Genes encoding plant WRKY transcription factors are important for stress response. In the current study, two WRKY transcription factor genes (JrWRKY6 and JrWRKY53) were identified from walnut (Juglans regia L.), and their function and involvement in stress responses were characterized. Under NaCl stress, JrWRKY6 and JrWRKY53 were upregulated in a short time (within 6 h of seedling exposure to salt) except in roots, in which the highest induction occurred at 24 and 48 h of salt exposure. The gene expression patterns under polyethylene glycol stress were similar to those under NaCl stress. Under heat stress, both genes were induced in all tissues, except for JrWRKY6 in leaf tissue of seedlings treated for 24 and 48 h. Both genes were also induced in all plants exposed to cold stress, except for JrWRKY6 in root tissue of seedlings exposed for 6 h and JrWRKY53 in root tissue exposed for 48 h. JrWRKY6 and JrWRKY53 also showed varied responses to abscisic acid (ABA), with the maximum expression being for JrWRKY6 in the roots of plants treated for 1 h, and JrWRKY53 in the leaves of plants treated for 3 h. Furthermore, under NaCl, sorbitol, heat, cold, and ABA treatments, yeast cells transformed with JrWRKY6 and JrWRKY53 showed an improved growth activity and density relative to the empty-vector-containing control yeast. Moreover, JrWRKY6 or JrWRKY53 could bind to the W-box motif. These results suggest that JrWRKY6 and JrWRKY53 can response positively to abiotic stressors and improve the plant tolerance to salinity, osmotic stress, and abnormal temperatures in a mechanism that likely involves the ABA signalling pathway and W-box binding activity.

A suppression subtraction hybridization (SSH) cDNA library of alfalfa (Medicago sativa L.) cv. Zhongmu NO.1 had been constructed to identify differentially expressed genes under stress. Based on the sequence of a 460 bp expressed sequence tags (ESTs), a cDNA of 1652 bp was cloned by rapid amplification of cDNA ends (RACE) method. This gene (MsPBL) was predicted to encode a 434-amino-acid protein, which contained a Phox and Bem1 (PB1) domain. PB1 domain is a functional domain comprising about 80 amino acid residues, which exists in many signal transduction proteins and mediates dimerization in the proteins. PB1 domain is mostly involved in two cell signal transduction pathways: MAPK and NF-KB. When fused to the green fluorescent protein, we found MsPBL localization in the nucleus of onion (Allium cepa L.) epidermal cells. The transcripts of MsPBL rose significantly when alfalfa was treated with 300 mM NaCl, 0.1 mM ABA, and 20 % polyethylene glycol (PEG-6000). These results indicated that MsPBL may be functional within the nucleus as a signal transduction protein to allow alfalfa to rapidly respond to the environmental stress signals.

Phenylalanine ammonia lyase (PAL) is the first enzyme in the phenylpropanoid pathway. In this study, we describe the molecular characteristics of four PAL genes (MaPAL1, MaPAL2, MaPAL3, and MaPAL4) cloned from banana (Musa acuminata L. AAA group, cv. Cavendish) using a rapid amplification of cDNA ends and real time quantitative PCR. The predicted molecular masses of corresponding PALs ranged from 70.2 to 77.3 kDa and their isoelectric points were acidic. At the amino acid level, they shared a high sequence similarity with PALs in the banana DH-Pahang (AA group) genome. Phylogenetic analysis shows that the deduced amino acid sequences of MaPALs had also a high similarity with PALs of other plant species. Expression analysis by semi-quantitative reverse transcriptase PCR reveals that these genes were differentially expressed in various tissues. Enzyme activity of PAL and expression of MaPALs in bananas were induced after infection with Fusarium oxysporum f. sp cubense Tropical Race 4. Our findings suggest that MaPALs play important roles in banana resistance to F. oxysporum.

