A 1-cm slice of 5–8 medium sized roots were collectedfrom 35 days after transplanting (DAT). At least 10 plantswere sampled at each time, and each plant possessedapproximately three roots. The fresh weight of all rootswas measured. The samples were frozen immediately inliquid nitrogen. Subsequently, we collected samples at 50, 75, 90, and 120 DAT.