Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 3.27

EXPRESSION OF THE VITREOSCILLA HEMOGLOBIN (VHb)-ENCODING GENE IN TRANSGENIC WHITE POPLAR: BIOCHEMICAL CHARACTERIZATION AND EFFECTS ON PLANT GROWTH RATE AND BIOMASS PRODUCTION

S. ZELASCO*, S. REGGI**, S. BISOFFI*, C. BONGIORNI***, P. CALLIGARI*, A. BALESTRAZZI****, C. FOGHER***, M. CONFALONIERI*****

*) Istituto di Sperimentazione per la Pioppicoltura, MiPAF, Casale Monferrato (AL)

**) Plantechno Srl, Casalmaggiore (CR)

***) Istituto di Genetica Vegetale - UCSC, Piacenza

****) Dipartimento Genetica e Microbiologia, Pavia

*****) Istituto Sperimentale per le Colture Foraggere - MiPAF, Lodi

biomass production, hemoglobin, genetic engineering, Populus, Vitreoscilla

Increasing growth rate, biomass production and wood quality of trees represent a main goal in most breeding programs worldwide. Constitutive over-expression of genes encoding proteins involved in the aerobic cellular metabolism is one of the strategies proposed to modify and improve these important agronomic traits. We describe a first attempt to increase vegetative growth and yield production in transgenic poplar by expressing a Vitreoscilla (VHb) hemoglobin-like protein. A chimeric construct consisting of the cauliflower mosaic virus 35S promoter and the coding region of the vhb gene was transferred into pBin19 for genetic transformation of white poplar (Populus alba L.) via Agrobacterium tumefaciens. Southern blot analysis confirmed the presence of vhb sequence in poplar genome. Accumulation of vhb transcript was detected in transgenic leaf tissue by Northern blot analysis. In vitro growth measurements showed that vhb gene expression in transgenic poplar plants did not significantly affect their growth patterns, including stem elongation, leaf enlargement, and shoot and root biomass. Transgenic VHb poplar lines displayed different levels of growth and biomass production in the greenhouse. Two of the selected transgenic lines showed significantly higher values for stem diameter, number of stem nodes and internodes, and exhibited enhancement of growth and biomass production when compared to the control plants. Transgenic plants showed higher chlorophyll a, b, and total protein contents compared to wild-type plants. In contrast, there were also two transgenic lines that revealed plant growth performances in greenhouse significantly lower than the control plants. Our results show that VHb expression in transgenic poplar can have erratic effects since it did not always result into enhancement of plant growth and biomass production. However, the promising results reported for some of the transgenic poplar lines and other plant species strongly indicate the potential future application of this approach to enhance these commercially important traits in breeding programs.