Induction of miR162 contributes to invasive habitat adaption of Alternanthera philoxeroides
Rapid phenotypic changes in adaptive traits are crucial for organisms to thrive in changing environments. Alternanthera philoxeroides, originally a terrestrial plant from South America, has become an invasive weed in Asia, capable of colonizing both aquatic and terrestrial habitats. The mechanism by which this invasive habitat is rapidly achieved without genetic variation remains unknown. Here, we demonstrate that miRNA activity in A. philoxeroides plays a significant role in its high invasive capacity. Our results highlight that an intact miRNA pathway is essential for the survival of A.philoxeroides in aquatic habitats. We identified one key miRNA, Aph-miR162, that promotes rapid elongation of stem in aquatic environments. Upon water submergence, the levels of miR162 significantly increased in stems from 3 hours to 24 hours. TRV based VIGS-mediated knockdown of Aph-miR162 significantly disrupted stem elongation in water submergence condition, ultimately resulting in a failure of plants protruding from the water surface. Interestingly, miR162 was not up-regulated in the non-invasive sibling species Alternanthera pungens, which also originates from South America but has retained its original terrestrial habitats in Asia. More importantly, delivering the antisense RNA oligos complementary to Aph-miR162 via the nanoparticle method significantly impaired stem elongation upon water submergence, causing A. philoxeroides to wither after 2-3 weeks. Thus, our findings reveal that the miRNA pathway can drive rapid phenotypic variation, facilitating adaptation to aquatic environments. Importantly, miR162 has the potential as a bio-pesticide for controlling the invasive capacity of A. philoxeroides. Overall design: Small RNA-Seq for miRNA in young stem and old stem at different time points on land or after waterlogged treatment was performed with 3 biological replicates each.