Efficient induction of microspore embryogenesis using abscisic acid,jasmonic acid and salicylic acid in Brassica napus L

The stress hormones abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) play an important role in the regulation of physiological processes and are often used in tissue culture to promote somatic embryogenesis and to enhance the quality of somatic embryos. Despite many studies on Brassica napus microspore culture, the effects of stress hormones (ABA, JA and SA) on microspore embryogenesis are not well explored. In this study, the effects of three incubation periods (6, 12 and 24 h) at different levels of ABA, JA and SA (0, 0.2, 0.5, 1.0, 2.0 and 5.0 mg l^?1) on microspore embryogenesis of rapeseed (B. napus L.) cv. ‘Regent’ were investigated. ABA (0.5 mg l^?1 for 12 h) enhanced microspore embryogenesis by about threefold compared with untreated cultures and increased normal plantlet regeneration by 68 %. ABA treatment also effectively reduced secondary embryo formation at all concentrations tested but enhanced callusing at high levels, for example 67 % at 1.0 mg l^?1 for 24 h. Highest embryo yield (286.0 embryos Petri dish^?1) was achieved using 1.0 mg l^?1 JA for 24 h and highest normal plantlet regeneration (54 %) was observed in cultures exposed to 0.5 mg l^?1 JA for 12 h. JA (5.0 mg l^?1 for 24 h) also reduced the germination of microspore-derived embryos on regeneration medium by 21 %. SA at 0.2 and 0.5 mg l^?1 for 6 h increased microspore embryogenesis (184.0 and 193.4 embryos Petri dish^?1) relative to the control (136.2 embryos Petri dish^?1). However, SA did not improve normal regeneration, secondary embryo formation or callusing. Microspore embryogenesis and plant regeneration could be improved by ABA, JA as well as SA when the appropriate level and duration of incubation were selected.     

The identification of candidate radio marker genes using a coexpression network analysis in gamma‐irradiated rice

Plant physiological and biochemical processes are significantly affected by gamma irradiation stress. In addition, gamma‐ray (GA) differentially affects gene expression across the whole genome. In this study, we identified radio marker genes (RMGs) responding only to GA stress compared with six abiotic stresses (chilling, cold, anoxia, heat, drought and salt) in rice. To analyze the expression patterns of differentially expressed genes (DEGs) in gamma‐irradiated rice plants against six abiotic stresses, we conducted a hierarchical clustering analysis by using a complete linkage algorithm. The up‐ and downregulated DEGs were observed against six abiotic stresses in three and four clusters among a total of 31 clusters, respectively. The common gene ontology functions of upregulated DEGs in clusters 9 and 19 are associated with oxidative stress. In a Pearson's correlation coefficient analysis, GA stress showed highly negative correlation with salt stress. On the basis of specific data about the upregulated DEGs, we identified the 40 candidate RMGs that are induced by gamma irradiation. These candidate RMGs, except two genes, were more highly induced in rice roots than in other tissues. In addition, we obtained other 38 root‐induced genes by using a coexpression network analysis of the specific upregulated candidate RMGs in an ARACNE algorithm. Among these genes, we selected 16 RMGs and 11 genes coexpressed with three RMGs to validate coexpression network results. RT‐PCR assay confirmed that these genes were highly upregulated in GA treatment. All 76 genes (38 root‐induced genes and 38 candidate RMGs) might be useful for the detection of GA sensitivity in rice roots.     

高温胁迫及其信号转导

高温是影响当前农业生产重要的不得环境因素之一。本文综述了４种信号分子脱落酸（ＡＢＡ）,Ｃa^2 ,水杨酸（ＳＡ）,茉莉酸（ＪＡ）对高温胁迫的响应以及它们的相互关系,高温胁迫能够诱导ＡＢＡ,Ｃa^2 ,ＳＡ的含量升高,并且通过外施ＡＢＡ,Ｃa^2 ,ＳＡ,ＪＡ都能提高植物的抗热性。作为胞内第二信使,外源Ｃa^2 Ｃ能够提高植物超氧化物歧化mei（ＳＯＤ）,过氧化氢mei（ＣＡＴ）以及抗杯血酸氧化mei（ＡＰＸ）的活性,且能     

