Identification of the role of autophagy during fruit ripening and stress resistance in Strawberry: Autophagy manipulation as a way to improve Strawberry fitness

Periodic Reporting for period 1 - FrATGaria (Identification of the role of autophagy during fruit ripening and stress resistance in Strawberry: Autophagy manipulation as a way to improve Strawberry fitness)

Okres sprawozdawczy: 2019-04-04 do 2021-04-03

Cells are small factories producing essential components for life. At certain moments they must also recycle those components in order to transform them into new building blocks or energy. This recycling process, called autophagy, it is very important for the development of life beings. Since plants cannot move, their only way to counteract stressful situation such nutrients depletion or water shortages is by modifying their metabolism and making a more efficient use of the available resources. Autophagy, by the recycling of unneeded or superfluous cellular components, has an important role in their response to these stressful situations

Strawberry is one of the most important crops in the south of Spain, being the first producer in Europe early in the year. Along its ripening, the strawberry fruit undergoes a number of changes as increasing in size, increasing in sweetness, color change and softening due to degradation of cell wall components. The present situation of global warming it is already having an effect over Spanish climate, with longer and dryer summers. This situation will undoubtedly have an impact in the crop production so the increase in the knowledge about the processes that direct fruit ripening and resistance to stress is crucial in order to develop varieties with better performance against these situations.

Based on previous data from the host group, we thought that autophagy could be taking place during strawberry ripening and might have a role in stress resistance. Therefore, the main objective of this project was to study autophagy during the development of strawberry fruit, with special emphasis on maturation/ripening process and in the response to abiotic stress.

The work performed along this project can be divided in two main groups. On one hand, I have identified genes related with autophagy in the genome of the wild and cultivated strawberry (Fragaria vesca and Fragaria x ananassa), I have analyzed the expression of these genes along ripening, I have measured the level of two important autophagy related proteins and I have identified at the cellular level the presence of autophagy related structures. Furthermore, I have analyzed fruits in which autophagy has been blocked, either biochemically or genetically. On the other hand, I have worked towards the generation of strawberry plants with induced autophagy. I have identified two independent transgenic lines in which important ATG genes are overexpressed and I have analyzed the effect that this overexpression has over fruit development.

Our results show the following:

1. Autophagy is an active process during strawberry ripening.
2. Autophagy during strawberry ripening seems to be directly related with the fruit vasculature formation.
3. Two waves of autophagy induction can be found during strawberry ripening.
4. Autophagy is a required process for the development and ripening of strawberry fruit.
5. We have identified a transcription factor that seems to have a regulatory role in the onset of the autophagy pathway during strawberry fruit ripening.

The results generated by FrATGaria to date have been disseminated in one peer reviewed research article, four conferences and one press release.

At the beginning of the FrATGaria project, there was no information whatsoever regarding autophagy in strawberry plant and very little was known about the role of autophagy in the process of fruit ripening. In the context of this project, we have published the first paper about autophagy in strawberry, which is also the first paper that identifies the important role of autophagy for the ripening of a fleshy fruit.

Our results show that autophagy is induced at two stages of strawberry ripening, at the white stage and at red stage. The second induction could be related with the initiation of fruit senescence. Fruit senescence is a relevant process due to its role in postharvest quality and duration of the fruit. Our results and developed tools can help for the analysis of strawberry cultivars which could potentially lead to the identification or generation of new cultivars with better postharvest behaviour. This would improve the efficiency of this crop production and reduce the waste due to its short shelf life, impacting positively in the Spanish, and therefore European, economy.

On the other hand, I will continue working in studying the role of autophagy in stress resistance with the help of the identified autophagy genes overexpressing lines. This work might lead to new knowledge about the mechanisms of resistance in strawberry to abiotic stresses such as drought or heat.

Autophagy during strawberry ripening

Periodic Reporting for period 1 - FrATGaria (Identification of the role of autophagy during fruit ripening and stress resistance in Strawberry: Autophagy manipulation as a way to improve Strawberry fitness)

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