Expression of the ipt Gene with the AGPase S1 Promoter in Tomato Results in Unbranched Roots and Delayed Leaf Senescence

Luo, Yuying; Gianfagna, Thomas J.; Janes, Harry W.; Huang, Bingru; Wang, Z.; Xing, Jinpeng

doi:10.1007/s10725-005-8647-4

Cited by 20 publications

(10 citation statements)

References 40 publications

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“…It has been previously reported that the elevated cytokinin production in ipt-transgenic plants often resulted in the release of apical dominance, in the form of excessive lateral branching or flower buds in many dicot plant species (Clark et al 2004;Khodakovskaya et al 2006), and in the form of increased tillering ability in tall fescue grass (Hu et al 2005). Many other studies reported decreased root branching after stress treatment in ipt-transgenic dicot plants (Clark et al 2004;Luo et al 2005), and severe reductions in root growth in plants transformed with ipt driven by constitutive promoters (Hewelt et al 1994;Van Loven et al 1993). In contrast, most of the transgenic creeping bentgrass with the senescence-inducible promoter produced more roots, and had greater total root length than the control line under both normal growth temperature and heat stress.…”

Section: Discussionmentioning

confidence: 99%

“…Different morphological and physiological changes have been observed in individual ipt transgenic plants due to the overproduction of cytokinins. Luo et al (2005) reported that expression of the ipt gene ligated to the AGPase S1 promoter, which is active exclusively in sink tissues in tomato (Lycopersicon esculentum L.), resulted in the retention of chlorophyll and cytokinin in excised leaves or discs, as well as the greater formation of unbranched roots on cuttings compared to the wild type. In transgenic ipt tobacco plants under the control of a promoter for the small subunit of RuBPCO (Pssu-ipt), overproduction of endogenous cytokinins caused stress responses such as overaccumulation of phenolic compounds, synthesis of pathogenesis related proteins and increase in peroxidase activities (Schnablova et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Effects of SAG12-ipt expression on cytokinin production, growth and senescence of creeping bentgrass (Agrostis stolonifera L.) under heat stress

Jing

Gianfagna

et al. 2008

Plant Growth Regul

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The study was conducted to determine the effects of expression of a transgene encoding adenine isopentenyl transferase (ipt), which controls cytokinin synthesis, on growth and leaf senescence of creeping bentgrass (Agrostis stolonifera L.), subjected to heat stress. Creeping bentgrass (cv. Penncross) was transformed with ipt ligated to a senescence-activated promoter (SAG12). Eight SAG12-ipt transgenic lines exhibiting desirable turf quality and a transgenic control line (transformed with the empty vector) were evaluated for morphological and physiological changes under normal growth temperature (20°C) and after 14 days of heat stress (35°C) in growth chambers. Six of the SAG12-ipt lines developed more tillers than the control line during establishment under normal growth temperature of 20°C. Following 14 days of heat stress, four of the SAG12-ipt lines had increased 65-83% of roots and for all six SAG12-ipt lines root elongation continued, whereas root production ceased and total root length decreased for the control line. Root isopentenyl adenine (iPA) content increased 2.5-3.5 times in five of the SAG12-ipt lines, whereas in the control line iPA decreased 20% after 14 days at 35°C. Total zeatin riboside (ZR) content was maintained at the original level or increased in five of the SAG12-ipt lines, whereas in the control line ZR decreased under heat stress. Our results suggest expression of SAG12-ipt in creeping bentgrass stimulated tiller formation and root production, and delayed leaf senescence under heat stress, suggesting a role for cytokinins in regulating coolseason grass tolerance to heat stress.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of SAG12-ipt expression on cytokinin production, growth and senescence of creeping bentgrass (Agrostis stolonifera L.) under heat stress

Jing

Gianfagna

et al. 2008

Plant Growth Regul

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“…5). Expression of IPT under the AGPase S1 promoter in tomato plants also resulted in delayed senescence of detached leaves (Luo et al, 2005). Yet, Chen et al (2001) found that in detached leaves and florets of broccoli only P SAG13 ::IPT plants exhibited retardation of chlorophyll degradation.…”

