Plant Materials and Growth Conditions
The B. napus cultivar ‘Westar 10’ curated in our laboratory was used for phenotypic analyses and mRNA expression profiling. Seeds were surface-sterilized for 12 minutes using 1% NaClO and washed five times with pure water. Then, the seeds were germinated on a piece of gauze moistened with pure water. After 7 days, uniformly sized seedlings were transferred to one-half strength Hoagland nutrient solution refreshed every four days. The normal concentration of KH2PO4 in Hoagland nutrient solution (Hoagland and Arnon, 1950) was 100 µM unless otherwise stated. Plants were cultivated in a growth room at 22℃ with a 16-h-light/8-h-dark photoperiod (with a photon flux density of 300-320 lmol m-2 s-1). Arabidopsis seedings were grown for one week on solid 1/2 MS (Murashige and Skoog) medium (Murashige and Skoog, 1962) then transferred to ANS (Arabidopsis nutrition solution) (Liu et al., 2016). For pot experiment, 7 kg soil/ pot was soaked 2,000 ml water including 3.005 g KNO3, 1.75 g MgSO4·7H2O, 4.643 g (NH4)2SO4 and 7 ml Arnon storage solution (1,000 ×), 7 ml FeSO4·EDTA Hogland storage solution (200 ×), 755.5 mg/kg or 2,518.3 mg/kg NaH2PO4·2H2O.