The morphological variability within a population of coffee somatic embryos produced in a bioreactor affects the regeneration and the development of plants in the nursery

A 1-liter bioreactor was used to obtain approximatively 800 Coffea arabica somatic embryos, 86% of which reached the `germinated' stage but with morphological heterogeneity. The population was sub-divided into three categories according to cotyledon area: 'small', 'medium' and 'large', that amounted to 32%, 36% and 4.5%, respectively. The effect of embryo morphology on plantlet conversion after direct sowing in soil and on plant development in the nursery was investigated. Somatic embryos with large cotyledons had only a 25% plantlet conversion rate, whereas somatic embryos with small to medium-sized cotyledons had conversion rates of 47% and 63%, respectively. The vigour of the aerial and root systems of regenerated plantlets at the end of the plant conversion stage was also affected as the embryos with small, medium and large cotyledon mostly regenerated small plantlets (0.5–1.5 cm), medium plantlets (1.5–2.5 cm) and large plantlets (2.5–5 cm), respectively. When transplanted in plastic bags, these 3 populations of plantlets exhibited distinct development rates. They had an initial slow growth phase, which was much longer for the small plantlets, followed by a rapid growth phase. After 40 weeks in the nursery, an analysis of the growth parameters of aerial and radical systems showed that the vigour of the plants was strongly related to the vigour of the plantlets transplanted. The heterogeneity of somatic embryos in the bioreactor affected both the plant conversion efficiency in soil and the plant growth in nursery, where it mainly resulted in retarded growth, primarily in plantlets derived from the somatic embryos with small cotyledons.     

Cycle characteristics in a temporary immersion bioreactor affect regeneration,morphology, water and mineral status of coffee (<Emphasis Type="Italic">Coffea arabica</Emphasis>) somatic embryos

Mass regeneration of Coffea arabica L. somatic embryos using a temporary immersion bioreactor was improved by optimizing the immersion cycles, i.e. both the duration and the frequency of immersions. It was demonstrated that increasing the frequency of short immersions (1 min immersions every 24, 12 and 4 h) stimulated embryo production (480, 2,094 and 3,081 embryos/1-l bioreactor, respectively) and improved quality (60, 79 and 85 of torpedo shaped embryos, respectively). On the other hand, an increase in the immersion duration (1, 5 and 15 min) inhibited embryo regeneration (from 2,094 to 428 embryos per 1-l bioreactor) and negatively affected their morphological quality (from 79 to 49 torpedo-shaped embryos) and the conversion of embryos into plants (from 70 to 33). A 15 min immersion duration applied every 4 h produced hyperhydric symptoms in 90 of the embryos. Hyperhydric embryos were characterized by higher fresh weight and water content, more negative values for water potential and higher K⁺ content when compared to normal torpedo-shaped embryos. Micrographs showed structural problems in the globular stage, such as the existence of an irregular epidermis and an absence of reserves. Whatever the immersion cycle used, the somatic embryos exhibited water and mineral characteristics very different from those of their zygotic counterparts. The use of 1 min immersions every 4 h led to the production of the largest quantities of torpedo-shaped embryos without hyperhydricity that succeeded in regenerating plants (75 conversion).     

Regeneration of somatic embryos in Theobroma cacao L. in temporary immersion bioreactor and analyses of free amino acids in different tissues

The present study aimed at developing temporary immersion bioreactor techniques for multiplication of cacao somatic embryos. Temporary Immersion System (TIS), i.e. flooding of plant tissue at regular time intervals provides an efficient way to propagate plants. Somatic embryos were regenerated in twin flask bioreactors. The TIS proved to be suitable for mass regeneration of somatic embryos and for their subsequent direct sowing. The number of embryos after 3 months of culture was significantly higher in TIS cultures than in the solid medium variant. TIS also improved embryo development regarding the conversion to torpedo shaped forms. Matured embryos derived from TIS and pre-treated with 6% sucrose were converted into plants after direct sowing. Additionally to the influence of culture conditions on the development of somatic embryogenesis the content and composition of free amino acids were analysed. The content of free amino acids in somatic embryos rose as immersion frequency increased. The endogenous free GABA content in embryogenic callus was significantly higher than in non-embryogenic callus.     

