Identification and expression analysis of FmPLT gene family of Fraxinus mandschurica

  Objective  PLT transcription factor family plays an important role in plant growth and organ formation and participates in the regeneration progress. This paper aims to explore the function of PLT transcription factors in the growth and abiotic stress in Fraxinus mandshurica, in order to provide more ideas for forest tree gene selection work.

  Method  By using homologous alignment and cloning techniques, we obtained and identified all members of FmPLT gene family. We conducted detailed bioinformatics analysis of FmPLTs, including physicochemical properties, phylogenetic relationships and gene structure, etc. Besides, we measured the gene expression levels of FmPLTs members in different tissues and seeds during germination, and the expression levels under abiotic stresses (NaCl, PEG6000, NaHCO₃, and low temperature 4 ℃) and signal hormone treatmentes (ABA, GA₃, IAA, SA and MeJA).

  Result  We revealed that the F. mandshurica genome contained 9 members, which were named as FmPLT2, FmPLT3, FmPLT4, FmPLT4A, FmPLT5, FmPLT5A, FmPLT7, FmPLT8 and FmPLT9, respectively, based on phylogenetic relationship, that could be further divided into 5 groups. The expression of PLT family members was the highest in roots and the lowest in leaves. On the fourth day of seed germination, cotyledons turned green, hypocotyls elongated, most members showed highest expression levels, in response to different hormones and abiotic stresses, FmPLTs showed significant responses to low temperature, drought, salt stress and MeJA treatment.

  Conclusion  FmPLTs are involved in seed germination and organ development of Fraxinus mandshurica, response to plant hormone signaling, and actively participate in the regulation of plant abiotic stress tolerance, including low temperature, high salt and drought stress. This study preliminarily reveals that the expression pattern of FmPLTs in response to both signal hormone treatmentes and abiotic stress, and lays a foundation for in-depth analysis of the basic functions and regulatory mechanisms of FmPLT gene family.