Na⁺/H⁺ exchanger (NHX)-mediated Na⁺ and H⁺ antiport is an important mechanism for salt tolerance in plants. In this study, an Na⁺/H⁺ antiporter gene, referred to as NsNHX1, was isolated from the halophyte Nitraria sibirica Pall. using degenerate polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE). The resulting 2 182 bp NsNHX1 cDNA contained a 1 635 bp open reading frame (ORF) that encoded 544 amino acids and showed striking sequence similarity to tonoplast-localized NHXs from other plants. Subcellular localization analysis confirmed NsNHX1 to be a tonoplast-localized protein. Cis-elements described as being responsive to biotic and abiotic stresses were present in the NsNHX1 promoter region, and reverse transcription (RT)-PCR analysis confirmed that NsNHX1 expression was induced by exogenous abscisic acid (ABA), cold, and NaCl. Transcription of NsNHX1 increased sharply 3 h after treatment with 200 mM NaCl revealing that NsNHX1 responded rapidly to the salt stress. Overexpression of NsNHX1 enhanced salt tolerance in transgenic Arabidopsis thalliana L. suggesting that NsNHX1-mediated Na⁺ compartmentalization played an important role in enhancing plant salt tolerance.

Auxin controls numerous processes in plant development and auxin/indoleacetic acid (Aux/IAA), an auxin response factor (ARF), and a lateral organ boundaries domain (LBD) were considered as early auxin response transcription factors (TFs). Till now, no Aux/IAA, ARF, and LBD TFs were identified in ramie (Boehmeria nivea L. Gaud). In this study, we used Arabidopsis and mulberry sequences as query to search against the ramie transcriptome database and the searched sequences were analyzed for a full-length coding sequence. In total, we obtained 16 BnAux/IAA, 14 BnARF, and 16 BnLBD TFs on which evolutionary analysis and expression profiling were conducted. Analysis of sequence conservation revealed close evolution relationships between ramie and mulberry. Expression analysis shows these genes were actively expressed in major ramie tissues, and several were auxin responsive. The expressions of these genes were also investigated under drought and a high temperature, main abiotic stresses during ramie life cycle. We found that most genes of the three families were stress-responsive and showed distinct expression patterns under the drought and high temperature stresses.

Plant WRKY genes encode a complex and ancient class of zinc-finger transcription factors that are involved in multiple biological processes, especially in regulating defense against abiotic stresses. Despite a growing number of studies on the genomic organization of the WRKY gene family in various species, little information is available about this family in hemp (Cannabis sativa L.). In this study, based on the hemp genome sequence, 40 hemp WRKY (CsWRKY) genes were classified into three main groups and five subgroups according to their orthologs in Arabidopsis. Among these, 23, 15, and 14 CsWRKY genes were responsive to drought, NaCl, and Cd stress, respectively. Interestingly, the expressions of all of the 23 drought stress-responsive genes were up-regulated. Moreover, 18 CsWRKY genes were induced by abscisic acid (ABA) treatment. A total of six up-regulated genes related to all three stresses were identified. Among these, five were up-regulated, and one was down-regulated by ABA. These results indicate a diverse function of the CsWRKY genes, which provides a basis for future clarification of their function in hemp tolerance to abiotic stresses.

The life cycle of flowering plants is partially defined by environmental cues like day length and temperature. In the model plant Arabidopsis thaliana and temperate cereals, such as barley (Hordeum vulgare) and wheat (Triticum spp.), differences in life cycle control have been associated with a natural variation in FLOWERING LOCUS C (FLC) and VERNALIZATION 1-3 (VRN1-3). In sugar beet (Beta vulgaris L.), variation in vernalization requirement and life cycle is determined by a major gene at the B locus. This gene has recently been identified as a pseudo-response regulator (PRR) gene BOLTING TIME CONTROL 1 (BTC1). A second gene in beet with homology to BTC1 and ARABIDOPSIS PSEUDO RESPONSE REGULATOR 7 (APRR7) in Arabidopsis was identified and termed Beta vulgaris PSEUDO RESPONSE REGULATOR 7 (BvPRR7). We functionally characterized BvPRR7 by transgenic analysis in Arabidopsis and expression profiling during development in beet. We show that BvPRR7 was diurnally regulated and responded to cold. Constitutive expression of BvPRR7 distorted diurnal rhythms and caused late flowering in Arabidopsis suggesting a conserved function of BvPRR7 in clock regulation. Conceivably, the retention of a functional role of BvPRR7 in clock regulation may have facilitated the evolution of a distinct role as major floral regulator of the second PRR7 homolog in beet, BTC1.

