Effects of a New Plant Growth Regulator Prohexadione Calcium (BX-112) on Shoot Elongation Caused by Exogenously Applied Gibberellins in Rice (&lt;italic&gt;Oryza sativa&lt;/italic&gt; L.) Seedlings

Nakayama, Ishizue; Miyazawa, Takeshige; Kobayashi, Masatomo; Kamiya, Yûji; Abe, Hiroshi; Sakurai, Akira

doi:10.1093/oxfordjournals.pcp.a077892

Cited by 22 publications

(9 citation statements)

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“…Although often functioning redundantly, GA 3 and GA 4 are produced in separate biosynthetic branches. A biologically meaningful distinction is that GA 4 is deactivated by GA2oxs, whereas GA 3 is protected by a double bond at the C2, preventing 2β-hydroxylation (Nakayama et al, 1990). In hybrid aspen, GA 4 application to dormant AXBs triggers outgrowth, whereas GA 3 fails to do so, and a high concentration induces AXB abscission (Rinne et al, 2011).…”

Section: Ga2ox Genes Are Early Responders During Axb Activationmentioning

confidence: 99%

“…The high GA2ox expression levels in AXBs appear to be developmentally controlled to keep AXB activation at bay and safeguard the proleptic nature of the shoot system. GA 3/6 can play a role in maintaining AXB quiescence ( Figure 8C) by upregulating GA2ox genes, thereby deactivating GA 1/4 , but not of itself (and GA 5/6 ) because it is not a substrate (Nakayama et al, 1990;Ito et al, 2017;Li et al, 2017). Thus, the specific presence of GA 3/6 in quiescent AXBs can effectively maintain them in a GA 4 -deficient state.…”

Section: Axb Activation and Outgrowth Require Diminished Ga-deactivationmentioning

confidence: 99%

“…Abbreviations: GGDP, geranylgeranyl diphosphate; CPS, ent-copalyl diphosphate synthase; KS, ent-kaurene synthase; KO, ent-kaurene oxidase; KAO, ent-kaurenoic acid oxidase. (Nakajima et al, 2006), its effective concentration can be low. GA-GID1 binding enhances interaction with growth-repressor DELLA proteins, which are also present in the cytoplasm and nucleus (Sun, 2011;Davière and Achard, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Dual Role of Gibberellin in Perennial Shoot Branching: Inhibition and Activation

et al. 2020

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Shoot branching from axillary buds (AXBs) is regulated by a network of inhibitory and promotive forces, which includes hormones. In perennials, the dwarfed stature of the embryonic shoot inside AXBs is indicative of gibberellin (GA) deficiency, suggesting that AXB activation and outgrowth require GA. Nonetheless, the role of GA in branching has remained obscure. We here carried out comprehensive GA transcript and metabolite analyses in hybrid aspen, a perennial branching model. The results indicate that GA has an inhibitory as well as promotive role in branching. The latter is executed in two phases. While the expression level of GA2ox is high in quiescent AXBs, decapitation rapidly downregulated it, implying increased GA signaling. In the second phase, GA3ox2-mediated de novo GA-biosynthesis is initiated between 12 and 24 h, prior to AXB elongation. Metabolite analyzes showed that GA 1/4 levels were typically high in proliferating apices and low in the developmentally inactive, quiescent AXBs, whereas the reverse was true for GA 3/6. To investigate if AXBs are differently affected by GA 3 , GA 4 , and GR24, an analog of the branch-inhibitor hormone strigolactone, they were fed into AXBs of single-node cuttings. GA 3 and GA 4 had similar effects on GA and SL pathway genes, but crucially GA 3 induced AXB abscission whereas GA 4 promoted outgrowth. Both GA 3 and GA 4 strongly upregulated GA2ox genes, which deactivate GA 1/4 but not GA 3/6. Thus, the observed production of GA 3/6 in quiescent AXBs targets GA 1/4 for GA2ox-mediated deactivation. AXB quiescence can therefore be maintained by GA 3/6 , in combination with strigolactone. Our discovery of the distinct tasks of GA 3 and GA 4 in AXB activation might explain why the role of GA in branching has been difficult to decipher. Together, the results support a novel paradigm in which GA 3/6 maintains high levels of GA2ox expression and low levels of GA 4 in quiescent AXBs, whereas activation and outgrowth require increased GA 1/4 signaling through the rapid reduction of GA deactivation and subsequent GA biosynthesis.

