Section 1 Vine Biotechnology

**3**

**Chapter 1**

**Abstract**

**1. Introduction**

along vegetative axes.

*and Laurent Torregrosa*

The Microvine: A Versatile Plant

in Physiology and Genetics

*Anne Pellegrino, Charles Romieu, Markus Rienth* 

Model to Boost Grapevine Studies

The microvine is a grapevine somatic variant. The Vvgai1 mutation results in a miniaturization of the vegetative organs of the plant keeping fruit size intact and a systematic conversion of tendrils into inflorescences. The physiological characterization of the vegetative and reproductive development of the microvine makes it possible to infer kinetic data from spatial phenotypes. This biological model allows experiments on vine and grape development in tightly controlled conditions, which greatly accelerate physiology, molecular biology, as well as genetic studies. After introducing the main biological properties of the microvine, main results from various research programs performed with the microvine model will be presented.

**Keywords:** research tools, microvine, grapevine model, physiology, genetics

of normal vines slow down advances in genetics and breeding.

As a perennial fruit crop, the grapevine (*Vitis vinifera*) needs a long juvenile period before the reproductive cycle starts. Even vine cuttings from adult plants allow the production of fruits only from the second year. Moreover, during the adult phase, common cultivars produce reproductive organs only once per growing cycle (generally once per year) and per proleptic axis. These biological features, together with the large size of an adult vine, represent major drawbacks for precise physiological, ecophysiological, and omics experiments on the plant and fruit development under well-controlled conditions. Furthermore, those characteristics

The microvine ML1 is a somatic variant obtained though somatic embryogenesis from Pinot Meunier cultivar. This phenotype results from a somatic mutation in the *Vvgai1* gene involved in gibberellin signaling. The mutation is originally present at the heterozygous state in the epidermal cells of Pinot Meunier, being responsible for its well-known hairy phenotype. However, the introduction of the mutation in all cell layers resulted in a miniaturization of all vegetative organs and in a conversion of tendrils into inflorescences, which leads to a continuous flowering and fruiting

The small size of the microvine renders this grapevine model very convenient for experiments in usual growth chambers, where a tight control of environmental factors (radiation, vapor pressure deficit (VPD), temperature, water and nutrient
