Improving water use and accelerating breeding pipelines in Mexican avocado
Lead Research Organisation:
University of Sheffield
Department Name: School of Biosciences
Abstract
Mexico is the world's leading avocado producer and Jalisco is the second largest avocado producing state. The global trade in this fruit makes avocado Mexico's most valuable agricultural product and this has a major impact on the the quality of life of thousands of farmers and workers employed in its cultivation and supply chain. Water availability has a major impact on avocado growth and yield, which is of major concern given the growing water crisis facing Mexico. Water demand is so great that ground water supplies are being depleted and droughts are frequent, with large areas of Jalisco being affected by severe drought. Given the economic importance of this crop to Mexico, it is therefore vital that breeding programs focus on improving the resilience of avocado to water stress and improve the amount of crop per drop. This has been recognized by policy makers in the Mexican Agri-Food Agenda, determining that the generation of varieties of avocado adaptable to different agro-ecological conditions is a priority issue. Avocado has a wealth of genetic resources that could be used to achieve this aim yet major barriers exists to utilising these resources. This is because avocado is a perennial species with a prolonged juvenile stage, meaning that it can take years to segregate outstanding characteristics in germplasm with commercial characteristics by traditional breeding. Further, whilst there are significant genetic resources in terms of different accessions, this is poorly supported by genomics resources. For example, as yet there is no genome sequence and limited gene expression data. This project aims to address these barriers and provide a platform for advancing avocado breeding programs. As improved resilience against water stress is a key trait and aim for breeders, as a case-study, we will focus on improving water use efficiency (WUE) and drought tolerance using knowledge gained from work with other plants. To address these issues, our project has three objectives. The first is focused on reducing the time that is required for avocado trees to flower. As a proof of concept, we will utilise biotechnology to increase the expression of a positive regulator of flowering with the future aim of developing non-transgenic approaches to achieve this. Our second objective is focused on identifying and then characterising avocado accessions with improved water use. Here, we will generate a number of genomic resources, in order to enable molecular research in this area, which is currently limited due to a lack of sequence information. Finally, we will focus on facilitating the use of gene editing technologies in avocado, which when coupled to our goal of faster flowering, should significantly accelerate the breeding pipelines of avocado. This research and the resources it develops will be made publicly available to the avocado research and breeding community and will be valuable for advancing breeding steps. This will enable targeted improvement of this Mexican crop and through improved water use, should also reduce the water requirements of this crop, and so reduce pressure on Mexico's freshwater supplies.
Planned Impact
Who will benefit from this research?
This project is aimed at accelerating flowering time in avocado, developing non-transgenic methods for gene editing in pollen, improving genomic resources and developing varieties with improved water use. The academic community will benefit through improved sequence resources, tools and data developed by this research and this is discussed elsewhere in this proposal. The major beneficiaries outside of academia will primarily be:
1) staff trained on the project;
2) Horticulture and plant breeders;
3) the farming community;
4) the general public.
How might they benefit from this research?
The staff employed on this project will benefit from an excellent training environment and these skills will then be of significant value to both the academic and commercial sector. Through publication and networking events, this will improve the employability and career aspirations of these staff. In particular, this proposal will involve training and knowledge exchange with members of the Mexican team spending time in Sheffield to learn techniques to ensure that these become routine in the laboratories in CIATEJ.
Abiotic stress, particularly limitations in water, are major issues that impact on avocado yields and the development of new varieties of avocado adaptable to different agro-ecological conditions is a priority issue, established in the Mexican Agri-Food Agenda. There is a wealth of avocado genetic resources available to breeders, with well over 300 accessions in Mexico alone. However, the long juvenile phase of means that it can take years to segregate outstanding characteristics in germplasm with commercial characteristics by traditional breeding. By accelerating flowering time, this project can substantially reduce these timings, allowing for much faster evaluation by breeders. In addition, this project will provide a wealth of new sequence information for several different accessions. By identifying sequence polymorphisms, the project will provide breeders with new markers for marker assisted breeding and, if expanded, even genome wide association studies. We will also identify accessions with better water use efficiency, providing breeders with information to introduce this trait into the most commercially significant varieties. Finally, we will develop non-transgenic editing in avocado as a means of targeted crop improvement, allowing translation of basic research from model species. We have enlisted the support of Dr Juan Carlos Reyes Alemán (Autonomous University of Mexico State), who will assist in translating our findings from the laboratory to the field.
