Rhodophyta Ipê

Nutrição

T: tensão superficialr: raio e curvatura da interfase ar-água

=

Difusão: gradiente de concentração.

D: coeficiente de difusão.X: distância.

Taxa de transporte

O MOVIMENTO DE ÁGUA SEMPRE ESTÁ DETERMINADO PELO:

Figure 2. Transcriptional profiles of genes differentially expressed in shootsof Arabidopsis plants subjected to N, P or K starvation. The number ofgenes responding to N, P or K deficiencies against a background of low andhigh shoot carbohydrate concentrations. Genes responding to high shootcarbohydrate concentrations were defined as genes differentially expressedin shoots of the pho3 mutant, which has constitutively high shootcarbohydrate concentrations, compared with wild-type plants [56]. Genes from segments highlighted in red and blue were classified in terms of theirGene Ontology (GO) categories.

Figure 1. The effect of mineral supply on the morphology of Arabidopsisthaliana. (a) Individual fresh biomass (histograms) of plants grown in short days for 6 weeks in hydroponic systems containing a complete nutrientsolution, then for 12 days in the same solution or one lacking the mineral element indicated. Biomass partitioning (pie charts) between root (R) andshoot (S) (mean of six values) is shown. Salt substitutions from the complete nutrient solution [43] were as follows: N deficiency, 0.2 mM CaNO3, 0.8 mMCaCl2; P deficiency, 0.25 mM KCl; K deficiency, 0.88 mM Na2SO4, 0.25 NaH2PO4; Mg deficiency, 1.00 mM Na2SO4. (b) Colour photographs of theplants in (a). (c) Iodine staining of the plants in (a). To visualize thedifferences in the distribution of starch (dark blue) following a dark period, iodine staining of whole plants was performed as a qualitative approach. Scale bar = 10 cm.

Metabolismo de C/fotossíntese vs nutrição mineral vs água (gráfico)...

Alteração na disponibilidade de nutrientes altera o padrão morfogenético

N e P: acúmulo de carboidratos nas folhas, aumenta a biomassa das raízes.

K e Mg: Por que não acontece o mesmo.....?

Quais são os nutrientes?Onde achá-los?Abundância relativa?

• Elementos essenciais – Ciclo completo

gerando sementes viáveis

– presente em moléculas essenciais

•Elementos não minerais (C, O e H) > 96% do peso seco.

-C ~45%-O ~45% -H ~6%

• Alterações morfológicas: FISIOLÓGICAS

• Como estudar?

Efeitos e respostas à deficiência nutricional

•Deficiência/excesso: hidroponia

•Inibidores de transporte

•Mutantes (de transportadores ou enzimas da assimilação) e complementaçao heteróloga

• Variação da concentração de um nutriente nos tecidos

– concentração crítica– zona adequada – faixa de deficiência– faixa de toxicidade

Deficiência e excesso

Deficiência: os sintomas dependem da função e da mobilidade do nutriente!!!!

?

Deficiência: os sintomas dependem da função e da mobilidade do nutriente!!!!

Deficiência: os sintomas

dependem da função e da

mobilidade do nutriente!!!!

Deficiência: Como resolver ?

Brassica napus (oil production) with or without S suplementation. Its seeds are rich in sulfur-containig compounds.

No solo...

•Disponibilidade dos íons no solodepende do pH e a concentração.•Alto pH/Baixo pH

•H2O:Fluxo de massa + Difusão=osmose•Concentração do xilema vscélulas?•Transporte ativo

Adaptações que auxiliam a absorção:

•Micorrizas (Pi): ectotróficase vesículo-arbusculres.

•fixação biológia de N(nódulos ou endofíticas)

Como entram os nutrientes ?

Nódulos de Rhizobium em Pea

Transporte de nutrientes

Estamos falando desde o ponto de vista do ion!!!!Por isso os livros falam de difusão e potencial electroquímico(ou de soluto) exclusivamente...

e/ou fluxo de massaDifusão facilitada

Simporte e Antiporte

Não há degradação de ATP?Força motriz?

Cotransporte

Transporte ativo (bombas) de nutrientes

Quem gera o gradiente de H+?

Transporte ativo (bombas) de H+: ATPases

P type

V type

Transporte de S

•Metionina e cisteina: composição e estrutura proteica.

•Sulfato entra por um simportepara ser assimilado nos plastídios: cisteína e glutatione.

APS: 5-adenilsulfatoPAPS:3-fosfoadenosina-5-fosfosulfato

?

Transporte de S

APS: 5-adenilsulfatoPAPS:3-fosfoadenosina-5-fosfosulfato

Transporte de S: o ciclo do enxofre.

