西北农林科技大学：《植物营养学》课程教学资源（PPT课件讲稿，英文版）Chapter 05 The nutrients translocation in the plant

Chapter 5 The nutrients translocation in the plant

Chapter 5

The short distance transports of nutrients There are two main steps nutrients translocation in plant after nutrients absorbed by the root. One is the centripetal transport from the rhizoplane through the cortex tissue of the roots towards the xylem vessels of the central cylinder. Another one is the vertical transport from from the root towards the leaves

There are two main steps nutrients translocation in plant after nutrients absorbed by the root. One is the centripetal transport from the rhizoplane through the cortex tissue of the roots towards the xylem vessels of the central cylinder. Another one is the vertical transport from from the root towards the leaves. The short distance transports of nutrients

The short distance transports of nutrients (1)短距离运输( short distance transport)也叫横向运 输( the centripetal transport),或径向运输。指养分由 根的外表皮,穿过皮层进入中柱的过程。 It is the centripetal transport from the rhizoplane through the cortex tissue of the roots towards the xylem vessels of the central cylinder中柱 There are two pathways of ions transportation in the centripetal process.即质外体途径( Apoplastic pathway)和共质体途径( Symplastic pathway)

（1）短距离运输(short distance transport) 也叫横向运 输(the centripetal transport)，或径向运输。指养分由 根的外表皮，穿过皮层进入中柱的过程。 It is the centripetal transport from the rhizoplane through the cortex tissue of the roots towards the xylem vessels of the central cylinder中柱. There are two pathways of ions transportation in the centripetal process. 即质外体途径(Apoplastic pathway)和共质体途径 (Symplastic pathway)。 The short distance transports of nutrients

Rhizodermis Endodermis Xylem Cortex parenchyma Xylem Cell wall Z cytoplasm Cytoplasm Vacuole Symplastic Apoplastic Exodermis Casparian of water and air filled spaces of the cell wall and is in close contact wath h The apoplast(apo, greek- away from the plasma)is the continuous syste the soil medium, the contact often being enhanced by numerous root hairs Water free space(水分自由空间) and Donnan free space(杜南自由空间) Cations interact with the fixed anions in the cell wall(pectin and proteins)and hence their motion is much restricted. The part of the apoplast is also called apparent free space(表观自由空间) as this space appears to be free for diffusion

Symplastic Apoplastic The apoplast (apo, greek= away from the plasma) is the continuous system of water and air filled spaces of the cell wall and is in close contact with the soil medium, the contact often being enhanced by numerous root hairs. Water free space(水分自由空间） and Donnan free space（ 杜南自由空间） Cations interact with the fixed anions in the cell wall (pectin and proteins) and hence their motion is much restricted. The part of the apoplast is also called apparent free space (表观自由空间）as this space appears to be free for diffusion

Apoplast: cell walls spaces between cells (intercellular spaces); filled with air,&water Cell walls Cortex Stele A Early metaxylem Late metaxylem Root hairs Phloem Endodermis Casparian band Exodermis (hypodermis Rhizogen外皮层 被层或表皮

‘Apoplast’: cell walls & spaces between cells (‘intercellular spaces’); filled with ‘air’ & water Cell walls 根被层或表皮层 外皮层

Root hair一 Apoplast path of waters -Symplast path of water Epidermis Plasmodesmata It should be borne in mind that the effect of metabolism on water uptake and retention is an indirect one ENdodermis rachear Tr elements导管分子 Water may also travel through the root cortex via the cellular pathway including membrane transport (transmembrane pathway)or through plasmodesmata 胞间连丝( symplastic pathway) The cytoplasm of one plant cell is generally connected to the cytoplasm of neighboring cells by numerous plasmodesmata This cytoplasmatic continuum is called the sympalst

导管分子 中柱鞘 Water may also travel through the root cortex via the cellular pathway including membrane transport (transmembrane pathway) or through plasmodesmata 胞间连丝(symplastic pathway) The cytoplasm of one plant cell is generally connected to the cytoplasm of neighboring cells by numerous plasmodesmata. This cytoplasmatic continuum is called the sympalst. It should be borne in mind that the effect of metabolism on water uptake and retention is an indirect one

Symplast共质体 and apoplast质外体 endodermis ylem symplastic route (intracellular) cortex phloem Casparian strip apoplastic route pericycle (extracellular)

Symplast共质体 and apoplast质外体 symplastic route (intracellular) apoplastic route (extracellular)

Part cross-section of primary root -two pathways for movement of water nutrients Within cells Cortex Symplastic Stele pathway Early metaxylem Late metaxylem Root hairs Phloem Endodermis Between chls Casparian band apoplast Exodermis (hypodermis c pathway Rhizodermis

‘Symplastic ’ pathway ‘Apoplasti c’ pathway Part cross-section of primary root - two pathways for movement of water & nutrients Within cells Between cells

The exodermis as a barrier(some species) Cortex皮层 Symplastic stee中柱 pathway Early metaxylem 早期后生木质部 Late metaxylem Root hairs ik Phloem 末期后生木质部 韧皮部 Endodermis内皮层 Casparian band 凯氏带 Uptake blocked Exodermis (hypodermis Rhizodermis外皮层 表皮层

‘Symplastic’ pathway The exodermis as a barrier (some species) Uptake blocked 外皮层 表皮层 早期后生木质部 末期后生木质部 皮层 中柱 韧皮部 内皮层 凯氏带

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