As a case-study, we will focus on identifying and investigating accessions with improved water use, which is important as much of Mexico and Jalisco, have annual water availability problems. As end users, farmers will benefit from the development of improved WUE and drought tolerance at several levels with reduced costs associated with irrigation (e.g. abstraction of water from rivers and boreholes and construction of on farm reservoirs) and improved crop security during periods of water stress. Accelerating breeding pipelines will also allow the development of other beneficial traits that will improve avocado resilience and ensure that farmers have improved yield security.
Agriculture is the major user of water supplies in Mexico and overall demand is so great that Mexico is significantly reducing its ground water supplies. This has major implications for the public, who are the second biggest user of these water supplies. By improving avocado water use, the public will potentially benefit not only through improvements to food security but importantly, through reductions in agricultural water use. Ultimately, this may help enable a more sustainable food supply network.
This project is aimed at accelerating flowering time in avocado, developing non-transgenic methods for gene editing in pollen, improving genomic resources and developing varieties with improved water use. The academic community will benefit through improved sequence resources, tools and data developed by this research and this is discussed elsewhere in this proposal. The major beneficiaries outside of academia will primarily be:
1) staff trained on the project;
2) Horticulture and plant breeders;
3) the farming community;
4) the general public.
How might they benefit from this research?
The staff employed on this project will benefit from an excellent training environment and these skills will then be of significant value to both the academic and commercial sector. Through publication and networking events, this will improve the employability and career aspirations of these staff. In particular, this proposal will involve training and knowledge exchange with members of the Mexican team spending time in Sheffield to learn techniques to ensure that these become routine in the laboratories in CIATEJ.
Abiotic stress, particularly limitations in water, are major issues that impact on avocado yields and the development of new varieties of avocado adaptable to different agro-ecological conditions is a priority issue, established in the Mexican Agri-Food Agenda. There is a wealth of avocado genetic resources available to breeders, with well over 300 accessions in Mexico alone. However, the long juvenile phase of means that it can take years to segregate outstanding characteristics in germplasm with commercial characteristics by traditional breeding. By accelerating flowering time, this project can substantially reduce these timings, allowing for much faster evaluation by breeders. In addition, this project will provide a wealth of new sequence information for several different accessions. By identifying sequence polymorphisms, the project will provide breeders with new markers for marker assisted breeding and, if expanded, even genome wide association studies. We will also identify accessions with better water use efficiency, providing breeders with information to introduce this trait into the most commercially significant varieties. Finally, we will develop non-transgenic editing in avocado as a means of targeted crop improvement, allowing translation of basic research from model species. We have enlisted the support of Dr Juan Carlos Reyes Alemán (Autonomous University of Mexico State), who will assist in translating our findings from the laboratory to the field.
As a case-study, we will focus on identifying and investigating accessions with improved water use, which is important as much of Mexico and Jalisco, have annual water availability problems. As end users, farmers will benefit from the development of improved WUE and drought tolerance at several levels with reduced costs associated with irrigation (e.g. abstraction of water from rivers and boreholes and construction of on farm reservoirs) and improved crop security during periods of water stress. Accelerating breeding pipelines will also allow the development of other beneficial traits that will improve avocado resilience and ensure that farmers have improved yield security.
Agriculture is the major user of water supplies in Mexico and overall demand is so great that Mexico is significantly reducing its ground water supplies. This has major implications for the public, who are the second biggest user of these water supplies. By improving avocado water use, the public will potentially benefit not only through improvements to food security but importantly, through reductions in agricultural water use. Ultimately, this may help enable a more sustainable food supply network.
