Abstract

Microorganisms play a key role in preserving soil fertility in forest agro-ecosystems.Arbuscular mycorrhizal (AM) fungi, which form symbioses with the roots of the most importantcrop species, are usually considered biofertilizers. AM fungi improve plant mineral nutrientacquisition, in exchange for C compounds derived from the photosynthetic process, which canresult in a positive host growth response and in an improved response to stress. Previous works,mainly performed in pots, suggest that the effects of the AM symbiosis on plant-water relationshipsare often subtle, transient, and probably circumstance- and symbiont-specific. Additionally, themechanisms involved in the mitigation to water stress effects on plant growth by AM fungi are stillto be elucidated. Within the framework of a project supported by CNR (AQUA), we studied theimpact of the AM symbiosis on tomato (var. San Marzano nano) tolerance to water stress. The firststep consisted in developing a protocol for water stress in presence/absence of an AM fungus. TwoAM species have been selected to be inoculated separately, i.e. Funneliformis mosseae andRizophagus intraradices, while non-mycorrhizal plants acted as controls. Leaf water potential(?leaf) and gas exchanges have been monitored until the plants reached a water stress state. Byvarying the duration of the drought, two levels of water stress were achieved, as confirmed by themeasurement of leaf water potential: moderate stress (water potential approximately -0.8 MPa) andsevere water stress (leaf water potential below -1.2 MPa), no stress (controls, leaf water potential at-0.3 MPa). Water Use Efficiency (WUE) has been calculated, showing a difference between the twoconsidered AM fungi. At the end of the experiment (when plants have reached a severe stress state),AM colonization degree has been calculated, and morphometric parameters have been considered(e.g., shoot length and diameter, internodal distance, stomatal density). For the followingbiochemical and molecular analyses, leaves and roots from all the set of plants have been collected.The levels of ABA, proline, H2O2 have been assessed, and the analysis of CAT and SOD activity isbeing determined. Gene expression analyses (RT-qPCR experiments) will be performed consideringgenes potentially involved in water stress response (e.g., a tomato gene coding for a dehydrin andLeNCED1) and in mycorrhizal symbiosis (e.g., fungal and plant PT genes), on leaves and rootsamples respectively. On the basis of the results so far obtained, R. intraradices has been selectedfor further experiments devoted to verify the impact of the AM symbiosis on the plant responses tobiotic stresses (i.e., aphids and nematodes) during drought conditions.

Autore Pugliese

• Ciancio Aurelio , Veronico Pasqua

Tutti gli autori

• Balestrini R.; Chitarra W.; Maserti B.E.; Gambino E.; Licchetta S.; Cascone P.; Iodice L.; Lumini E.; Ciancio A.; Veronico P.; Guerrieri E.

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Anno di pubblicazione

2015

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