The tonoplast and plasma membrane localized sodium (potassium)/proton antiporters have been shown to play an important role in plant resistance to salt stress. In this study, AtNHX1 and AtNHX3, two tonoplast Na⁺(K⁺)/H⁺ antiporter encoding genes from Arabidopsis thaliana, were expressed in poplar to investigate their biological functions in the resistance to abiotic stresses in woody plants. Transgenic poplar plants expressing either gene exhibited increased resistance to both salt and water-deficit stresses. Compared to the wild type (WT) plants, transgenic plants accumulated more sodium and potassium ions in the presence of 100 mM NaCl and showed reduced electrolyte leakage in the leaves under water stress. Furthermore, the proton-translocating and cation-dependent H⁺ (Na⁺/H⁺ or K⁺/H⁺) exchange activities in the tonoplast vesicles isolated from the leaves of transgenic plants were higher than in those isolated from WT plants. Therefore, constitutive expression of either AtNHX1 or AtNHX3 genetically modified the salt and water stress tolerance of transgenic poplar plants, providing a potential tool for engineering tree species with enhanced resistance to multiple abitotic stresses.

The nuclear factor Y (NF-Y) is one of the largest transcription factor families in plants consisting of NF-YA, NF-YB, and NF-YC subunits. It could play important roles in various processes such as flowering time, seed development, and response to drought. In this study, 6 NF-YA, 13 NF-YB, and 8 NF-YC proteins were identified and characterized in Prunus mume. Analyses of a conserved domain indicated that the PmNF-Y subunits shared an elevated degree of homology with the corresponding Arabidopsis NF-Y ones. Phylogenetic analysis showed that each NF-Y subunit family from Prunus mume and Arabidopsis could be divided into 4 or 2 clades based on their full-length proteins. The gene expression patterns of all 27 PmNF-Y genes were examined under abscisic acid (ABA), osmotic, salt, and H₂O₂ treatments using real-time quantitative PCR analyses. PmNF-YA1/2/4/5/6, PmNF-YB3/4/8/10/11/13, and PmNF-YC1/2/4/5/6/8 were found to be up-regulated under the ABA and osmotic treatments. PmNF-YA1/2/3/4/5/6, PmNF-YB1/3/8/10/11/13, and PmNF-YC1/2/5/6/8 were obviously induced by the H₂O₂. In addition, only PmNF-YA2 and PmNF-YB3 expressions were enhanced under the salt stress. These findings could provide an entry point to investigating the roles of PmNF-Y genes during abiotic stress responses.

In wheat seeds, starch synthase I or the Waxy protein is an enzyme involved in amylose synthesis. The gene encoding this enzyme is Wx and in this study, eight novel Wx alleles were identified in three diploid Taeniatherum species. The variability of these alleles was evaluated, and their nucleotide sequences were compared with those of homologous alleles from wheat. Two types of Taeniatherum Wx alleles were detected in three diploid species Ta. caput-medusae, Ta. asperum, and Ta. crinitum. A phylogenetic analysis indicates that the Taeniatherum Wx alleles were more closely related to Wx alleles from Aegilops species with C, D, M, and U genomes than to Wx alleles of other species. These alleles represent a potential genetic resource that may be useful in wheat breeding programs.

