Prasad T K, Cline M G
Department of Botany, The Ohio State University, Columbus 43210, USA.
Plant Sci. 1985;38:163-72. doi: 10.1016/0168-9452(85)90034-2.
Shoot inversion induces outgrowth of the highest lateral bud (HLB) adjacent to the bend in the stem in Pharbitis nil. In order to determine whether or not ethylene produced by shoot inversion plays a direct role in promoting or inhibiting bud outgrowth, comparisons were made of endogenous levels of ethylene in the HLB and HLB node of plants with and without inverted shoots. That no changes were found suggests that the control of apical dominance does not involve the direction action of ethylene. This conclusion is further supported by evidence that the direct application of ethylene inhibitors or ethrel to inactive or induced lateral buds has no significant effect on bud outgrowth. The hypothesis that ethylene evolved during shoot inversion indirectly promotes the outgrowth of the highest lateral bud (HLB) in restricting terminal bud (TB) growth is found to be supported by the following observations: (1) the restriction of TB growth appears to occur before the beginning of HLB outgrowth; (2) the treatment of the inverted portion of the shoot with AgNO3, an inhibitor of ethylene action, dramatically eliminates both the restriction of TB growth and the promotion of HLB outgrowth which usually accompany shoot inversion; and (3) the treatment of the upper shoot of an upright plant with ethrel mimics shoot inversion by retarding upper shoot growth and inducing outgrowth of the lateral bud basipetal to the treated region.
在牵牛属植物中，茎倒置会诱导茎干弯曲处相邻的最高侧芽（HLB）生长。为了确定茎倒置产生的乙烯是否在促进或抑制芽生长中起直接作用，对有或没有倒置茎的植物的HLB和HLB节中的乙烯内源水平进行了比较。未发现变化表明顶端优势的控制不涉及乙烯的直接作用。乙烯抑制剂或乙烯利直接应用于休眠或诱导的侧芽对芽生长没有显著影响，这一证据进一步支持了这一结论。以下观察结果支持了茎倒置过程中产生的乙烯通过限制顶芽（TB）生长间接促进最高侧芽（HLB）生长的假说：（1）TB生长的限制似乎发生在HLB生长开始之前；（2）用乙烯作用抑制剂硝酸银处理茎的倒置部分，可显著消除通常伴随茎倒置的TB生长限制和HLB生长促进；（3）用乙烯利处理直立植物的上部茎，通过延缓上部茎生长并诱导处理区域下方的侧芽生长，模拟了茎倒置。
