Biomedical subjects

Giovanni Mele

Publications and source records attributed to Giovanni Mele.

4 recordsLinked to original sources

PubMed2004

The role of knox genes in plant development.

knox genes encode homeodomain-containing transcription factors that are required for meristem maintenance and proper patterning of organ initiation. In plants with simple leaves, knox genes are expressed exclusively in the meristem and stem, but in dissected leaves, they are also expressed in leaf primordia, suggesting that they may play a role in the diversity of leaf form. This hypothesis is supported by the intriguing phenotypes found in gain-of-function mutations where knox gene misexpression affects leaf and petal shape. Similar phenotypes are also found in recessive mutations of genes that function to negatively regulate knox genes. KNOX proteins function as heterodimers with other homeodomains in the TALE superclass. The gibberellin and lignin biosynthetic pathways are known to be negatively regulated by KNOX proteins, which results in indeterminate cell fates.

Gene Expression Regulation, Developmental↗

PubMed2003

Isolation and characterization of a maintenance DNA-methyltransferase gene from peach (Prunus persica [L.] Batsch): transcript localization in vegetative and reproductive meristems of triple buds.

A cDNA coding for a DNA (cytosine-5)-methyltransferase (METase) was isolated from peach (Prunus persica [L.] Batsch) and the corresponding gene designated as PpMETI. The latter encoded a predicted polypeptide of 1564 amino acid residues and harboured all the functional domains conserved in the maintenance METases group type I. PpMETI was a single copy in the cultivar Chiripa which was used as a model in the present study. Expression analyses revealed that PpMETI transcripts were more abundant in tissues with actively proliferating cells such as apical tips, uncurled leaves, elongating herbaceous stems, and small immature fruits. Peach plants bear bud clusters (triads or triple buds), consisting of two lateral and one central bud with floral and vegetative fates, respectively. PpMETI in situ hybridization was performed in triple buds during their entire developmental cycle. High and low levels of PpMETI transcript were related to burst and quiescence of vegetative growth, respectively. Message localization distinguished lateral from central buds during the meristem switch to the floral phase. In fact, the PpMETI message was abundant in the L1 layer of protruding domes, a morphological trait marking the beginning of floral transition. The PpMETI transcript was also monitored during organ flower formation. Altogether, these data suggest a relationship between DNA replication and PpMETI gene expression.

Animals↗

PubMed2003

The knotted1-like homeobox gene BREVIPEDICELLUS regulates cell differentiation by modulating metabolic pathways.

Members of the KNOX gene family have important roles in plant meristems by regulating cell division and differentiation. BREVIPEDICELLUS (BP), one of seven KNOX genes in Arabidopsis, has a primary role in internode patterning. We carried out a comparison of RNA expression profiles between wild-type seedlings and bp mutants at a developmental stage prior to a visible phenotypic difference. Transcript differences were found for a number of genes in cell wall biosynthesis, especially genes in the lignin pathway. The regulation of lignin biosynthesis by BP was demonstrated by observing increased lignin deposition in bp mutants following bolting, decreased lignification in plants overexpressing BP, and aberrant lignin deposition in discrete regions of the bp stem. Furthermore, we showed that BP binds promoters of some genes in the lignin pathway. Our results provide a metabolic fingerprint for BP and identify the lignin pathway as one of the coordinate processes that BP regulates.

Arabidopsis↗

PubMed2003

Expression profiling of plant development.

Microarrays have been used to study the response of plants to many signals, including light, hormones and transcription factors. The results in each case can give an overall view of the global response to the signal or identify direct targets of the signal, and can reveal new links between different signaling pathways.

Gene Expression Profiling↗