Research on Olive Biodiversity Is Key to Tackling Climate Change

Identifying traits that allow olives to resist extreme weather events, volatile temperature changes and diseases will allow farmers to plant more resilient olive varieties in the future.

Investigating olive trees in the nursery (Photo: Claudio Cantini)
Feb. 8, 2022
By Ylenia Granitto
Investigating olive trees in the nursery (Photo: Claudio Cantini)

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In recent years, there has been increas­ing inter­est in char­ac­ter­iz­ing and cat­a­loging the olive vari­eties,” said Claudio Cantini, the head of the Institute for BioEconomy of the National Research Council’s (IBE-CNR) Santa Paolina exper­i­men­tal farm, in Follonica.

This led to the cre­ation of large col­lec­tions like ours, which includes over 1,000 acces­sions, flow­ing into the world olive germplasm bank estab­lished by United Nations Food and Agriculture Organization (FAO) and sup­ported by the International Olive Council,” he added.

On the basis of the pre­lim­i­nary find­ings, we are already able to hypoth­e­size an ideal olive tree.- Claudio Cantini, lead researcher, Santa Paolina exper­i­men­tal farm

Santa Paolina was estab­lished in 1966 to pre­serve plant bio­di­ver­sity and hosts impor­tant vari­etal col­lec­tions of pear, peach, per­sim­mon, apple and quince, along­side olives. In addi­tion, it includes a pre­mul­ti­pli­ca­tion cen­ter of cer­ti­fied olive plant mate­r­ial and a facil­ity for the reha­bil­i­ta­tion of olive trees affected by virus dis­eases.

See Also:Researchers Work to Identify Olive Varieties Best Adapted to Higher Temperatures

The germplasm banks are very vast, and yet the world’s vari­etal rich­ness is far from being com­pletely cat­a­loged,” Cantini said.

He recalled that the olive tree species – Olea Europaea – has more than 2,000 known vari­eties, of which about 540 are native to Italy, the coun­try with the rich­est olive bio­di­ver­sity.

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Let’s just think about the sev­eral minor vari­eties, espe­cially those recently redis­cov­ered, which still have to be stud­ied and char­ac­ter­ized,” Cantini said. We can say that the grow­ing inter­est of oper­a­tors, eager to test new vari­eties in order to improve their olive oil pro­duc­tion, is push­ing in favor of this research.”

At this stage, the germplasm banks, where researchers store the genes that cor­re­spond to the dif­fer­ent char­ac­ter­is­tics of the olive vari­eties, take on cru­cial impor­tance: they can pro­vide the farm­ing sec­tor a greater choice of plants, espe­cially in light of cli­mate change.

The olive germplasm banks, vast col­lec­tions of genetic diver­sity, are becom­ing a fun­da­men­tal resource,” Cantini said. It goes with­out say­ing that pre­serv­ing bio­di­ver­sity is a pri­or­ity at this moment, as it is fun­da­men­tal for the qual­ity of ecosys­tems.”

Thus, the more we char­ac­ter­ize our vast olive bio­di­ver­sity, the more we can ade­quately enhance it and use it to cope with the new chal­lenges ahead,” he added.

Research on olive bio­di­ver­sity can help find new ways to mit­i­gate the effects and cope with extreme weather events, sud­den tem­per­a­ture changes and water stress, all of which occur with increas­ing fre­quency and cre­ate the con­di­tions for the devel­op­ment of dis­eases.

Cantini is cur­rently super­vis­ing a research group of PhD stu­dents study­ing the resis­tance of olive vari­eties to these envi­ron­men­tal stresses.

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Photosynthesis assessment (Photo: Claudio Cantini)

Just as with the vari­a­tions in the human species, where there are resis­tance mech­a­nisms within some indi­vid­u­als and pop­u­la­tions, also within the olive tree species there may be char­ac­ters in the genome of the dif­fer­ent vari­eties that are diverse and there­fore can give diverse responses when the plant is under stressed con­di­tions,” Cantini said. I can say that when we delve into the sphere of olive vari­eties, a new whole world opens up.”

The research group is now work­ing on three pub­li­ca­tions about the stress caused by ultra­vi­o­let radi­a­tion.

