Showing papers by "Leonardo Bruno published in 2009"

Role of geranylgeranyl reductase gene in organ development and stress response in olive (Olea europaea) plants

Abstract: The NADPH-dependent geranylgeranyl reductase gene (OeCHLP) was characterised in olive (Olea europaea L.). OeCHLP catalyses the formation of carbon double bonds in the phytolic side chain of chlorophyll, tocopherols and plastoquinones and, therefore, is involved in metabolic pathways related to plant productivity and stress response, besides to nutritional value of its products. The nuclear OeCHLP encodes a deduced product of 51kDa, which harbours a transit peptide for cytoplasm-to-chloroplast transport and a nicotinamide binding domain. Two estimated identical copies of gene are harboured per haploid genome of the cv. 'Carolea' used in the present study. Levels and cytological pattern of OeCHLP transcription were investigated by quantitative RT-PCR and in situ hybridisation. In line with the presence of ubiquitous tocopherols and/or chlorophyll, OeCHLP transcripts were present in various organs of plants. In leaves and fruits at different developmental stages, OeCHLP was differentially expressed in relation to their morpho-physiological features. An early and transient enhancement of gene transcription was detected in leaves of different age exposed to cold treatment (4 � C), as well as in fruits mechanically wounded. Moreover, OeCHLP transcriptslocallyincreasedinspecificcelldomainsoffruitsseverelydamagedbythepathogenBactroceraolea.Combined, these data show that OeCHLP expression early responds to biotic and abiotic stressful factors. Levels of tocopherols also increasedinleavesexposedtocoldconditionsandfruitsseverelydamagedbypathogen.Wesuggestthatgeneactivityunder stress condition could be related to tocopherol action.

The peach (Prunus persica [L.] Batsch) homeobox gene KNOPE3, which encodes a class 2 knotted-like transcription factor, is regulated during leaf development and triggered by sugars.

Abstract: Class 1 KNOTTED1-like transcription factors (KNOX) are known to regulate plant development, whereas information on class 2 KNOX has been limited. The peach KNOPE3 gene was cloned, belonged to a family of few class 2 members and was located at 66 cM in the Prunus spp. G1 linkage-group. The mRNA localization was diversified in leaf, stem, flower and drupe, but recurred in all organ sieves, suggesting a role in sap nutrient transport. During leaf development, the mRNA earliest localized to primordia sieves and subsequently to mesophyll cells of growing leaves. Consistently, its abundance augmented with leaf expansion. The transcription was monitored in leaves responding to darkening, supply and transport block of sugars. It peaked at 4 h after darkness and dropped under prolonged obscurity, showing a similar kinetic to that of sucrose content variation. Feeding leaflets via the transpiration stream caused KNOPE3 up-regulation at 3 h after fructose, glucose and sucrose absorption and at 12 h after sorbitol. In girdling experiments, leaf KNOPE3 was triggered from 6 h onwards along with sucrose and sorbitol raise. Both the phloem-associated expression and sugar-specific gene modulation suggest that KNOPE3 may play a role in sugar translocation during the development of agro-relevant organs such as drupe.