Abstract
GRAS
is a transcription regulator factor, which plays an important role in plant growth and development. Previous analyses found that several
GRAS
functions have been identified, such as axillary bud meristem formation, radial root elongation, gibberellin signaling, light signaling, and abiotic stress. The
GRAS
family has been comprehensively evaluated in several species. However, little finding is on the
GRAS
transcription factors (TFs) in Chinese white pear. In this study, 99
PbGRAS
were systemically characterized and renamed
PbGRAS
1 to
PbGRAS
99 according to their chromosomal localizations. Phylogenetic analysis and structural features revealed that could be classified into eight subfamilies (LISCL, Ls, SHR, HAM, SCL, PAT, SCR, and DELLA). Further analysis of introns/exons and conserved motifs revealed that they are diverse and functionally differentiated in number and structure. Synteny analysis among
Pyrus bretschenedri, Prunus mume, Prunus avium, Fragaria vesca
, and
Prunus persica
showed that
GRAS
duplicated regions were more conserved. Dispersed duplication events are the most common mechanism and may play a crucial role in the expansion of the
GRAS
gene family. In addition,
c
is-acting elements of the
PbGRAS
gene were found in promoter regions associated with hormone and environmental stress responses. Notably, the expression pattern detected by qRT-PCR indicated that
PbGRAS
genes were differentially expressed under gibberellin (GA), abscisic acid (ABA), and auxin (IAA) conditions, which are responsive to abiotic stress.
PbGRAS89
and
PbGRAS99
were highly expressed at different stages of hormone treatment and may play important role in leaf development. Therefore, we selected
PbGRAS89 and PbGRAS99
to clone and construct pCAMBIA1301-
PbGRAS89, 99
and transferred them into
Arabidopsis thaliana
. Finally, we observed and compared the changes of overexpressed plants and wild-type plants during regeneration. This method was used to analyze their roles in leaf regeneration of Chinese white pear. In addition, we also constructed pCAMBIA1305-
PbGRAS89, 99
, and transferred them into onion cells to determine the subcellular localization. Subcellular localization experiments showed that
PbGRAS89
and
PbGRAS99
were localized in the nucleus. In summary, the results of this study indicate that
PbGRAS89
and
PbGRAS99
are mainly responsible for leaf regeneration of Chinese white pear, which plays a positive role in callus formation and provides rich resources for studying
GRAS
gene functions.