Young Plantlets Research Articles

Phenolic changes during in vitro organogenesis of cotton ( Gossypium hirsutum L.) shoot tips

Browning and subsequent death of the cultured explants are major problems for many tissue culture non/hard-adaptive species and usually depended on the phenolic compounds and the quantity of total phenols. Many studies, using shoot tips as explant source indicated various problems such as phenolic exudation, media discoloration, rooting deficiencies and explant browning and death. The phenols are synthesized by the plants and in many tissue culture studies, excreted and then oxidized phenols effect in vitro proliferation negatively. In addition, amount of phenolics can be more or less in different stages of organogenesis due to metabolic actions. Therefore determination of phenolics and calculating the amounts of phenols may be another research area for many tissue culture studies. In this study, total phenol amounts of shoot tip cultures were evaluated during in vitro organogenesis of cotton (Gossypium hirsutum L.). Cotton var. Nazilli 84S was used as explant source and total phenols of young leaves, shoots and the MS (Murashige and Skoog) media (for excreted phenols from explants to medium) were calculated in 7-14-21 and 28 days of culturing period. Seeds were germinated in hormone free MS media in 7 days. After germination, 7 day old meristematic shoot tips were dissected out from seedlings and cultured on MS media, supplemented with 0.1 mg/L Kinetin (KIN). They were grown at 25oC under fluorescent light (7500 lx) 16 h light and 8 h dark for 3 weeks. Singleton-Rossi method based Folin-Ciocaelteu reactive was used for determination of total phenol amount of the young plantlets and it was observed that different parts of the plantlets synthesized more or less amounts of phenolics in different stages of organogenesis. Key words: Cotton, tissue culture, phenolics, browning, organogenesis, shoot tip.

Potential implications of biopriming in banana (Musa spp) plantlets against banana bunchy top virus (BBTV)

Transplant media as a means for the introduction of biological agents is currently being investigated in a variety of crops. This study aimed to investigate the impact of microbial inoculation in micropropagated banana plantlets to enhance their resistance against Banana bunchy top virus (BBTV). Virus indexed micropropagated plantlets of banana were subjected to root colonization followed by foliar spraying with bacterial strains Pseudomonas fluorescens Pf1, CHA0 and Bacillus subtilis EPB22 during primary and secondary hardening stage in the nursery, at the time of repotting and 3 months after planting in the pot. Microbe inoculated plantlets showed enhanced PR proteins and defense enzymes besides reducing banana bunchy top disease incidence under glasshouse condition. The results indicated the effective use of beneficial microbes in reducing the disease incidence of BBTV in tissue culture banana plantlets. In addition, the molecular characterization of endophytes isolated from banana plantlets, using SDS-PAGE and RAPD-PCR revealed that endophytes were categorized into two distinct groups. These results emphasize the significance of microorganisms in protection of young plantlets from transplanting stresses in field. Further, the use of beneficial microorganisms instead of chemicals sustains an ecological niche in the agricultural ecosystem.

Utilization of Shoot Cuttings for Elimination of PLRV and PVY by Thermotherapy and Chemotherapy from Potato (Solanum tuberosum L.)

Heat and ribavirin treatments were applied for the elimination of potato leaf roll virus (PLRV) and potato virus Y (PVY) from the potato genotype F 9-99. The explants, rooted young plantlets, cultured on MS medium with and without ribavirin (20 mg l<sup>-1</sup>) were subjected to thermotherapy (35ºC/31ºC, 4 h alternating periods) and room temperature (25ºC) for 30 days. Double antibody sandwich - enzyme linked immunosorbent assay (DAS-ELISA) testing following the therapies revealed that ribavirin alone was enable to eliminate 10% each of PLRV and PVY, whereas along with thermotherapy its efficacy increased to 25% PLRV and 20% PVY elimination. In another experiment, three potato genotypes F 9-99 infected with PLRV and PVY, Gui Valley with PLRV infection and Rose Valley with PVY infection were evaluated. Ribavirin (20 mg l<sup>-1</sup>) and ASA (acetylsalicylic acid) (10<sup>-5</sup> M) were supplemented in liquid culture medium alone or in combination with thermotherapy for three successive cycles of 30-36 days interval. Heat and/or ribavirin suppressed survival and plant height whereas ASA promoted the survival as well as plant height even under heat treatment. After each cycle, the effect of treatment on virus elimination was evaluated by DAS-ELISA. The combined application of ribavirin and ASA with thermotherapy after three cycles of treatment showed up to 47.4% PLRV and 57.9% PVY elimination in F 9-99. In the case of single viral infection of PLRV or PVY the same combined treatment showed up to 58.8% PLRV and 61.1% PVY free plantlets. Virus elimination was also confirmed by transplanting in vitro grown plantlets in a net house and then retesting after 45 days of in vivo growth. This novel technique would be highly efficient for virus elimination within a short duration in diverse genotypes of potato. <i>Nepal Journal of Science and Technology </i> 7 2006

