CHAPTER 24 Plant Development PPT Notes 4 26 2014 o o o o o o o o plants grow develop through life bc of ability to de differentiate produce proteins typical of another cell type growth development occur w o cell migration unlike animals plants adjust to changing environmental conditions through continuous growth and development of roots stems leaves possible bc of meristems located tips of shoots roots initiation of leaf development depends on concentration of auxin in parts of shoot apical meristem cell cell signals 3 leaf axes form proximal distal vertical on a vertical leaf lateral horizontal on a vertical leaf upper lower adaxial abaxial leaf thickness adaxial on top o no germ cells set aside early in development unlike animals flowering gametogenesis occur when shoot apical meristem converts from vegetative to reproductive development floral meristem modified shoot apical meristem that produces flowers w reproductive organs o produces 4 whorls of organs modified leaves sepals petals stamens carpels although diff genes involved logic of how to put a multicellular body together Hox vs MADS box genes similar in plants animals ABC model hypothesis for genetic control of flower development prongs 1 each of 3 genes involved expressed in 2 adjacent whorls 2 total of 4 different combinations of gene products proteins can occur 3 each of 4 combinations of gene products proteins triggers development of different floral organ testing of ABC model discovered that A and C proteins inhibit production of each other MADS box DNA binding domain encoded by DNA sequences of floral organ identity genes genes part of regulatory cascade controlling floral organ identity genes floral genes encode for regulatory transcription factors that bind to enhancers other regulatory sequences via MADS box genes similar to Hox genes o trigger expression of genes required for sepal petal carpel stamen formation model organism Arabidopsis thaliana easy to grow large s of offspring life cycle is 6 weeks o o mutants w misshapen bodies studied to identify genes involved in establishing body axes monopteros gene critical in setting up apical basal axis codes for transcription factor MONOPTEROS protein homeotic mutants can be divided into 3 general classes disc by Meyerowitz homeotic mutants one kind of floral organ replaced by another each mutant type lacks elements normally found in 2 of whorls embryogenesis process of embryo formation development occurs in ovule as seed matures o o produces tiny simplified plant plant embryonic structures take shape bc cell divisions occur in precise orientations differential cell growth 4 26 2014 CHAPTER 24 Plant Development Blue Thread Questions Label the apical basal and radial axes on the globular stage embryo 4 26 2014 Relate the location location location quip to the differentiation of epidermal ground and vascular tissue Predict the effect on the MONOPTEROS gene and on the embryo of adding auxin to embryonic root cells How do the body axes in plants compare and contrast with the body axes in animals Design a procedure for producing new root meristems from stem tissue Describe an experimental approach for potentially changing a plant that produces simple leaves into one that produces compound leaves If you understand the ABC model you should be able to explain why in mutants that lack C gene expression A genes become expressed across all whorls Describe fundamental differences in the generation of plant and animal reproductive cells and strucutres Compare and contrast the MADS box genes of plants with the Hox genes of animals You should be able to predict how the types of patterning mutants obtained by Gerd Jurgens and colleagues see figure 24 4 would be different if there were only one master regulatory gene that determined pattern along the apical basal axis You should be able to describe what an imaginary fly would look like if it underwent the continuous vegetative development found in plants You should be able to predict according to the ABC model the phenotype of a mutant that lacked both the B and C genes 4 26 2014
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