Fruit crops have a growing economic importance worldwide and molecular genetics might be useful in solving many problems that arise during commercial production. One of the fields that have attracted intense attention is the molecular basis of self-incompatibility that may result in low fruit set. In tree fruits of the Rosaceae family, the incompatibility reactions take place between the pistil S-ribonuclease (S-RNase) and the pollen-expressed S-haplotype specific F-box (SFB) proteins. In most cases, the loss of self-incompatibility was associated with mutations in the S-RNase or SFB genes. A total of 27 non-functional S-haplotypes have been identified and characterized, most (24) of which emerged as a consequence of natural mutations. In the Prunoideae, most haplotypes are pollen-part mutants (50 %), while 8 are stylar-part mutants (36 %), one haplotype shows both pollen- and stylar-part mutations, and molecular changes for two haplotypes still have not been clarified. In contrast, non-functional natural haplotypes in the Maloideae are all stylar-part mutants. The analysis of such mutants may shed light on underlying molecular mechanisms as was the case with the establishment of the general inhibitor model that describes interactions between pollen and pistil S-proteins. However, several other molecules were supposed to contribute to the molecular interactions, at least in Solanaceae, a family with a similar self-incompatibility system. This review also endeavours to delineate the evolutionary implications of the S-locus mutations and collect limited data on non-S-locus molecular interactions and signaling events after self- and cross-pollination of fruit tree species.

MicroRNAs (miRNAs) are small non-coding RNAs that play crucial regulatory roles in diverse developmental processes via cleavage or translational inhibition of their target mRNAs. Although a growing number of miRNAs and their targets have been predicted and discovered via experimentation in many plants, little is known about conserved miRNAs and their target genes in Pinus densata. In the present study, the conserved miRNAs, miR171 and miR482, from Pinus densata were characterized. Analysis of miR171 and miR482 reveal that these miRNAs were highly conserved in other plant species. In addition, the precursors of miR171 and miR482 were validated by real time-PCR and sequencing. Using real-time quantitative PCR, miR171 and miR482 as well as their corresponding targets were found to be differentially expressed in needles, stems, and roots of Pinus densata. Furthermore two target genes, one GRAS family transcription factor protein gene and one nucleotide-binding site leucine-rich repeat (NBS-LRR) resistance protein gene, were experimentally verified to be the targets of pde-miR171 and pde-miR482, respectively, using RNA ligase-mediated 5'-rapid amplification of cDNA ends (RLM-RACE).

Jasmonate ZIM domain (JAZ) proteins are key regulators of the jasmonic acid (JA) signaling pathway. Repressors of JAZ remain bound to the myelocytomatosis 2 (MYC2) or MYC3/MYC4 transcription factors in the absence of JA and negatively regulate transcription of the JA responsive genes. In the presence of JA, JAZ proteins interact with coronative insensitive 1 (COI1), the recognition molecule of E3 ubiquitin ligase SCF^COI1 (COI1 stabilized by Skp, cullin, F-box containing complex), get ubiquitinated, and subsequently degraded by the 26S proteasome. However, there is a dearth of knowledge about this gene family in monocot cereals, specifically its role in finger millet is unknown till date. Here we present the isolation and characterization of a novel JAZ family repressor gene from nonsequenced Eleusine coracana (EcJAZ) utilizing available genome information of Oryza, Sorghum, and Setaria. The EcJAZ sequence showed the presence of a conserved ZIM domain, the Jas motif, and N-terminal motif 7 like other Group1 TIFY sequence containing proteins. We observed coronatine (an analog of JA-Ile) dependent and time dependent degradation of recombinant EcJAZ that thereby fulfilled the basic characteristic of the JAZ proteins. We found a proteasome inhibitor N-(phenylmethoxy) carbonyl-L-leucyl-N-[(1R)-1-formyl-3-methylbutyl]-L-leucinamide) (MG132) mediated degradation inhibition of EcJAZ that supported its 26S proteasome mediated degradation. Our study shows the nuclear localization of GFP-EcJAZ by Agrobacterium mediated transient transformation of onion scale epidermal cells. In Eleusine leaves, transcription of EcJAZ increased 4.2-fold by salt stress and 5.5-fold by coronatine application; thus ascertained its inducibility by the abiotic stress as well as by bioactive JA-Ile. Taken together, all these results contribute to our understanding of the JA signaling pathway in Eleusine coracana.