Cloning of a cDNA encoding a cystatin from grain amaranth ( Amaranthus hypochondriacus) showing a tissue-specific expression that is modified by germination and abiotic stress

A cDNA, encoding a cysteine protease inhibitor ( AhCPI), was isolated from an immature seed cDNA library of grain amaranth ( Amaranthus hypochondriacus L.) and characterized. It encoded a polypeptide of 247 amino acids (aa), including a putative N-terminal signal peptide. Other relevant regions found in its sequence included the G and PW conserved aa motifs, the consensus LARFAV sequence for phytocystatins and the reactive site QVVAG. The predicted aa sequence for AhCPI showed a significant homology to other plant cystatins. Gene expression analyses indicated that AhCPI was constitutively expressed in mature seeds, and gradually decreased during germination. In vegetative tissues, AhCPI was expressed in the radicle and hypocotyls of seedlings and in the stems and roots of young plantlets. Its expression in roots and stems increased substantially in response to water deficit, salinity-, cold- and heat-stress, whereas heat-stress induced a rapid and transient accumulation of AhCPI transcripts in leaves. The results obtained were suggestive of multiple roles for AhCPI in grain amaranth, acting as a regulator of seed germination and as a protective agent against diverse types of abiotic stress, which induced this gene in a tissue- and stress-specific manner. The work herewith described reports a novel, and apparently, single cystatin protein in which, in agreement with other plant model systems, could have a regulatory role in germination, and further expands previous findings linking the accumulation of protease inhibitors, mostly of the serine proteinase type, with protection against (a)biotic stress in A. hypochondriacus.

Fast, efficient and reproducible genetic transformation of Phaseolus spp. by Agrobacterium rhizogenes

This transformation procedure generates, with high efficiency (70-90%), hairy roots in cultivars, landraces and accessions of Phaseolus vulgaris (common bean) and other Phaseolus spp. Hairy roots rapidly develop after wounding young plantlets with Agrobacterium rhizogenes, at the cotyledon node, and keeping the plants in high-humidity conditions. Callogenesis always precedes hairy-root formation, and after 15 days, when roots develop at wounded sites, the stem with the normal root is cleaved below the hairy root zone. Transgenic roots and nodules co-transformed with a binary vector can be easily identified using a reporter gene. This procedure, in addition to inducing robust transgenic hairy roots that are susceptible to being nodulated by rhizobia and to fixing nitrogen efficiently, sets the foundation for a high-throughput functional genomics approach on the study of root biology and root-microbe interactions. This protocol can be completed within 30 days.

MOLECULAR AND PHENOTYPIC CHARACTERIZATION OF SOMACLONAL VARIATION IN DATE PALM OFF-TYPES ORIGINATED FROM TISSUE CULTURE

ISHS International Symposium on Biotechnology of Temperate Fruit Crops and Tropical Species MOLECULAR AND PHENOTYPIC CHARACTERIZATION OF SOMACLONAL VARIATION IN DATE PALM OFF-TYPES ORIGINATED FROM TISSUE CULTURE

Germin-like genes are expressed during somatic embryogenesis and early development of conifers

Germins and germin-like proteins (GLPs) are members of a superfamily of proteins widely distributed in plants. Their localization within the extracellular matrix and in some cases their hydrogen peroxide-producing activity suggests that these proteins are involved in cell wall metabolism during stress responses and developmental processes. Several very highly conserved conifer GLPs have been identified in somatic embryo tissues. In order to gain more knowledge on their potential involvement in the development of this particular tissue, we have characterized a new GLP gene, LmGER1 in hybrid larch. Anti-GLP immunserum and in-gel activity analyses suggested the presence of superoxide dismutase activity in apoplastic proteins from larch somatic embryos. These results could indicate a possible role for LmGER1 in this physiological process. The expression of LmGER1 has been followed during the maturation of somatic embryos and in different organs of young plantlets by homologous transformation with a promoter-gus construct. This promoter was activated in the root cap of young embryos and, later on, in the cotyledons and in the vascular procambium and xylem. Furthermore, the importance of this gene in embryo development was evaluated by transforming embryonal masses with a gene construct encoding a hairpin RNA leading to gene silencing. The potential role of LmGER1 in cross-linking of cell wall components is discussed.

