Cytokinins and Their Possible Role in Seed Size and Seed Mass Determination in Maize

Rijavec, Tatjana; Li, Qin-Bao; Dermastia, Marina; Chourey, Prem S.

doi:10.5772/33076

Cited by 4 publications

(5 citation statements)

References 37 publications

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“…Furthermore, exogenous application of CK improves grain filling in the spikelets significantly, and this is accompanied by significant decrease in the levels of expression of most of the CKX isoforms, both in apical and basal spikelets. The findings not only support the reported negative relationship of CKX activity with grain number [ 19 ], but also explain observation of high CK level in immature seeds [ 58 , 60 ], as both the processes precede an enhanced cellularization, which CK supports [ 55 , 56 ]. At the level of maintaining cellular homeostasis of cytokinin, it may be said that the hormone acts as repressor of CKX expression through type-A RRs, as evidenced by transgenic experiments [ 81 , 82 ], although the process is far more complex [ 35 , 62 , 65 , 66 , 68 , 77 ].…”

Section: Discussionsupporting

confidence: 82%

“…2A ) coupled with differential filling of grains in them (Table 1 ) also indicates that the poor filling of grain in the basal than in the apical spikelets might be related to the level of the hormone in their endosperm cells. A study of CK levels in maize caryopses has in fact revealed highest peak between 8 and 12 DAP (days after pollination), the active period of grain filling, followed by a drop of CK content at 16 DAP [ 60 ]. A sharp increase in endogenous CKs has been reported during the phase of active division of endosperm cells in the developing grain in wheat [ 61 ].…”

Section: Discussionmentioning

confidence: 99%

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Biochemical and molecular characterisation of exogenous cytokinin application on grain filling in rice

et al. 2018

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BackgroundPoor filling of grains in the basal spikelets of large size panicles bearing numerous spikelets has been a major limitation in attempts to increase the rice production to feed the world’s increasing population. Considering that biotechnological intervention could play important role in overcoming this limitation, the role of cytokinin in grain filling was investigated based on the information on cell proliferating potential of the hormone and reports of its high accumulation in immature seeds.ResultsA comparative study considering two rice varieties differing in panicle compactness, lax-panicle Upahar and compact-panicle OR-1918, revealed significant difference in grain filling, cytokinin oxidase (CKX) activity and expression, and expression of cell cycle regulators and cytokinin signaling components between the basal and apical spikelets of OR-1918, but not of Upahar. Exogenous application of cytokinin (6-Benzylaminopurine, BAP) to OR-1918 improved grain filling significantly, and this was accompanied by a significant decrease in expression and activity of CKX, particularly in the basal spikelets where the activity of CKX was significantly higher than that in the apical spikelets. Cytokinin application also resulted in significant increase in expression of cell cycle regulators like cyclin dependent kinases and cyclins in the basal spikelets that might be facilitating cell division in the endosperm cells by promoting G1/S phase and G2/M phase transition leading to improvement in grain filling. Expression studies of type-A response regulator (RR) component of cytokinin signaling indicated possible role of OsRR3, OsRR4 and OsRR6 as repressors of CKX expression, much needed for an increased accumulation of CK in cells. Furthermore, the observed effect of BAP might not be solely because of it, but also because of induced synthesis of trans-zeatin (tZ) and N6-(Δ2-isopentenyl)adenine (iP), as reflected from accumulation of tZR (tZ riboside) and iPR (iP riboside), and significantly enhanced expression of an isopentenyl transferase (IPT) isoform.ConclusionThe results suggested that seed-specific overexpression of OsRR4 and OsRR6, and more importantly of IPT9 could be an effective biotechnological intervention towards improving the CK level of the developing caryopses leading to enhanced grain filling in rice cultivars bearing large panicles with numerous spikelets, and thereby increasing their yield potential.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1279-4) contains supplementary material, which is available to authorized users.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Biochemical and molecular characterisation of exogenous cytokinin application on grain filling in rice

et al. 2018

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“…During normal seed development cytokinins act to stimulate cell division and lead to increased organ size and enhanced sink strength (reviewed in [ 54 ]). However, during infection, U .…”

Section: Discussionmentioning

confidence: 99%

Phytohormone Involvement in the Ustilago maydis– Zea mays Pathosystem: Relationships between Abscisic Acid and Cytokinin Levels and Strain Virulence in Infected Cob Tissue

2015

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Ustilago maydis is the causative agent of common smut of corn. Early studies noted its ability to synthesize phytohormones and, more recently these growth promoting substances were confirmed as cytokinins (CKs). Cytokinins comprise a group of phytohormones commonly associated with actively dividing tissues. Lab analyses identified variation in virulence between U. maydis dikaryon and solopathogen infections of corn cob tissue. Samples from infected cob tissue were taken at sequential time points post infection and biochemical profiling was performed using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI MS/MS). This hormone profiling revealed that there were altered levels of ABA and major CKs, with a marked reduction in CK glucosides, increases in methylthiol CKs and a particularly dramatic increase in cisZ CK forms, in U. maydis infected tissue. These changes were more pronounced in the more virulent dikaryon relative to the solopathogenic strain suggesting a role for cytokinins in moderating virulence during biotrophic infection. These findings highlight the fact that U. maydis does not simply mimic a fertilized seed but instead reprograms the host tissue. Results underscore the suitability of the Ustilago maydis– Zea mays model as a basis for investigating the control of phytohormone dynamics during biotrophic infection of plants.

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“…Plant hormones are small molecules that have important regulatory roles in plant growth, survival, and immunity [162][163][164][165][166][167][168][169][170][171][172]. Plant hormones also trigger plant defense mechanisms against pathogen attacks [173,174].…”

Section: The Interaction Of Phytoplasma With Plant Hormonesmentioning

confidence: 99%

Genetic Modification of Plant Hormones Induced by Parasitic Nematodes, Virus, Viroid, Bacteria, and Phytoplasma in Plant Growing

Bozbuğa¹,

Arpacı²,

Uluışık³

et al. 2022

Plant Hormones - Recent Advances, New Perspectives and Applications

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Plant hormones, such as auxin, play crucial roles in many plant developmental processes, which is crosstalk with gibberellin and strigolactone. The roles of hormones may vary in the biosynthesis of metabolisms. During the pathogen attack, including plant-parasitic nematodes, viroid, phytoplasma, virus, and bacteria, plant hormones are involved in several plant processes. Ethylene (ET), salicylate (SA), jasmonate (JA), and abscisic acid (ABA) primarily regulate synergistically or antagonistically against pathogens. Those pathogens—nematodes, bacteria, viroid, phytoplasma, and viruses regulate several plant hormones for successful parasitism, influencing the phytohormone structure and modifying plant development. Several genes are related to plant hormones that are involved in pathogens parasitism. In this chapter, how pathogens affect plant hormones in plants growing are discussed.

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Cytokinins and Their Possible Role in Seed Size and Seed Mass Determination in Maize

Cited by 4 publications

References 37 publications

Biochemical and molecular characterisation of exogenous cytokinin application on grain filling in rice

Biochemical and molecular characterisation of exogenous cytokinin application on grain filling in rice

Phytohormone Involvement in the Ustilago maydis– Zea mays Pathosystem: Relationships between Abscisic Acid and Cytokinin Levels and Strain Virulence in Infected Cob Tissue

Genetic Modification of Plant Hormones Induced by Parasitic Nematodes, Virus, Viroid, Bacteria, and Phytoplasma in Plant Growing

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