BIOL10004 Lecture Notes - Lecture 12: Meristem, Root Cap, Regular Sequence
14 Jun 2018
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BIOL – Lecture 12
Plant growth and development
• Plants have intermediate growth (keep growing) and are modular
o Lose stems and leaves, and keep producing them
• Do’t usuall reah a terial groth stage ad do’t die of old age
• often limited by disease, environment (drought, frost etc.) or own success (too large)
• cell division and enlargement
• cell differentiation – all are totipotent (Can become anything)
• cell maturation is patterned/organised
• tissue patterning – internal structure (anatomy) and external form (morphology)
plants grow at their tips
• when growing, there is a region at tip of shoot at root !
• apical meristems add length to the plants, and roots grow down
o they grow upwards and leave tissue behind
• root apical meristem
o hairs increase surface area, and there are where water is taken up
o meristem is protected by root cap
▪ root cap cells secrete gelatinous substance that protects root tip as it
grows through the soil
o no lateral organs !
• shoot apical meristem
o dome-shaped
o produces leaf primordia and primary stem tissues
o differet to root eause it does’t hae a shoot ap
o produces tissues that it leaves behind as it grows up – make stem
apical meristem can be described in different ways
• tunic-corpus model is based on cell patterns and divisions
o tunica – top 4 or so layers of cell are organised in a regular sequence
o corpus – disorganised area of cells below tunica
• leaf-stem model is widely used for describing plant construction as is consistent with
tunic-corpus model
• developmental genetic models are based on the regions of gene expression and
regulation
• metameric and phytonic models also describe structure in different ways
o metameric – internode, node and leaf
o phytonic – eah leaf is’t diserile fro the ste
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