Liu Xiang-Yu, Li Juan, Liu Meng-Meng, Yao Qing, Chen Jie-Zhong
College of Horticulture, South China Agricultural University, Guangzhou, Guangdong, China.
Qingdao Agricultural University, Qingdao, Shandong, China.
PLoS One. 2017 Jan 12;12(1):e0169897. doi: 10.1371/journal.pone.0169897. eCollection 2017.
To obtain insight into potential mechanisms underlying the influence of rootstock on scion growth, we performed a comparative analysis of 'Shatangju' mandarin grafted onto 5 rootstocks: Fragrant orange (Citrus junons Sieb. ex. Tanaka), Red tangerine (Citrus reticulata Blanco), 'Shatangju' mandarin (Citrus reticulata Blanco), Rough lemon (Citrus jambhiri Lush) and Canton lemon (Citrus limonia Osbeck). The tree size of 'Shatangju' mandarin grafted onto Canton lemon and Rough lemon were the largest, followed by self-rooted rootstock trees, and the lowest tree sizes correspond to ones grafted on Red tangerine and Fragrant orange rootstocks. The levels of indoleacetic acid (IAA) and gibberellin (GA) were significantly and positively related to growth vigor. The differences of gene expression in leaves of trees grafted onto Red tangerine, Canton lemon and 'Shatangju' mandarin were analyzed by RNA-Seq. Results showed that more differentially expressed genes involved in oxidoreductase function, hormonal signal transduction and the glycolytic pathway were enriched in 'Red tangerine vs Canton lemon'. qRT-PCR analysis showed that expression levels of ARF1, ARF8, GH3 and IAA4 were negatively correlated with the growth vigor and IAA content. The metabolism of GA was influenced by the differential expression of KO1 and GA2OX1 in grafted trees. In addition, most of antioxidant enzyme genes were up-regulated in leaves of trees grafted onto Red tangerine, resulting in a higher peroxidase activity. We concluded that different rootstocks significantly affected the expression of genes involved in auxin signal transduction pathway and GA biosynthesis pathway in the grafted plants, and then regulated the hormone levels and their signal pathways.
为深入了解砧木对接穗生长影响的潜在机制，我们对嫁接到5种砧木上的‘砂糖橘’进行了比较分析，这5种砧木分别是：香橙（Citrus junons Sieb. ex. Tanaka）、红橘（Citrus reticulata Blanco）、‘砂糖橘’（Citrus reticulata Blanco）、粗柠檬（Citrus jambhiri Lush）和广东柠檬（Citrus limonia Osbeck）。嫁接到广东柠檬和粗柠檬上的‘砂糖橘’树体大小最大，其次是自根砧木树，而树体大小最小的是嫁接到红橘和香橙砧木上的植株。吲哚乙酸（IAA）和赤霉素（GA）水平与生长势显著正相关。通过RNA测序分析了嫁接到红橘、广东柠檬和‘砂糖橘’上的植株叶片中的基因表达差异。结果表明，在‘红橘vs广东柠檬’中，更多参与氧化还原酶功能、激素信号转导和糖酵解途径的差异表达基因得到富集。qRT-PCR分析表明，ARF1、ARF8、GH3和IAA4的表达水平与生长势和IAA含量呈负相关。GA的代谢受嫁接树中KO1和GA2OX1差异表达的影响。此外，嫁接到红橘上的植株叶片中大多数抗氧化酶基因上调，导致过氧化物酶活性更高。我们得出结论，不同砧木显著影响嫁接植物中生长素信号转导途径和GA生物合成途径相关基因的表达，进而调节激素水平及其信号途径。
