Arbuscular
mycorrhizae (AM) symbiosis can enhance plant resistance
to drought stress (DS). This study aimed to investigate the DS effects
on lipids at different stages of symbiosis and to link lipid profiles
to arbuscule dynamics in tomato roots colonized by AM fungi. DS increased
mycorrhizal colonization and arbuscule abundance at an early stage
but decreased them at a later stage, delayed arbuscule development,
and accelerated arbuscule senescence at a later stage. DS decreased
the contents of phospholipids (PLs) and saturated neutral lipids (NLs)
at the early stage but increased the contents of saturated PLs and
unsaturated NLs at the late stage. Specifically, DS inhibited AM-specific
PL contents but increased AM-specific NL contents, which was supported
by the expression of RAM2, STR/STR2. These data indicate the negative effect of DS on AM
symbiosis and arbuscule dynamics with the effect size depending on
the symbiosis stage, which highlights the importance of the symbiosis
stage under abiotic stress.