Taiz and Zeiger – Chapter 16, Smith et al. – Chapter 5 Vegetative Development of Plants HORT 301 – Plant Physiology December 4, 2009 Taiz and Zeiger – Chapter 16, Smith et al. – Chapter 5 paul.m.hasegawa.1@purdue.edu Three basic stages of plant development are embryogenesis, vegetative growth/development and reproductive growth/development Smith et al. (2010) Plant Biology

Genetic programs regulate plant development Plant development is affected also by the environment Smith et al. (2010) Plant Biology

Pollination and embryogenesis leads to seed development Hartmann et al. Plant Propagation 2002

Graham et al. 2006, Plant Biology Asymmetric and symmetric cell divisions are involved in embryogenesis Double fertilization causes the formation of the zygote and endosperm Graham et al. (2006) Plant Biology Graham et al. 2006, Plant Biology

Stages of embryogenesis Smith et al. (2020) Plant Biology Plant Biology (2010) Smith et al

Coordinated program is responsible for embryo development

Auxin is a primary regulator of embryogenesis Auxin movement and accumulation establishes polarity that regulates cell patterning Proembyro Prosuspensor

Genes involved in embryogenesis Axial patterning

Radial patterning WOODEN LEG (WOL) encodes a cytokinin receptor and regulates phloem development, wol – no proto-phloem

scr Ground tissue (cortex and endodermis) development scr – cortex and endodermis are disturbed (merged) shr – no endodermis wol – no phloem scr

Seed development/dormancy and germination is regulated by ABA and GA Smith et al. (2010) Plant Biology Plant Biology (2010) Smith et al

Repeated unit is leaf, lateral meristem and internode Shoot apical meristem (SAM) is the progenitor of the repeated unit of the shoot Repeated unit is leaf, lateral meristem and internode Smith et al. (2010) Plant Biology Plant Biology (2010) Smith et al

Shoot apical meristem may not be directly affected by auxin

Coordination of WUSCHEL (WUS) and CLAVATA 3 (CLV3) expression is indicative of genes that regulate cell patterning during shoot development

Shoot apical meristem (SAM) organization and shoot and root development – genetic programs for which numerous important determinants have been identified

Polar auxin transport regulates shoot elongation Smith et al. (2010) Plant Biology Plant Biology (2010) Smith et al

Lateral suppression reduces branching in tomato and maize Smith et al. (2008) Plant Biology Plant Biology (2010) Smith et al.

Leaf meristem has three developmental axes Tip to base, radial, and upper (adaxial) and lower (abaxial) surfaces

Vertical and horizontal leaf growth Plant Biology (2010) Smith et al

Root apical meristem (RAM) and zonation Plant Biology (2010) Smith et al

Auxin is involved in root apical meristem cell identity and root development

Root development

Lateral root branching is due to divisions of the pericycle

Senescence/and programmed cell death are an aging process Soybean plants are similar age but flowers were removed from the plant on the right