Composition of Flax Hypocotyl Fibres

Fibres in the middle part of the hypocotyl of young flax plantlets are organised in a circle of one hundred cells around the vascular cylinder. Apart from cellulose, their walls, of large thickness (2-5 μm), contain 30 to 50% of non-cellulosic polysaccharides (NCPs). NCPs consist mainly of β-(1-4)-galactan, together with rhamnogalacturonan of type I and polygalacturonic acid. Transmission electronic microscopy, coupled with immunocytochemical labellings shows that arabinogalactan proteins are also present and may contribute to the galactose and arabinose contents of cell walls. Mannose is one of the sugars tightly bound to cellulose residue, indicating that mannoseenriched polymers are good candidates to cross-link pectins with cellulose microfibrils.

Analysis of Accumulation Patterns of Barley yellow dwarf virus-PAV (BYDV-PAV) in Two Resistant Wheat Lines

Barley yellow dwarf (BYD) is one of the main viral diseases of small-grain cereals. This disease, reported on numerous plant species of the Poaceae family, is caused by a complex of eight viral species including the species Barley Yellow Dwarf Virus-PAV (BYDV-PAV), frequently found in western Europe. Resistance sources against BYDV-PAV are scarce and only identified in perennial Triticineae. Some BYDV-resistant wheat lines have been obtained by introgressing these resistances into bread wheat germplasms. Genetic and biological characterization of the resulting lines has been undertaken. However, little information on the resistant behaviour of these lines during the early stages of the infection process is available. To evaluate the resistance of two genetically distinct resistant lines (Zhong ZH and TC14), 1740 young plantlets, belonging to susceptible reference hosts (barley cv. Express and wheat cv. Sunstar), Zhong ZH or TC14 wheat lines, were inoculated in controlled conditions with French BYDV-PAV isolates. The infection process was monitored during the first 21 days after inoculation (DAI) using a semi-quantitative ELISA. A standardized protocol including five successive samplings of leaves from all inoculated plants and the collection of plant roots at the end of the monitored period was carried out. This protocol enabled an assessment of the infection percentage and the evolution of the viral load in plants from the 7th DAI to the 21st DAI. Statistical analyses of the BYDV infection kinetics using raw ELISA data, a model of the time-dependent variation of the percentage of infected plants and the area under concentration progress curves (AUCPC) demonstrated that Zhong ZH and TC14 lines (1) reduce the development rate of the BYD disease during the first days of infection, (2) decrease the infection efficiency of BYDV-PAV isolates, in the leaves, from 98.7% for susceptible plant genotypes to 81.9% and 71.7% for Zhong ZH and TC14, respectively, (3) reduce the virus load in the leaves of infected plants and (4) are not spared from BYDV infection, as 95.1% of Zhong ZH and 90.2% of TC14 inoculated plants accumulated viral particles in roots and/or in leaves at 21 DAI. These results confirm the BYDV-partial resistant behaviour of both Zhong ZH and TC14 lines. The development rate of the disease was the single parameter that allowed the distinction between the two resistant sources present in the tested lines.

The expression of the hydroxyproline-rich glycopeptide systemin precursor A in response to (a)biotic stress and elicitors is indicative of its role in the regulation of the wound response in tobacco (Nicotiana tabacum L.)

