The Effect of Growth Regulators on Tuber Initiation and Growth in Rooted Leaves of Two Sweet Potato Cultivars

McDavid, C.R.; Alamu, S.

doi:10.1093/oxfordjournals.aob.a085833

Cited by 20 publications

(13 citation statements)

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“…In sweetpotato, endogenous levels of cytokinin and auxin rapidly increase in the roots during tuberous root development (Nakatani & Komeichi, 1991). Exogenous application of cytokinin also activates tuberous root formation (McDavid & Alamu, 1980;Eguchi & Yoshida, 2008). Given that SRD1, a gene which activates the development of storage roots, is highly induced by exogenous auxin treatment (Noh et al, 2010), manipulations of root hormonal levels using pharmacological treatments or environmental regulation may be employed to increase the tuberous root yield.…”

Section: Resultsmentioning

confidence: 99%

Effect of Pot Volume on the Growth of Sweetpotato Cultivated in the New Hydroponic System

Sakamoto¹,

Suzuki²

2018

SAR

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Hydroponics is an effective means for promoting plant growth as it facilitates water and nutrient uptake by plant roots. For increasing the production of sweetpotato (Ipomoea batatas), we developed the new hydroponic cultivation system in which tuberous roots were grown in solid media in the pots whereas fibrous roots were grown in the nutrient solution. Using this method, the effect of pot volume (1.6, 3.0, and 4.5 L) on the growth of sweetpotato was investigated. When plants were grown in small-sized pots (1.6 L), the fresh weight of the top and that of tuberous roots were decreased compared with plants grown in 3.0 L and 4.5 L pots. No clear difference was observed between the top and the tuberous roots in terms of the dry weight ratio, regardless of the pot size. The number of tuberous roots per plant and the maximum tuberous root weight were not influenced by the pot size either. However, the number of tuberous roots weighing more than 100 g was decreased in plants grown in small pots. Some of the tuberous roots grown in this hydroponic system contained a non-hypertrophic parts with severely lignified metaxylems. These results suggest that the environment surrounding the tuberous root influenced by the pot volume may be important for root enlargement in this hydroponic system.

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Section: Resultsmentioning

confidence: 99%

Effect of Pot Volume on the Growth of Sweetpotato Cultivated in the New Hydroponic System

Sakamoto¹,

Suzuki²

2018

SAR

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“…t-ZR content of storage roots of normal cultivar was fourfold greater than that of fibrous roots at week 4, but declined twofold at week 6. t-ZR content of storage roots of the mutant line was nearly 1.5 fold greater than that of fibrous roots at week 6 (Nakatani et al 2002). Furthermore, the exogenous applications of synthetic cytokinins were reported to be effective in promoting storage root formation (Spence and Humphries, 1972;McDavid and Alamu, 1980;Nakatani 1994). The exogenous application of cytokinin induced storage root formation in the presence of high sucrose concentrations (Eguchi and Yoshida, 2008).…”

Section: A Cytokininsmentioning

confidence: 96%

“…Increase in both cell number and size is under the control of endogenous growth regulators such as cytokinin and auxin (IAA). Several reports suggest a relationship between storage root formation (initiation) and cytokinins (Spence and Humphries 1972;Hozyo 1973;McDavid and Alamu, 1980;Sue et al 1982;Matsuo et al 1983Matsuo et al , 1988Oritani et al 1983;Koda et al 1985;Sugiyama and Hashizume 1989;Komeichi 1991, 1992a;Nakatani and Matsuda 1992;Gan et al 2001). Zeatin riboside (ZR), trans-zeatin riboside (t-ZR), and 9-glucosyl-N-6(Δ 2 -isopentenyl adenosine (i6Ado) are the major cytokinins involved in storage root formation by developing and activating the primary cambium (Sue et al 1982;Matsuo et al 1983Matsuo et al , 1988Nakatani and Matsuda, 1992;Wang et al 2005;Tanaka et al 2008).…”

Section: A Cytokininsmentioning

confidence: 99%

“…Zeatin riboside (ZR), trans-zeatin riboside (t-ZR), and 9-glucosyl-N-6(Δ 2 -isopentenyl adenosine (i6Ado) are the major cytokinins involved in storage root formation by developing and activating the primary cambium (Sue et al 1982;Matsuo et al 1983Matsuo et al , 1988Nakatani and Matsuda, 1992;Wang et al 2005;Tanaka et al 2008). The endogenous ZR rapidly increased and concentrated around the root in primary (vascular) cambium and significantly influenced cell division during the early period of storage root development (Spence and Humphries 1972;McDavid and Alamu 1980;Nakatani 1994). The longitudinal distribution of cytokinins in developing storage roots showed that the concentration of t-ZR was greater in proximal parts than in the distal parts (Matsuo et al 1988;Tanaka et al 2008).…”

Section: A Cytokininsmentioning

confidence: 99%

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Molecular Regulation of Storage Root Formation and Development in Sweet Potato

