Role of the seed microbiome on seed and seedling vigour

As multicellular organisms, plants contain micro-organisms inside and on their surface of their body, commonly called plant microbiome. Plant microbiomes, most of which are bacteria and fungi, can benefit plant growth and health by producing volatile organic compounds (VOCs) and phytohormones, improving nutrient acquisition and stimulate plant defense mechanisms. Plant microbiome also have the ability to adapt to extreme environments, e.g. salinity and drought, for their survival. Interestingly, their adaptability may benefit plant growth and performance under abiotic stress conditions as well. The transmission of microbiome adaptive abilities can be achieved by vertical transmission via seeds as seed microbiome. Therefore, the seed microbiome is an important microbial habitat that is passed on to the next generation of plants. It is also expected to aid in the initial stages of plant development, such as seed germination and seedling establishment, especially under abiotic stress conditions. Maternal environment can affect abiotic stress resistance in plant offspring. The maternal environment, including soil conditions, is expected to have a direct and indirect effect on the seed microbial community. The influence of maternal environment in shaping plant microbiomes, especially root and rhizosphere, as well as its ability to help plants to withstand stress has been well documented across various plant species. However, relative little knowledge is available for the role of the seed microbiome. In this project, we will focus only seed endophytic bacteria. We aim to study (1) The influence of maternal environment on bacterial communities of Arabidopsis thaliana seeds across different generations, and how these seed endophytic bacteria affect abiotic stress tolerance during seed germination and early seedling growth (2) The effect of VOCs produced by bacterial endophytes isolated from wild cabbage seeds on seed germination and seedling growth of Arabidopsis thaliana (3) Techniques to introduce the selected beneficial bacteria isolated from wild cabbage seeds into non-host plant seeds, and whether it helps promote seed germination and seedling growth of non-host plants under abiotic stress conditions. We hypothesized that (1) Seed endophytic bacteria communities differ when the mother plants are grown on different environmental conditions, and some of these seed microbial taxa can be transmitted and inherited across generations (2) Abiotic stressors in the maternal environment encourages mother plants to recruit specific seed endophytic bacteria and produce progeny seeds with bacteria endophytes adapted to the same stress that mother plants experiences, enabling the next generation seeds and seedlings to be more tolerance to theses stress conditions (3) VOCs released by bacterial isolates from wild cabbage seeds stimulate the germination of Arabidopsis seeds, even under stress conditions (4) Selected beneficial microbiome isolated from wild cabbage seeds can be introduced to non-host plants progeny seeds via various techniques such as bio-priming and flower dip inoculation, and seeds infected with selected beneficial bacteria promote seed and seedling vigour under stress conditions. We will conduct seed germination and seedling vigour tests under abiotic stress conditions, and use high-throughput sequencing to characterize seed endophytic bacteria community structure. Understanding the factors that shape seed microbial communities and their ability to adapt to harsh environmental conditions as well as investigating how specific microbes affect seedling resilience to abiotic stresses could provide a new way in shaping more stress-resilient crops that require less external inputs, e.g. fertilisers and pesticides, improve plant health and contribute to more sustainable agriculture and food security.