation in Brazil

As jatropha (Jatropha curcas L.) is a recent crop in Brazil, the studies for defining its suitability for different regions are not yet available, even considering the promises about this plant as of high potential for marginal zones where poor soils and dry climate occur. Based on that, the present study had as objective to characterize the climatic conditions of jatropha’s center of origin in Central America for establishing its climatic requirements and to develop the agro-climatic zoning for this crop for some Brazilian regions where, according to the literature, it would be suitable. For classifying the climatic conditions of the jatropha’s center of origin, climate data from 123 weather stations located in Mexico (93) and in Guatemala (30) were used. These data were input for Thornthwaite and Mather’s climatological water balance for determining the annual water deficiency (WD) and water surplus (WS) of each location, considering a soil water-holding capacity (SWHC) of 100 mm. Mean annual temperature (T _m), WD, and WS data were organized in histograms for defining the limits of suitability for jatropha cultivation. The results showed that the suitable range of T _m for jatropha cultivation is between 23 and 27 °C. T _m between 15 and 22.9 °C and between 27.1 and 28 °C were classified as marginal by thermal deficiency and excess, respectively. T _m below 15 °C and above 28 °C were considered as unsuitable for jatropha cultivation, respectively, by risk of frosts and physiological disturbs. For WD, suitability for rain-fed jatropha cultivation was considered when its value is below 360 mm, while between 361 and 720 mm is considered as marginal and over 720 mm unsuitable. The same order of suitability was also defined for WS, with the following limits: suitable for WS up to 1,200 mm; marginal for WS between 1,201 and 2,400 mm, and unsuitable for WS above 2,400 mm. For the crop zoning, the criteria previously defined were applied to 1,814 climate stations in the following Brazilian regions: Northeast (NE) region and the states of Goiás (GO), Tocantins (TO), and Minas Gerais (MG). The suitability maps were generated by crossing the crop climate requirements with the interpolated climate conditions of the selected regions. The maps showed that only 22.65 % of the areas in the NE region are suitable for jatropha as a rain-fed crop. The other areas of the region are classified as marginal (62.61 %) and unsuitable (14.74 %). In the states of GO and TO, the majority of the areas (47.78 %) is classified as suitable, and in the state of MG, 33.92 % of the territory has suitability for the crop. These results prove that jatropha cannot be cultivated everywhere and will require, as any other crop, minimum climatic conditions to have sustainable performance and high yields.     

干旱胁迫与施氮对麻疯树幼苗渗透调节物质积累的影响

采用盆栽控水的方法,研究干旱胁迫(80％ FC、60％ FC、40％ FC和20％ FC)及施氮(N0 0 g·pot-1、N1 1.2 g·pot1、Nm3.6 g·pot-1和Nh6.0 g·pot-1)对麻疯树幼苗叶、茎和根部主要渗透调节物质积累的影响.结果表明:干旱胁迫条件下,麻疯树幼苗茎和根部的游离脯氨酸、可溶性蛋白和茎部可溶性糖大量积累,叶片中脯氨酸含量也随干旱胁迫程度的增加大幅度上升;Na+、Ca2+和Mg2+在麻疯树幼苗叶、茎和根中大量积累,而K+仅在茎中大量积累,叶片和根部K+含量略微上升.施氮对植株渗透调节物质的影响与干旱胁迫强度和施氮水平有关.在80％ FC和60％ FC水分条件下,增加N肥施用量能明显促进麻疯树幼苗各组分渗透调节物质的积累;在40％ FC水分条件下,Nh处理对渗透调节物质积累的促进作用减弱;而在20％ FC条件下,N1处理植株的渗透调节能力较高,Nm和Nh处理对植株渗透调节的促进作用不明显甚至转为抑制.     

Biodiesel production from Jatropha curcas: a critical review

The fuel crisis and environmental concerns, mainly due to global warming, have led researchers to consider the importance of biofuels such as biodiesel. Vegetable oils, which are too viscous to be used directly in engines, are converted into their corresponding methyl or ethyl esters by a process called transesterification. With the recent debates on “food versus fuel,” non-edible oils, such as Jatropha curcas, are emerging as one of the main contenders for biodiesel production. Much research is still needed to explore and realize the full potential of a green fuel from J. curcas. Upcoming projects and plantations of Jatropha in countries such as India, Malaysia, and Indonesia suggest a promising future for this plant as a potential biodiesel feedstock. Many of the drawbacks associated with chemical catalysts can be overcome by using lipases for enzymatic transesterification. The high cost of lipases can be overcome, to a certain extent, by immobilization techniques. This article reviews the importance of the J. curcas plant and describes existing research conducted on Jatropha biodiesel production. The article highlights areas where further research is required and relevance of designing an immobilized lipase for biodiesel production is discussed.     

Isolation and identification of miRNAs in Jatropha curcas

MicroRNAs (miRNAs) are small noncoding RNAs that play crucial regulatory roles by targeting mRNAs for silencing. To identify miRNAs in Jatropha curcas L, a bioenergy crop, cDNA clones from two small RNA libraries of leaves and seeds were sequenced and analyzed using bioinformatic tools. Fifty-two putative miRNAs were found from the two libraries, among them six were identical to known miRNAs and 46 were novel. Differential expression patterns of 15 miRNAs in root, stem, leave, fruit and seed were detected using quantitative real-time PCR. Ten miRNAs were highly expressed in fruit or seed, implying that they may be involved in seed development or fatty acids synthesis in seed. Moreover, 28 targets of the isolated miRNAs were predicted from a jatropha cDNA library database. The miRNA target genes were predicted to encode a broad range of proteins. Sixteen targets had clear BLASTX hits to the Uniprot database and were associated with genes belonging to the three major gene ontology categories of biological process, cellular component, and molecular function. Four targets were identified for JcumiR004. By silencing JcumiR004 primary miRNA, expressions of the four target genes were up-regulated and oil composition were modulated significantly, indicating diverse functions of JcumiR004.     

