Improving water use and accelerating breeding pipelines in Mexican avocado

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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.