Cuttings of a tobacco mutant, <i>rae</i>, undergo cell divisions but do not initiate adventitious roots in response to exogenous auxin

Lund, Steven T.; Smith, Alan G.; Hackett, Wesley P.

doi:10.1034/j.1399-3054.1996.970223.x

Cited by 39 publications

(32 citation statements)

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“…O boro é um elemento ativador de enzimas que atuam em diversos processos metabólicos, tais como transporte de carboidratos, metabolismo das auxinas e formação de raízes por meio da divisão, alongamento e junção da parede celular e atividade das membranas celulares (MARSCHNER, 1995;LUND et al, 1996;ONO e RODRIGUES, 1996). Dentre suas funções, vale destacar a participação no alongamento celular, por fazer parte dos polissacarídeos da parede celular, sendo sua desordem nutricional prejudicial ao crescimento radicular (OBATA, 1995).…”

Section: Introductionunclassified

Boro em arroz de terras altas cultivado em solução nutritiva

et al. 2009

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RESUMOO objetivo deste trabalho foi avaliar o efeito de doses de boro na produção de matéria seca e nos parâmetros morfológicos das raízes de duas cultivares de arroz de terras altas. O experimento foi desenvolvido de abril a julho de 2004, em casa de vegetação, em Botucatu (SP), empregando-se duas cultivares de arroz -Caiapó e BRS Talento. As plântulas foram obtidas em condições controladas e após cinco dias, transferidas para vasos de plástico com capacidade para 8 L, utilizando areia lavada como suporte, deixando quatro plantas por vaso. Os tratamentos foram: 0,0; 0,5; 1,0; 2,0; 4,0 e 8,0 mg L -1 de B, aplicados via solução nutritiva. O corte foi realizado aos 70 dias após o transplante, sendo coletadas parte aérea e sistema radicular separadamente, determinado suas matérias secas e concentrações de N e B, bem como o comprimento, área superficial e diâmetro médio radicular. Não foi possível obter efeito positivo da aplicação de boro, evidenciando que para a cultura do arroz a dose ótima é a inferior a 0,5 ml L -1 de B. A aplicação de 3,8 e 3,4 mg L -1 de B causou efeitos tóxicos às cultivares Caiapó e Talento respectivamente. O limite de toxicidade para raízes das duas cultivares é a concentração de 2,7 mg L -1 de B. Sob toxicidade severa de B as plantas de arroz reduzem expressivamente o comprimento e aumentam o diâmetro radicular, resultando em menor área de absorção de nutrientes. Palavras-chave:Oryza sativa L., doses de boro, nutrição de plantas, produção de matéria seca. ABSTRACT BORON IN UPLAND RICE CULTIVATED IN NUTRIENT SOLUTIONThe objective of this work was to evaluate the effects of boron rates on dry matter yield and root morphologic parameters of two varieties of upland rice. The experiment was carried out from April to July of 2004, in a greenhouse, in Botucatu, São Paulo State, with two varieties of rice, Caiapó and BRS Talento. The seeds were germinated in a controlled chamber, and five days later, the plants were transplanted in plastic pots of 8 L, being supported by cleaned sand, being kept four plants per pot. The boron rates were 0.0; 0.5; 1.0; 2.0; 4.0 and 8.0 mg of B L -1 , applied via nutrient solution. The harvest was accomplished 70 days after planting, being collected separately the shoot and root, and being determined their dry matter and N and B concentrations, as length, surface area and medium diameter of the roots. It was not able to get to the positive effects of boron application, evidencing that, for the rice cropping the optimum rate was lower than 0.5 ml L -1 of B. The application of 3.4 and 3.8 mg L -1 of B caused toxic effects to the Caiapó and Talento cvs., respectively. The toxic limit for the two cvs. roots is the 2.7 mg L -1 of B concentration. Under several boron toxic, the plants of rice reduced drastically the length and increased the radicular diameter, resulting in a smaller absorption nutrients area.

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Section: Introductionunclassified

Boro em arroz de terras altas cultivado em solução nutritiva

et al. 2009

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“…Auxin synthesized in shoot tips is important during adventitious rooting, since removal of the shoot apex decreases both the level of endogenous auxin in the basal portion of a cutting and the number of adventitious roots produced (Nordstrom and Eliasson, 1991). Elevated auxin concentrations give rise to new root primordia by activating the differentiation and elongation of phloem parenchyma cells adjacent to vascular bundles in the stem (Lund et al, 1996;De Klerk et al, 1999).…”

