Trees (Impact Factor: 1.65). 10/2009; 23(5):899-910. DOI: 10.1007/s00468-009-0331-2
The understanding of flower initiation, development, and maturation in mangosteen is of paramount importance to shorten its
long juvenile phase and to synchronize its flowering or fruiting time. In this study, we have identified 97 tentative unique
genes with higher expression levels in young flower buds compared to young shoots by using suppressive subtraction hybridization
and reverse northern analysis. Sequence analysis showed that 63.9% of these transcripts had non-significant matches to sequences
in the non-redundant protein database in GenBank, 19.6% had significant matches to unknown proteins while the remaining 16.5%
had putative functions in transcription, stress, signal transduction, cell wall biogenesis, photosynthesis and miscellaneous.
The full-length cDNA of GmAGMBP encoding AG-motif binding protein (a zinc finger transcriptional factor), and 3′ termini cDNA
sequences of GmHSA32 and GmBZIP, encoding heat-stress-associated 32 (HSA32) and bZIP transcription factor, respectively; were
cloned and further analysed. Real-time PCR analysis revealed that these three genes have different transcript profiles in
flowers of different developmental stages and young shoots. The highest abundance of transcripts was achieved in flowers with
diameters ranging from 0.5 to 0.9cm for GmAGMBP and GmBZIP and in flowers with diameters less than 0.5cm for GmHSA32. Southern
analysis suggested that GmAGMBP might be single copy gene while GmHSA3A could possibly belong to a small gene family in the
[Show abstract][Hide abstract] ABSTRACT: The 70-kD heat shock proteins (Hsp70s) have been shown to be important for protein folding, protein translocation, and stress responses in almost all organisms and in almost all subcellular compartments. However, the function of plastid stromal Hsp70s in higher plants is still uncertain. Genomic surveys have revealed that there are two putative stromal Hsp70s in Arabidopsis thaliana, denoted cpHsc70-1 (At4g24280) and cpHsc70-2 (At5g49910). In this study, we show that cpHsc70-1 and cpHsc70-2 could indeed be imported into the chloroplast stroma. Their corresponding T-DNA insertion knockout mutants were isolated and designated as Deltacphsc70-1 and Deltacphsc70-2. No visible phenotype was observed in the Deltacphsc70-2 mutant under normal growth conditions. In contrast, Deltacphsc70-1 mutant plants exhibited variegated cotyledons, malformed leaves, growth retardation, and impaired root growth, even though the protein level of cpHsc70-2 was up-regulated in the Deltacphsc70-1 mutant. After heat shock treatment of germinating seeds, root growth from Deltacphsc70-1 seeds was further impaired, indicating that cpHsc70-1 is important for thermotolerance of germinating seeds. No Deltacphsc70-1 Deltacphsc70-2 double mutant could be obtained, suggesting that the Deltacphsc70 double knockout was lethal. Genotype analyses of F(1) seedlings from various crosses indicated that double-knockout mutation was lethal to the female gametes and reduced the transmission efficiency of the male gametes. These results indicate that cpHsc70s are essential for plant development and the two cpHsc70s most likely have redundant but also distinct functions.
[Show abstract][Hide abstract] ABSTRACT: The vegetative and reproductive (flowering) phases of Arabidopsis development are clearly separated. The onset of flowering is promoted by long photoperiods, but the constans (co) mutant flowers later than wild type under these conditions. The CO gene was isolated, and two zinc fingers that show a similar spacing of cysteines, but little direct homology, to members of the GATA1 family were identified in the amino acid sequence. co mutations were shown to affect amino acids that are conserved in both fingers. Some transgenic plants containing extra copies of CO flowered earlier than wild type, suggesting that CO activity is limiting on flowering time. Double mutants were constructed containing co and mutations affecting gibberellic acid responses, meristem identity, or phytochrome function, and their phenotypes suggested a model for the role of CO in promoting flowering.
[Show abstract][Hide abstract] ABSTRACT: More than 200 years ago, Goethe proposed that each of the distinct flower organs represents a modified leaf . Support for this hypothesis has come from genetic studies, which have identified genes required for flower organ identity. These genes have been incorporated into the widely accepted ABC model of flower organ identity, a model that appears generally applicable to distantly related eudicots as well as monocot plants. Strikingly, triple mutants lacking the ABC activities produce leaves in place of flower organs, and this finding demonstrates that these genes are required for floral organ identity . However, the ABC genes are not sufficient for floral organ identity since ectopic expression of these genes failed to convert vegetative leaves into flower organs. This finding suggests that one or more additional factors are required [3, 4]. We have recently shown that SEPALLATA (SEP) represents a new class of floral organ identity genes since the loss of SEP activity results in all flower organs developing as sepals . Here we show that the combined action of the SEP genes, together with the A and B genes, is sufficient to convert leaves into petals.
Current Biology 03/2001; 11(3):182-4. DOI:10.1016/S0960-9822(01)00024-0 · 9.57 Impact Factor
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