Direct somatic embryogenesis from leaf and petiole explants of Spathiphyllum ‘Supreme’ and analysis of regenerants using flow cytometry

This study established a method of regenerating Spathiphyllum ??Supreme?? through direct somatic embryogenesis. Somatic embryos occurred in leaf and petiole explants cultured in the dark on a Murashige and Skoog basal medium supplemented with 2.27, 4.54, or 9.08???M N-phenyl-N??-1,2,3-thiadiazol-5-ylurea (TDZ) in combination with 1.08???M ??-naphthalene acetic acid or 2.26???M 2,4-dichlorophenoxyacetic acid (2,4-D). Explants with somatic embryos were transferred to fresh medium containing the same concentrations of growth regulators under lighted conditions for embryo conversion. The highest frequencies of leaf explants with somatic embryos and embryo conversion were both 84.4?%, which were induced by 9.08???M TDZ with 2.26???M 2,4-D. The frequencies for somatic embryo induction and embryo conversion were both 100?% when petiole explants were induced by 4.54???M TDZ with 2.26???M 2,4-D. The number of plantlets produced per leaf explant and petiole explant were as high as 67.4 and 74.4, respectively. Plantlets after transplanting to a soilless substrate grew vigorously in a shaded greenhouse. Liners were stable without phenotypic variation. Flow cytometry analysis of randomly selected plants showed that they all had a single identical peak. The mean nuclear DNA index for ??Supreme?? was 1.568, and the nuclear DNA content was 14.222?pg 2C^?1. The estimated genome size for ??Supreme?? was 6,954.5?Mbp 1C^?1 with a CV at 4.008?%. The results suggest that the regenerated plants have a stable ploidy level and this established regeneration method can be used for highly effective propagation of uniform Spathiphyllum ??Supreme??.     

Production of carrot somatic embryos in a bioreactor

Somatic carrot embryos were grown as batch cultures in a stirred 10-l bioreactor. Embryo production in the bioreactor was comparable to that obtained in shake-flasks. A production of about 50·10³ embryos/l per day was commonly achieved with an inoculum density of 0.1% volume of tissues/volume of medium. Regularly changing of the medium increased embryo viability. A filtering unit coupled to the bioreactor was developed in order to calibrate embryos. The characteristics of the population of harvested embryos are described. Correspondence to: J.-P. Ducos     

Effect of dissolved oxygen concentration on differentiation of somatic embryos of Coffea arabica cv. Catimor 9722

The effect of two different dissolved oxygen (DO) concentrations (50 and 80%) on differentiation of somatic embryos (SE) from cell suspensions of coffee (Coffea arabica cv. Catimor 9722) was analyzed. Two bioreactors CMF-100 (CHEMAP AG) designed for the culture of cells, with 2-l glass vessels and a maximum work volume of 1.8 l were used. Each one was equipped with a gas blending unit (air, O₂, N₂, CO₂) for the control of DO concentration. The inoculation density of embryogenic cells was 1.0 gram of fresh weight per liter (g FW l^–1). The number of somatic embryos was greater (71 072 SE l^–1) with 80% DO, but the major proportion were globular and heart shaped SE (66 399 SE l^–1) and only 6.6% with regard to total was torpedo shaped SE. However, the 50% DO produced the higher number in the torpedo shaped SE (7389 SE l^–1) what represented 20.0% with regard to total. Thus, higher concentrations of DO induced globular and heart shaped SE differentiation, but for production of torpedo shaped SE lower concentrations DO are needed. The somatic embryos obtained in the bioreactor with 50% DO showed similar behavior to the somatic embryos obtained in the rotary shaker. After 8 weeks of culture, 49.2% germination was obtained, which allowed a total of 1725 plantlet to be transferred to conditions ex vitro. After 6 months of culture, 89.2% of conversion was achieved and 1539 plants obtained were transferred to field conditions.     

Post-maturation treatment improves and synchronizes somatic embryo germination of three species of Japanese pines

Somatic embryos of three Japanese pines, Pinus thunberghii, P. densiflora, and P. armandii var. amamiana, were subjected to different post-maturation treatments to improve both germination and plant conversion frequencies. Slow desiccation of somatic embryos at high relative humidity resulted not only in a marked increment in germination frequencies but also subsequently improved plant conversion rates in all genotypes of the three species tested. Overall three species, germination and plant conversion frequency of somatic embryos was improved by more than fourfold (19?C81%) and more than fivefold (15?C77%), respectively, compared to those of untreated control. In addition, this treatment resulted in a considerable improvement of synchronization of the germination period. The time required for root emergence was synchronized over a half period (28?C14?days) compared with the control. Somatic plants were acclimatized and their growth was monitored in the field.     