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The Cytokinin Type-B Response Regulator PtRR13 Is a Negative Regulator of Adventitious Root Development inPopulus

et al. 2009

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Adventitious root formation at the base of plant cuttings is an innate de novo organogenesis process that allows massive vegetative propagation of many economically and ecologically important species. The early molecular events following shoot excision are not well understood. Using whole-genome microarrays, we detected significant transcriptome remodeling during 48 h following shoot removal in Populus tremula 3 Populus alba softwood cuttings in the absence of exogenous auxin, with 27% and 36% of the gene models showing differential abundance between 0 and 6 h and between 6 and 24 h, respectively. During these two time intervals, gene networks involved in protein turnover, protein phosphorylation, molecular transport, and translation were among the most significantly regulated. Transgenic lines expressing a constitutively active form of the Populus type-B cytokinin response regulator PtRR13 (DDDKPtRR13) have a delayed rooting phenotype and cause misregulation of CONTINUOUS VASCULAR RING1, a negative regulator of vascularization; PLEIOTROPIC DRUG RESISTANCE TRANS-PORTER9, an auxin efflux transporter; and two APETALA2/ETHYLENE RESPONSE FACTOR genes with sequence similarity to TINY. Inappropriate cytokinin action via DDDKPtRR13 expression appeared to disrupt adventitious root development 24 h after shoot excision, when root founder cells are hypothesized to be sensitive to the negative effects of cytokinin. Our results are consistent with PtRR13 acting downstream of cytokinin to repress adventitious root formation in intact plants, and that reduced cytokinin signaling after shoot excision enables coordinated expression of ethylene, auxin, and vascularization pathways leading to adventitious root development.

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“…Some phloem parenchyma or inner cortical parenchyma cells in rac cuttings form callus in response to exogenous IBA. The auxin-induced callus formations in heterozygous rac cuttings are more organized than those in the homozygous yac cuttings, but none of the callus formations develop into adventitious root meristems (Lund et al, 1996). Thus, the Yac mutation blocks adventitious root initiation prior to the first organized cell divisions that normally lead to the formation of an adventitious root meristem.…”

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confidence: 88%

“…Auxin treatments were carried out as previously described (Lund et al, 1996). Two-centimeter cuttings of wild-type, heterozygous, and homozygous rac axillary shoots derived from in vitro culture were placed upright on basal media containing no IBA for 24 h in continuous light to deplete endogenous IAA (d O).…”

Section: Auxin Treatmentmentioning

confidence: 99%

“…Wild-type, heterozygous, and homozygous rac axillary shoots of tobacco (Nicotiana tabacum cv Xanthii) were propagated in vitro as previously described (Lund et al, 1996). Heterozygous rac plants hemizygous for the iaa4/5-GUS (Ballas et al, 1993), gh3-GUS , or HRGPnt3-GUS constructs (Keller and Lamb, 1989) used for the GUS analyses were generated by hand-pollinating the emasculated flowers of each of the homozygous transformant genotypes with pollen from a homozygous rac shoot that was grafted onto a N. tabacum cv Wisconsin 38 rootstock.…”

Section: Plant Materials and Growth Conditionsmentioning

confidence: 99%

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Differential Gene Expression in Response to Auxin Treatment in the Wild Type and rac, an Adventitious Rooting-Incompetent Mutant of Tobacco

Lund

Smith²,

Hackett

1997

Plant Physiology

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Histological analyses of auxin-treated cuttings from the wild type and the rac mutant of tobacco (Nicotiana tabacum cv Xanthii) previously revealed that some rac phloem parenchyma or inner cortical parenchyma cells form callus in response to exogenous auxin treatment but these cells never undergo the organized divisions associated with adventitious root initiation in the wild type. Here we report the effect of the rac mutation on the temporal and spatial expression patterns of three genes previously shown to be associated with adventitious root meristems, HRGPnt3, iaa4/5, and gh3. Using histochemical staining analyses of HRGPnt3-GUS transformant cuttings, we determined that the rac mutation blocks auxin activation of the HRGPnt3 promoter. Thus, activation of the HRGPnt3 promoter occurs specifically during adventitious root initiation in tobacco cuttings. Histochemical staining analyses of iaa4/5-GUS and gh3-GUS transformant cuttings revealed that the rac mutation does not repress the auxin activation of the iaa4/5 and gh3 promoters. Based on our histochemical staining analyses, we conclude that differential gene expression occurs in response to auxin treatment during adventitious root initiation in the wild type compared with callus formation in rac cuttings. We also determined that HRGPnt3 mRNA accumulation occurs in response to components of our root-induction protocol other than auxin, indicating that HRGPnt3 expression is regulated both developmentally and environmentally.

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Cuttings of a tobacco mutant, rae, undergo cell divisions but do not initiate adventitious roots in response to exogenous auxin

Cited by 39 publications

References 20 publications

Boro em arroz de terras altas cultivado em solução nutritiva

Boro em arroz de terras altas cultivado em solução nutritiva

The Cytokinin Type-B Response Regulator PtRR13 Is a Negative Regulator of Adventitious Root Development inPopulus

Differential Gene Expression in Response to Auxin Treatment in the Wild Type and rac, an Adventitious Rooting-Incompetent Mutant of Tobacco

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