Ravi¹,

Chakrabarti²,

Makeshkumar³

et al. 2014

Horticultural Reviews: Volume 42

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Storage root formation and development in sweet potato [Ipomoea batatas (L) Lam. Convolvulaceae] is a complex process characterized by the cessation of root elongation, genesis of vascular cambium, anomalous and interstitial cambia, and increase in radial growth by increased cell proliferation and expansion concomitant with the massive deposition of starch and storage proteins that eventually result in storage root enlargement. Phytohormones play a crucial role in the formation of storage roots. Three class I knotted-like homeobox (KNOX1) genes-SRF1, SRF5, and SRF6-modulate carbohydrate metabolism and cell division. The genes Ibkn1 and Ibkn2 activate cytokinin biosynthesis. Transcription factors derived from MADS box genes IbMADS1, IbMADS3, IbMADS4, and IbAGL17 induce signal transduction pathway leading to storage root formation and development. The occurrence of SRD1 transcripts mainly in the actively dividing cells, including the vascular and cambium cells, and the increase in endogenous indole-3-acetic acid (IAA) content and three auxin-inducible AUX/IAA gene transcripts concomitantly with SRD1 transcripts suggest the involvement of SRD1 during the early stage of storage root development. Along with IbMADS1 induction, two storage root marker genes, which encode a major storage protein sporamin and IbAGPase that encodes AGPase for ADP-glucose production in starch biosynthesis, are up-regulated during the early period of storage root development. A class III HD-Zip protein 8 regulating the development of cambia and secondary vascular tissues, a short-root protein that is a key regulator in root 157 radial patterning, meristem maintenance, and asymmetric cell division, the expansin gene IbEXP1 encoding a cell wall loosening protein, genes encoding cyclin A-and cyclin D-like proteins, and five cyclin-dependent kinases are upregulated during storage root formation. Genes encoding ADP-glucose pyrophosphorylase, granule-bound starch synthase, starch synthase, and phosphoglucomutase are up-regulated, whereas genes encoding pyruvate decarboxylase and lactate dehydrogenase are down-regulated during storage root development. The endogenous sucrose levels influence the expression of two AGPase isoforms: ibAGP1 and ibAGP2. The expression of cell wall-bound (extracellular/apoplast) acid invertase activity gene (cwINV) predominates during early period, whereas the expression of cytosolic activity of sucrose synthase gene (SuSy) predominates during later period of storage root enlargement. The competition between lignification and formation of anomalous cambia and the associated starchaccumulating cells determine storage root development. Genes encoding enzymes such as coumaroyl-CoA synthase, caffeoyl-CoA O-methyltransferase, and cinnamyl alcohol dehydrogenase during storage root formation reduce lignification in tissue sections of storage roots.

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“…The endogenous cytokinin level has been shown to rapidly increase in sweetpotato roots at the beginning of storage root formation (Nakatani & Komeichi 1991), whereas in a mutant with a late-storage, root-forming phenotype, this rapid increase was suppressed (Nakatani et al 2002). The enhancement of storage root formation by exogenous application of a synthetic cytokinin has also been reported (McDavid & Alamu 1980). As a recent study in Arabidopsis showed that cytokinins are central regulators of cambial activity (Matsumoto-Kitano et al 2008), cytokinins probably play important roles in storage root formation through regulation of the primary cambium activity.…”

Section: Anatomical Physiological and Genetic Studies On Storage Roomentioning

confidence: 81%

Recent Progress in Molecular Studies on Storage Root Formation in Sweetpotato (<i>Ipomoea batatas</i>)

Tanaka

2016

JARQ

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Elucidating the mechanisms underlying the formation of storage roots is important for further improvement of sweetpotato. Although the process of storage root formation in sweetpotato has been extensively studied anatomically and physiologically, the genetic and molecular mechanisms remain largely unknown. Recently, extensive gene expression analysis has identified numerous genes differentially expressed between fibrous and storage roots. The results of these analyses agreed with previous anatomical and physiological observations in that genes related to starch and storage protein biosynthesis were up-regulated, and those related to lignin biosynthesis were down-regulated in the storage roots. Also, molecular biological studies and analyses using transgenic sweetpotato plants have suggested that an expansin protein and several transcription factor genes, such as a Dof-type zinc finger protein, MADS-box proteins, and KNOXI proteins, are involved in the characteristic physiological process of storage root formation. Furthermore, ongoing whole-genome sequencing of sweetpotato and the related Ipomoea species is expected to identify genetic differences related to storage root formation. Although these studies are valuable as a first step in elucidating the critical genes and genetic network that control the formation of storage roots, further physiological, genetic, and molecular biological studies are needed to reveal the entire molecular process.

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The Effect of Growth Regulators on Tuber Initiation and Growth in Rooted Leaves of Two Sweet Potato Cultivars

Cited by 20 publications

References 0 publications

Effect of Pot Volume on the Growth of Sweetpotato Cultivated in the New Hydroponic System

Effect of Pot Volume on the Growth of Sweetpotato Cultivated in the New Hydroponic System

Molecular Regulation of Storage Root Formation and Development in Sweet Potato

Recent Progress in Molecular Studies on Storage Root Formation in Sweetpotato (<i>Ipomoea batatas</i>)

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