BIOL 2242 Lecture Notes - Lecture 17: Maize, Root Cap, Allelopathy
5 Feb 2018
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24-3, p561: overlapping zones at tip, division, differentiation, mature primary tissues. Elongation: simple because lateral roots originate from mature tissues. Zea mays root cap (p. 561): mass of parenchyma, produced by ram. Continually sloughed: thin walls, little intercellular space, lots of golgi. Produces cho-rich mucigel sheath: promotes soil microbial loop re nutrient cycling, central columella with many amyloplasts. Increases mineral access in rhizosphere: may produce allelopathic compounds to deter growth of nearby plants, chemical territoriality e. g. , juglans (walnut) Allium (onion) root tip l. s. (p. 563: consists of root apical meristem (ram) and primary meristems. Generates new cells for increasing root length: ram (also known as the promeristem) contains 2 types of undifferentiated, non-vacuolated cells, apical initials (remain in ram) Summer 2017: apical derivatives (produced by initials, eventually pushed out) Once pushed outside zone of division, derivatives elongate and eventually differentiate. 24. 7 zea mays ram (p. 563: central portion of ram. Surrounded by actively dividing cells: error-free backup.
