The plant hormone jasmonate (JA) functions as a defense signal to regulate plant defense against insect attack and pathogen infection. It also acts as a developmental signal to regulate plant development and growth, including root growth, stamen development, trichome initiation, and leaf senescence. The JA receptor CORONATINE INSENSITIVE1 (COI1) perceives JA signals for interaction with JASMONATE-ZIM-DOMAIN (JAZ) proteins and subsequent ubiquitination of JAZs, thereby regulating the JA responses. The single mutants of the bHLH subgroup IIId factors (bHLH3, bHLH13, bHLH14 and bHLH17), which interact with JAZs, show no obvious phenotype in resistance to the fungus Botrytis cinerea and defense against the herbivore Spodoptera exigua. However, the quadruple mutant shows enhanced resistance to B. cinerea and defense against S. exigua. We investigated whether the overexpression of bHLH17 in Arabidopsis affected the resistance to B. cinerea and defense against S. exigua. Similar to the JA receptor mutant coi1-1, Arabidopsis bHLH17-overexpressing plants were more susceptible to B. cinerea and S. exigua than the wild type. As compared with the wild type, bHLH17 overexpression attenuated the JA-inducible expression of defense- or wounding-related genes, such as Thi2.1, VSP2, AOS, JAZ1, JAZ9 and JAZ10. Further transient expression analysis revealed that the N-terminus of bHLH17 was essential for its transcriptional repression function. Overexpression of bHLH17 negatively regulates plant defense against B. cinerea and S. exigua.

The four conserved guanine-base-binding motifs of Rab GTPase―G1, G3, G4 and G5―are involved in the binding and hydrolysis of GTP. We obtained the full-length coding sequence of the Arabidopsis thaliana RabD2b mutant allele AtRabD2b^[N121I] within the conserved G4 motif by changing asparagine 121 to isoleucine and studied the effects of N121I mutation on the sublocalization and functions of AtRabD2b. The N121I mutation altered the specific localization of AtRabD2b from Golgi stacks to both Golgi and cytoplasm. AtRabD2b could completely complement the functional defect induced by the mutation of Saccharomyces cerevisiae Ypt1, which is homologous to AtRabD2b in yeast. However, At-RabD2b^[N121I] only partly complemented the function of Ypt1. AtRabD2b^[N121I] transgenic A. thaliana showed dwarf, bushy, sterile and necrotic phenotypes, which differed from that of AtRabD2b-overexpressing Arabidopsis with its abnormal main-inflorescence extension phenotype. The N121I mutation alters the subcellular localization of AtRabD2b and affects its normal functions.

A fragile and leaf-tip dead mutant, fld1, was identified from the progeny of the restorer line Jinhui10 with seeds treated with ethyl methanesulfonate (EMS). The mutant showed stable inherited traits of brittleness as well as dry and withered leaf tip throughout development. Besides showing significantly decreased mechanism strength, in fld1, cellulose and lignin content in culm occupied only 67.92% and 50.16% of that in the wild type, for a significant difference. The content of photosynthetic pigment was lower in fld1 than the wild type, as was that of carotenoid. Photosynthetic parameters of photosynthetic rate (P_n), stomatal conductance (G_s) and transpiration rate (T_r) were lower and intercellular CO₂ concentration (C_i) were higher in fld1 than the wild type. The mutational traits of brittleness and dead leaf-tip were co-segregated and controlled by one recessive nuclear gene. The FLD1 gene was mapped on chromosome 9 between Indel markers Ind09-2 and Ind09-3 with 215 kb physical distance with F₂ groups of Xinong 1A/fld1 and fld1/Nipponbare. The restricted region has 33 annotated genes. These results provide a stable foundation for FLD1 gene cloning and its application in molecular breeding.

We used CHIPS, CUSP and Codon W online programs to confirm the codon bias of the complete coding sequence of PPDK in the grain Amaranthus hypochondriacus, then compared the codon bias with PPDK genes from different plant species. We constructed a phylogenetic tree based on codon bias to provide a basis for selecting appropriate PPDK receptors for A. hypochondriacus by high-photosynthesis gene engineering. PPDK in A. hypochondriacus and several other dicotyledonous crops was biased toward synonymous codons with A and T at the third codon position, but Zea mays, Oryza sativa and other monocotyledons use the end of the G or C codon. Phylogenetic analysis suggested that PPDK of A. hypochondriacus was evolutionarily closer to dicotyledons such as Solanum tuberosum and Medicago truncatula than the monocotyledons Z. mays, Sorghum bicolor and Echinochloa crusgalli. However, O. sativa is an exception in that the codon bias of PPDK is closer to that of dicotyledons A. hypochondriacus than the monocotyledons Z. mays or S. bicolor. To select the appropriate protein expression system, we compared the PPDK codon bias expression in A. hypochondriacus and Escherichia coli or yeast. Differences between A. hypochondriacus and yeast expression were less than between A. hypochondriacus and E. coli. The yeast system may be more suitable for expressing PPDK of A. hypochondriacus.

We cloned a proline dehydrogenase gene from Celastrus orbiculatus using degenerate primers and RACE and named it NstProDH1. Sequence alignment showed that NstProDH1 has high sequence similarity with corresponding genes from Arabidopsis and tobacco. Enzymatic characteristic analysis identified the activity of proline dehydrogenase. Comparison of gene expression patterns and proline dehydrogenase activity were not associated in different organs, so NstProDH1 was regulated by transcription and translation. The gene expression pattern of NstProDH1 was similar to that of Arabidopsis ProDH1, therefore NstProDH1 may be functionally similar to Arabidopsis ProDH1.

