Fig. 4

ABA immunolocalization in the stem bases of rejuvenated and mature soft shoots. a–e Transverse sections of rejuvenated soft shoots in walnut. a After 1 day of induction, ABA was found in S&Cs. b By 4 days, as the cambium thickened, ABA signal was concentrated in the cambium. c By 5 days, some meristem cells had divided and the ABA signal was located mainly in the meristem cells, part of cambium and ray cell. d By 7 days, some ABA signals were evident mainly in S&Cs and surrounding tissue of the initial cells of the root primordia. e The ABA level in root primordia formed by 9 days was minimal, comparison with supplementary (Additional file 1: Fig. s1 c), the dark color at the tip of the primordium were not ABA signals. f–h ABA signals from the bases of mature soft shoots; 1 day (f), 5 days (g), and 9 days (h). The temporal and spatial patterns of ABA expression did not change. The arrows indicate ABA signals. Arrowheads indicate the tissue structure. ca cambium, co cortex, m meristem, ph phloem, rp root primordia, rpic root primordia initial cells, S&Cs sieve and companion cells, sr sclerenchyma, xy xylem. Scale bars: 200 μm (e); 100 μm (b–d, f–h); 50 μm (a)