Comparison of somatic embryogenesis-derived coffee (Coffea arabica L.) plantlets regenerated in vitro or ex vitro: morphological,mineral and water characteristics

Coffea arabica L. plantlets obtained ex vitro after sowing somatic embryos produced in a bioreactor in horticultural substrate were compared with those obtained in vitro from the same embryo population under conventional culturing conditions on semi-solid media. The intensity and quality of aerial and root system development were compared. Shoot emergence was more efficient in vitro but rooting frequencies were low. In contrast, all ex vitro-regenerated embryos rooted. The cotyledon area of mature embryos produced in a bioreactor positively affected plantlet development when regeneration was carried out ex vitro. Embryos with an intermediate cotyledon area (0.86 cm2) had the highest rates of plant conversion ex vitro (63%), and also resulted in vigorous plantlets. Mortality was higher in nursery conditions, but better plant development was obtained. The quality of plantlets produced under ex vitro conditions was reflected in better growth of the aerial and root systems, and also by similar morphological, mineral and water status characteristics to seedlings. Unlike roots formed on semi-solid media, those produced in soil were branched, fine (30-50% had a diameter of less than 0-5 mm) and they bore root hairs. Leaves of plantlets regenerated ex vitro had a histological structure similar to that of seedling leaves, and a lower stomatal density (100 vs. 233 mm-2). Moreover, they were more turgid, as indicated by higher pressure potential (psiP) (0.91 s. 0.30 MPa) and relative water content values (97 vs. 93%). Furthermore, under in vitro conditions, leaves had larger stomata which were abnormally round and raised. Direct sowing of germinated somatic embryos resulted in the rapid production of vigorous plantlets under ex vitro conditions, whilst removing the need for problematical and costly conventional acclimatization procedures.     

Preparation of lipophilic alkyl (hydroxy)benzoates by solvent-free lipase-catalyzed esterification and transesterification

Agal-fermentation-based microbio-diesel production was realized through high-cell-density fermentation of Chlorella protothecoides and efficient transesterification process. Cell density achieved was 16.8 g l⁻¹ in 184 h and 51.2 g l⁻¹ in 167 h in a 5-l bioreactor by performing preliminary and improved fed-batch culture strategy, respectively. The lipid content was 57.8, 55.2, and 50.3% of cell dry weight from batch, primary, and improved fed-batch culture in 5-l bioreactor. Transesterification was catalyzed by immobilized lipase, and the conversion rate reached up to 98%. The properties of biodiesel from Chlorella were comparable to conventional diesel fuel and comply with US standard for Biodiesel. In a word, the approach including high-density fermentation of Chlorella and enzymatic transesterification process were set up and proved to be a promising alternative for biodiesel production.     

Plant regeneration via somatic embryogenesis from solid and suspension cultures of Vitis vinifera L. cv. ‘Manicure Finger’

Vitis vinifera L. cv. ‘Manicure Finger’ is one of the major table grape varieties in China. To provide a strong foundation for genetic transformation with potential for crop improvement, we undertook plant regeneration via somatic embryogenesis. Anthers and gynoecia were harvested from immature flowers and used as explants to induce embryogenic calli. Explants cultured in MS1 medium (based on Murashige and Skoog basal salts), supplemented with 4.5-μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 4.4-μM 6-benzylaminopurine (6-BA) showed the highest rates of embryogenic callus induction (3.7%?±?1.3% for anthers and 4.8%?±?2.5% for gynoecia). After several months, somatic embryos were produced from embryogenic calli cultured in plant growth regulator-free MS2 medium (with reduced sucrose). Somatic embryos (SE) at the cotyledonary stage were isolated and cultured on three different media (MS2, MS3, or B) for conversion into plantlets, the efficiency of which ranged from 63.9%?±?4.8% to 83.9%?±?8.4%. After 1 mo of in vitro culture, 80% of plants with at least six leaves were successfully transplanted into soil. SE was repeatedly induced from previously induced somatic embryos for up to 1.5 yr. Using embryogenic calli as starting material, suspension cultures containing embryogenic cell aggregates were also established in liquid MS medium supplemented with 4.5-μM 2,4-D. The embryogenic cell aggregates continued to proliferate without differentiating for successive subculture cycles. After transfer to 2,4-D-free liquid medium for 4 wk, an average of 63.7%?±?9.0% mature SEs were produced per 20 mL of liquid medium. More than 40% of somatic embryos at cotyledonary stage, derived from the suspension cultures, successfully germinated into plants using solid medium.     