One of the largest families of transcriptional regulators contains WRKY proteins. They play important roles in plant defense responses. In this study, a novel WRKY gene, CsWRKY2, was isolated from the tea [Camellia sinensis (L.) O. Kuntze] plant. The full-length cDNA of CsWRKY2 was 2 050 bp in length and encoded a 522-amino acid peptide chain containing two typical WRKY domains and two zinc finger motifs, suggesting that CsWRKY2 was member of the WRKY group I family. A subcellular localization assay shows that CsWRKY2 was localized to the nucleus. Real time qPCR analysis shows that CsWRKY2 expression was higher in leaves than in other organs and was induced by cold (4 °C), drought stress, and exogenous abscisic acid (ABA). Additionally, ABA content was enhanced after the cold or drought stress and the effects were relieved by an ABA biosynthesis inhibitor. Furthermore, the expression of CsWRKY2 was up-regulated by exogenous ABA under the cold and drought stresses and down-regulated by an ABA biosynthesis inhibitor. Our findings indicate that CsWRKY2 played an important role in plant defense responses to the cold and drought stresses by participating in the ABA signaling pathway, downstream to ABA.

Rosaceae is a large family, however, our understanding of its phylogeny is based largely on morphological observations. To understand the relationship between subfamilies Rosoideae, Amygdaloideae, Maloideae and Spiraeoideae at a molecular level, we isolated and compared the plant phosphatidyl ethanolamine-binding protein-like genes TERMINAL FLOWER1 (TFL1)-like and CENTRORADIALIS (CEN)-like, which are involved in the control of shoot meristem identity and flowering time. A comparison of gene structures and phylogenetic tree analyses by the Neighbor-Joining method showed that each of the two TFL1-like (MdTFL1-1 and MdTFL1-2) and CEN-like genes (MdCENa and MdCENb) in Maloideae were classified into two distinct clades. The TFL1-like and CEN-like genes of Gillenia in Spiraeoideae belonged to monophyletic Maloideae groups, suggesting that Gillenia and Maloideae have a common near ancestor. However, the Gillenia TFL1-like gene does not contain the insertion sequence of the third intron that is found in MdTFL1-2-like genes of the members of Maloideae such as apple, Korean whitebeam, quince, and Siberian mountain ash. Therefore, after the Maloideae ancestor genome became polyploid through hybridization between Gillenia-like species or genome doubling, an insertion sequence of the third intron of MdTFL1-2-like genes was generated.

The dehydration responsive element binding (DREB) transcription factor (TF) family comprises unique and important proteins involved in abiotic stress responses and tolerance in plants. Although DREB TFs have been well identified and characterized in a few model plants, there is no detailed information available for mulberry. In this study, 110 AP2/ERF family genes were identified based on a genome-wide analysis of the Morus genome database. Among them, 30 Morus notabilis DREB family genes (MnDREBs) were identified. A comparative analysis with DREB gene families from other plants suggests that MnDREBs could be divided into six subgroups (A-1 to A-6) and could have similar functions in response to abiotic stresses since they have similar conserved domains/motifs within each subgroup. The expression patterns of MnDREBs were analyzed using transcriptome data of different organs from M. notabilis and the quantitative real-time polymerase chain reaction. The expression of most MnDREBs was detected in different organs and induced by various abiotic stresses, which suggest their vital roles in abiotic stress tolerance.

SnRK2 are plant-specific serine/threonine kinases that are involved in plant responses to abiotic stresses. In this study, four novel genes SnRK2s:TpSnRK2.11, TpSnRK2.2, TpSnRK2.5, and TpSnRK2.10 from dwarf Polish wheat (Triticum polonicum L.) were characterized and classified into three groups. TpSnRK2.5 and TpSnRK2.11 were members of group 1; TpSnRK2.2 was member of group 2; TpSnRK2.10 belonged to group 3. The expression of TpSNRK2.2 was strongly regulated by polyethylene glycol (PEG), NaCl, and cold in roots and leaves, as well as by ABA in leaves. The transcript of TpSnRK2.5 was intensely induced by all the treatments in roots and leaves. The distinct expression patterns of TpSnRK2.10 indicate that this gene was very sensitive to ABA and NaCl, less sensitive to cold and PEG. The transcript of TpSnRK2.11 was activated significantly by PEG, NaCl, and cold, but weakly by ABA. Our results indicate that these four genes were probably involved in wheat responses to different abiotic stresses in different tissues.

