Insights into heat response mechanisms in Clematis species: physiological analysis, expression profiles and function verification.

Ruonan Gai,Yi Zhang,Shucheng Feng,Feng Ming,Changhua Jiang,Hao Zhang,Chanjuan Mao,Long Zhang,Jianbin Mo,Siyuan Peng,Rui Wang,Yuxia Lou

doi:10.1007/s11103-021-01174-4

Abstract

Our results provide insights into heat response mechanisms among Clematis species. Overexpressing CvHSFA2 enhanced the heat resistance of yeast and silencing NbHSFA2 reduced the heat resistance of tobacco. Clematis species are commonly grown in western and Japanese gardens. Heat stress can inhibit many physiological processes mediating plant growth and development. The mechanism regulating responses to heat has been well characterized in Arabidopsis thaliana and some crops, but not in horticultural plants, including Clematis species. In this study, we found that Clematis alpina 'Stolwijk Gold' was heat-sensitive whereas Clematis vitalba and Clematis viticella 'Polish Spirit' were heat-tolerant based on the physiological analyses in heat stress. Transcriptomic profiling identified a set of heat tolerance-related genes (HTGs). Consistent with the observed phenotype in heat stress, 41.43% of the differentially expressed HTGs between heat treatment and control were down-regulated in heat-sensitive cultivar Stolwijk Gold, but only 9.80% and 20.79% of the differentially expressed HTGs in heat resistant C. vitalba and Polish Spirit, respectively. Co-expression network, protein-protein interaction network and phylogenetic analysis revealed that the genes encoding heat shock transcription factors (HSFs) and heat shock proteins (HSPs) may played an essential role in Clematis resistance to heat stress. Two clades of heat-induced CvHSFs were further identified by phylogenetic tree, motif analysis and qRT-PCR. Ultimately, we proposed that overexpressing CvHSFA2-2 could endow yeast with high temperature resistance and silencing its homologous gene NbHSFA2 reduced the heat resistance of tobacco. This study provides first insights into the diversity of the heat response mechanisms among Clematis species.

Highlights

Clematis is a genus that includes approximately 300 species belonging to the buttercup family (Ranunculaceae)
Gene Ontology (GO) enrichment analyses revealed that heat stress mainly influences components of biological membrane and two heat-tolerant Clematis varieties have obvious positive regulation to heat stress whereas the heat-sensitive Clematis variety does not
Our data showed that the relative conductivity (RC) and malondialdehyde content were significantly higher in Stolwijk Gold than in C. vitalba and Polish Spirit, whereas the relative water content (RWC), soluble protein content, and superoxide dismutase activity (SOD) were lower in Stolwijk Gold than in C. vitalba and Polish Spirit (Fig. 1b)

Summary

Introduction

Clematis is a genus that includes approximately 300 species belonging to the buttercup family (Ranunculaceae). Environmental changes have a broad arrange of influences on plant growth and development. High temperatures lead to various changes of plant morphology including elongation of the hypocotyl and petiole, early flowering, and reduced stomata number (Li et al 2018a). How plant cells perceive the thermal signal remains unclear (Zhang et al 2019), previous research has identified thermosensors such as H2A.Z-containing nucleosomes and phytochromes (Legris et al 2016). Some key factors involved in heat-shock signal transduction were identified (Ding et al 2020), for example, a heat activated calcium channel AtCNGC8 is involved in heat shock responses (Gao et al 2012), molecular and genetic evidence support that AtCaM3 plays a crucial part in heat-shock signal transduction in Arabidopsis (Liu et al 2008; Zhang et al 2009)

Methods

Results

Conclusion