Two hydroxyproline-rich glycopeptide systemin (TobHS) precursor proteins known as preproTobHypSys-A and B were recently discovered in tobacco (Nicotiana tabacum L.) [Pearce et al. in Nature 411:817-820, 2001]. In this work, the effect of elicitors, insect damage, and abiotic stress on the expression of preproTobHypSys-A ppTobHS-A) in tobacco plants was evaluated. Foliar application of methyl jasmonate preferentially induced the systemic expression of ppTobHS-A in leaves phyllotactically one position above-treated leaves. Abscisic acid strongly induced ppTobHS-A, but water-stress did not. Mechanical wound-induction of ppTobHS-A in young plantlets was rapidly (1 h) and simultaneously detected in wounded and upper unwounded leaves, whereas in older plants induction was slow (12 h) and localized. ppTobHS-A was induced in plants infested with Bemisia tabaci or damaged by herbivory with Manduca sexta larvae. Compared to mechanical wounding, larval herbivory induced a stronger and more stable expression of ppTobHS-A. Moreover, exposure to Manduca-damaged plants induced its expression in neighboring intact plants. In most treatments, the expression patterns of ppTobHS-A coincided with those of selected wound-responsive (WR) genes (e.g., PIOX, NtPI-I, TPI). This correlation was tighter in the wounded and MeJA-treated leaves, whereas in distal, undamaged leaves, it appeared to depend on the type of WR gene examined and on the type of damage sustained by the plant. These results are consistent with the perceived role of the TobHS in defense signaling.

Microprogagation of endangered Chinese aloe

A rapid micropropagation protocol was established for Aloe vera L. var. chinensis (Haw.) Berger, Chinese Aloe. The effects of three factors, namely BA, NAA and sucrose, on bud initiation were evaluated by L9 (34) orthogonal design. The variance analysis of the experimental results showed that the actions of the three factors were all considerable. Among the three factors, sucrose was the most important for bud initiation followed by BA, and NAA had the weakest effect. The best medium for bud initiation was semi-solid MS supplemented with 2.0 mg l−1 BA, 0.3 mg l−1 NAA, 30 g l−1 sucrose and 0.6 g l−1 PVP (pH 5.8), on which Chinese aloe could multiply 15 times in 4 weeks. Some shoots rooted spontaneously on 1/2 strength MS medium, but the rooting percentage was improved in the presence of 0.2 mg l−1 NAA. Rooted plantlets were acclimatized to greenhouse conditions. The young plantlets from tissue culture were transplanted successfully. In vitro propagation can be a useful tool in the conservation of this endangered medicinal species.

IN VITRO AND EX VITRO ROOTING AND PLANTLET ACCLIMATIZATION IN NERIUM OLEANDER

Oleander (Nerium oleander L.) is cultivated recently as a flowering pot plant and therefore abundant propagation plant material for commercial use is of great importance. In this study an effort was undertaken to investigate microcutting rooting in vitro and ex vitro and also acclimatization of young microplants. A single white flower clone of oleander was used for the experiments. Microshoots derived from in vitro stock cultures were used as microcuttings and placed for rooting in vitro or ex vitro. For in vitro rooting, the microcuttings were placed in WPM supplemented with IAA or NAA in various concentrations (0, 0.5, 1 or 2 pM). The best rooting was achieved with 2 pM NAA (23%). For ex vitro rooting, the microcuttings were first dipped in various concentrations (0, 0.13, 0.25 or 0.5 g l -1 ) of K-IBA and then were planted in perlite and kept in a fog system with relative humidity adjusted to 96-99%. Rooting was up to 70% with 0.5 g l -1 K-IBA. After rooting in vitro or ex vitro, the young plantlets were transplanted in pots and placed for hardening in a fog system with initial relative humidity at 95%, which then was decreased gradually to 80% in two weeks. The plantlets in the fog system were either under direct sunlight or under 50% shading provided by a net which lasted for 1 week and was removed afterwards. The transplanting losses for those rooted in vitro for both treatments were less than 5%, whereas no losses were noticed in those plantlets derived from ex vitro rooting.

ACCLIMATIZATION OF CALLISTEMON SP. MICROPLANTS IN FOG AS INFLUENCED BY SHADING

In vitro rooted microcuttings of Callistemon sp. were transplanted into pots and placed for hardening in a fog system in the greenhouse, with or without application of 50% shading. The transplanted microplants remained in these conditions for 1 or 2 weeks and then were moved to greenhouse conditions. At the end of the 3 rd week after transplantation the survival rate was measured. Also, at the end of the 3 rd and 4 th week, measurements regarding plantlet height and number of new leaves were taken. Reduced light over microplants (application of shading) in the fog system increased the transplanting losses. The lowest transplanting losses (3%) were noticed when the microplants were kept without shading in the fog system for 2 weeks and then were transferred to the greenhouse. The height of the young plantlets was not influenced by the light regime, while the number of new leaves was higher for those that were maintained in fog without shading for 1 week.

