【目的】评价青钱柳(Cyclocarya paliurus)不同家系受自然低温胁迫后的耐寒性,筛选出耐寒能力强的家系,为青钱柳的引种、选育和栽培提供参考。【方法】以青钱柳23个家系的1年生枝条为研究材料,在自然低温胁迫后测定其相对电导率(REC),丙二醛(MDA)、可溶性糖(SS)、可溶性蛋白(SP)、淀粉(ST)和游离脯氨酸(Pro)含量,以及过氧化物酶(POD)、超氧化物歧化酶(SOD)活性等指标,并结合主成分分析、聚类分析等方法对不同家系青钱柳的耐寒性进行初步评价。【结果】自然低温胁迫后,23个家系的1年生枝条中相对电导率、过氧化物酶和超氧化物歧化酶活性,以及丙二醛、可溶性糖、可溶性蛋白、淀粉和游离脯氨酸含量等指标存在显著差异。主成分分析发现,4个主成分能够代表各项生理指标72.4%的信息。将各家系的主成分综合得分进行聚类分析,23个家系的耐寒性可分为3大类:第1类综合得分为1.208~1.284,耐寒性较强,仅包含2个家系(SCMC31和ZJTTS2);第2类综合得分为-0.343~0.631,耐寒性一般,包含GZSQ12、GXBS12、ZJFYS6、AHQLF8、HBWF10等17个家系;第3类综合得分为-1.259~-0.745,耐寒性较差,包含GZSQ9、ZJTTS3、SCMC22、SCMC30等4个家系。【结论】自然低温胁迫后,不同家系青钱柳1年生枝条的相关耐寒性生理指标差异显著,综合主成分分析和聚类分析结果,23个青钱柳家系在耐寒性上可以分为3大类。研究结果可为深入研究青钱柳耐寒机理及耐寒青钱柳家系(品种)的筛选提供参考。

The plant hormone jasmonate (JA) fulfils essential roles in plant defense and development. While most of our current understanding of the JA pathway comes from the dicotyledonous model plant Arabidopsis thaliana, new studies in monocotyledonous plants are providing additional insights into this important hormone signaling pathway. In this review, we present a comparative overview of the JA biosynthetic and signaling pathways in monocots. We highlight recent studies that have revealed molecular mechanisms (mostly conserved but also diverged) underlying JA signaling and biosynthesis in the economically important plants: maize and rice. A better understanding of the JA pathway in monocots should lead to significant improvements in pest and pathogen resistance in cereal crops, which provide the bulk of the world's food and feed supply.

Plants synthesize many fatty acid derivatives, several of which play important regulatory roles. Jasmonates are the best characterized examples. Jasmonate-insensitive mutants and mutants with a constitutive jasmonate response have given us new insights into jasmonate signalling. The jasmonate biosynthesis mutant opr3 allowed the dissection of cyclopentanone and cyclopentenone signalling, thus defining specific roles for these molecules. Jasmonate signalling is a complex network of individual signals and recent findings on specific activities of methyl jasmonate and (Z)-jasmone add to this picture. In addition, there are keto, hydroxy and hydroperoxy fatty acids that might be involved in cell death and the expression of stress-related genes. Finally, there are bruchins and volicitin, signal molecules from insects that are perceived by plants in the picomole to femtomole range. They highlight the importance of fatty acid-derived molecules in interspecies communication and in plant defence.

Biosynthesis of the phytohormone jasmonoyl-isoleucine (JA-Ile) requires reduction of the JA precursor 12-oxo-phytodienoic acid (OPDA) by OPDA reductase 3 (OPR3). Previous analyses of the opr3-1 Arabidopsis mutant suggested an OPDA signaling role independent of JA-Ile and its receptor COI1; however, this hypothesis has been challenged because opr3-1 is a conditional allele not completely impaired in JA-Ile biosynthesis. To clarify the role of OPR3 and OPDA in JA-independent defenses, we isolated and characterized a loss-of-function opr3-3 allele. Strikingly, opr3-3 plants remained resistant to necrotrophic pathogens and insect feeding, and activated COI1-dependent JA-mediated gene expression. Analysis of OPDA derivatives identified 4,5-didehydro-JA in wounded wild-type and opr3-3 plants. OPR2 was found to reduce 4,5-didehydro-JA to JA, explaining the accumulation of JA-Ile and activation of JA-Ile-responses in opr3-3 mutants. Our results demonstrate that in the absence of OPR3, OPDA enters the β-oxidation pathway to produce 4,5-ddh-JA as a direct precursor of JA and JA-Ile, thus identifying an OPR3-independent pathway for JA biosynthesis.

Jasmonates are ubiquitously occurring lipid-derived compounds with signal functions in plant responses to abiotic and biotic stresses, as well as in plant growth and development. Jasmonic acid and its various metabolites are members of the oxylipin family. Many of them alter gene expression positively or negatively in a regulatory network with synergistic and antagonistic effects in relation to other plant hormones such as salicylate, auxin, ethylene and abscisic acid.This review summarizes biosynthesis and signal transduction of jasmonates with emphasis on new findings in relation to enzymes, their crystal structure, new compounds detected in the oxylipin and jasmonate families, and newly found functions.Crystal structure of enzymes in jasmonate biosynthesis, increasing number of jasmonate metabolites and newly identified components of the jasmonate signal-transduction pathway, including specifically acting transcription factors, have led to new insights into jasmonate action, but its receptor(s) is/are still missing, in contrast to all other plant hormones.

