Gene regulatory network in almond (Prunus dulcis Mill.) in response to frost stress

Abstract

Regulatory networks govern the plant molecular responses against environmental stress. The underpinning regulatory networks of almond (Prunus dulcis Mill.) in response to frost are largely unknown. Here, based on cold responsive genes in almond pistils, we constructed a gene regulatory network in response to cold stress. Some of the central genes in the regulatory network were further validated by RT-qPCR in frost-tolerant and frost-sensitive genotypes. Central genes in the regulatory network (SIZ1, ICE1, CBF/DREB1, WRKY21, HOS1, ANK) showed significant differential gene expression patterns between frost-tolerant and frost-sensitive genotypes. Among the key transcription factors, members of DOFF family were the central regulators of genes in the constructed network. In line with this observation, the Pddof4 transcript had significant over-expression in the tolerant genotypes compared to the sensitive genotypes during cold stress. These findings may highlight the importance of Pddof4 in conferring frost tolerance to almond. PdMIR7122-3p was predicted as a negative regulator of PdHOS1. PdMIR7122-3p/ PdHOS1 was found to be the only post-transcriptional regulator of genes in the network. Taken together, our network model will be useful to unravel the mechanisms involved in almond tolerance to cold stress and to highlight the role of different regulatory factors and their interactions in response to this commonly occurring environmental condition.