1. Introduction
Soil salinization, as one of the major factors compromising crop growth
and leading to soil degeneration in natural ecological environment,
which have become a global concern (Haj-Amor et al., 2022; Singh, 2016).
Currently, 20% of cultivated land and 50% of irrigated land globally
are under the threat of salinization (Hopmans et al., 2021; Rozentsvet
et al., 2017). With climate change, population increase, intensive food
production and irrigation practices, soil salinization is expected to be
exacerbated (Singh, 2021). The area of saline-alkali land in China is
approximately 36 million ha,
distributed mainly in the north-eastern and north-western parts and
along the coast (Jiang et al.,
2022; Wang et al., 2020).
Excessive salt in saline-alkali soils have always been regarded to be
the greatest hazard to crop production (Zörb et al., 2019). Salt stress
have profound influences on the regulation of plant morphology,
physiology and metabolic process (Yang & Guo, 2018), which can lead to
plant dehydration, ion toxicity, and even plant death (McDowell et al.,
2022).
Plants possess a wide range of
metabolic strategies to promote osmotic adaptation and antioxidant
mechanisms under salt stress (de Freitas et al., 2019). Roots are the
main organ for sensing salt stress signals and responding to excess salt
(Redwan et al., 2017). The analysis of root metabolite differences under
different salinity conditions is important in elucidating the salt
tolerance mechanism of plants (Barding
et al., 2013; Ben Hsouna et al.,
2022).
M. azedarach has high adaptability and strong salt tolerance;
hence, growing M.
azedarach on saline-alkali
land has been considered as a
promising strategy for degraded land restoration (Dias et al., 2014;
Husain & Anis, 2009). M.
azedarach can effectively increase bacterial communities diversity and
enhance environmental carrying
capacity (Li et al., 2021b;
Shahbaz & Ashraf, 2013).
Understanding
of how M. azedarach metabolome responds to different soil
salinities is poor. In this paper, soil properties andM. azedarach root
metabolome were characterized under high, medium and low salinity to
explore the ameliorative effects
of M. azedarach on soils
with different salt content and the metabolome changes of M.
azedarach in response to different severities of salt stress.