Wood material from the sapwood of the studied tree species is as useful as cellulose for studying environmental effects on tree-ring δ(18)O and δ(13)C values at a short-term scale as considered in most ecophysiological studies. The more variable response of oak may require further investigations.

Summary The wheat Lr34res allele, coding for an ATP ‐binding cassette transporter, confers durable resistance against multiple fungal pathogens. The Lr34sus allele, differing from Lr34res by two critical nucleotide polymorphisms, is found in susceptible wheat cultivars. Lr34res is functionally transferrable as a transgene into all major cereals, including rice, barley, maize, and sorghum. Here, we used transcriptomics, physiology, genetics, and in vitro and in vivo transport assays to study the molecular function of Lr34 . We report that Lr34res results in a constitutive induction of transcripts reminiscent of an abscisic acid ( ABA )‐regulated response in transgenic rice. Lr34‐ expressing rice was altered in biological processes that are controlled by this phytohormone, including dehydration tolerance, transpiration and seedling growth. In planta seedling and in vitro yeast accumulation assays revealed that both LR 34res and LR 34sus act as ABA transporters. However, whereas the LR 34res protein was detected in planta the LR 34sus version was not, suggesting a post‐transcriptional regulatory mechanism. Our results identify ABA as a substrate of the LR 34 ABC transporter. We conclude that LR 34res‐mediated ABA redistribution has a major effect on the transcriptional response and physiology of Lr34res ‐expressing plants and that ABA is a candidate molecule that contributes to Lr34res ‐mediated disease resistance.

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