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Lab equipment. © INRA, William Beaucardet

Green biotechnologies: paving new paths for agriculture

In vitro culture methods

There are many in vitro breeding technologies, including meristem cultures, embryo cultures, protoplast fusion, doubled-haploid method, in vitro reproduction and embryo rescue. They are all based on a property that is unique to the plant kingdom: the totipotency of plant cells. That is, the capacity of a cell taken from any plant organ to reproduce an entire plant identical to the parent.

In vitro reproduction: the origin of many crops

In vitro culture © JAY-ALLEMAND Christian
In vitro culture © JAY-ALLEMAND Christian
In the 1950s, research at INRA conducted by Pierre Limasset, Pierre Cornuet, Georges Morel and Claude Martin showed that meristem cultures led to the production of virus-free plants. The technique has been applied to many species, including ornamental plants (dahlia, orchid, etc.), market produce (potatoes), and fruit (raspberry), whose development has been historically beset with viral disease. To this day, meristem culture is the only technique that guarantees healthy yields of sugar cane, manioc, yam and banana in tropical zones where disease is particularly prevalent.

Meristem cultures soon led to breeding by microcuttings, which speeds things up considerably. That is how in vitro plant breeding was introduced at INRA in France. Since 1988, over 450 plant species have been micro-propagated. One of the latest results, herbaceous grafting developed for grape vines, was patented in 1986 (INRA-Mumm Perrier Jouet patent) and is now being applied to various species such as citrus fruits and ornamental plants such as mimosa and roses.

A groundbreaking discovery based on protoplast fusion

In 1994, INRA and Serasem registered the first hybrid rapeseed variety in France: Synergy. Hybrids yield more productive plants that have multiple uses. However, rapeseed being a hermaphrodite plant, the large-scale production of hybrids was only made possible by a major innovation: the generation of a sterile male line by introducing male sterility from radish into rapeseed. The transfer of this trait, present in cytoplasm, was made possible by protoplast fusion. INRA researchers then isolated the cytoplasmic sterility gene, resulting in one of the most widely used INRA patents (Ogu-INRA, 1990). More recently, INRA researchers have isolated another gene that restores fertility. By crossing a sterile male line with a fertility-restoring line, fertile hybrids can be generated that produce seeds, and thus oil (patent R2000, 2003).

References:
- Cytoplasmic male sterility gene:
Bonhomme S., Budar F., Lancelin D., Small I., Defrance M-C., Pelletier G. 1992. Sequence and transcript analysis of the Nco2.5 Ogura-specific fragment correlated with cytoplasmic male sterility in Brassica cybrids. Mol Gen Genet. Nov;235(2-3):340-8.

- Fertility restoration gene:
Desloire S., Gherbi H., Laloui W., Marhadour S., Clouet V., Cattolico L., Falentin C., Giancola S., Renard M., Budar F., Small I., Caboche M., Delourme R., Bendahmane A. 2003. Identification of the fertility restoration locus, Rfo, in radish, as a member of the pentatricopeptide-repeat protein family.  EMBO Rep. 4:588-594.

From lab to factory: “milking plants”, a success story

Researchers at the Agronomy and Environment Joint Research Unit INPL (ENSAIA)-INRA in Nancy have developed an innovative way of growing plants without soil, combining in vitro breeding techniques in reactors and in-field. The technology is based on plants that secrete valuable molecules through their roots. They are grown in greenhouses, in suspended pots allowing their roots to protrude. The hanging roots are dipped into a solution with liquid nutrients, bringing out high-value molecules that are collected in successive rounds, allowing for three to eight harvests per year for one plant. A new term to describe the phenomenon was coined: “milking plants”.

The process, simple and cost-effective, led to the creation of a Start-Up in 2005: Plant Advanced Technologies.

Among the substances produced from milking plants are tropane alkaloids, used in pharmaceuticals (hyoscyamine and scopolamine, both sedatives), taxol and furocoumarins, used to treat psoriasis and some forms of cancer, and shikonin, a cosmetic dye.

The technology of milking plants won four awards in 2005:
- winner of Ministry of Research award (creativity category)
- winner of Plug and Start contest (Champagne, France)
- winner of “Tremplin-Entreprises” contest,  2005, Senate
- winner of “Entreprendre” contest in Lorraine

Contact(s)
Scientific contact(s):

Associated Division(s):
Environment and Agronomy, Plant Biology and Breeding
Associated Centre(s):
Versailles-Grignon, Grand Est - Nancy