Liu Hao, Gao Ying, Song Xiaobo, Ma Qingguo, Zhang Junpei, Pei Dong
1State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091 China.
2College of Horticulture and Landscape, Tianjin Agricultural University, Tianjin, 300384 China.
Plant Methods. 2018 Feb 9;14:13. doi: 10.1186/s13007-018-0280-0. eCollection 2018.
is a difficult-to-root tree. In the present study, we successfully rejuvenated stock plants by grafting and then burying them horizontally.
Rooting rates of rejuvenated shoots were 98.1% 20 days after cutting. We recorded spatial and temporal variation in endogenous indole-3-acetic acid (IAA), abscisic acid (ABA), gibberellin A (GA) and zeatin-riboside (ZR) under root induction. The four types of endohormones were mainly confined to the phloem sieve and companion cells (S&Cs) at the base of either rejuvenated or mature soft shoots. IAA and ABA levels were higher in rejuvenated shoots than in mature shoots, whereas the opposite was true for GA and ZR. During rooting induction, GA was the first hormone to be observed outside phloem S&Cs, followed by IAA, ABA and ZR. In rejuvenating soft shoots, IAA accumulated in the cross-sectional areas of the cambium and phloem, where root primordia were evident.
The improvement in the rooting ability that was evident after rejuvenation most likely results a transformation of the plant to a juvenile form, from elevated IAA levels in phloem S&Cs and from a promotion of all four endohormones outside phloem S&Cs, in particular, from an accumulation of IAA in the cross-sectional areas of the cambium and phloem.
是一种难生根的树。在本研究中，我们通过嫁接然后水平掩埋成功使母株复幼。
扦插20天后复幼嫩枝的生根率为98.1%。我们记录了根诱导过程中内源吲哚 - 3 - 乙酸（IAA）、脱落酸（ABA）、赤霉素A（GA）和玉米素核苷（ZR）的时空变化。这四种内源激素主要局限于复幼或成熟嫩枝基部的韧皮部筛管和伴胞（S&Cs）中。复幼嫩枝中的IAA和ABA水平高于成熟嫩枝，而GA和ZR则相反。在生根诱导过程中，GA是首先在韧皮部S&Cs外被观察到的激素，其次是IAA、ABA和ZR。在复幼嫩枝中，IAA在形成层和韧皮部的横截面积处积累，此处根原基明显。
复幼后生根能力的提高很可能是由于植物转变为幼态形式，韧皮部S&Cs中IAA水平升高，以及韧皮部S&Cs外所有四种内源激素的促进作用，特别是IAA在形成层和韧皮部横截面积处的积累。
