plant science lec 4

endoreduplication

continuing to make extra chromosomes without divinding

what are some ideas on the plant body plan

flexible layout, can mix and match leaves and other organs, change shape in response to environment

Embryogenesis

process that lays down the basic body plan

how many parts is the plant body plan divided into

2

Apical-basal

the axis (stem) decides if it is the top or the bottom

Radial pattern

tissues decide if they are internal or external

what does the first division cause/establish

polarity

what does the polarity in plant cells help with

allows cells to know where in a body of a plant they go

which part of a plant does most of the early cell division

the apical cell (top)

protoderm

early divisions of plant cell development

what does the basic cell form

suspensor

suspensor

attaches embryo to ovule and provides nourishment

what is formed after the protoderm is formed

ground meristem

ground tissue

fills most the plant and provides support and storage

procambium

becomes plant vasculature

meristems

undifferentiated cells that make new tissues

what are the three primary meristems

protoderm, ground meristem, procambium

what do protoderm, ground meristem, procambium eventually become

epidermis, ground tissue, vascular tisssues

cotyledons

first pair or set of leaves formed

what is the first organ that can be seen in plant development

cotyledons

what is the heart stage

the emergence of cotyledons

what is the torpedo stage

elongation of embryo, stem becoming discernable

what is the difference between cell division in the early and later stages of embryogensis.

at the beginning all cells divide and at the end it remains restricted to the apical meristems. (shoot and root)

WUSCHEL-RELATED HOMEOBOX (WOX) genes

establish apical-basal polarity

PIN-FORMED (PIN) auxin transporters

distribute auxin

WOX2

promotes apical fate

WOX8/WOX9

promote basal fate

Auxin is a key plant hormone, involved in

polarity

Monocots

have a single cotyledon and a meristem on the side

Single cotyledon called a

scutellum

parts of a seed

embryo, endosperm, seed coat

Seed coat

hard covering derived from the outer surface (integument) of the

ovule

caryopsis

ana entire fruit with the ovary wall included

Endosperm

is nutritive tissue

what happens in the maturation stage of a seed

Build up food reserves (starch, proteins, oils)

Desiccation (lose up to ~90% water)

Stop metabolism

Results in a seed ready to be dormant until favorable germination conditions

arise

germination

the sprouting of seeds

what are common environmental signals for germination

water, oxygen, temperature

what are the first steps of germination

Seed rehydrates

Activation of enzymes to digest food

Cell enlargement and division

what are the two types of germination

quiescent, dormant

Quiescent

will germinate whenever conditions are good

Dormant

seeds ignore good conditions until particular needs are met

what can be used to promote germination

gibberellic acid

what are the second steps of seed germination

Primary root (the embryo’s root) emerges

Develops lateral roots (roots that branch off of the primary root)

Develops root hairs (single-celled structures that do the actual absorption)

primary root

embryo’s root

lateral root

roots that branch off of the primary root

root hairs

single-celled structures that do the actual absorption

epigeous

emerge on soil

hypogenous

emerge below the soil