Identificació de gens i processos rellevants pel fel·lema i la suberina usant noves aproximacions

The periderm is a complex structure that protects plants’ secondary organs and wounded tissues. This function is given by the phellem, a multilayered tissue formed by cells with suberized cell walls located on the outer part of the periderm. Suberin is a basic polymer for protection thanks to its lipid nature. Exceptionally, the cork oak has a great capacity to produce layers of phellem. Recently, transcriptomics studies, as well as reverse genetic approaches, have contributed to the knowledge of the formation and regulation of the periderm and the synthesis and transport of the suberin components. However, the molecular bases that control these processes are still quite unknown. For this reason, new regulatory and transport candidate genes have been characterized. In addition, a faster and less expensive roots transformation system has been developed. Finally, a global transcriptome analysis of the outer bark of cork oak during its growth has been performedEl periderma és una estructura complexa que protegeix els òrgans secundaris i els teixits cicatricials. Aquesta funció la dóna el fel·lema,teixit pluriestratificat format per cèl·lules amb parets suberificades situat a la part externa del periderma. La suberina és un polímer bàsic per la protecció gràcies a la seva naturalesa lipídica. De forma excepcional l’alzina surera té una gran capacitat per produir capes de fel·lema. En els últims anys, estudis transcriptòmics, així com de genètica inversa, han contribuït al coneixement de la formació i regulació del periderma i la síntesi i transport de la suberina. No obstant, les bases moleculars que controlen aquests processos són encara força desconegudes. Per aquest motiu s'han caracteritzat nous gens candidats reguladors i de transport. A més, s'ha posat a punt un sistema de transformació d'arrels més ràpid i menys costós. Per últim, s'ha realitzat un anàlisi global del transcriptoma de l'excorça externa de l'alzina surera durant el seu creixemen

Identificació de gens i processos rellevants pel fel·lema i la suberina usant noves aproximacions

The periderm is a complex structure that protects plants’ secondary organs and wounded tissues. This function is given by the phellem, a multilayered tissue formed by cells with suberized cell walls located on the outer part of the periderm. Suberin is a basic polymer for protection thanks to its lipid nature. Exceptionally, the cork oak has a great capacity to produce layers of phellem. Recently, transcriptomics studies, as well as reverse genetic approaches, have contributed to the knowledge of the formation and regulation of the periderm and the synthesis and transport of the suberin components. However, the molecular bases that control these processes are still quite unknown. For this reason, new regulatory and transport candidate genes have been characterized. In addition, a faster and less expensive roots transformation system has been developed. Finally, a global transcriptome analysis of the outer bark of cork oak during its growth has been performedEl periderma és una estructura complexa que protegeix els òrgans secundaris i els teixits cicatricials. Aquesta funció la dóna el fel·lema,teixit pluriestratificat format per cèl·lules amb parets suberificades situat a la part externa del periderma. La suberina és un polímer bàsic per la protecció gràcies a la seva naturalesa lipídica. De forma excepcional l’alzina surera té una gran capacitat per produir capes de fel·lema. En els últims anys, estudis transcriptòmics, així com de genètica inversa, han contribuït al coneixement de la formació i regulació del periderma i la síntesi i transport de la suberina. No obstant, les bases moleculars que controlen aquests processos són encara força desconegudes. Per aquest motiu s'han caracteritzat nous gens candidats reguladors i de transport. A més, s'ha posat a punt un sistema de transformació d'arrels més ràpid i menys costós. Per últim, s'ha realitzat un anàlisi global del transcriptoma de l'excorça externa de l'alzina surera durant el seu creixemen

Transcriptomic analysis of cork during seasonal growth highlights regulatory and developmental processes from phellogen to phellem formation

Abstract The phellogen or cork cambium stem cells that divide periclinally and outwardly specify phellem or cork. Despite the vital importance of phellem in protecting the radially-growing plant organs and wounded tissues, practically only the suberin biosynthetic process has been studied molecularly so far. Since cork oak (Quercus suber) phellogen is seasonally activated and its proliferation and specification to phellem cells is a continuous developmental process, the differentially expressed genes during the cork seasonal growth served us to identify molecular processes embracing from phellogen to mature differentiated phellem cell. At the beginning of cork growth (April), cell cycle regulation, meristem proliferation and maintenance and processes triggering cell differentiation were upregulated, showing an enrichment of phellogenic cells from which phellem cells are specified. Instead, at maximum (June) and advanced (July) cork growth, metabolic processes paralleling the phellem cell chemical composition, such as the biosynthesis of suberin, lignin, triterpenes and soluble aromatic compounds, were upregulated. Particularly in July, polysaccharides- and lignin-related secondary cell wall processes presented a maximal expression, indicating a cell wall reinforcement in the later stages of cork formation, presumably related with the initiation of latecork development. The putative function of relevant genes identified are discussed in the context of phellem ontogeny

Silencing of StRIK in potato suggests a role in periderm related to RNA processing and stress.