↓ ↑

• Absorção- Simporte

• Transporte – xilema: captação– floema: translocação

• Dois transportadores– alta afinidade (I) [↓K+]– baixa afinidade (II) [↑K+ou Na2+]

Transporte de K+: livre pela planta

Transporte de K+: vários canais com expressão diferencial

Transporte de Pi

•Associação com micorrizas.•Acidificação do solo para solubilizar Pi inorgánico.•Liberação de fosfohidroxylases para liberação de Pi de compostos organicos.•Pi entra por um simporte.

(Fosfatases)

Mono não gramíneas e dicot

• Redução do Fe3+ a Fe2+ pela redutase férrica.• Entrada por simporte na célula.• Indução da ATP ase para acidificar a rizosfera

aumentando a solubilidade• Ferritina: proteína que auxilia no transporte xilemático

Transporte de Fe

Gramíneas

• Fitosideróforo (PS) a partir da metionina.• Saída do PS .• Associação do PS com o Fe3+.• Entrada do complexo e liberação do Fe3+

no interior.

Figure 2. Transcriptional profiles of genes differentially expressed in shootsof Arabidopsis plants subjected to N, P or K starvation. The number ofgenes responding to N, P or K deficiencies against a background of low andhigh shoot carbohydrate concentrations. Genes responding to high shootcarbohydrate concentrations were defined as genes differentially expressedin shoots of the pho3 mutant, which has constitutively high shootcarbohydrate concentrations, compared with wild-type plants [56]. Genes from segments highlighted in red and blue were classified in terms of theirGene Ontology (GO) categories.

Figure 1. The effect of mineral supply on the morphology of Arabidopsisthaliana. (a) Individual fresh biomass (histograms) of plants grown in short days for 6 weeks in hydroponic systems containing a complete nutrientsolution, then for 12 days in the same solution or one lacking the mineral element indicated. Biomass partitioning (pie charts) between root (R) andshoot (S) (mean of six values) is shown. Salt substitutions from the complete nutrient solution [43] were as follows: N deficiency, 0.2 mM CaNO3, 0.8 mMCaCl2; P deficiency, 0.25 mM KCl; K deficiency, 0.88 mM Na2SO4, 0.25 NaH2PO4; Mg deficiency, 1.00 mM Na2SO4. (b) Colour photographs of theplants in (a). (c) Iodine staining of the plants in (a). To visualize thedifferences in the distribution of starch (dark blue) following a dark period, iodine staining of whole plants was performed as a qualitative approach. Scale bar = 10 cm.

Metabolismo de C/fotossíntese vs nutrição mineral vs água...

N e P: acúmulo de carboidratos nas folhas e altos níveis de C alocados nas raízes (aumenta a biomassa das raízes). Alteram fotossíntese e partição de C (fonte-dreno).

K e Mg: imposibilidade de transportar sacarose para as raízes pelo floema.

Figure 4. Model of plant response to nutrient shortage by allocating biomass tospecific organs. Abbreviations: MC, mesophyll cell; VP, vascular parenchyma; BSC, bundle sheath cells; CC, companioncell; SE, sieve element; HC, heterotrophiccell. (a) The root is devoted to mineral nutrient acquisition 5, 6, 7, 8, 9 and 10and is the first organ to sense and signalmineral starvation 18, 71, 79 and 80. Crosstalk between root and shoot is established through xylem and phloemvascular tissues. (b) N, P, K and Mg deficiencies induce sugar accumulation in MC, affecting photosynthesis and sugar metabolism 7, 11, 13, 16, 20, 28,30, 34, 43, 52, 65, 68, 70 and 75. (c) From thepoint of synthesis in MC to HC, sucrose is loaded into the SE–CC complex eitherthrough plasmodesmata by the symplasticroute or by the apoplastic route, depending on the mode of phloemloading. The apoplastic pathway requiressucrose export from MC or BSC and re-entry into the SE–CC complex, mediatedby sucrose–H+ symporters, energized byplasma membrane H+-ATPase andfacilitated by K+ channels. Mg deficiencycan affect sucrose phloem loading(probably though H+-ATPase activity) 33, 42 and 43 and K deficiency can affect K+ phloem loading [78], limiting sucroseexport to sink organs. By contrast uponN and P deficiencies, carbonpartitioning favours root growth at theexpense of the shoot. (d,e) Phloemunloading in sink cells can occursymplastically or through efflux carriers. It is postulated that the flux of sugarsdelivered to sink organs is crucial for responses to mineral deficiencies. Sugarsregulate nutrient-responsive genes in sinks [66] and modify root morphology in tandem with changes in theconcentrations of hormones 7, 11, 16, 30,

N and P starvation: Sugar acumulation(starch),though, photosynthesisrepresion(negativefeedback)

By contrast upon N and P deficiencies, carbonpartitioning favours rootgrowth at the expense ofthe shoot.