Apple (Malus × domestica Borkh.) is a perennial woody plant that undergoes a period of dormancy (in cv. Jonathan between late September and mid-December) to survive freezing temperatures of winter. DORMANCY-ASSOCIATED MADS-BOX (DAM) genes play important roles in the regulation of growth cessation and terminal bud formation in peach. To understand the role of DAM orthologs in apple, we isolated and characterized four DAM-like genes (designated as MdDAMa, MdDAMb, MdDAMc, and MdDAMd) and monitored their expression in apical buds throughout the season by real-time quantitative polymerase chain reaction analyses. The transcription of MdDAMa peaked in October and that of MdDAMc was elevated from August to October, whereas MdDAMb and MdDAMd were practically undetectable. The tandemly arranged genes MdDAMa/MdDAMb and MdDAMc/MdDAMd were localized to chromosomes 16 and 8, respectively. Based on these observations, we infer that MdDAMa and MdDAMc acted in a dominant fashion on each locus and were correlated with the period of endodormancy.

A photoperiod-sensitive soybean [Glycine max (L.) Merr] cv. ZhongDou 24 (ZD24) exhibiting delayed flowering when grown under long-days (LD, a 16-h photoperiod) was used to identify the genetic control of flowering delay. A differential expression profiling technique enabled identification of a gene fragment that was up-regulated under LD. This fragment was homologous to a gene encoding methionine synthase (MS) in soybean and was named GmMS. The RNA content confirmed that GmMS was expressed in roots, stems, and leaves of soybean grown under LD. The highest expression was in stems. Full length GmMS, encoding 763 amino acids, was transferred into tobacco plants. The ectopic expression of GmMS in tobacco resulted in delayed flowering. Other effects included stunting, an increased MS activity and methionine content, a higher content of alcohol-soluble proteins and of chlorophylls, and a lower content of anthocyanins.

Phospholipase D (PLD) and its product phosphatidic acid are now considered to be one of the key elements of numerous physiological processes in plants including the salicylic acid signalling pathway. The presented study investigates the transcriptional regulation of Brassica napus PLDs following treatments with defense-related stimuli. We cloned eight B. napus genes encoding members of PLDβ, γ, and δ isoforms and performed phylogenetic analysis with its ancestor species Brassica rapa and Brassica oleracea, and with the model plant Arabidopsis thaliana. Transcription of the identified genes was monitored after treatment with benzothiadiazole (BTH), methyl jasmonate (MeJA), bacterial elicitor flg22, wounding, and after infection with fungal pathogens Sclerotinia sclerotiorum and Leptosphaeria maculans. Most of the genes responded specifically to a particular treatment. Remarkably the genes encoding the PLDγ and PLDβ isoforms were up-regulated by stimuli associated with the salicylic acid signalling pathway. The generality of this finding was confirmed by the analysis of public transcriptional data from Arabidopsis thaliana.

Potassium uptake and transport is facilitated by KT/HAK/KUP transporters. In this study, we identified 16 putative K⁺-uptake transporter genes in peach (Prunus persica). To investigate the role of PpeKUP in maintaing K⁺ uptake, transport, and homeostasis, we applied abiotic stresses to peach seedlings and analysed physiological reactions and transcriptional responses of PpeKUP genes. The peach seedlings were sensitive to polyethylene glycol (PEG), Pb, and Cd, as evidenced by impaired growth, K⁺ nutrition, and photosynthetic performance. However, the peach seedlings were tolerant to aluminum. K⁺ deficiency mainly increased, whereas K⁺ excess reduced the PpeKUP gene expression in roots. The Al treatments enhanced the PpeKUP transcription in shoots, whereas PEG, Pd, and Cd enhanced the PpeKUP transcription in all tissues. Our findings provided molecular basis for K⁺ uptake, transport, and homeostasis in the peach seedlings, and revealed potential candidate genes for further functional determination or breeding of peaches.

