Quantitative changes of free-base, riboside, ribotide and glucoside cytokinins in developing rice grains

Takagi, Makiko; Yokota, Takao; Murofushi, Noboru; Saka, Hitoshi; Takahashi, Nobutaka

doi:10.1007/bf00024665

Cited by 23 publications

(25 citation statements)

References 17 publications

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“…1B). In agreement with previous studies (Jones et al, 1990), zeatin riboside was higher than zeatin, and although several additional cytokinin compounds have been detected in maize kernels (von Staden and Forsyth, 1986), a11 cytokinin compounds appear to have the same time course of accumulation during development (Takagi et al, 1989;Jones et al, 1990). Similar patterns of transient cytokinin accumulation by whole kemels and associated tissues have been reported for several cereal-grain species (Rademacher and Graebe, 1984;Mengel et al, 1985;Lee et al, 1989;Takagi et al, 1989), including maize (Jones et al, 1990).…”

Section: Endogenous Cytokinin and Auxinsupporting

confidence: 91%

“…Studies of hormone concentrations in cereal-grain kernels (caryopses) have indicated that cytokinin is maximal at early stages (Rademacher and Graebe, 1984;Mengel et al, 1985;Lee et al, 1989;Takagi et al, 1989;Jones et al, 1990), overlapping with endosperm cell division (Chojeck et al, 1986;Ober et al, 1991), whereas IAA is maximal at later stages (Rademacher and Graebe, 1984;Mengel et al, 1985;Lee et al, 1989). However, these temporal associations have not established the functions of cytokinin and auxin in developing kernels.…”

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confidence: 99%

“…Furthermore, although maize kernels have been shown to be rich sources of IAA (Carnes and Wright, 1988;Reed and Singletary, 1989), the temporal patterns of IAA accumulation during development of maize kernels or endosperms have not been reported. A limitation of the above studies is that they involved extractions from whole kemels, consisting of composite samples of endosperm, embryo, pericarp, nucellus, and in some cases (Rademacher and Graebe, 1984;Takagi et al, 1989) the lemma, palea, and glumes. In cereal grains such nonendosperm tissues develop to their maximum size in advance of the endosperm and constitute the predominant fresh weight fraction at early DAP when the maximal wholekernel cytokinin contents are reached.…”

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confidence: 99%

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Role of Auxin in Maize Endosperm Development (Timing of Nuclear DNA Endoreduplication, Zein Expression, and Cytokinin)

1993

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The timing of developmental events and regulatory roles of auxin were examined in maize (Zea mays 1.) endosperms. Zeatin, zeatin riboside, and indole-3-acetic acid (IAA) levels were determined by enzyme-linked immunosorbent assay (ELISA). Zeatin and zeatin riboside increased to maximal concentrations at an early stage (9 d after pollination [DAP]), corresponding to the stage when cell division rate was maximal. In contrast, IAA concentration was low at 9 DAP and abruptly increased from 9 to 11 DAP, thus creating a sharp decline in the cytokinin to auxin ratio. Coincident with the increase in IAA was an increase in DNA content per nucleus, attributed to postmitotic DNA replication via endoreduplication. Exogenous application of 2,4-dichlorophenoxyacetic acid (2,4-D) at 5 or 7 DAP hastened the time course of DNA accumulation per nucleus and increased the average nuclear diameter, whereas 2-(para-ch1orophenoxy)isobutyric acid delayed such development. Exogenously applied 2,4-D hastened the accumulation of the zein polypeptides of apparent molecular masses of 12, 14, and 16 k D and the expression of mRNA hybridizing with a zein DNA probe.We conclude that an abrupt increase in auxin induces cellular differentiation events in endosperm, including endoredupliction and expression of particular zein storage proteins..Endosperm constitutes the majority of kemel dry matter in maize (Zea mays L.) and is the predominate sink for photosynthate and other assimilates during reproductive growth. Studies of the cytology and morphology of maize endosperm have indicated that its development, starting with the formation of the triploid primary endosperm nucleus at the time of fertilization, consists of several sequential stages: (a) mitosis, (b) cell enlargement and differentiation, (c) storage material accumulation, and (d) desiccation and maturation. The developmental events that precede rapid storage material accumulation are crucial for establishing the capacity for endosperm growth. Studies of genotypes differing in endosperm size and of environmental treatments that affect endosperm growth have indicated that cell number, cell size, and starch granule number are correlated with endosperm mass at maturity (Reddy and Daynard, 1983). Thus, the Supported in part by a fellowship from the Ministry of Education, Taiwan, Republic of China, to H.-S. L. and funds provided by U.S. Department of Agriculture, regional projects NE-157 and NE-175.