Jatropha curcas: a review on biotechnological status and challenges

Plant tissue culture and molecular biology techniques are powerful tools of biotechnology that can complement conventional breeding, expedite crop improvement and meet the demand for availability of uniform clones in large numbers. Jatropha curcas Linn., a non-edible, eco-friendly, non-toxic, biodegradable fuel-producing plant has attracted worldwide attention as an alternate sustainable energy source for the future. This review presents a consolidated account of biotechnological interventions made in J. curcas over the decades and focuses on contemporary information and trends of future research.     

Combined action of antioxidant defense system and osmolytes in chilling shock-induced chilling tolerance in Jatropha curcas seedlings

Low non-freezing temperature is one of the major environmental factors affecting growth, development and geographical distribution of chilling-sensitive plants, Jatropha curcas is considered as a sustainable energy plants with great potential for biodiesel production. In this study, chilling shock at 5 °C followed by recovery at 26 °C for 4 h significantly improved survival percentage of J. curcas seedlings under chilling stress at 1 °C. In addition, chilling shock could obviously enhance the activities of antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR), and the levels of antioxidants ascorbic acid (AsA) and glutathione (GSH), as well as the contents of osmolytes proline and betaine in leaves of seedlings of J. curcas compared with the control without chilling shock. During the process of recovery, GR activity, AsA, GSH, proline and betaine contents sequentially increased, whereas SOD, APX and CAT activities gradually decreased, but they markedly maintained higher activities than those of control. Under chilling stress, activities of SOD, APX, CAT, GR and GPX, and contents of AsA, GSH, proline and betaine, as well as the ratio of the reduced antioxidants to total antioxidants [AsA/(AsA + DHA) and GSH/(GSH + GSSG)] in the shocked and non-shock seedlings all dropped, but shocked seedlings sustained significantly higher antioxidant enzyme activity, antioxidant and osmolyte contents, as well as ratio of reduced antioxidants to total antioxidants from beginning to end compared with control. These results indicated that the chilling shock followed by recovery could improve chilling tolerance of seedlings in J. curcas, and antioxidant enzymes and osmolytes play important role in the acquisition of chilling tolerance.     

New Cercospora species on Jatropha curcas in central Brazil

A new cercosporoid hyphomycete, Cercospora jatrophiphila, herein described and molecularly characterized, was found in Planaltina, DF, Brazil on Jatropha curcas (Euphorbiaceae).     

Esterase and lipase activity in Jatropha curcas L. seeds

Two new esterases (JEA and JEB) and a lipase (JL) were extracted from the seeds of Jatropha curas L. Lipase activity was only found during germination of the seeds and increased to a maximum after 4 days of germination. All enzymes were found to be most active in the alkaline range at around pH 8 and the purified (fractionated precipitation with ethanol and gel filtration) esterases were very stable at high temperatures. The molecular weight (SDS-PAGE) of both esterases was determined to be 21.6-23.5 kDa (JEA) and 30.2 kDa (JEB) and the isoelectric point was 5.7-6.1 for esterase JEA and 9.0 for esterase JEB. Most ions caused a negative influence on the activity of both esterases. Using p-nitrophenyl butyrate as a substrate JEA showed a K(m) of 0.02 mM and a v(max) of 0.26 micromol mg(-1) min(-1). Under the same conditions JEB showed a K(m) of 0.07 mM and a v(max) of 0.24 micromol mg(-1) min(-1). Both esterases hydrolyzed tributyrin, nitrophenyl esters up to a chain length of =C4 and naphtylesters up to a chain length =C6. In transesterification reactions, JL was found to be most active at very low water activities (0.2) and in high water activities, the lipase hydrolysed triglycerides into conversions above 80%. The lipase hydrolysed both short chain and long chain triglycerides at about the same rate but was inactive on alpha-methylbenzyl acetate. JL is a potentially useful biocatalyst in the hydrolysis of triglycerides in organic solvents.     

Reciprocal grafting between clones with contrasting drought tolerance suggests a key role of abscisic acid in coffee acclimation to drought stress

The role of abscisic acid (ABA) in drought tolerance of Coffea canephora is unknown. To determine whether ABA is associated with drought tolerance and if the use of tolerant rootstocks could increase ABA and drought tolerance, we performed reciprocal grafting experiments between clones with contrasting tolerance to drought (clone 109, sensitive; and clone 120, tolerant). Plants were grown in large (120 L) pots in a greenhouse and subjected to drought stress by withholding irrigation. The non-grafted 120 plants and graft treatments with 120 as a rootstock showed a slower reduction of predawn leaf water potential (Ψ_pd) and a lower negative carbon isotopic composition ratio compared with the other grafting combinations in response to drought. The same 120 graft treatments also showed higher leaf ABA concentrations, lower levels of electrolyte leakage, and lower activities of ascorbate peroxidase and catalase under moderate (Ψ_pd?=???1.0 or ??1.5 MPa) and severe (Ψ_pd?=???3.0 MPa) drought. Root ABA concentrations were higher in plants with the 120 rootstocks regardless of watering regime. The 120 shoots could also contribute to drought tolerance because treatment with 120/109 rootstock/scion combination showed postponed dehydration, higher leaf ABA concentration, and lower leaf electrolyte leakage compared with the sensitive clone. We conclude that both the shoot and root systems of the tolerant clone can increase the concentrations of ABA in leaves in response to drought. This further suggests that ABA is associated with a delayed onset of severe water deficit and decreased oxidative damage in C. canephora.