‘Defence lignin’ and hydroxycinnamyl alcohol dehydrogenase activities in wounded Eucalyptus gunnii

‘Defence lignin’ and hydroxycinnamyl alcohol dehydrogenase activities in wounded <i>Eucalyptus gunnii</i>

IN VITRO SOMATIC EMBRYOGENESIS AND REGENERATION OF SOMATIC EMBRYOS FROM PIGMENTED CALLUS OF KAPPAPHYCUS ALVAREZII (DOTY) DOTY (RHODOPHYTA, GIGARTINALES)1

In vitro somatic embryogenesis and regeneration of somatic embryos to whole plants through micropropagules was successfully demonstrated from pigmented uniseriate filamentous callus of Kappaphycus alvarezii (Doty) Doty in axenic cultures. More than 80% of the explants cultured on 1.5% (w/v) agar‐solidified Provasoli enriched seawater (PES) medium showed callus development. The callus induction rate was consistently higher for laboratory‐adapted plants. The excised callus grew well in subcultures and maintained its growth for prolonged periods if transferred to fresh medium in regular intervals. Some subcultured calli (&lt;10%) did undergo transformation and produced densely pigmented spherical or oval‐shaped micropropagules (1–5 mm in diameter) that subsequently developed into young plantlets in liquid PES medium. The micropropagule production was further improved through somatic embryogenesis by a novel method of culturing thin slices of pigmented callus with naphthaleneacetic acid (NAA) or a mixture of NAA and 6‐benzylaminopurine. Transfer of embryogenic callus along with tiny somatic embryos to liquid medium and swirling on orbital shaker facilitated rapid growth and morphogenesis of somatic embryos into micropropagules that grew into whole plants in subsequent cultivation in the sea. The daily growth rate of one tissue cultured plant was monitored for seven generations in field and found to be as high as 1.5–1.8 times over farmed plants. The prolific somatic embryogenesis together with high germination potential of somatic embryos observed in this study offers a promising tool for rapid and mass clonal production of seed stock of Kappaphycus for commercial farming.

Stress-induced somatic embryogenesis in vegetative tissues of Arabidopsis thaliana.

Somatic embryogenesis is an obvious experimental evidence of totipotency, and is used as a model system for studying the mechanisms of de-differentiation and re-differentiation of plant cells. Although Arabidopsis is widely used as a model plant for genetic and molecular biological studies, there is no available tissue culture system for inducing somatic embryogenesis from somatic cells in this plant. We established a new tissue culture system using stress treatment to induce somatic embryogenesis in Arabidopsis. In this system, stress treatment induced formation of somatic embryos from shoot-apical-tip and floral-bud explants. The somatic embryos grew into young plantlets with normal morphology, including cotyledons, hypocotyls, and roots, and some embryo-specific genes (ABI3 and FUS3) were expressed in these embryos. Several stresses (osmotic, heavy metal ion, and dehydration stress) induced somatic embryogenesis, but the optimum stress treatment differed between different stressors. When we used mannitol to cause osmotic stress, the optimal conditions for somatic embryogenesis were 6-9 h of culture on solid B5 medium containing 0.7 m mannitol, after which the explants were transferred to B5 medium containing 2,4-dichlorophenoxyacetic acid (2,4-D, 4.5 microm), but no mannitol. Using this tissue culture system, we induced somatic embryogenesis in three major ecotypes of Arabidopsis thaliana-Ws, Col, and Ler.

Micropropagation of oregano (Origanum vulgare×applii) from meristem tips

‘Mendocino’ oregano (Origanum vulgare × applii) cultivated in Argentina has been subject to progressive yield loss as a consequence of continuous vegetative propagation. A method of reducing damage to the shoot tip during sterilization procedures for micropropagation is proposed. Single shoot cuttings are less sensitive to disinfecting substances than green tips. Meristems taken from young plantlets that grew in vitro produced less oxidation during the culture than those dissected immediately after disinfecting from plants grown in the field. This work describes the effects of the growth regulators benzyladenine (BA) and naphthaleneacetic acid (NAA) at various concentrations and combinations on micropropagation of O. vulgare × applii. Treatment with 0.28 μM BA and 0.53 μM NAA gave greatest effiency (mean: 22.2 nodes per plantlet). After 60 d 100% of rooted plantlets could be formed per explant under optimum conditions.