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Section: Endogenous Cytokinin and Auxinsupporting

confidence: 91%

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confidence: 99%

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confidence: 99%

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Role of Auxin in Maize Endosperm Development (Timing of Nuclear DNA Endoreduplication, Zein Expression, and Cytokinin)

1993

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“…Furthermore, in a bacterial system, the maize cytokinin receptor ZmHK1 responded to cZ and tZ with comparable affinities (Yonekura-Sakakibara et al, 2004;Lomin et al, 2011). cZ and its derivatives are abundant not only in maize but also in other species, including chickpea (Cicer arietinum; Emery et al, 1998) and rice (Oryza sativa; Takagi et al, 1985Takagi et al, , 1989Kojima et al, 2009). In addition, a recent comprehensive screen showed that higher levels of cZ than tZ derivatives can be found in species across the complete evolutionary tree of land plants (Gajdošová et al, 2011).…”

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Cytokinin Activity of cis-Zeatin and Phenotypic Alterations Induced by Overexpression of Putative cis-Zeatin-O-glucosyltransferase in Rice

et al. 2012

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cis-Zeatin (cZ) is generally regarded as a cytokinin with little or no activity, compared with the highly active trans-zeatin (tZ). Although recent studies suggested possible roles for cZ, its physiological significance remains unclear. In our studies with rice (Oryza sativa), cZ inhibited seminal root elongation and up-regulated cytokinin-inducible genes, and its activities were comparable to those of tZ. Tracer experiments showed that exogenously supplied cZ-riboside was mainly converted into cZ derivatives but scarcely into tZ derivatives, indicating that isomerizations of cZ derivatives into tZ derivatives are a minor pathway in rice cytokinin metabolism. We identified three putative cZ-O-glucosyltransferases (cZOGT1, cZOGT2, and cZOGT3) in rice. The cZOGTs preferentially catalyzed O-glucosylation of cZ and cZ-riboside rather than tZ and tZ-riboside in vitro. Transgenic rice lines ectopically overexpressing the cZOGT1 and cZOGT2 genes exhibited short-shoot phenotypes, delay of leaf senescence, and decrease in crown root number, while cZOGT3 overexpressor lines did not show shortened shoots. These results propose that cZ activity has a physiological impact on the growth and development of rice.

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“…The evidence for the regulatory functions of cytokinins has been obtained by correlation between grain weight and the level of endogenous cytokinins in barley and wheat by Michael et al (1970) and Herzog and Geisler (1982). The highest amounts of cytokinins were recorded at the early growth stages, viz., heading or anthesis or at milk stage, suggesting that the cytokinins may play important role in grain development (Takagi et al, 1989). Analysis of cytokinin levels in developing grains of wheat and rice grains has shown a large transient increases in zeatin (Z) and zeatin riboside (ZR) contents, which coincided with the period of maximum endosperm cell division (Morries et al, 1993).…”

Section: Hormonal Regulation Of Grain Developmentmentioning

confidence: 99%

Studies on endogenous hormonal changes during grain development in wheat genotypes

Gutam¹

2017

Preprint

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Pot culture experiment was conducted in the Rabi seasons of 2001 and 2002 in order to study the genotypic differences in grain growth rates and endogenous hormonal contents in the developing grains. The hexaploid new plant types and extant variety and other tetraploids are taken up for the study. The data on yield and yield components show that the tetraploids had higher ear number per plant but lesser number of seeds per ear and lower seed weight per ear. The most important yield component 1000-grain yield was also possessed by hexaploids. The mean plant height was found to be higher in hexaploids over tetraploids in general, and among them DL- 1266-1 and DL-1266-2 (new plant types) recorded higher plant height. Similarly, the ear length was also higher in these new plant types. But, the tiller number/plant and ear number/plant were significantly higher in tetraploids. The new plant types (hexaploids) possessed maximum grain growth rate at 5–15 DAA. DL-1266-2 recorded highest grain growth rate 0.093 g/g/day. The photosynthetic rate values show that the hexaploids possessed higher rate than tetraploids. At 7 and 15 DAA, in general, photosynthetic rate was more when compared to 25 DAA and 35 DAA. The results showed that the endogenous hormonal contents in grains during grain development had changed in sequence. At 7 DAA, gibberellic acid (GA3) content was at maximum and at 15 DAA (rapid growth phase), indole-acetic acid (IAA) reached maximum and at 25 DAA (dough stage), ABA was at the maximum. At the 35 DAA, ABA reached all time high and GA3 the least, IAA being intermediate. Among the genotypes, hexaploids recorded higher concentrations of endogenous hormones. The total chlorophyll content in flag leaves of hexaploids was higher than tetraploids. The mean total chlorophyll had increased slightly at 20 DAA when compared to 10 DAA and it decreased at 30 DAA. It appears that the high yielding hexaploids (DL-1266-1 & Dl- 1266-2) by the virtue of possessing more 1000-grain weight and leaf area along with endogenous hormones might be responsible for higher yield as compared to tetraploids. It appears that better photosynthetic rate and better mobilization of photosynthates during grain filling stage contributes for higher yield in hexaploids.

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Quantitative changes of free-base, riboside, ribotide and glucoside cytokinins in developing rice grains

Cited by 23 publications

References 17 publications

Role of Auxin in Maize Endosperm Development (Timing of Nuclear DNA Endoreduplication, Zein Expression, and Cytokinin)

Role of Auxin in Maize Endosperm Development (Timing of Nuclear DNA Endoreduplication, Zein Expression, and Cytokinin)

Cytokinin Activity of cis-Zeatin and Phenotypic Alterations Induced by Overexpression of Putative cis-Zeatin-O-glucosyltransferase in Rice

Studies on endogenous hormonal changes during grain development in wheat genotypes

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