Two HbHsfA1 and HbHsfB1 genes from the tropical woody plant rubber tree confer cold stress tolerance in Saccharomyces cerevisiae

Abstract

Plant heat stress factors are abiotic stress-responsive regulators. In model or non-model plants, heat stress factors could be divided into different subgroups based on their amino acids through comprehensive bioinformatic analysis. In this study, two cold-inducible HbHsfA1 and HbHsfB1 genes in cold-resistant rubber tree clone ‘93-114’ were identified. Both genes were highly expressed in leaves and stems. Phylogenetic analysis revealed that HbHsfA1 and HbHsfB1 belong to class A and class B Hsf families. MEME analysis showed that different motifs were distributed in the HbHsfA1 and HbHsfB1 proteins. Both HbHsfA1 and HbHsfB1 were located in the nucleus, but only HbHsfA1 exhibited strong transcriptional activation activity in yeasts. Relatively higher expression levels in cold-tolerant rubber tree clone ‘93-114’ than that of cold-sensitive clone ‘Reken501’ were correlated with their roles in cold stress tolerance. The enhanced tolerance observed in eukaryotic yeasts, respectively overexpressed HbHsfA1 and HbHsfB1, suggested that these two Hsf transcription factors may be candidates for genetic engineering to improve cold stress tolerance of rubber trees.