Large-scale plantlets conversion from cotyledonary somatic embryos of Kalopanax septemlobus tree using bioreactor cultures

A suitable bioreactor system for large scale embryo-to-plantlets conversion of Kalopanax septemlobus was established. In temporary immersion with net (TIN) bioreactor, 85% of embryos successfully produced plantlets whereas in continuous immersion with net (CIN) bioreactor, only conversion rate of 29.3% was obtained. Embryos cultured in TIN bioreactor produced more vigorous plantlets in terms of fresh weight, height, root length, roots and leaves quantity. In CIN bioreactor, Kalopanax plantlets showed high malondialdehyde (MDA) content and increased activities of reactive oxygen species (ROS)-processing enzymes, such as ascorbate peroxidase (APX) and glutathione reductase (GR) indicating the occurrence of oxidative stress. However, superoxide dismutase (SOD) and catalase (CAT) showed similar activities in plantlets grown in different bioreactors. Kalopanax plantlets grown in both TIN and CIN bioreactors were harvested and transferred to greenhouse for their acclimatization. Plantlets grown in CIN bioreactor exhibited low survival rate (75.8%) compared to those grown in TIN bioreactor (100%). MDA content decreased with progression of acclimatization indicating a decrease in oxidative stress. However, MDA level in CIN derived plantlets was higher than TIN derived plantlets. In TIN derived plantlets, an increase in SOD and GR activities were observed after 1 week and thereafter decreased. CAT activity decreased while APX activity started to increase after 1 week of acclimatization. The results indicated that Kalopanax plantlets were able to overcome oxidative stress mainly through SOD activity. However, levels of antioxidant enzyme activities were higher in CIN derived plantlets than TIN derived plantlets. Kalopanax plantlets obtained from TIN bioreactor performed better during the acclimatization phase and showed higher survival rate than material obtained on CIN bioreactor or conventional culture systems.     

Field planting of alfalfa artificial seeds

Summary Encapsulated somatic embryos (artificial seeds) and naked (uncoated) somatic embryos of alfalfa (Medicago sativa L.) were planted directly into the field to demonstrate the feasibility of using artificial seeds for direct sowing. Various row coverings that provided protection for the somatic embryos during conversion (plant formation) in the field and encapsulation methods were investigated. The highest conversion obtained in the field was 25% when naked somatic embryos were planted under the protective covering of inverted styrofoam cups. In comparison, 60% conversion was obtained when embryos were planted in potting mix in a growth chamber. Somatic embryos encapsulated by the thin-coat method converted at 23% under cups in the field and 40% in potting mix in the growth chamber. Naked somatic embryos had an average of 13 and 9% conversion in the field under plastic and cloth coverings, respectively, whereas encapsulated embryos converted at 5 and 14%, respectively. Direct-planted embryos (no row covering) converted at 1% in the field. Successful conversion of coated and naked somatic embryos planted in the field supports the concept of artificial seeds serving as a substitute for natural seeds.     

Factors Affecting Somatic Embryogenesis Induction and Conversion in “Paradise Tree” (<Emphasis Type="Italic">Melia azedarach</Emphasis> L.)

Factors affecting somatic embryogenesis induction and conversion in paradise tree (Melia azedarach) were evaluated. Somatic embryogenesis was influenced by plant growth regulators, explant stage, carbohydrate source and concentration, gelling agents, light, and induction times. MS medium with 4.54 μM thidiazuron (TDZ) was optimal for the induction of embryogenic tissue. Zygotic embryos that were 1-1.5 mm long (torpedo and early cotyledonal stage) had a greater embryogenic response than smaller or larger embryos and better conversion of somatic embryos into plants. In general, embryos that formed in medium containing 1% or 5% carbohydrate were hyperhydrics or fused, respectively, whereas those that formed in medium with a carbohydrate concentration of 3% had better morphology. Raffinose at 3% yielded satisfactory somatic embryo induction with good morphology and the best values of conversion into plants. Induction and conversion of somatic embryos were superior on medium solidified with agar A-1296. The explants maintained under 160 μmol m⁻² s⁻¹ or 1 week in darkness and later 160 μmol m⁻² s⁻¹ produced a significantly higher embryogenic index. Only 4 days of treatment on induction medium, with either raffinose or sucrose at 3% as a carbohydrate source, were required to induce somatic embryogenesis, but longer exposure, until 18 days, increased the yield and improved the morphology of somatic embryos.     

