CsSCL1 is differentially regulated upon maturation in chestnut microshoots and is specifically expressed in rooting-competent cells

Abstract

The Castanea sativa SCL1 gene (CsSCL1) has previously been shown to be induced by auxin during adventitious root (AR) formation in rooting-competent microshoots. However, its expression has not previously been analyzed in rooting-incompetent shoots. This study focuses on the regulation of CsSCL1 during maturation and the role of the gene in the formation of AR. The expression of CsSCL1 in rooting-incompetent microshoots and other tissues was investigated by quantitative reverse transcriptase--polymerase chain reaction. The analysis was complemented by in situ hybridization of the basal segments of rooting-competent and --incompetent microshoots during AR induction, as well as in AR and lateral roots. It was found that CsSCL1 is upregulated by auxin in a cell-type- and phase-dependent manner during the induction of AR. In root-forming shoots, CsSCL1 mRNA was specifically located in the cambial zone and derivative cells, which are rooting-competent cells, whereas in rooting-incompetent shoots the hybridization signal was more diffuse and evenly distributed through the phloem and parenchyma. CsSCL1 expression was also detected in lateral roots and axillary buds. The different CsSCL1 expression patterns in rooting-competent and -incompetent microshoots, together with the specific location of transcripts in cell types involved in root meristem initiation and in the root primordia of AR and lateral roots, indicate an important role for the gene in determining whether certain cells will enter the root differentiation pathway and its involvement in meristem maintenance.

Localized Induction of the ATP-Binding Cassette B19 Auxin Transporter Enhances Adventitious Root Formation in Arabidopsis

“…The increases in auxin-induced reporter expression occurred prior to the earliest cell division events leading to formation of adventitious root primordia and is blocked by treatment with auxin transport inhibitors. This finding is consistent with other auxin-dependent gene expression events that increase upon excision in tree seedlings determined by PCR and quantitative real time-PCR (Hutchison et al, 1999;Sánchez et al, 2007;Solé et al, 2008;Vielba et al, 2011) but goes beyond those prior findings to visualize the position of these localized changes using auxinresponsive reporter constructs. Together, these experiments clearly indicate an important role of auxin transport and localized auxin accumulation in excision-induced root formation.…”

1,3-di(benzo[d]oxazol-5-yl)urea acts as either adventitious rooting adjuvant or xylogenesis enhancer in carob and pine microcuttings depending on the presence/absence of exogenous indole-3-butyric acid

“…In cultured chestnut shoots the expression of a SCR-LIKE (SCL) gene, i.e., CsSCL1, is induced by the IBA treatment before AR formation, i.e., at the onset of cell divisions, which are restricted to the cambial zone and derivative cells (Vielba et al 2011). A similar expression pattern has been shown by a PrSCL1 gene in 21-days-old pine hypocotyls cultured under the same IBA-treatment presently adopted, in which a PrSHR gene is also early activated in the same cambial region, but independently of the exogenous auxin input (Sánchez et al 2007;Solé et al 2008).…”

Preservation of sweet chestnut genetic resources (Castanea sativa Mill.) against attack by chestnut gall wasp (Dryocosmus kuriphilus Yasumatsu, 1951)

“…Gonҫalves et al (1998) used a combination of Gresshoff and Doy (macronutrients) and MS-medium (micronutrients) supplemented with 3 mg/l IBA for successful rooting of hybrid chestnut (C. sativa × C. crenata) microshoots. Sanchez and Vieitez (1991) and Vielba et al (2011) succeeded to root European chestnut by quick-dipping (0.5 -3 min. or 1 min.)…”