Development of an experimental device allowing plant-plant interaction studies and in situ dynamic trapping of volatile organic compounds emitted by barley (Hordeum distichon L.) roots

in Communications in Agricultural and Applied Biological Sciences (2013, February), 78(1), 97-102

In response to wounding or herbivore attack, leaves and roots of higher plants release volatile organic compounds (VOCs). To date, VOCs analysis and plant−plant interaction studies have been mainly ... [more ▼]

In response to wounding or herbivore attack, leaves and roots of higher plants release volatile organic compounds (VOCs). To date, VOCs analysis and plant−plant interaction studies have been mainly performed on aboveground plant tissues, leaving the roles played by root VOCs in plant−plant interaction unexplored. In this context, this project aims at setting up an original experimental device allowing both dynamic trapping of VOCs emitted by mechanically damaged H. distichon roots and the study of the roles played by root VOCs in intra and interspecific plant−plant interactions. The experimental device consists of Barley seedlings cultivated in closed PTFE reactors filled with wet sand. Before being analysed by gas chromatography−mass spectrometry, root VOCs are trapped via a dynamic system on Tenax cartridges using a charcoal-filtered and humidified air. Preliminary results show that 7 day-old wounded Barley roots emit C9 fatty acid derivatives (E-non-2-enal and nona-2,6-dienal) as major compounds, contrasting with aboveground plant tissues that mainly emit C6 alcohols, aldehydes, and their derivative esters. For plant−plant interaction studies, receiver plants are exposed to an airflow enriched with VOCs from root damaged Barley plants of the same age. [less ▲]

Describing and modelling root and shoot growth and development in Brachypodium distachyon (L.) Beauv

Poster (2011, October 19)

Due to its small size, its short developmental cycle and its close phylogenetic relationship with the Triticeae tribe, Brachypodium distachyon (L.) Beauv. has been proposed as a model species for ... [more ▼]

Due to its small size, its short developmental cycle and its close phylogenetic relationship with the Triticeae tribe, Brachypodium distachyon (L.) Beauv. has been proposed as a model species for temperate cereals. In this context, this work aims to describe and model root and shoot growth and development of B. distachyon (Bd21-1) grown under controlled environmental conditions [22°C, 65% RH, 20h light, 95 µmol.m-2.s-1 (PAR, LED lighting)]. For this purpose, vernalized caryopses were sown in a substrate consisting of vermiculite and compost (80/20, v/v). Growth and development of the above and belowground parts were monitored for 70 days. Dry and fresh masses of plant organs were measured every seven days from sowing. Biomasses of adventitious and seminal roots were measured separately. The number of spikelets on the main stem and on tillers was also counted on plants aged of 70 days. The modelling of root and shoot growth was achieved by calibrating sigmoidal growth models to the mean biomass values measured at each day of analysis. For each plant organ, the growth model selected was the one with the lowest residual variance. Finally, developmental stages identified for B. distachyon were compared with those defined for cereal crops by Zadoks et al. (1974). Maximum rates of fresh and dry shoot biomass production were 29,5 and 14,2 mg.day-1 respectively. Based on modelling, these values seem to be reached 49 and 72 days after sowing. Results also show that the fresh mass of adventitious roots at day 42 is significantly higher than that of seminal roots. Maximum rates of fresh and dry root biomass production were 6,9 and 0,8 mg.day-1 respectively, and were reached after 37 and 43 days. [less ▲]

Modélisation de la croissance chez l'orge (Hordeum distichon L.) et la Poaceae modèle Brachypodium distachyon (L.) Beauv. et analyse du contenu racinaire en composés organiques volatils de l'orge

Master's dissertation (2011)

Unlike the volatile organic compounds emitted by the aerial parts of plants, those emitted by roots are less documented and their roles remain unknown. In this context, this study firstly aims at ... [more ▼]

Unlike the volatile organic compounds emitted by the aerial parts of plants, those emitted by roots are less documented and their roles remain unknown. In this context, this study firstly aims at modelling and comparing root and shoot growth and development of an agronomically important cereal (Hordeum distichon L.) with a model species for the Poaceae family (Brachypodium distachyon (L.) Beauv.). Observations allowed us to emphasize morphological and anatomical similarities between shoot of both species. Nevertheless, the developmental scheme being significantly different from one species to another, the use of the decimal code published by ZADOKS et al. (1974) did not appear to be relevant for the characterization of B. distachyon growth stages. Root architecture of both model species differed mainly for the youngest growth stages as the number of seminal roots emerging from the coleorhiza of H. distichon was higher. In our growth conditions, the adventitious root mass became significantly higher than the mass of seminal roots from the 28th and 42nd day of cultivation, respectively for H. distichon and B. distachyon. Growth models calibrated on biomass measurements made at regular intervals allowed us to identify key stages of growth and development for H. distichon and B. distachyon, notably those for which root or shoot growth speed reached its maximum. Afterwards, volatile organic compounds contained in H. distichon roots were identified by SPME-GC/MS. A total of 110 compounds were detected. Among them, 77 compounds were tentatively identified thanks to their mass spectra. Alcohols, aldehydes, ketones and organic acid esters represented 55.5% of the total number of detected volatiles in H. distichon roots. Four organic acids, two furans and three pyrazines were also identified in volatile profiles. Multivariate analysis revealed qualitative and quantitative changes in such profiles found in H. distichon roots according to the developmental stage. In general, the volatile content was the highest when young roots just emerged from the coleorhiza, and decreased as the plants reach older phenological stages. [less ▲]