AUTHOR=An Feifei , Xiao Xinhui , Chen Ting , Xue Jingjing , Luo Xiuqin , Ou Wenjun , Li Kaimian , Cai Jie , Chen Songbi 

TITLE=Systematic Analysis of bHLH Transcription Factors in Cassava Uncovers Their Roles in Postharvest Physiological Deterioration and Cyanogenic Glycosides Biosynthesis

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.901128

DOI=10.3389/fpls.2022.901128

ISSN=1664-462X

ABSTRACT=<p>The basic helix-loop-helix (bHLH) proteins are a large superfamily of transcription factors, and play a central role in a wide range of metabolic, physiological, and developmental processes in higher organisms. However, systematic investigation of <italic>bHLH</italic> gene family in cassava (<italic>Manihot esculenta</italic> Crantz) has not been reported. In the present study, we performed a genome-wide survey and identified 148 <italic>MebHLH</italic>s genes were unevenly harbored in 18 chromosomes. Through phylogenetic analyses along with <italic>Arabidopsis</italic> counterparts, these <italic>MebHLHs</italic> genes were divided into 19 groups, and each gene contains a similar structure and conserved motifs. Moreover, many <italic>cis</italic>-acting regulatory elements related to various defense and stress responses showed in <italic>MebHLH</italic> genes. Interestingly, transcriptome data analyses unveiled 117 <italic>MebHLH</italic> genes during postharvest physiological deterioration (PPD) process of cassava tuberous roots, while 65 <italic>MebHLH</italic> genes showed significantly change. Meanwhile, the relative quantitative analysis of 15 <italic>MebHLH</italic> genes demonstrated that they were sensitive to PPD, suggesting they may involve in PPD process regulation. Cyanogenic glucosides (CGs) biosynthesis during PPD process was increased, silencing of <italic>MebHLH72</italic> and <italic>MebHLH114</italic> showed that linamarin content was significantly decreased in the leaves. To summarize, the genome-wide identification and expression profiling of <italic>MebHLH</italic> candidates pave a new avenue for uderstanding their function in PPD and CGs biosynthesis, which will accelerate the improvement of PPD tolerance and decrease CGs content in cassava tuberous roots.</p>