Large-scale growth and taxane production in cell cultures of Taxus cuspidata (Japanese yew) using a novel bioreactor

 A novel type of bioreactor was successfully developed for the production of taxol and its precursors by culturing cells of Taxus cuspidata (Japanese yew) on a pilot-scale. Rapidly growing cell lines were selected from callus cultures derived from immature embryos of yew. The cells were inoculated in 20-l capacity bioreactors of different types to test the growth performance. The models of small-scale bioreactors incorporated in this study included a balloon-type bubble bioreactor (BTBB), a bubble-column bioreactor (BCB), a BCB with a split-plate internal loop, a BCB with a concentric draught-tube internal loop, a BCB with a fluidized bed bioreactor, and two different models of stirred tank reactors. Among the reactors, BTBB appeared to be the most efficient in promoting cell growth. The doubling time of cell growth in BTBB was 12 days with a 30% inoculation cell density. The optimum time for medium replacement or feeding was 12–15 days after inoculation as determined by monitoring both the levels of sugars and medium conductivity. When yew tree cells were grown in different sizes (100–500-l) of BTBBs, more than 70% cell viability was recorded at the time of harvest. The growth pattern of the cells in the pilot-scale BTBB appeared to be the same as that of cells in the 20-l bioreactors. Approximately 3 mg/l of taxol and 74 mg/l total taxanes were obtained after 27 days of culture. Received: 6 April 1999 / Revision received: 23 August 1999 / Accepted: 31 August 1999     

Regeneration of pineapple (Ananas comosus L.) plant through somatic embryogenesis

An efficient protocol for a complete plant regeneration by somatic embryogenesis was developed with Smooth Cayenne pineapple (Ananas comosus L.). Previous works showed that this species is responsive to somatic embryogenesis. In the present work the influence of components of culture medium in the induction, development and conversion of somatic embryos was investigate in order to establish a somatic embryogenesis protocol. Nodular callus (83.67%) was initiated from leaf explants of young plants on CIM₃ medium. The highest frequency (37.6%) of embryogenic callus induction was obtained from 4-week-old calluses on EIM₃ medium supplemented with 3.0 mg/l picloram. The highly organized callus induction and the development of somatic embryos were achieved after the transfer of callus clumps onto EIM₃ medium containing 1.0 mg/l BAP + 0.1 mg/l NAA. The frequency of somatic embryo formation was of 39.5?±?2.45 embryos per callus. Up to 97% of the somatic embryos were converted into complete plants within 4 week on MSB medium with 1.0 mg/l BAP + 0.05 mg/l GA₃ + 500 mg/l glutamine. The continuation of the elongation of the shoots occurred on this medium). Shoots obtained from all the above methods were rooted in MSB medium with activated charcoal. Complete plantlets were transferred onto specially made polyethylene bags containing soil mixture and transferred to the greenhouse. Survival rate of the plantlets under ex vitro conditions was 98% and maximum average number of plantlets (80?±?0.6). The well-developed plantlets were transferred to an open field where the plants produced normal fruits.     

Cotton somatic embryo morphology affects its conversion to plant

Somatic embryos differentiated from hypocotyl explant in cotton (Gossypium hirsutum L.) exhibited very divergent morphologies. Six different types of somatic embryos based on cotyledon development were observed. The growth hormones (2,4-dichlorophenoxyacetic acid and kinetin) used in induction and maintenance media did not affect embryo rooting and germination. The 95 % conversion of normal embryos (with two cotyledons) was achieved, while an overall conversion was only 38 %. Horn shaped embryos failed to exhibit shoot growth. Poorly developed apical meristems were responsible for lower conversion percentages in some of embryo classes. However, regenerated plants phenotypically resembled to seed grown control plants regardless of somatic embryo morphology.     

Haploid plant regeneration via embryogenesis from anther cultures of Hepatica nobilis

An anther culture technique for the production of haploid plants was developed in Hepatica nobilis. Embryos with bipolar meristem regions were induced from microspores within the cultured anthers. Embryo formation was promoted by first culturing anthers on NN medium (Nitsch and Nitsch, 1969) supplemented with 1% activated charcoal (AC) at 5 or 35?°C for a few days and by then incubating them in the dark at 25?°C. Pre-culturing anthers at 35?°C for 4?days (thermal-shock treatment) led to the best embryo formation (45 embryos/Petri dish with 30 anthers). Plant regeneration was achieved by culturing the anther-derived embryos on NN medium without AC at 15?°C. Flow cytometric analysis of anther-derived embryos and chromosome counts in regenerated plants showed that they were haploid plants.     

