Expression of IPT in Asakura-sanshoo (Zanthoxylum piperitum (L.) DC. f. inerme Makino) Alters Tree Architecture, Delays Leaf Senescence, and Changes Leaf Essential Oil Composition

Abstract

The IPT gene encodes isopentenyl pyrophosphate transferase, a key enzyme in cytokinin biosynthesis. We introduced IPT under the control of the CaMV35S promoter into Asakura-sanshoo (Zanthoxylum piperitum (L.) DC. f. inerme Makino) via stable Agrobacterium tumefaciens-mediated transformation. Three of 3-year-old transgenic Asakura-sanshoo lines Y5, Y16, and Y17 were used to evaluate the effects of IPT expression on the morphological characteristics, leaf senescence, and essential oil composition. Introduced IPT into Asakura-sanshoo stimulated an increase in cytokinin content and a decrease in auxin level. The increase in the cytokinin/auxin ratio affected the tree architecture in 3-year-old transgenic lines. The phenotypes of transgenic lines included reduced stem elongation, decreased leaf surface area, increased branching, and delayed leaf senescence. The expression of IPT in Asakura-sanshoo also affected the leaf essential oil composition. The amount of oxygenated sesquiterpenoid compounds in Y5 and Y16 was 21.1 and 15.8 % higher, respectively, than that in wild type (WT). The amount of aromatic compounds in Y5 and Y16 was 2.9 and 24.6 % lower, respectively, than that in WT. These results show that ipt expression in Asakura-sanshoo conferred desirable traits, including a dwarf growth habit, delayed senescence, and increased concentrations of some sesquiterpenoid compounds.Electronic supplementary materialThe online version of this article (doi:10.1007/s11105-015-0948-9) contains supplementary material, which is available to authorized users.

A Genotypic Comparison Reveals That the Improvement in Nitrogen Remobilization Efficiency in Oilseed Rape Leaves Is Related to Specific Patterns of Senescence-Associated Protease Activities and Phytohormones

“…This is correlated with the general decrease in cytokinin content observed during leaf senescence in N. tabacum while an increase in the endogenous cytokinin level leads to a delay in senescence processes (Yu et al, 2009). Our results are also in agreement with the fact that over-expression of the isopentenyltransferase gene, responsible for cytokinin biosynthesis, generally leads to senescence delay and stay-green phenotypes in numerous species including B. napus (Kant et al, 2015; Zeng and Zhao, 2016). Because ABA, SA and cytokinins seem to be strongly involved in the regulation of leaf senescence in B. napus L., we focused our analysis on the content of these phytohormones.…”

A novel adenylate isopentenyltransferase 5 regulates shoot branching via the ATTTA motif in Camellia sinensis

“…[ 4 , 6 ]. Isopentenyltransferase (IPT) catalyzes the first and rate-limiting step of CTK biosynthesis [ 7 , 8 ]. The isopentenyladenine (iP)-type CTKs biosynthesized in the stem node of tomato ( Solanum lycopersicum ) promote axillary bud sprouting and lateral branch growth [ 4 ].…”

“…Cook et al [ 10 ] reported that the upregulated expression of A-IPT in axillary buds and stem nodes stimulates the outgrowth of axillary buds. Overexpression of the A-IPT gene in Asakurasanshoo [ 7 ], Chrysanthemum [ 1 , 8 ] and Arabidopsis [ 8 ] resulted in increased branching.…”

Proteomic Investigations of Proteases Involved in Cotyledon Senescence: A Model to Explore the Genotypic Variability of Proteolysis Machinery Associated with Nitrogen Remobilization Efficiency during the Leaf Senescence of Oilseed Rape

“…These pathways play a role at all stages of senescence, whether they be the initiation, progression, or final stage of senescence [ 18 , 19 , 20 , 21 , 22 , 23 ]. Cytokinins (CKs), gibberellins (GAs), and auxin (IAA) are hormones involved in the negative regulation of senescence [ 20 , 24 , 25 , 26 , 27 ]. In contrast, abscisic acid (ABA), salicylic acid (SA), ethylene (ET), methyl jasmonate (MeJA), brassinosteroids (BR), and strigolactones (SL) have the capacity to positively regulate senescence [ 18 , 19 , 20 , 21 , 23 ].…”