Plant material and growth conditions
‘Pinyiensis ’ (Malus hupehensis Rehd. ) andArabidopsis thaliana (Columbia ecotype) were used in this study.
‘Pinyiensis ’ fruits were collected from National Engineering
Research Center for Apple of Shandong Agricultural University and the
seeds were harvest. ‘Pinyiensis ’ seeds were first laminated for
30 days using wet sand in 4℃, dark. Then the seeds were planting onto
the nursery (substrate: meteorite 3:1) for germination at 25℃. After
germination the seedlings were cultivated on nursery for 2 weeks and
then transferred into vermiculite moistened with the complete nutrient.
The complete nutrient was composed of following components:10 µM MnSO4;
100 µM H3BO3; 0.1 µM
CuSO4; 0.1 µM Na2MoO4;
30 µM ZnSO4; 5 µM KI; 0.1 µM CoCl2; 4 mM
CaCl2; 1 mM MgSO4; 1 mM
KH2PO4; 50 µM Fe(Ⅲ)-EDTA; 5 mM
KNO3. For
phenotypic analysis, 6-week-old
seedlings with the same growth status were transplanted to a new
vermiculite pot and subjected with following treatments for 3 weeks:
0.5 mM KNO3 + 50 µM
Fe, 15 mM KNO3 + 50 µM Fe, 0.5 mM KNO3-Fe (-Fe solution supplemented with 200 µM ferrozine) or 15 mM
KNO3 -Fe (-Fe solution supplemented with 200 µM
ferrozine), with KCl was added to maintain the same K+concentration (15 mM). Seedlings were cultivated in a controlled
environment: 25℃, 60% relative humidity and a 16h day/8h night rhythm.
The treatment solutions were renewed every 7 days.
Columbia ecotype Arabidopsis thaliana seeds were
surface-sterilized and germinated on substrate containing agar and 1/2
MS (Murashige & Skoog, 1962) nutrient. After 1 week of growth,
seedlings were transferred to vermiculite moistened with complete
nutrient for 1 week. The vermiculite was washed with deionized water
from top to bottom for 4 times before
subjected with following
treatments:
0.2
mM KNO3 + 50 µM Fe, 20 mM KNO3 + 50 µM
Fe, 0.2 mM KNO3 -Fe ( -Fe solution supplemented with 200
µM ferrozine), 20 mM KNO3 -Fe (-Fe solution supplemented
with 200 µM ferrozine), with KCl was added to maintain the same
K+ concentration (20 mM). Seedlings of similar rosette
diameters were picked for treatment. The seedlings were cultivated in a
growth room at 22℃, 65% relative humidity and a 16h day/8h night
rhythm. The treatment solutions were renewed every 3 days.