Developing a cell suspension system for Musa-AAA-EA cv. ‘Nakyetengu’: a critical step for genetic improvement of Matooke East African Highland bananas

Embryogenic cell suspensions of triploid East African Highland bananas (Musa AAA-EA) were initiated and generated using cooking cultivar ‘Nakyetengu’ belonging to the Nakabululu clone set. Immature male flowers produced embryogenic calli consisting of embryos and friable tissue after 4 mo culture on a modified MA1 callus induction medium. Friable calli were initiated and maintained in liquid MA2 medium. A cell growth rate of 1.5–2.0 sedimented cell volume (SCV) per month was observed. Embryo development was observed at 2.18?×?10³ embryos per mL SCV. Germination of these embryos was observed at 2.8% and 6.2% for two cell suspension lines. Plant regeneration efficiency was 60–100%, all producing normal plants with a shoot and roots at weaning. In the field, somatic cell-derived plants were all normal morphology and comparable to control plants during vegetative and reproductive stages. This study is a breakthrough for recalcitrant East African Highland banana and offers a system that can provide essential raw materials for associated germplasm improvement through genetic engineering approaches.     

High-frequency somatic embryogenesis from germinated zygotic embryos of <Emphasis Type="Italic">Schisandra chinensis</Emphasis> and evaluation of the effects of medium strength,sucrose, GA<Subscript>3</Subscript>, and BA on somatic embryo development

We developed a new protocol for highly efficient somatic embryogenesis and plantlet conversion of Schisandra chinensis. Friable embryogenic callus was induced from cotyledonary leaves and hypocotyls of germinated zygotic embryos on Murashige and Skoog (MS) agar medium containing 2,4-dichlorophenoxyacetic acid (2,4-D). Preculture of zygotic embryos on 2,4-D-containing medium increased embryogenic callus induction efficiency. The highest embryogenic callus induction frequency of 56.7% was obtained from shoot apical meristem-containing hypocotyl explants from 1-week-old germinated embryos on MS medium containing 4.0 mg l⁻¹ 2,4-D. Embryogenic callus proliferation, somatic embryo (SE) formation, and subsequent plantlet conversion occurred under optimal culture conditions. The effects of MS medium strength, sucrose, gibberellic acid (GA₃), and 6-benzyladenine (BA) on SE formation and plantlet conversion were evaluated. Low MS medium strength (1/4 to 1/2) was necessary for SE formation, and the optimal sucrose concentration was 2.0%. Supplementing medium with GA₃ negatively impacted SE formation and subsequent development. BA significantly increased the number of SEs and the plantlet conversion capacity. One-third-strength MS medium with 1.0% sucrose and 0.5 mg l⁻¹ BA produced the highest number of SEs (309 embryos from 9 mg embryogenic callus) and the highest frequency of plantlet conversion from germinated SEs (52.6%). When transplanted to soil, 90% of the regenerated plants developed into normal plants.     

Early changes in root characteristics of maize (Zea mays) following seed inoculation with the PGPR Azospirillum lipoferum CRT1

The effect of direct inoculation of seeds with the plant growth promoting rhizobacteria (PGPR) Azospirillum lipoferum CRT1 was assessed on maize (Zea mays) grown for 35 days after sowing (d.a.s.) in controlled conditions (greenhouse) in a luvisol soil from south-eastern France. WhinRhizo^® software was used to describe the following changes in the root system morphology for each plant: distribution and average root diameter, root surface and the number of tips. The stress at breakage and stiffness of the roots in tension were also determined. Evaluation of biochemical components of roots was achieved by direct Attenuated Total Reflectance (or reflection) (ATR)-Fourier transform infrared (FTIR) on root section. Inoculated roots exhibited significantly larger numbers of tips and extending surface to rhizosphere when compared to controls. Measured mechanical parameters of inoculated roots showed a slight increase in rupture stress up to the largest diameter (1.2 mm) when compared to controls. Stiffness (Young’s modulus) values were nearly constant for inoculated plants with higher values than for non-inoculated plants at day 26 and day 35. Using Principal Components Analysis of ATR-FTIR profiles, the polysaccharide enrichment of inoculated roots compared to controls was found at day 35. Noticeable absorbance at wavenumber specific to aromatic ether (lignin) was observed in control plants. All these data had a pattern of immature root properties, when maize was inoculated with Azospirillum lipoferum CRT1. Observed modifications of root development are possibly conducive to unseen beneficial effects, like water retention, resistance to mechanical stress, or root litter quality. Studies on more mature plants are required to assess if the differences between inoculated and control plants would persist or become accentuated with time until harvest.