We are study­ing the resis­tance of some vari­eties to the stress caused by lack of water,” Cantini added. Significant dif­fer­ences within the vari­eties are already emerg­ing, as we note very dif­fer­ent mech­a­nisms.”

The researchers are also con­sid­er­ing mor­pho­log­i­cal char­ac­ter­is­tics, includ­ing the water trans­port mech­a­nism while focus­ing on the anatomy of some vari­eties that have com­pletely dif­fer­ent trans­port ves­sels in size and shape. Besides the anatom­i­cal aspect, they also con­sider the for­ma­tion of some sub­stances.

If we look at what hap­pens inside these vari­eties when we put them under stress, we note the pro­duc­tion of var­i­ous sub­stances that in some way tend to coun­ter­act the stress,” Cantini said. Preliminary results revealed to us the pres­ence of a pro­tein, which is known in other species but not much stud­ied at this time, that would seem to rep­re­sent a con­ve­nient ele­ment in the olive tree.”

We are focus­ing on this pro­tein to under­stand if it can play a key role,” he added. Above all, we are look­ing into the inter­ac­tion between this pro­tein and the genome; there­fore, the action of the gene that is acti­vated, and pos­si­bly how this might be related to other char­ac­ter­is­tics of the plant, anatom­i­cally, and in other respects.”

The assump­tion is that within the diver­sity rep­re­sented by the numer­ous vari­eties from all over the world in the olive tree species, resis­tance mech­a­nisms may be exploited in the future.

Our goal, one of all researchers, is to iden­tify these mech­a­nisms,” Cantini said. To give an exam­ple with a well-known vari­ety, Leccino is resis­tant to Xylella fas­tidiosa and also to cold, and some bac­te­ria and fungi as well, which makes us think that there must be a unique mech­a­nism act­ing within this vari­ety.”

We have then intro­duced Leccino in our stud­ies, together with other vari­eties that, instead, have dif­fer­ent sus­cep­ti­bil­i­ties, and we are ver­i­fy­ing what hap­pens within these vari­eties,” he added.

The aim is to have a data­base with a wealth of infor­ma­tion, through which researchers can not only char­ac­ter­ize exist­ing vari­eties that are ready to be used but also cre­ate new ones.

On the basis of the pre­lim­i­nary find­ings, we are already able to hypoth­e­size an ideal olive tree,” Cantinti said.

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Measuring chlorophyll and nitrogen (Photo: Claudio Cantini)

His group extrap­o­lated four model plants from the Santa Paolina data­base for their study.

We are try­ing to fig­ure out what hap­pens when we put these model plants under stress,” he said. So, for exam­ple, let’s sup­pose we have a cold-resis­tant vari­ety and a non-cold-resis­tant vari­ety, which have respec­tively wide and nar­row trans­port ves­sels, one being resis­tant to Xylella and one non-resis­tant. We put them under water stress; we note that the mech­a­nism of how the plants relate to envi­ron­men­tal stresses changes com­pletely accord­ing to their vari­ety, and this is found at the cel­lu­lar and genetic level.”

Then, for exam­ple, if we iden­tify a pro­tein like the one above­men­tioned, we access the data­base and check the lev­els of this pro­tein within each vari­ety,” Cantini added. If we find out that a gene is acti­vated, we go and see which vari­ety has a high acti­va­tion. If this hap­pens, this is con­sid­ered as a marker.”

We can have pro­tein, genetic or phys­i­o­log­i­cal mark­ers, that can also be seen in seedlings,” he con­tin­ued. We then can make cross­ings, look for that marker in all the sib­lings and select only those who have that marker, which will be taken into account in the sub­se­quent stud­ies. A con­sis­tent num­ber of mark­ers allow us either to redis­cover old vari­eties, which were set aside by farm­ers over the cen­turies or to develop new ones.”

Currently, the IBE researchers are car­ry­ing out the genetic fin­ger­print­ing of 1,200 olive trees, includ­ing vari­eties and acces­sions, which are part of the Santa Paolina col­lec­tion.

We believe that start­ing from an in-depth screen­ing of the col­lec­tions, and a far-sighted vision of play­ers, these stud­ies could lead to inter­est­ing dis­cov­er­ies for the treat­ment and pre­ven­tion of cer­tain plant patholo­gies in the near future,” Cantini con­cluded.


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