MADS-box gene is a key transcription factor that plays crucial roles in plant development, especially controlling the formation and development of floral organs. We cloned the flower-specific gene from floral organs of Ananas comosus, named AcMADS1 (GeneBank accession no. KC257408), was cloned by homology-based cloning and RACE. The open reading frame of AcMADS1 was 726 bp, encoding 241 amino acids with molecular weight 27.5 kDa and isoelectric point 9.26. Sequence alignment and phylogenetic tree analysis indicated that the deduced protein AcMADS1 contained a conservative MADS-box and semi-conservative K domain and belonged to the AGL6 clade of the MADS-box family. Bioinformatics analysis demonstrated that AcMADS1 was an alkaline and hydrophilic protein; the secondary structure comprised an α-helix, a random coil and an extended strand; the protein core structure agreed with the transcription factors and the function of the common DNA combining domain MADS-box in its protein 3D model and was located in the nucleus as a transcription factor. Tissue-specific analysis showed that AcMADS1 was expressed in floral organs (pistils, petals and sepals) and flesh of pineapple, with nearly no transcription detected in vegetative organs (roots, stems and leaves) and stamens. Furthermore, the expession of AcMADS1 was higher at the early phase of floral development, then reduced at the late phase. AcMADS1 may have important roles in floral induction and floral development of pineapple.

Tomato zonate spot virus (TZSV) and Potato virus Y (PVY) commonly co-infect the same plant under natural conditions. We compared the pathological characterization resulting from mixed and single infection of tobacco. Cells with mixed infection showed increased number of TZSV particles, and the particles clustered into the vesicles to form inclusion bodies, which cross-distributed in the cytoplasm with pinwheel and laminated inclusions and particles. The number of mitochondria was increased. The structure of mitochondria, chloroplasts, and the nucleus maintained relative integrity. The number of particles, inclusion bodies, and inclusions was increased but did not cause more severe damage on the subcellular structure when TZSV or PVY co-infected the same tobacco plant. A synergism may exist among TZSV, PVY and the plant host during co-infection.

We used DNA barcoding to identify the species of Pinellia and its adulterants, to authenticate medicinal plants of Pinellia. In this study, the matK region was amplified and sequenced for Pinellia ternata and its adulterants. The intraspecific and interspecific variation and barcoding gap were analyzed for ITS, ITS2, psbA-trnH, rbcL, matK region combined with GenBank database information, and the identification efficiency was evaluated based on Nearest Distance and BLAST1 methods. The results shown that matK region had the largest interspecific variation, and the rbcL region owned the smallest intraspecific variation. The rbcL region possessed the smallest overlap of intra- and interspecific genetic variation, followed by the matK region. Neighbor-joining tree of regions could divide species obviously. In conclusion, DNA barcoding could be used to accurately identify medicinal plants of Pinellia and its adulterants. The region of matK and rbcL was the ideal barcode combination for identifying the species of Pinellia and its adulterants.

Plants contain about 12 000 kinds of alkaloids. Alkaloids belong to small-molecule nitrogen heterocyclic compounds. The metabolic pathways of alkaloids are controlled by specific enzymes, and the locations of some key enzymes can determine the cellular and subcellular structure of specific cells where synthesis, transport and storage of alkaloid take place. Here we summarize findings for the isoquinoline alkaloid sanguinarine in biosynthesis, transport and storage functions at the cellular and subcellular levels. Biosynthesis of isoquinoline alkaloids mainly occurs in the cortex, sieve tubes, companion cells, and latex tubes. Vesicles, vacuoles, cytoplasmic matrix, microsomes, endoplasmic reticulum, and chloroplast thylakoid are involved in transport and storage. We discuss related results of several other types of alkaloids found in medicinal plants.

Leaves are important organs for plant photosynthesis. Their senescence is triggered by external environmental stimuli and internal developing signals and are precisely controlled by complex gene regulatory networks. Recent studies have shown that the aging process is adjusted at the epigenetic level by reprogramming gene expression. In this review, we briefly introduce epigenetic molecular mechanisms and address recent advances in leaf senescence regulation through histone modification, chromatin remodeling and small RNA pathways, while presenting existing problems and future directions in the field.

Nelumbo plants contain edible and pharmaceutical products; nelumbinis folium, rhizomatis nodus, semen, plumula, receptaculum, and stamen are all used in medicine. The efficacy of the medicine varies greatly between different parts. In total, 61 flavonoids, including 8 anthocyanins, 2 flavonols, 29 flavonol glycosides, 1 flavone, 16 flavone glycosides (13 C-glycosyl flavones) and 5 flavanols, have been identified in various lotus tissues. These flavonoid compounds are widely used in the health-food and medicine industries. This paper summarizes the recent progress in the detection and purification, composition, content and pharmacological studies of flavonoids in different Nelumbo tissues, comprising lotus leaves, petals, stamens, pistils, tori, leaf veins, leaf stalk, flower stalk, seed pods, seed coats, kernels, plumules and rhizome. Petals and stamens possess plentiful quercetin and kaempferol glycosides; quercetin glycosides are dominant components in other tissues except for plumules. Abundant C-glycosyl flavones were identified in plumules. In addition, the total content of flavonoids was significantly high in leaves. HPLC-DAD and HPLC-ESI-MSⁿ are becoming the main detection methods because of their high sensitivity and accuracy. The most effective method for separating and purifying the single compound is high-speed counter-current chromatography (HSCCC). Because of the wide range of biological activities of Nelumbo tissues, including antioxidant, antibiotic, anti-HIV, anti-atherothrombotic, anti-inflammatory and anti-obesity properties, promoting the comprehensive study and development of the nutritional and pharmacodynamic material in each tissue is important.