Due to its many advantages, dwarfing and dense planting is an important mode of modern fruit tree cultivation. Phenols have been reported to play various roles in the growth regulation of plants. Here, to verify the correlation between chlorogenic acid (CGA) and the growth of pear trees, the CGA content of standard and dwarf pear trees as well as the effect of exogenous CGA upon their growth, were investigated and analyzed. Our results showed that the CGA content of two dwarf-type varieties, ‘Zhongai 1′ (Z1) and ‘PY-9′ was significantly higher than that of two standard-type Pyrus betulaefolia (P1 and P2). Whereas a low concentration of CGA accelerated pear tree growth, and a high concentration of CGA could inhibit it. Then, through an expression pattern analysis of four CGA synthesis-related genes, PbHCT1–4, we found that the dwarf phenotype might be related to the expression levels of PbHCTs, especially to those of PbHCT2–4 in shoots. Of these, PbHCT4 was selected as a candidate gene and transformed into tobacco. When compared with control tobacco plants, the transgenic plants attained taller heights and had a greater CGA content, as well as increased expression levels of the auxin efflux carrier gene, NbPIN. Accordingly, we speculate the PbHCT4 gene promotes the synthesis of CGA, which influences plant growth by mediating auxin's transport in pear trees. These findings are helpful for advancing analysis of dwarf mechanism, which is critical for the breeding of new dwarf pear varieties.

矮化密植因其诸多优势成为现代果树栽培的重要模式。据报道，酚类在植物的生长调节中起多种作用。在此，为了验证绿原酸（CGA）与梨树生长的相关性，对标准梨树和矮化梨树的CGA含量以及外源CGA对其生长的影响进行了调查和分析。我们的研究结果表明，'中爱1号'（Z1）和'PY-9'两个矮化型品种的CGA含量显着高于两个标准型桦树（P1和P2）。而低浓度的 CGA 会加速梨树的生长，而高浓度的 CGA 会抑制它。然后，通过四个CGA合成相关基因的表达模式分析，PbHCT1-4，我们发现矮化表型可能与PbHCTs的表达水平有关，特别是与PbHCT2-4在芽中的表达水平有关。其中，PbHCT4被选为候选基因并转化到烟草中。与对照烟草植物相比，转基因植物的高度更高，CGA 含量更高，生长素外排载体基因NbPIN 的表达水平也更高。因此，我们推测PbHCT4基因促进 CGA 的合成，其通过介导生长素在梨树中的转运来影响植物生长。这些发现有助于推进矮化机制的分析，这对于育成新的矮化梨品种至关重要。