Publications
Bertolino L
(2022)
Stomatal Development and Gene Expression in Rice Florets
in Plant and Cell Physiology
Salazar-González J
(2023)
In-planta transient transformation of avocado (Persea americana) by vacuum agroinfiltration of aerial plant parts
in Plant Cell, Tissue and Organ Culture (PCTOC)
Tamayo-Ramos D
(2022)
Old and new horizons on Persea americana transformation techniques and applications
in Plant Cell, Tissue and Organ Culture (PCTOC)
| Description | A major objective of this research is to understand and improve water use efficiency (WUE), the amount of water used for carbon gained, of Mexican avocado. We have initially screened approximately 50 Mexican avocado cultivars and identified 10-12 with altered WUE that will allow us to now probe the mechanisms regulating this complex trait. To determine whether the changes in WUE are due to above ground versus root based traits, we grafted scions (upper plant cutting) from our varieties onto a clonal root stock. Once these grafted plants had established, we took both young and more mature leaf material for analysis. Here we have looked at both the genes expressed in these leaves as well as proxy measurements for their WUE. Our initial gene expression data indicates that the cultivars that have better WUE, group together, which gives confidence that the improved WUE may (in part) be determined by scion determined gene expression patterns. We are also in the process of analysing this gene expression data to identify differences in the DNA sequence between the different cultivars. These sequence polymorphisms can then be mapped to the avocado genome and will be a tool that breeders can then use to 'follow' genes during breeding programmes. In our gene expression analysis, we have identified a number of genes and metabolic pathways that correlate with improved water use efficiency in our different avocado cultivars. As it is difficult to perform genetic work in avocado, we are currently assessing whether mutations of homologous genes in the model plant, Arabidopsis thaliana, affects WUE in this species. If single genes can influence WUE in both avocado and arabidopsis, then we will have good targets for improving the WUE of avocado cultivars. |
| Exploitation Route | The outputs of this proposal may be used by avocado breeders to facilitate faster and more focused breeding programmes. Our proposal aims to not only accelerate the major bottleneck in avocado breeding (the time it takes for avocado trees to flower) but also to provide a suite of new molecular markers that will facilitate more accurate breeding. The major trait we are focusing on is water use efficiency. Water availability is a major concern for Mexicans, both civilians and farmers. A major objective of this project is to provide the tools to generate more water use efficient avocado, which would enable reduced water inputs at the level of farming, reducing pressure on water supplies elsewhere. |
| Sectors | Agriculture, Food and Drink,Environment |
| URL | https://doi.org/10.1007/s11240-022-02436-9 |
| Description | International collaboration with CIATEJ. |
| Organisation | The Center for Research and Assistance in Technology and Design of the State of Jalisco, AC (CIATEJ) |
| Country | Mexico |
| Sector | Academic/University |
| PI Contribution | Our research team is focused on: 1) Providing out CIATEJ partners with plasmid constructs to induce rapid flowering in avocado. 2) To analyse Mexican avocado samples to determine long term water use efficiency (carbon isotope analysis) and hormone analysis (primarily ABA, abscisic acid). 3) To perform RNA-seq analysis on different avocado cultivars and generate transcriptome data and identify polymorphisms. 4) To perform physiological analysis of specific avocado cultivars 5) To perform genome editing of the avocado genome, with a focus on pollen. |
| Collaborator Contribution | The CIATEJ team will: 1) Use transient transformation methods using constructs supplied by the UK team, to induce flowering in avocado. 2) To provide samples to determine WUE in different avocado cultivars. 3) To provide avocado seedlings for experimental analysis in the UK. 4) To perform genome editing of avocado. |
| Impact | At present, we have screened a panel of ~50 Mexican avocado varieties and identified 10-12 with altered water use efficiency that will form the basis of the next phase of the project. The CIATEJ collaborators visited Sheffield in October 2019 to map out project details and refine timelines. |
| Start Year | 2019 |