“…Unfortunately, the holobiome of the vast majority of plants is still awaiting to be discovered, which applies particularly to the bacterial diversity in the endo-phyllosphere—meaning the niche spaces inside the leaves of land plants ( Vorholt, 2012 ; Khare et al, 2018 ; Cordovez et al, 2019 ; Harrison and Griffin, 2020 ; Chaudhry et al, 2021 ; Hawkes et al, 2021 ; Chialva et al, 2022 ). Many studies considered bacterial taxa enhancing plant defense ( Matsumoto et al, 2021 ; Cernava and Berg, 2022 ; Shalev et al, 2022 ) besides other plant growth-promoting functions ( Glick, 2012 ; Backer et al, 2018 ; Leontidou et al, 2020 ), but current studies expanded their focus on a wide range of ecological aspects such as the contribution of bacterial communities to the rapid adaption to local environments enforced by bacterial communities ( Li et al, 2021 ) that coincide with diversification patterns ( Abedlfattah et al, 2021 ) as argued in the SYMPHY proposal ( Tripp et al, 2017 ) and the Plant Holobiont Theory ( Lyu et al, 2021 ). Notable aspects studied include the enhanced resistance of plants to environmental stresses supported by endophytic bacteria, e.g., salt tolerance ( Vaishnav et al, 2019 ) and heavy metal tolerance ( Zhu et al, 2014 ; Xu et al, 2016 ; Gu et al, 2018 ; Banach et al, 2020 ; Yang et al, 2020 ; Antenozio et al, 2021 ) or even support the adaptation to extreme environments, e.g., deserts ( Zhang et al, 2019 ) and karst habitats ( Li F. et al, 2019 ).…”