Forward Genetics Approach Reveals a Mutation in bHLH Transcription Factor-Encoding Gene as the Best Candidate for the Root Hairless Phenotype in Barley

Abstract

Root hairs are the part of root architecture contributing significantly to the root surface area. Their role is particularly substantial in maintaining plant growth under stress conditions, however, knowledge on mechanism of root hair differentiation is still limited for majority of crop species, including barley. Here, we report the results of a map-based identification of a candidate gene responsible for the lack of root epidermal cell differentiation, which results in the lack of root hairs in barley. The analysis was based on the root hairless barley mutant rhl1.b, obtained after chemical mutagenesis of spring cultivar ‘Karat’. The rhl1 gene was located in chromosome 7HS in our previous studies. Fine mapping allowed to narrow the interval encompassing rhl1 gene to 3.7 cM, which on physical barley map spans a region of 577 kb. Five high confidence genes are located within this region and their sequencing resulted in the identification of A>T mutation in one candidate, HORVU7Hr1G030250 (MLOC_38567), differing the mutant from its parent variety. The mutation, located in the 3′ splice-junction site, caused the retention of the last intron, 98 bp long, in mRNA of rhl1.b allele. This resulted in the frameshift, the synthesis of 71 abnormal amino acids and introduction of premature STOP codon in mRNA. The mutation was present in the recombinants from the mapping population (F2 rhl1.b × ‘Morex’) that lacked root hairs. The candidate gene encodes a bHLH transcription factor with LRL domain and may be involved in early stages of root hair cell development. We discuss the possible involvement of HORVU7Hr1G030250 in this process, as the best candidate responsible for early stages of rhizodermis differentiation in barley.

Transcriptome analysis reveals that multiple metabolic pathways operate in Zea mays roots subjected to graphene

“…Studies also showed that bHLH transcription factor genes were involved in the root hair and meristem development in plants [43][44][45], and NAC transcription factor genes regulated lateral root development in potato [50] and enhances root length in wheat [51]. In our study, we identi ed some differentially expressed WRKY, MYB and MYB-like, bHLH as well as NAC transcription factor genes in response to the graphene treatment.…”

“…Many studies have proved that plant root development could be regulated by ERF [40], WRKY [41,42], bHLH [43][44][45], MYB and MYB-like [46][47][48][49], NAC [50,51], AP2 [52,53] as well as MADS-box [54,55] TF genes. After exposure to graphene treatment of Z. mays roots, there were three up and one down-regulated ethylene-responsive (ERF) transcription factor genes ( Fig.…”

Genome-wide Survey of the bHLH Super Gene Family in Brassica napus

“…Participates in auxin metabolism [41,68]. Act redundantly to positively regulate the deve root hairs [45,46,83].…”

Genome-wide Survey of the bHLH Super Gene Family in Brassica napus and its Role in Roots

“…Partially redundantly regulates anthocyanin bi trichome and root hair development [27,28,35 Act redundantly to positively regulate the deve root hairs [45,46,83].…”