Scientists from VIB at Ghent University have succeeded in converting annual
plants into perennials.
They discovered that the deactivation of two genes in annuals led to the
formation of structures that converted the plant into a perennial. This was
most likely an important mechanism in plant evolution, initiating the
formation of trees.

Annuals and perennials

Annual crops grow, blossom and die within one year. Perennials overwinter
and grow again the following year. The life strategy of many annuals
consists of rapid growth following germination and rapid transition to
flower and seed formation, thus preventing the loss of energy needed to
create permanent structures. They germinate quickly after the winter so that
they come out before other plants, thus eliminating the need to compete for
food and light. The trick is basically to make as many seeds as possible in
as short a time as possible.

Perennials have more evolved life strategies for surviving in poor
conditions. They compose perennial structures such as overwintering buds,
bulbs or tubers. These structures contain groups with cells that are not yet
specialised, but which can later be converted when required into new organs
such as stalks and leaves.

The flowering of annuals

Annual crops consume all the non-specialised cells in developing their
flowers. Thus the appearance of the flower signals means the end of the
plant. But fortunately they have left seeds that sense ? after winter ? that
the moment has come to start up. Plants are able to register the lengthening
of the days. With the advent of longer days in the spring, a signal is sent
from the leaves to the growth tops to activate a limited number of
blooming-induction genes.

Deactivating two genes

VIB researchers, such as Siegbert Melzer in Tom Beeckman's group*, have
studied two such flower-inducing genes. They have deactivated them in thale
cress (Arabidopsis thaliana), a typical annual. The VIB researchers found
that mutant plants can no longer induce flowering, but they can continue to
grow vegetatively or come into flower much later. Melzer had found that
modified crops did not use up their store of non-specialised cells, enabling
perennial growth. They can therefore continue to grow for a very long time.

As with real perennials these plants show secondary growth with wood
formation creating shrub-like Arabidopsis plants.

Raising the veil of evolution

Researchers have been fascinated for a long time by the evolution of
herbaceous to woody structures. This research clearly shows only two genes
are in fact necessary in this process. This has probably been going on
throughout the evolution of plants. Furthermore it is not inconceivable this
happened independently on multiple occasions.

Relevant scientific publication

The research appears in the leading journal Nature Genetics (Siegbert Melzer
et al., Flowering-time genes modulate meristem determinacy and growth form
in Arabidopsis thaliana).

Funding

This research was financed by VIB, UGent, IWT, FWO.

* Tom Beeckman is in charge of the Root Development research group in the
VIB Plant Systems Biology department, UGent ? under the management of Dirk
Inzé.

About VIB
VIB is a non-profit research institute in life sciences. Approximately 1100
scientists and technicians perform basic research into the molecular
mechanisms that are responsible for the functioning of the human body,
plants and micro-organisms. By means of a strong partnership with four
Flemish universities ? UGent, K.U.Leuven, Universiteit Antwerpen and Vrije
Universiteit Brussel ? and a robust investment programme, VIB bundles the
strengths of 65 research groups into one institute. Their research aims at
fundamentally pushing out the boundaries of our knowledge. With its
technology transfer activities VIB aims to convert research results into
products for the consumer and the patient. VIB develops and disseminates a
broad range of scientifically based information on all aspects of
biotechnology. More information on www.vib.be.

About the Universiteit Gent
The Universiteit Gent (UGent) is one of the largest Dutch-speaking
universities, with more than 30,000 students. The course options include
almost all academic courses that are offered in Flanders.

The UGent prides itself on being an open, socially engaged and pluralistic
university with an international perspective. More information on
www.ugent.be
www.checkbiotech.org