Unidade VI

Translocação de Solutos

Prof. José Vieira Silva

2012

UFAL – Campus Arapiraca

Curso Agronomia

Disciplina de Fisiologia Vegetal

Unidade VI– Translocação de solutos pelo floema

1 – Introdução

2 – Vias de translocação

3 – Padrões de translocação (fonte para o dreno)

4 – Material translocado pelo floema

5 – Carregamento do floema

6 – Descarregamento do floema

7 – Mecanismo de translocação pelo floema

8 – Alocação e partição de fotoassimilados

Caption: Nasturtium stem. Coloured scanning electron

micrograph (SEM) of a freeze-fractured Nasturtium (Tropaeolum

sp.) stem, showing numerous vascular bundles (such as at upper

centre) with an inner xylem (pink) and outer phloem (orange).

Magnification: x100 when printed at 10 centimetres wide.

Caption: Maize root. Polarised light micrograph of a

section through the root of a maize plant (Zea mays)

showing a vascular cylinder. The cylinder is comprised of a

central cluster of parenchyma cells, surrounded by fused

vascular bundles and the endodermis. The largest vessels

seen here are metaxylem, part of the xylem tissue in the

vascular bundles. Xylem transports water and mineral

nutrients from the roots throughout the plant, while phloem,

the other component of the bundles, transports

carbohydrates and plant hormones.

Caption: Monocotyledon leaf. Illustration showing the anatomy and cell structure of a monocotyledon leaf. The lower surface of

the leaf is seen at top. Stomata (brown, pores) are present on the lower epidermis through which gaseous exchange occurs.

Under the one-cell thick epidermis, spongy mesophyll cells are found loosely packed (grey). Leaf veins occur in parallel in

monocotyledons. Here, two veins (vascular bundles) are seen among mesophyll cells. Schlerenchyma sheath cells (yellow)

strengthen the vein; within the sheath are xylem (pink) and phloem (white) cells which transport water and nutrients.

Anelamento do Caule ou Anel de Malpighi Como proceder e suas implicações

Experimento realizado pelo

biólogo italiano Marcelo

Malpighi, em 1679.

Caption: Dicotyledon plant stem. Light

micrograph of a longitudinal radial section

through a typical dicotyledon stem. The

section has passed through a vascular

bundle and other stem tissue (some of

which have ring thickening, red). The

tissue layers at right are mostly xylem and

parenchyma. There is also a layer of

cambium (light blue, centre). Several rows

of phloem sieve tubes (yellow-green) are at

centre left. At left are large parenchyma

cells (blue) of the inner cortex of the stem.

Magnification: x45.

Caption: Castor oil stem. Light micrograph

of a longitudinal section through the stem

of a castor oil (Ricinus communis) plant. At

right are large and small parenchyma cells

(blue). Immediately to their left are two

rows of proto-xylem vessels and one row

of spiral meta-xylem (both red), which

transport water around the plant. To the left

of this is a bundle of phloem fibres (red)

sandwiched between two groups of phloem

cells (blue). Magnification: x45