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

Abstract

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 bHLH gene family in cassava (Manihot esculenta Crantz) has not been reported. In the present study, we performed a genome-wide survey and identified 148 MebHLHs genes were unevenly harbored in 18 chromosomes. Through phylogenetic analyses along with Arabidopsis counterparts, these MebHLHs genes were divided into 19 groups, and each gene contains a similar structure and conserved motifs. Moreover, many cis-acting regulatory elements related to various defense and stress responses showed in MebHLH genes. Interestingly, transcriptome data analyses unveiled 117 MebHLH genes during postharvest physiological deterioration (PPD) process of cassava tuberous roots, while 65 MebHLH genes showed significantly change. Meanwhile, the relative quantitative analysis of 15 MebHLH 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 MebHLH72 and MebHLH114 showed that linamarin content was significantly decreased in the leaves. To summarize, the genome-wide identification and expression profiling of MebHLH 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.

Magnesium chelatase subunit D is not only required for chlorophyll biosynthesis and photosynthesis, but also affecting starch accumulation in Manihot esculenta Crantz

“…Therefore, it is necessary to develop a powerful method for rapidly analyzing gene function in vivo. VIGS system based on CsCMV is widely used to investigate gene function in cassava [30,32]. In this study, VIGS-induced reduction of MeChlD expression resulting in the mosaic leaves or the fully yellow leaves of VIGS-MeChlD plants in comparison to VIGS-NC control plants (Fig.…”

“…Currently, chlorophyll content in different silent plants of cassava was performed as described [38]. The content of the total starch was measured as described [32].…”

“…VIGS is mostly drive on RNA viruses, such as tobacco rattle virus (TRV), tobacco mosaic virus (TMV), cucumber mosaic virus (CMV), potato virus X (PVX) and cassava common mosaic virus (CsCMV). Especially, TRV and CsCMV are widely used in cassava for rapid gene function analysis [29][30][31][32], due to high silencing e ciency, long silencing duration, and obvious virusinduced disease symptoms. A magnesium chelatase subunit I (ChlI) was successfully silenced in tobacco and different cassava varieties by CsCMV-mediate VIGS system [30].…”

Basic Helix-Loop-Helix Transcription Factors: Regulators for Plant Growth Development and Abiotic Stress Responses

“… Phylogenetic analysis of the species based on genome-wide association study of the basic helix-loop-helix (bHLH) family. The total number of bHLH transcription factors identified from the genome of each species are indicated [ 5 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. …”

Integrated multi-omics reveals the molecular mechanisms underlying efficient phosphorus use under phosphate deficiency in elephant grass (Pennisetum purpureum)

“…Primers used to amplify genes for qRT-PCR analysis are listed in Supplementary Table S23. Relative expression values were calculated by the 2 -DDCT method (An et al, 2022).…”