Feldman L J, Arroyave N J, Sun P S
Department of Botany, University of California, Berkeley 94720, USA.
Planta. 1985;166:483-9.
The occurrence and distribution of abscisic acid (ABA), xanthoxin (Xa) and the carotenoid violaxanthin (Va) were investigated in root tips of maize (Zea mays L. cv. Merit). In roots grown in the dark, Va and ABA were present in relatively high amounts in the root cap and in low amounts in the adjacent terminal 1.5 mm of the root. Xanthoxin was present in equal concentrations in both regions. In roots exposed to light, the ABA distribution was reversed, with relatively low levels in the root cap and high levels in the adjacent 1.5-mm segment. Light also caused a decrease in Va in both regions of the root and an increase in Xa, especially in the cap. In the maize cultivar used for this work, light is necessary for gravitropic curving. This response occurs within the same time frame as the light-induced ABA redistribution as well as the changes in the levels of Va and Xa. These data are consistent with a role for ABA in root gravitropism and support the proposal that Xa may arise from the turnover of Va.
对玉米（Zea mays L. cv. Merit）根尖中脱落酸（ABA）、黄质醛（Xa）和类胡萝卜素紫黄质（Va）的产生及分布进行了研究。在黑暗中生长的根中，Va和ABA在根冠中含量相对较高，而在相邻的根尖1.5毫米处含量较低。黄质醛在这两个区域中的浓度相等。在光照下的根中，ABA的分布发生了逆转，根冠中含量相对较低，而在相邻的1.5毫米区段中含量较高。光照还导致根的两个区域中Va含量下降，Xa含量增加，尤其是在根冠中。在用于这项研究的玉米品种中，光照对于向重力性弯曲是必需的。这种反应与光诱导的ABA重新分布以及Va和Xa水平的变化发生在同一时间范围内。这些数据与ABA在根向重力性中的作用一致，并支持了Xa可能由Va的周转产生的提议。
