Hybrid vines: adapting winemaking to climate change

Vit­i­cul­ture is threatened by cli­mate change, but wine­makers have sev­er­al ways to coun­ter­act this issue. They can adapt cul­tiv­a­tion tech­niques, for example by modi­fy­ing plant­a­tion dens­ity, by set­ting up irrig­a­tion sys­tems, or even by relo­cat­ing vines to pre­serve sim­il­ar cli­mate con­di­tions. How­ever, genet­ic solu­tions are also a prom­ising aven­ue which avoid the need to move vines to new loc­a­tions; a sig­ni­fic­ant advant­age for the wine sec­tor for which the notion of “terroir” [region where the wine is pro­duced] is very important.

Under­stand­ing the grapevine

There are spe­cif­ic genet­ic traits that are sought in vines which are more tol­er­ant to cli­mate change. These include tol­er­ance to hydric stress, res­ist­ance to an increase in tem­per­at­ures or the con­tin­ued pro­duc­tion of tar­tar­ic acid (a com­pound which ensures the grape’s acid­ity and con­trib­utes to the fla­vour of wine). It must be said that the object­ive is not to pro­duce a spe­cif­ic molecule or to use a well-char­ac­ter­ised gene, for example to increase res­ist­ance to a dis­ease. Fit­ness traits to cli­mate change are often com­plex, quant­it­at­ive, coded by sev­er­al genes which inter­act together.

Fur­ther­more, vines are to some extent double plants because they are made of both a scion and a root­stock. It is there­fore easy to under­stand the extent of the prob­lem. The scion is the upper part of the plant and its genet­ic mater­i­al is expressed through the fruits and leaves. The root­stock, on the oth­er hand, is the under­ground sec­tion and its genes con­trol the root sys­tem. Water stress tol­er­ance implic­ates both roots as well as leaves, and each of which are depend­ent on a dif­fer­ent genome.

Choos­ing characteristics

To identi­fy a scion/rootstock pair adap­ted to cli­mate change, one does not just sequence their two gen­omes and select the pairs car­ry­ing the most inter­est­ing genes. Our cur­rent state of know­ledge can­not pre­dict the beha­viour of a giv­en pair based only on the sequen­cing of a few tar­geted genes. How­ever, it is pos­sible to use genet­ics to high­light the rela­tion­ships between the genet­ic mater­i­al of a grape vari­ety and its char­ac­ter­ist­ics. To that end, we ana­lyse a large num­ber of grape vari­et­ies to identi­fy prom­ising pro­files. Our aim is to identi­fy molecu­lar mark­ers on the DNA cor­res­pond­ing to inter­est­ing char­ac­ter­ist­ics. We can then use these mark­ers to select vari­et­ies without need­ing to under­stand the whole com­plex­ity of the molecu­lar mech­an­ism. Sub­sequently, our genet­i­cists ensure that the desir­able traits are main­tained by study­ing the des­cend­ants of hybridisation.

The cre­ation of a vari­ety by selec­tion of gen­o­types is a long pro­cess. Ten to fif­teen years of research are some­times required, includ­ing the legis­lat­ive time­frames to assess a new grape vari­ety. Most French vine­yards are com­mit­ted to such under­tak­ings. Though they can­not pre­pare their adapt­a­tion in the face of cli­mate change, they can at least cul­tiv­ate vines that are more res­ist­ant to dis­eases such as mil­dew or oidium.

Cre­at­ing new varieties

This approach uses genet­ics to select the vines most res­ist­ant to the effects of cli­mate change. In the­ory, it is also pos­sible to cre­ate these vari­et­ies by using genet­ic engin­eer­ing tech­niques. How­ever, in prac­tice, the com­plex­ity of the tar­geted bio­lo­gic­al sys­tems makes this dif­fi­cult. We are far from plant­ing genet­ic­ally mod­i­fied vines. Oth­er tech­nic­al imped­i­ments also make it dif­fi­cult to imple­ment this bio­tech­no­logy. Genet­ic edit­ing tools, such as CRIS­PR-Cas9, are harder to use on plant gen­omes than on anim­al organ­isms. Moreover, we still lack the abil­ity to grow vines from just a cluster of cells.

Such prac­tices also seem to raise prob­lems for the con­sumer accept­ab­il­ity. Indeed, the modi­fic­a­tion of gen­omes is not an author­ised prac­tice for products sold in Europe and this con­sid­er­ably reduces com­mer­cial oppor­tun­it­ies. Like­wise, wine is a con­sumer product which is incom­pat­ible with poten­tially con­tro­ver­sial debates. Like all lux­ury products, its pro­duc­tion must not raise any questions.