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Section: Ga2ox Genes Are Early Responders During Axb Activationmentioning

confidence: 99%

Section: Axb Activation and Outgrowth Require Diminished Ga-deactivationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dual Role of Gibberellin in Perennial Shoot Branching: Inhibition and Activation

et al. 2020

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“…As a new plant growth retardant, prohexadione-calcium (Pro-Ca) can prevent the transformation of GA 20 to GA 1 , maintain and prolong the activity level of existing gibberellin, reduce the plant height, and shorten the internode length, thus resisting lodging at a lower dose 23 . Nakayama et al 24 found that Pro-Ca can shorten the height of rice stalks, and increase the chlorophyll content, thus increasing the photosynthetic rate of plants and promoting crop growth. Studies have witnessed that spraying Pro-Ca has remarkable effects on soybean, tomato, and sweet potato [25][26][27] .…”

Section: Introductionmentioning

confidence: 99%

“…Studies have witnessed that spraying Pro-Ca has remarkable effects on soybean, tomato, and sweet potato [25][26][27] . Pro-Ca can also increase the number of grains per ear, with no residue, no pollution, and a broad application prospec 24 . To sum up, previous studies have been made on the damage of salt stress to rice tillering ability and the related factors affecting rice tillering, but they are not comprehensive enough.…”

Section: Introductionmentioning

confidence: 99%

Effect of NaCl stress on tillering of rice (Oryza sativa L.) and mitigation regulation of prohexadione-calcium

Zhang

Zheng

Feng

et al. 2022

Preprint

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Salt stress inhibits crop quality and yields, and growth regulators are used to enhance salt tolerance of crops. Here, we report the effect of prohexadione-calcium (Pro-Ca) on rice tillering under salt stress. The results showed the malondialdehyde (MDA) levels and electrolyte leakage in leaves were increased as well as the expression of the antioxidant enzymes was induced under salt stress. Foliar application of Pro-Ca reduced seedling height, increased the stem base width, improved the lodging resistance of rice, decreased MDA content and electrolyte leakage, and alleviated the membrane damage of rice under salt stress. Exogenous Pro-Ca also increased the net photosynthetic rate (Pn) and the stomatal conductance (Gs) of rice, decreased the intercellular CO2 concentration (Ci), and increased the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) of rice at the tillering stage under salt stress. In conclusion, Pro-Ca improved the salt tolerance of rice at the tillering stage by enhancing the lodging resistance of rice, alleviating cell membrane damage of leaves caused by NaCl stress, and enhancing photosynthesis and antioxidant capacity. Effect of Pro-Ca on rice at the tillering stage under 0.3% NaCl stress was discussed, which provided a theoretical basis for revealing physiological changes at the rice tillering stage.

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The relative significance for stem elongation and flowering in Lolium temulentum of 3?-hydroxylation of gibberellins

Evans

King

Mander

et al. 1993

Planta

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Abstract.In previous experiments with many gibberellins (GAs) and GA derivatives applied to Lolium temulentum L., quite different structural requirements were evident for stem elongation on the one hand and for the promotion of flowering on the other. Whereas hydroxylation at carbons 12, 13 and 15 enhanced flowering relative to stem growth, the reverse was the case at carbon 3 (L.T. Evans et al. 1990, Planta 182, 97-106). The significance of hydroxylation at carbon 3 is examined in this paper. The application of inhibitors of 3[3-hydroxylation, including C/D-ring-rearranged GAs, reduced stem growth but, in the case of the two acylcyclohexanediones, increased the flowering response when applied on the inductive long day. Later applications of the acylcyclohexanediones, made after floral initiation had occurred, were inhibitory to flowering, suggesting that subsequent inflorescence development requires 313-hydroxylated GAs. Applications of the 3~-hydroxy epimers of GA 1, GA 3 and GA 4 gave slightly less promotion of flowering in comparison with the 313-hydroxy GAs, but far less promotion of stem elongation, except in the case of 3-epi-GA 4, which was comparable to GA 4. The 3~-hydroxy epimer of 2,2-dimethyl GA 4 gave less promotion of flowering than its 313-hydroxy epimer but almost no promotion of stem elongation. The 3~-hydroxy epimers of GA 3 and 2,2-dimethyl GA 4 did not act as competitive inhibitors of the stem elongation elicited by GA 3 and 2,2-dimethyl GA4, respectively. These results extend the differences in GA structure which favour flowering as opposed to stem elongation, and indicate that 3-hydroxylation and its epimeric configuration are of much greater importance to stem elongation than to flower initiation in Lolium.

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Effects of a New Plant Growth Regulator Prohexadione Calcium (BX-112) on Shoot Elongation Caused by Exogenously Applied Gibberellins in Rice (<italic>Oryza sativa</italic> L.) Seedlings

Cited by 22 publications

References 0 publications

Dual Role of Gibberellin in Perennial Shoot Branching: Inhibition and Activation

Dual Role of Gibberellin in Perennial Shoot Branching: Inhibition and Activation

Effect of NaCl stress on tillering of rice (Oryza sativa L.) and mitigation regulation of prohexadione-calcium

The relative significance for stem elongation and flowering in Lolium temulentum of 3?-hydroxylation of gibberellins

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