BACKGROUND: The periderm is a protective barrier crucial for land plant survival, but little is known about genetic factors involved in its development and regulation. Using a transcriptomic approach in the cork oak (Q. suber) periderm, we previously identified an RS2-INTERACTING KH PROTEIN (RIK) homologue of unknown function containing a K homology (KH)-domain RNA-binding protein, as a regulatory candidate gene in the periderm. RESULTS: To gain insight into the function of RIK in the periderm, potato (S. tuberosum) tuber periderm was used as a model: the full-length coding sequence of RIK, hereafter referred to as StRIK, was isolated, the transcript profile analyzed and gene silencing in potato performed to analyze the silencing effects on periderm anatomy and transcriptome. The StRIK transcript accumulated in all vegetative tissues studied, including periderm and other suberized tissues such as root and also in wounded tissues. Downregulation of StRIK in potato by RNA interference (StRIK-RNAi) did not show any obvious effects on tuber periderm anatomy but, unlike Wild type, transgenic plants flowered. Global transcript profiling of the StRIK-RNAi periderm did show altered expression of genes associated with RNA metabolism, stress and signaling, mirroring the biological processes found enriched within the in silico co-expression network of the Arabidopsis orthologue. CONCLUSIONS: The ubiquitous expression of StRIK transcript, the flower associated phenotype and the differential expression of StRIK-RNAi periderm point out to a general regulatory role of StRIK in diverse plant developmental processes. The transcriptome analysis suggests that StRIK might play roles in RNA maturation and stress response in the periderm

Silencing against the conserved NAC domain of the potato StNAC103 reveals new NAC candidates to repress the suberin associated waxes in phellem

Both suberin and its associated waxes contribute to the formation of apoplastic barriers that protect plants from the environment. Some transcription factors have emerged as regulators of the suberization process. The potato StNAC103 gene was reported as a repressor of suberin polyester and suberin-associated waxes deposition because its RNAi-mediated downregulation (StNAC103-RNAi) over-accumulated suberin and associated waxes in the tuber phellem concomitantly with the induction of representative biosynthetic genes. Here, to explore if other genes of the large NAC gene family participate to this repressive function, we extended the silencing to other NAC members by targeting the conserved NAC domain of StNAC103 (StNAC103-RNAi-c). Transcript profile of the StNAC103-RNAi-c phellem indicated that StNAC101 gene was an additional potential target. In comparison with StNAC103-RNAi, the silencing with StNAC103-RNAi-c construct resulted in a similar effect in suberin but yielded an increased load of associated waxes in tuber phellem, mainly alkanes and feruloyl esters. Globally, the chemical effects in both silenced lines are supported by the transcript accumulation profile of genes involved in the biosynthesis, transport and regulation of apoplastic lipids. In contrast, the genes of polyamine biosynthesis were downregulated. Altogether these results point out to StNAC101 as a candidate to repress the suberin-associated waxes

Silencing against the conserved NAC domain of the potato StNAC103 reveals new NAC candidates to repress the suberin associated waxes in phellem

Both suberin and its associated waxes contribute to the formation of apoplastic barriers that protect plants from the environment. Some transcription factors have emerged as regulators of the suberization process. The potato StNAC103 gene was reported as a repressor of suberin polyester and suberin-associated waxes deposition because its RNAi-mediated downregulation (StNAC103-RNAi) over-accumulated suberin and associated waxes in the tuber phellem concomitantly with the induction of representative biosynthetic genes. Here, to explore if other genes of the large NAC gene family participate to this repressive function, we extended the silencing to other NAC members by targeting the conserved NAC domain of StNAC103 (StNAC103-RNAi-c). Transcript profile of the StNAC103-RNAi-c phellem indicated that StNAC101 gene was an additional potential target. In comparison with StNAC103-RNAi, the silencing with StNAC103-RNAi-c construct resulted in a similar effect in suberin but yielded an increased load of associated waxes in tuber phellem, mainly alkanes and feruloyl esters. Globally, the chemical effects in both silenced lines are supported by the transcript accumulation profile of genes involved in the biosynthesis, transport and regulation of apoplastic lipids. In contrast, the genes of polyamine biosynthesis were downregulated. Altogether these results point out to StNAC101 as a candidate to repress the suberin-associated waxes