The secretory (Sec) pathway is one of the most important systems for transporting proteins across the thylakoid membrane into the lumen. Two Arabidopsis genes encoding SecY translocon proteins, designated SCY1 and SCY2, were characterized in this study. Semi-quantitative RT-PCR and histochemical staining β-glucuronidase (GUS) activity reveal that both SCY1 and SCY2 promoters were active in germinating seeds, etiolated cotyledons, and flowers, but not in roots. In particular, the expression of GUS gene driven by the SCY1 promoter was almost undetectable in green leaves, whereas GUS staining controlled by the SCY2 promoter was clearly detected. Moreover, homozygous scy1-1 plants could grow heterotrophically but appeared sensitive to radiation. Further studies show that chloroplasts of scy1-1 were arrested in early developmental stages with fewer thylakoid membranes. Real-time quantitative RT-PCR reveals that a number of nuclear-encoded genes involved in chlorophyll biosynthesis and photosynthesis were substantially down-regulated in the scy1-1 mutant. All these results indicate that the SCY1/2 genes were regulated developmentally and spatially, and a loss-of-function mutation in SCY1 triggered chloroplast-to-nucleus retrograde signaling in Arabidopsis thaliana.

Desiccation tolerance (DT) is the ability to tolerate dehydration to levels below 0.1 g(H₂O) g^-1(dry mass) and subsequent rehydration without lethal damage. Here, it is proposed that Leucaena leucocephala, a tree species, has potential to be model tolerant species in seed research. Using flow cytometry and transmission electron microscopy, cytological changes related to loss of DT in Leucaena primary roots were followed during germination. Leucaena seeds lost their DT at the end of germination and this coincided with an increase in cellular 4C DNA content. A negative correlation between the 8C DNA content and the capacity of germinating Leucaena seeds to tolerate desiccation was also observed. Apparently, the seeds of Leucaena underwent extra cycles of endoreduplication and accumulated a high content of DNA - an event not previously linked to DT. The ultrastructural damage imposed by drying overcame Leucaena primary root cell resilience and their ability to resume normal growth. Nuclear DNA content may be used as indicator of progress of germination and loss of DT in Leucaena.

A new member of the APETALA2/ethylene responsive element binding protein (AP2/EREBP) transcription factor family, HhDREB2, was isolated from Halimodendron halodendron. Based on the similarity of the AP2/ERF domain, HhDREB2 was classified into A-5 group of the DREB subfamily. The expression of HhDREB2 gene was induced by drought, high salinity, and low temperature, but not by exogenous plant hormones. Trans-activity assay demonstrated that HhDREB2 gene encodes a transcription activator. Furthermore, over-expression of HhDREB2 gene under the stress-inducible rd29A promotor in Arabidopsis resulted in enhanced tolerance to salt and drought stresses. The overall results reveal that HhDREB2 functioned as important transcription factor in regulation of stress-responsive signaling in plants and may be used for improving plant tolerance to abiotic stresses.

Chloride channels (CLCs) play pivotal roles in plant development and anion transport. However, little research has been conducted about the CLC in fruit-bearing plants. Here we provide an insight into the evolution and expression patterns of CLC gene family members in various tissues of trifoliate orange [Poncirus trifoliata (L.) Raf.] and their responses to several treatments. Genome-wide analysis identified six PtrCLC genes. The predicted proteins had similar numbers of amino acids, but shared a low sequence identity. Phylogenetic analysis revealed that PtrCLC were classified into two separate subgroups, and PtrCLC4 and PtrCLC6 in subgroup II were more closely related to bacterial CLCs. Sequence comparison with EcCLCA from Escherichia coli reveals that PtrCLC showed amino acid divergence in anion selectivity of CLC proteins. Real time qPCR analysis shows that PtrCLC genes, particularly PtrCLC6, preferentially expressed in leaves. Nitrogen deficiency irreversibly inhibited expression of PtrCLC genes except for PtrCLC1. In contrast, NaCl stress profoundly induced expression of PtrCLC genes, particularly PtrCLC2 and PtrCLC4, both of which were also upregulated by ABA treatment. The results presented here provide a solid foundation for a future functional research on citrus CLC genes.

