EjCaM7 and EjCAMTA3 synergistically alleviate chilling-induced
lignification in loquat fruit by repressing the expression of lignin
biosynthesis genes under cold stress
Abstract
Flesh lignification is a typical chilling injury (CI) symptom of loquat
fruit during cold storage.
[Calcium](D:/D%E7%9B%98/Youdao/Dict/8.9.9.0/resultui/html/index.html) [chloride](D:/D%E7%9B%98/Youdao/Dict/8.9.9.0/resultui/html/index.html)
(CaCl 2) could enhance chilling tolerance in loquat
fruit, but the molecular mechanism is still not illuminated. In this
study, CaCl 2 treatment suppressed the increase in
firmness and lignin content, and retained higher extractable juice,
thereby alleviating chilling-induced lignification in loquat fruit.
Moreover, CaCl 2 enhanced the
[calmodulin](javascript:;) (CaM) content, free Ca
2+ distribution, EjCaM7, and CaM binding
transcription activators 3 ( EjCAMTA3) expression in loquat fruit
during cold storage, indicating Ca 2+/CaM-CAMTA played
a key role in response to cold stress. The EjCAMTA3 and EjCaM7 proteins
were identified and characterized from loquat fruit. Importantly,
EjCAMTA3 bound to the CG-box in EjPODP7-like and
EjLAC12-like promoters to repress their transcription. Further
analysis revealed that EjCaM7 interacted with EjCAMTA3 in a Ca
2+-dependent manner, and this interaction enhanced the
EjCAMTA3-mediated transcriptional repression of EjPODP7-like and
EjLAC12-like genes. Taken together, these findings suggested that
CaCl 2 treatment alleviates chilling-induced
lignification in loquat fruit, which probably via the synergistic role
of EjCaM7 and EjCAMTA3 in the modulation of EjPODP7-like and
EjLAC12-like genes expression, leading to the repression of
lignin polymerization.