Identification of Picea mongolica LEA Gene Family Implicates PmLEA25 in Drought Resistance

Picea mongolica is a rare and valuable tree species in China, having high tolerance for drought, cold, and sand burial. The late embryogenesis abundant protein (LEA protein) is a crucial transcription factor that plays a key role in both plant embryonic development and stress response. LEA genes have, however, not yet been reported in P. mongolica. In this study, through the analysis of genome data from Picea abies and transcriptome data from P. mongolica, a total of 49 PmLEAs were discovered and categorized into eight subfamilies based on their Pfam domain and phylogenetic relationship. RNA-Seq research revealed that 37 PmLEAs were differentially expressed at various stages of embryonic development. Using qRT-PCR, we found that most PmLEAs responded strongly to drought stress, with genes in the same subfamily exhibiting identical expression patterns. In particular, PmLEA25 is the most highly induced by drought treatment. Furthermore, we heterologously transformed PmLEA25 into Arabidopsis. The overexpression of PmLEA25 remarkably increased the germination rate, root length, and antioxidant capacity in Arabidopsis under drought treatment, compared with WT. The results serve as a point of reference for gaining a deeper comprehension of the function of PmLEA25 in the molecular process of stress resistance in P. mongolica. Additionally, they offer significant genetic materials for the purpose of breeding stress-resistant spruce species.