In this study we identified and characterized a major latex lectin - designated as EtLLH - with antimicrobial activity from the succulent African milk tree Euphorbia trigona. The lectin is highly concentrated in the latex of E. trigona and appears to be composed of at least two subunits with a molecular mass of 32 kDa. EtLLH shares significant similarities to known plant lectins - ricin from Ricinus communis and agglutinin from Viscum album coloratum - which specifically bind D-galactose and N-acetyl-D-glucosamine, the major building blocks of many fungal cell walls. Antimicrobial activity assays revealed an impact of EtLLH on three phytopathogenic filamentous ascomycetes. The germination of the conidiospores and the hyphal growth of Aspergillus niger and Fusarium graminearum were severely inhibited by EtLLH already at concentrations below 0.1 mg cm^-3, while the effect on germination of the melanized conidiospores of Botrytis cinerea was less significant.

Four new microsatellite primer pairs were developed in tree peony (Paeonia suffruticosa) based on the database mining and other twenty-six primer pairs by fast isolation by AFLP of sequences containing repeats (FIASCO) method. The polymorphism of each locus was further evaluated in 40 individuals of one population plus 5 tree peony related species. The number of alleles per locus ranged from 3 to 7 and the expected (H_e) and observed (H_o) heterozygosity at each locus ranged from 0.42 to 0.78 and 0.28 to 0.59, respectively. These microsatellite markers will be useful for investigating genetic diversity and studies of population genetic structure of tree peony.

Anthocyanins from mulberry fruits are used in medicine. However, little anthocyanin can be detected in other tissues and sometimes also mulberry fruits are colorless. The aim of this study was to investigate which gene or genes have the strongest correlation with the anthocyanin biosynthesis. The expression of several anthocyanin synthesis genes were determined in different tissues of two white and two purple fruit cultivars. Genes encoding dihydroflavonol reductase (MaDFR) and anthocyanidin synthase (MaANS) showed a high expression only in fruit tissue of purple-fruit cultivars. During the development of mulberry fruits, the anthocyanin content was well correlated with the transcripts abundance of MaDFR, MaANS, and MaCHS (encoding chalcone synthase). The skin of female mulberry flowers turns red under irradiance because of up-regulated expressions of MaCHS, MaDFR, and MaANS. These three genes may control the anthocyanin biosynthesis in mulberry and up-regulation of them may greatly increase the anthocyanin content.

Water transport across the cell membranes is regulated largely by a family of proteins known as aquaporins (AQPs). Plasma membrane intrinsic protein (PIP) is an important subfamily of plant AQPs localized on the plasma membrane. To investigate the molecular mechanism of water regulation in seed germination, seven genes encoding PIP were initially cloned and sequenced from the germinating seed cDNA pool of Brassica napus. They belong to the PIP1 and PIP2 subfamilies. The transcription of the seven cloned genes plus three previously identified AQP genes from B. napus were analyzed in different organs and different stages of seed germination by quantitative real-time PCR (qRT-PCR). The results show that the expressions of the ten AQP genes were lower or scarcely detected in dry seeds, but were up-regulated during germination as well as in young seedlings. In addition, the expression of these ten AQP genes in response to an abiotic stress during seed germination was investigated and the results also show differential responses to abiotic stress treatments. Our findings suggest that these ten genes play different roles during plant development and response to abiotic stresses in B. napus.

Understanding the basis of the genetic variations responsible for the complex traits found in Eucalyptus cladocalyx under arid environmental conditions is crucial for designing genetic architecture studies. Forty-five half-sib families from Australia were used to identify inter-simple sequence repeat (ISSR) markers that are associated with growth (height, diameter at breast height, and stem straightness), flowering traits (flowering intensity, flowering precocity, reproductive capacity, and late flowering) and tree survival under arid conditions in southern Atacama Desert, Chile. Each DNA pellet consisted of a pool of five trees from each family. ISSR markers were associated with all the traits studied and accounted for 9.8 to 23.4 % of the phenotypic variation. Several loci were associated with more than one trait. For example, UBC_{810(450-500 bp)}, ISO_{1(600-610 bp)}, and TGT_{9(780-800 bp)} were associated with three of the traits studied. These identified genomic regions may contribute to the increase of the efficiency of the conventional tree breeding program for E. cladocalyx.