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 - 1.33

GENETIC ANALYSIS OF NEW VIVIPAROUS MUTANTS OF MAIZE

A. GIULINI*, G. CONSONNI*, F. DALLA VECCHIA**, N. RASCIO**, N. LA ROCCA**, R. PILU*, S. STEFANELLI***, R. TUBEROSA***, G. GAVAZZI*

*) Department of Crop Production, Via Celoria 2, 20133 Milano, Italy

**) Department of Biology, Via Colombo 3, 35121 Padova, Italy

***) Department of Agroenvironmental Sciences and Technology, Via Farin 44, 40127 Bologna, Italy

abscisic acid, maize, viviparous mutants

Abscisic acid (ABA) regulates many agronomically important aspects of plant development, in cluding the sinthesis of seed storageAbscissic acid (ABA) regulates many agronomically important aspects of plant development, including synthesis of seed storage proteins and lipids, promotion of seed desiccation tolerance and dormancy. In addition, ABA mediates some physiological responses to environmental stresses such as stomatal closure, or induction of tolerance to water. Mutants, altered in ABA metabolism, provide a good opportunity to identify which functions at the molecular, biochemical, cellular and/or whole plant level are affected by impaired ABA biosynthesis or sensitivity.

We selected out of a large sample of vp mutants, originated in our lab or received from other scientists, four mutants yielding green seedlings. The majority of the vp mutants in maize are associated to white or pale yellow endosperm and seedling because they are due to a mutational event occurring in the first part of the biosynthetic route that is shared by ABA biosynthesis and carotenogenesis.

The mutants thus selected and provisionally symbolized vp374*, vp390*, vp105*, vp D*, affect in downstream steps of the biosynthesis or they represent regulatory genes involved in the perception and/or transduction of ABA signal.

They were intercrossed to establish their allelism relationship and crossed to vp1, a regulatory gene of the ABA signal and to vp13, a mutant specific of the ABA biosynthesis.

Double mutants vp1/vpD* and vp1/vp105* were also tested. We will present data on their response to exogenous ABA, on their endogenous ABA content, on their pattern of ABA inducible genes during embryo maturation.

Their analysis will be extended to vegetative tissues to establish how the mutation affects water loss and stomatal aperture with the aim to establish whether the genes under study are specifically expressed during embryogenesis or if they are also important during vegetative growth.