对低温胁迫和常温处理的桂糖08-1180和ROC22进行转录组测序,比较不同甘蔗品种抗寒性分子机制的差异。结果表明：测序共产生57.41 G 的clean bases,拼接后获得183 515个unigenes,将获得的基因在NR、NT、Swiss-Prot、PFAM、KOG/COG、KEGG、GO数据库进行比对,有110 021个unigenes获得注释。低温胁迫下,桂糖08-1180有16 145个基因的表达发生了显著变化,ROC22有20 317个基因的表达发生了显著变化,且均表现为上调表达基因多于下调表达基因。ROC22与桂糖08-1180共有13 113个差异表达基因相同,ROC22特有7 204个差异表达基因,桂糖08-1180特有3 032个差异表达基因。对2个品种的共有差异表达基因进行富集分析,在对寒害逆境反应、膜系统、光合作用等的功能小类富集较多。对特有差异表达基因进行富集分析,桂糖08-1180在DNA整合、RNA聚合酶、ADP结合及代谢酶中富集较多,而ROC22在有机化合物的合成、运输和转运蛋白活性相关的条目富集得较多。

Wild sugarcane Saccharum spontaneum plants vary in ploidy, which complicates the utilization of its germplasm in sugarcane breeding. Investigations on cold tolerance in relation to different ploidies in S. spontaneum may promote the exploitation of its germplasm and accelerate the improvement of sugarcane varieties.A hypoploid clone 12-23 (2n = 54) and hyperploid clone 15-28 (2n = 92) of S. spontaneum were analysed under cold stress from morphological, physiological, and transcriptomic perspectives. Compared with clone 15-28, clone 12-23 plants had lower plant height, leaf length, internode length, stem diameter, and leaf width; depressed stomata and prominent bristles and papillae; and thick leaves with higher bulliform cell groups and thicker adaxial epidermis. Compared with clone 15-28, clone 12-23 showed significantly lower electrical conductivity, significantly higher water content, soluble protein content, and superoxide dismutase activity, and significantly higher soluble sugar content and peroxidase activity. Under cold stress, the number of upregulated genes and downregulated genes of clone 12-23 was higher than clone 15-28, and many stress response genes and pathways were affected and enriched to varying degrees, particularly sugar and starch metabolic pathways and plant hormone signalling pathways. Under cold stress, the activity of 6-phosphate glucose trehalose synthase, trehalose phosphate phosphatase, and brassinosteroid-signalling kinase and the content of trehalose and brassinosteroids of clone 12-23 increased.Compared with hyperploid clone 15-28, hypoploid clone 12-23 maintained a more robust osmotic adjustment system through sugar accumulation and hormonal regulation, which resulted in stronger cold tolerance.

Previous publications reported that the artemisinin level was increased in Artemisia annua following a night-frost period. However, the molecular mechanism was not clear. In this study, we found that exogenous jasmonate (JA) effectively enhanced the freezing tolerance of A. annua. The JA biosynthetic genes (LOX1, LOX2, allene oxide cyclase [AOC], and jasmonate resistant 1 [JAR1]) were induced by cold stress, leading to an increase in endogenous JA in cold-treated A. annua. Increased endogenous JA enhanced the expression of three JA-responsive transcription factors, ethylene response factor 1, ethylene response factor 2, and octadecanoid-responsive AP2/ERF, all of which were reported to transcriptionally activate the expression of artemisinin biosynthetic genes, such as amorpha-4,11-diene synthase (ADS), CYP71AV1, DBR2, and aldehyde dehydrogenase 1 (ALDH1). Furthermore, the expression levels of the four artemisinin biosynthetic genes were also significantly increased under cold stress. Consequently, the levels of artemisinin and related secondary metabolites, such as dihydroartemisinic acid, artemisinin B, and artemisinic acid, were increased in A. annua under cold stress. Our study points to a molecular mechanism in which the production of artemisinin is regulated by cold stress in A. annua.© 2016 International Union of Biochemistry and Molecular Biology, Inc.

Jasmonates are important regulators in plant responses to biotic and abiotic stresses as well as in development. Synthesized from lipid-constituents, the initially formed jasmonic acid is converted to different metabolites including the conjugate with isoleucine. Important new components of jasmonate signalling including its receptor were identified, providing deeper insight into the role of jasmonate signalling pathways in stress responses and development.The present review is an update of the review on jasmonates published in this journal in 2007. New data of the last five years are described with emphasis on metabolites of jasmonates, on jasmonate perception and signalling, on cross-talk to other plant hormones and on jasmonate signalling in response to herbivores and pathogens, in symbiotic interactions, in flower development, in root growth and in light perception.The last few years have seen breakthroughs in the identification of JASMONATE ZIM DOMAIN (JAZ) proteins and their interactors such as transcription factors and co-repressors, and the crystallization of the jasmonate receptor as well as of the enzyme conjugating jasmonate to amino acids. Now, the complex nature of networks of jasmonate signalling in stress responses and development including hormone cross-talk can be addressed.