高温胁迫及其信号转导

高温是影响当前农业生产重要的不利环境因素之一。本文综述了4种信号分子脱落酸(ABA),Ca2+,水杨酸(SA),茉莉酸(JA)对高温胁迫的响应以及它们的相互关系,高温胁迫能够诱导ABA,Ca2+,SA的含量升高,并且通过外施ABA,Ca2+,SA,JA都能提高植物的抗热性。作为胞内第二信使,外源Ca2+能够提高植物超氧化物歧化酶(SOD),过氧化氢酶(CAT)以及抗坏血酸氧化酶(APX)的活性,且能提高钙调蛋白水平。ABA诱导的抗热性受胞质游离的Ca2+介导。SA被认为是对胁迫反应所必需的信号分子,H2O2很可能是信号转导链的一部分。JA和ABA在生理功能上有很多相似之处,JA独自或通过提高ABA含量来起作用,JA和SA有不同的生理功能,也有相同的(不过它们的信号转导途径可能不同),最后,提出了今后高温胁迫信号转导研究的一些思路。     

A simple and efficient method for analysis of plant growth regulators: a new tool in the chest to combat recalcitrance in plant tissue culture

This report presents a simple, rapid and accessible validated method for quantification of eight major plant growth regulators (PGR): cytokinins (6-(γ,γ-dimethylallylamino)purine (2-iP), benzylaminopurine (BA) and zeatin), auxin (indole-3-acetic acid; IAA), jasmonic acid (JA), salicylic acid (SA), gibberellic acid (GA3) and abscisic acid (ABA) by liquid chromatography mass spectrometry. This method was tested in eight species including agricultural, ornamental and medicinal species: St. John’s wort, African violet, banana, American elm, tobacco, potato, sweet wormwood, and fennel. The method has good reproducibility and good sensitivity with %RSD (percent relative standard deviation) between 1 and 10% for all matrices and recovery values of 89 to 118% for all analytes. Method detection limits were 50.65 ng/g, 203.4 ng/g, 50.65, ng/g, 50.65 ng/g, 203.4 ng/g, 12.7 ng/g, 193 pg/g and 3.08 ng/g, for SA, IAA, zeatin, JA, GA3, ABA, 2-iP, and BA, respectively. Our results with a range of plant species show that this method represents a simple, low-cost method for analysis of PGRs, and may also serve as an useful starting point for the analysis of other related PGRs, as demonstrated by inclusion of the SA derivative, acetylsalicylic acid, and the JA derivatives: 12-oxo-phytodienoic acid and JA-isoleucine. The efficiency of this method will enable its incorporation into the plant tissue culture work flow and through characterization of endogenous PGR levels, will allow for improved method development for recalcitrant species facilitating fundamental and applied studies in plant morphogenesis, propagation and conservation.     

Multi-omics analysis reveals the ontogenesis of basal chichi in Ginkgo biloba L.

Chichi is a unique biological phenomenon observed in Ginkgo biloba L.. In this study, multi-omics analysis was used to compare basal chichi (C) with roots (R) and stems (S) to explore the regulatory mechanisms of basal chichi ontogenesis. The results showed that compared with roots and stems, the tZ, SA and ABA contents in basal chichi were the highest, and the ratio of IAA/tZ was the lowest. Nucleotides and their derivatives in basal chichi were upregulated, and phenylpropane metabolites were downregulated. Some differentially expressed genes (DEGs) strongly correlated to plant hormones were screened. We speculate that auxin and cytokinin are involved in the morphogenesis of basal chichi and that cytokinin plays a major role. The ontogenesis of basal chichi is closely related to environmental stress, and it may be a coping strategy of G. biloba in the face of environmental stress.     

Jasmonic acid is involved in the water-stress-induced betaine accumulation in pear leaves

Jasmonic acid (JA) is known to be involved in the response of plants to environmental stresses such as drought, and betaine (glycinebetaine) is an osmopretectant accumulated in plants under environmental stresses including drought. However, it remains currently unclear whether JA is involved in the water‐stress‐induced betaine accumulation in plant leaves. The present experiment, performed with the whole pear plant (Pyrus bretschneideri Redh. cv. Suli), revealed that the exogenously applied JA induced a significant increase of the betaine level in the pear leaves when the plants were not yet stressed by drought, and when the plants were subjected to water stress, the ‘JA plus drought’ treatment induced a significant higher betaine level than did the drought treatment alone. Meanwhile, the ‘JA plus drought’ treatment induced higher levels of betaine aldehyde dehydrogenase (BADH, E C 1.2.1.8) and activities in the leaves than did the drought treatment alone. These results obtained in the whole plant experiments were supported by the results of detached leaf experiments. In detached leaves JA induced significant increases in betaine levels, BADH activities and BADH protein amounts in a time‐ and concentration‐dependent manner. These data demonstrate that JA is involved in the drought‐induced betaine accumulation in pear leaves.