Transcript levels of AtMRPs after cadmium treatment: induction of AtMRP3

ABSTRACTIn yeasts, the ABC‐type transporters are involved in vacuolar sequestration of cadmium. In plants, transport experiments with isolated vacuoles indicate that this is also true. In order to know more about the response of AtMRPs, a subclass of Arabidopsis ABC transporters, to cadmium, their expression pattern was analysed using the microchip technology and semi‐quantitative reverse transcriptase‐polymerase chain reaction. From 15 putative sequences coding for AtMRPs, transcript levels were detected for 14. All were expressed in the roots as well as in the shoots, although at a different level. In 4‐week‐old Arabidopsis, transcript levels of four AtMRPs were up‐regulated after cadmium treatment. In all cases up‐regulation was exclusively observed in the roots. The increase of transcript levels was most pronounced for AtMRP3. A more detailed analysis revealed that induction of AtMRP3 could also be observed in the shoot when leaves were cut and cadmium allowed to be taken up in the shoot. In young plantlets, a far higher portion of Cd2+ was translocated in the aerial part compared with adult plants. Consequently, AtMRP3 transcript levels increased in both root and shoot of young plants. This suggests that 7‐day‐old seedlings do not exhibit such a strict root–shoot barrier as 4‐week‐old plants. Expression analysis with mutant plants for glutathione and phytochelatin synthesis as well as with compounds producing oxidative stress indicate that induction of AtMRP3 is likely due to the heavy metal itself.

Cultivation of Cimicifuga racemosa (L.) nuttal and quality of CR extract BNO 1055

Objectives: For Cimicifuga racemosa, well-founded investigations concerning multiplication, germination of seeds and field cultivation have not yet been published. Defined origins or varieties with certain agronomic properties and a specific pattern of active compounds are not commercially available. Special challenges are found with regard to growing of young plantlets from seeds. Comprehensive investigations have been started to find optimal conditions for all steps of the whole process to establish cultivation for Cimicifuga. Aim is to get defined varieties or sources with desirable agronomic characteristics and specific reproducible compound patterns in order to reach homogeneous plant raw material. Methods: For analytical tests, validated HPLC and TLC methods were used. Results: Results from germination experiments with different temperature regimens show that the time for germination can be shortened from about 20 months to about 6 months. Gibberellic acid had positive influence on the development of the embryo. Content of triterpenglycosides and phenolic compounds was highest in May and June and decreased then from July until September. The quality of the ethanolic extract BNO 1055 (contained in Klimadynon® and Menofem®) differs from that of an isopropanolic extract. Comparison was carried out by means of TLC pattern of triterpenglycosides and phenolic compounds. Conclusion: Extensive systematic research on cultivation parameters with regard to all stages from the seeds to the herbal drug enables commercial field cultivation of Cimicifuga. Controlled cultivation (according to good agricultural practice or GAP) ensures the availability of homogenous standardized raw material. For pharmacological and clinical studies, standardized extracts and finished herbal medicinal products are required. Results of these studies are never transferable to other products and therefore valid only for the tested extracts/products.

CDNA-AFLP display for the isolation of differentially expressed genes during chicory root development

To identify genes expressed during root enlargment during the early vegetative growth of chicory (Cichorium intybus L.), we used the cDNA-AFLP technology. The radial pattern of chicory roots was investigated by histological analysis to determine the spatial vascular cambium setting. In young plantlets, serial root sections showed that differentiation of secondary tissues occurred along a gradient extending from the apex to the crown. The cDNA-AFLP technique was carried out on total mRNAs extracted from root tissues producing secondary structures and root tissues developing primary structures only. This study reports on the isolation of two transcript-derived fragments (TDFs) referred to as Y-16 and Y-21. Sequence analysis at the protein level showed that Y-16 carries a sequence highly homologous (93% identities) to the amino acid transporter-like protein 1 (AATL 1) from Arabidopsis and Y-21 presents 72% identity to AAD25141.1 Arabidopsis protein. The expression pattern of both these TDFs was analysed by northern blot and showed an over-expression during early development of chicory roots.