Identification, expression, and functional analysis of CLE genes in radish (Raphanus sativus L.) storage root

Abstract

BackgroundRadish (Raphanus sativus L.) is a widespread agricultural plant forming storage root due to extensive secondary growth which involves cambium proliferation and differentiation of secondary conductive tissues. Closely related to the model object Arabidopsis thaliana, radish is a suitable model for studying processes of secondary growth and storage root development. CLE peptides are a group of peptide phytohormones which play important role in the regulation of primary meristems such as SAM, RAM, and procambium, as well as secondary meristems. However, the role of CLE peptides in lateral growth of root during storage root formation has not been studied to date.ResultsIn present work we studied the role of CLE peptides in the development of storage root in radish. We have identified 18 CLE genes of radish (RsCLEs) and measured their expression in various plant organs and also at different stages of root development in R. sativus and Raphanus raphanistrum—its close relative which does not form storage root. We observed significant decline of expression levels for genes RsCLE1, 2, 11, 13, and 16, and also multifold increase of expression levels for genes RsCLE19, and 41 during secondary root growth in R. sativus but not in R. raphanistrum. Expression of RsCLE 2, 19, and 41 in R. sativus root was confined to certain types of tissues while RsCLE1, 11, 13, and 16 expressed throughout the root. Experiments on overexpression of RsCLE2, 19 and 41 or treatment of radish plants with synthetic CLE peptides revealed that CLE19 and CLE2 increase the number of xylem elements, and CLE41 induces the formation of extra cambium foci in secondary xylem. Expression levels of RsCLE2 and 19 strongly decrease in response to exogenous cytokinin, while auxin causes dramatic increase of RsCLE19 expression level and decrease of RsCLE41 expression.ConclusionsOur data allow us to hypothesize about the role of RsCLE2, 19 and 41 genes in the development of storage root of Raphanus sativus, e.g. RsCLE19 may play a role in auxin-dependent processes of xylem differentiation and RsCLE41 stimulates cambium activity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0687-y) contains supplementary material, which is available to authorized users.

Genetic control of regeneration processes of radish plants in vitro: from phenotype to genotype

“…In radishes, an analysis of CLE genes expression during the development of spontaneous tumors showed a manifold increase in the relative expression levels of eight CLE genes. Among them are CLE19 and CLE41, which according to our data also play a central role in cambium proliferation and xylem differentiation in the development of the radish crop-root (Gancheva et al, 2016(Gancheva et al, , 2018. The activity of CLE19 and CLE41 promoters in spontaneous radish tumors was also confirmed using reporter constructs, while the CLE41 promoter activity was detected in the meristem-like zones of tumor, and the CLE19 promoter was active in the xylem parenchyma and young vessels (Kuznetsova et al, 2018).…”

Comprehensive identification and clustering of CLV3/ESR‐related (CLE) genes in plants finds groups with potentially shared function

“…Bioinformatic approaches have been used to identify members of the CLE gene family within individual plant genomes. Genome‐wide characterization of CLE genes in Pinaceae, Arabidopsis , tomato, soybean, common bean, poplar, radish, rice and maize has also been conducted using B last P (Cock & McCormick, ; Kinoshita et al ., ; Mortier et al ., ; Strabala et al ., ; Zhang et al ., ; Hastwell et al ., ; Gancheva et al ., ; Han et al ., ; Je et al ., ). Oelkers et al .…”

“…Bioinformatic approaches have been used to identify members of the CLE gene family within individual plant genomes. Genome-wide characterization of CLE genes in Pinaceae, Arabidopsis, tomato, soybean, common bean, poplar, radish, rice and maize has also been conducted using BLASTP (Cock & McCormick, 2001;Kinoshita et al, 2007;Mortier et al, 2011;Strabala et al, 2014;Zhang et al, 2014;Hastwell et al, 2015;Gancheva et al, 2016;Han et al, 2016;Je et al, 2016). Oelkers et al (2008) made one of the few attempts to assess the extent of the family across a broad set of species, using a combination of profile hidden Markov models (HMMs) and a position-specific iterative BLAST method.…”

QTL mapping for tuberous stem formation of kohlrabi (Brassica oleracea var. gongylodes L.)

“…Cytokinin signaling and its' downstream transcriptional regulation play an essential role in the radial growth of radish roots (Jang et al 2015). The expression of CLE genes was altered due to auxin and cytokinin application (Gancheva et al 2016). Overexpression of RsCLE genes, CLE19 and CLE2, increased the number of xylem elements and CLE41 induced the formation of additional cambium foci in R. sativus.…”