Section: Discussionmentioning

confidence: 99%

Effects of Cytokinin Production under Two SAG Promoters on Senescence and Development of Tomato Plants

et al. 2006

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Two promoters of senescence-associated ARABIDOPSIS genes, SAG12 and SAG13, were used in tomato plants to express IPT that catalyzes the rate-limiting step in cytokinin biosynthesis. Expression of these heterologous promoters in tomato plants was analyzed using the reporter gene beta-glucuronidase. Both promoters are expressed in tomato leaves in a manner similar to their expression in ARABIDOPSIS plants. The SAG12 promoter is very specific to senescing leaves, whereas the SAG13 promoter is expressed in mature leaves prior to the onset of visible senescence and its expression increases in senescing leaves. Expression of both promoters in tomato tissues other than leaves was very low . IPT expressed under the control of SAG12 and SAG13 promoters ( PSAG12::IPT and PSAG13::IPT, respectively) resulted in suppression of leaf senescence and advanced flowering, as well as in a slight increase in fruit weight and fruit total soluble solids (TSS). However, expression of PSAG13::IPT also led to stem thickening, short internodal distances and loss of apical dominance. In contrast to the autoregulation of PSAG12::IPT, PSAG13::IPT is expressed at higher levels in mature leaves. This difference is likely due to PSAG13::IPT exhibiting two phases of expression - a senescence-independent expression prior to the onset of senescence that is not subjected to autoregulation by cytokinin, and enhanced expression throughout senescence which is autoregualted by cytokinin. This moderate different autoregulated behavior of PSAG12::IPT and PSAG13::IPT markedly influenced plant development, emphasizing the biological effects of cytokinin in addition to senescence inhibition.

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“…This gene has been introduced into various plant species, mostly dicotyledonous plants, such as tobacco (Nicotiana tabacum) (Gan and Amasino, 1996), cauliflower (Brassica oleracea var. botrytis) (Nguyen et al, 1998), lettuce (Lactuca sativa) (McCabe et al, 1998;McCabe et al, 2001), arabidopsis (Arabidopsis thaliana) (Huynh et al, 2005), petunia (Petunia •hybrida) (Chang et al, 2003;Clark et al, 2004;Khodakovskaya et al, 2005), chrysanthemum (Dendranthema •grandiflorum) (Khodakovskaya et al, 2005), and tomato (Solanum lycopersicum) (Luo et al, 2005), and in a limited number of monocot plant species such as tall fescue (Festuca arundinacea) (Hu et al, 2005) and wheat (Triticum aestivum) (Sykorova et al, 2008). Most studies have confirmed that increases in endogenous production of CK delayed leaf senescence.…”

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confidence: 99%

Suppression of Shade- or Heat-induced Leaf Senescence in Creeping Bentgrass through Transformation with the ipt Gene for Cytokinin Synthesis

Xing¹,

Xu²,

Jing³

et al. 2009

J. Amer. Soc. Hort. Sci.

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Cytokinins have been associated with delaying or suppressing leaf senescence in plants. The objectives of this study were to determine whether the expression of the ipt gene that encodes adenine isopentenyltransferase would delay leaf senescence induced by shade or heat stress in a perennial grass species. Creeping bentgrass (Agrostis stolonifera cv. Penncross) was transformed with ipt isolated from agrobacterium (Agrobacterium tumefaciens) using two gene constructs (SAG12-ipt and HSP18-ipt) designed to activate cytokinin synthesis during shade or heat stress. Whole plants of nine SAG12-ipt transgenic lines and the nontransgenic control plants were incubated in darkness at 20 °C for 20 days. Chlorophyll content of all transgenic lines and the control line decreased after dark treatment, but the decline was less pronounced in transgenic lines. All transgenic lines had higher isopentenyladenine (iP/iPA) content than the control line after 20 days of treatment. In six of the transgenic lines, iP/iPA content remained the same or higher after dark treatment. Whole plants of nine HSP18-ipt transgenic lines and the control plants were incubated at 35 °C for 7 days. Chlorophyll and iP/iPA content declined in the control plants, but the nine transgenic lines had a significantly higher concentration of iP/iPA and were able to maintain chlorophyll content at the prestress level. Our results suggest that expression of SAG12-ipt or HSP18-ipt in creeping bentgrass resulted in increases in cytokinin production, which may have led to the delay and suppression of leaf senescence induced by shade or heat stress.

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Expression of the ipt Gene with the AGPase S1 Promoter in Tomato Results in Unbranched Roots and Delayed Leaf Senescence

Cited by 20 publications

References 40 publications

Effects of SAG12-ipt expression on cytokinin production, growth and senescence of creeping bentgrass (Agrostis stolonifera L.) under heat stress

Effects of SAG12-ipt expression on cytokinin production, growth and senescence of creeping bentgrass (Agrostis stolonifera L.) under heat stress

Effects of Cytokinin Production under Two SAG Promoters on Senescence and Development of Tomato Plants

Suppression of Shade- or Heat-induced Leaf Senescence in Creeping Bentgrass through Transformation with the ipt Gene for Cytokinin Synthesis

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