Effects of Lanthanum(Ⅲ) on Copper(Ⅱ) stressed rice (Oryza sativa) and
its molecular mechanism revealed by transcriptome profiling
Abstract
Rare earth elements are known to alleviate heavy metal stress. However,
the potential mechanisms of alleviation remain unclear. This study
compared the effects of La(NO3)3 and La(NO3)3-amino acid chelates
(La(Ⅲ)-AA) on growth, oxidative stress, ultrastructure, bioaccumulation
and gene expression in rice. Results demonstrated that 20 mg/L La(Ⅲ)-AA
can effectively ameliorate CuSO4 (50 mg/L) stress in rice by reducing
oxidative stress and increasing chlorophyll content, thus promoting
growth. ICP and TEM revealed an antagonistic effect between La(Ⅲ) and
Cu(Ⅱ). Exogenous La(Ⅲ)-AA decreased Cu(Ⅱ) content in rice leaves, stems
and roots by 55.56%, 59.46% and 26.29%, and ameliorated Cu(Ⅱ) damage
by maintaining the ultrastructure of mesophyll cells. RNA sequencing
identified 7020 differentially expressed genes, and 8 were validated by
qRT-PCR. Indole-3-acetic acid (IAA) concentration was detected by HPLC.
Correlation analysis between OsGH3.4-IAA-Expansin revealed that IAA
content is negatively correlated with OsGH3.4 (r=-0.82, P
<0.05), and positively correlated with Expansin (r = 0.78, P
<0.05). It’s assumed that La(Ⅲ)-induced OsGH3.4 could inhibit
IAA-dependent Expansin expression, thereby conferring resistance to Cu
stress. This work provides novel insights into the molecular basis
underlying La-induced Cu tolerance in rice.