Article révisé par les pairs
Résumé : Iron chlorosis is a serious deficiency that affects orchards and vineyards reducingquality and yield production. Chlorotic plants show abnormal photosynthesis andyellowing shoots. In grapevine iron uptake and homeostasis are most likely controlledby a mechanism known as “Strategy I,” characteristic of non-graminaceous plantsand based on a system of soil acidification, iron reduction and transporter-mediateduptake. Nowadays, grafting of varieties of economic interest on tolerant rootstocksis widely used practice against many biotic and abiotic stresses. Nevertheless, manyinterspecific rootstocks, and in particular those obtained by crossing exclusivelynon-vinifera genotypes, can show limited nutrient uptake and transport, in particularfor what concerns iron. In the present study, 101.14, a commonly used rootstockcharacterized by susceptibility to iron chlorosis was subjected to both Fe-absenceand Fe-limiting conditions. Grapevine plantlets were grown in control, Fe-deprived,and bicarbonate-supplemented hydroponic solutions. Whole transcriptome analyses, viamRNA-Seq, were performed on root apices of stressed and unstressed plants. Analysisof differentially expressed genes (DEGs) confirmed that Strategy I is the mechanismresponsible for iron uptake in grapevine, since many orthologs genes to the Arabidopsis“ferrome” were differentially regulated in stressed plant. Molecular differences in the plantresponses to Fe absence and presence of bicarbonate were also identified indicatingthe two treatments are able to induce response-mechanisms only partially overlapping.Finally, we measured the expression of a subset of genes differentially expressed in101.14 (such as IRT1, FERRITIN1, bHLH38/39) or known to be fundamental in the“strategy I” mechanism (AHA2 and FRO2) also in a tolerant rootstock (M1) findingimportant differences which could be responsible for the different degrees of toleranceobserved.

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