... (several lines of customized programming code appear here) Jon Horridge's SEMs of apical meristems

Plant Apical Meristems




Scanning Electron Micrographs (SEMs)
of apical meristems.
 


Here is a list of a few commercially important species I looked at:



Chrysanthemum
Tomato
Cucumber
Poinsettia
Celery

Most of these SEMs illustrate the progression of embryogenesis that occurs at the apical meristem throughout most of the life span of flowering plants. This continues in the axillary buds when the terminal apex ceases to initiate primordia.

Unfortunately all these examples show a spiral, alternate phyllotaxis.

Other phyllotaxy are decussate, as in the Common or European Ash (Fraxinus excelsior) and distichous, as in a begonia eg. Begonia scabrida.



Genetically modified crops


In conventional plant breeding some alleles controlling characters such as size of tubers might be stuck together with alleles of desirable characters such as resistance to diseases like Potato Blight. In this case of potato we have bred varieties that have large tubers and therefore poor resistance to Potato Blight. In the genetically modified variety the two characters have been separated providing a large potato along with the "natural" wild type of resistance to blight. No genes have been brought in from species distantly related as would be the case with glowing mice for instance.




References relevant to GM:


     "The R1 gene for potato resistance to late blight (Phytophthora infestans) belongs to the leucine zipper/NBS/LRR class of plant resistance genes" by Agim Ballvora, Maria Raffaella Ercolano, Julia Weiû, Khalid Meksem, Christina Angelika Bormann, Petra Oberhagemann, Francesco Salamini and Christiane Gebhardt, The Plant Journal (2002) 30(3), 361-371

     BLIGHT-RESISTANT POTATO: AN “ACCEPTABLE” GMO? April 12, 2013 by Viet Le in In the News and Media, This is Science!

     THIS HOUSE WOULD BAN THE DEVELOPMENT OF GENETICALLY MODIFIED ORGANISMS





References to some other species:


     Fragaria vesca (Strawberry)
     Arabidopsis thaliana





References to some general principles:


     What determines a leaf's shape? by Jeremy Dkhar and Ashwani

     Flowering and apical meristem growth dynamics by Dorota Kwiatkowska

     Size of the Chrysanthemum Shoot Apex in Relation to Inflorescence Initiation and Development by J. S. HORRIDGE and K. E. COCKSHULL

     A Model of Flowering in Chrysanthemum D. A. CHARLES-EDWARDS, K. E. COCKSHULL, J. S. HORRIDGE and J. H. M. THORNLEY







Glasshouse Crops Research Institute





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Some other images found on the web:

Chrysanthemum petal, SEM - Science Photo Library
Chrysanthemum pistil, SEM - Science Photo Library

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Complete list of references with Jon Horridge one of the authors:
1974 Flower initiation and development in the glasshouse rose
1977 Apical dominance and flower initiation in the rose
1978 2 chloroethylphosphonic acid flower initiation by Chrysanthemum morifolium Ramat. in short days and in long days [1978]
1979 Size of the Chrysanthemum shoot apex in relation to inflorescence initiation and development
1979 A model of flowering in Chrysanthemum
1985 A study of leaf and inflorescence initiation and development in Chrysanthemum morifolium Ramat. cv. Snowdon by scanning electron microscopy
1988 Further evidence of a relationship between size of the Chrysanthemum shoot apex and inflorescence development.
1989 The effect of the timing of a night-break on flower initiation in Chrysanthemum morifolium Ramat.
1997 Are gibberellins involved in temperature-mediated stem extension responses in tomato?
1998 Effect on fruit yield of bending (kinking') the peduncles of tomato inflorescences
2000 Effects of the glasshouse environment on leaf temperature of pot chrysanthemum and dieffenbachia
2002 Control and optimization of the greenhouse environment using infra-red sensors
2006 The effects of averaging sub-and supra-optimal temperatures on the flowering of Chrysanthemum morifolium
2007 Overproduction of abscisic acid in tomato increases transpiration efficiency and root hydraulic conductivity and influences leaf expansion


E-mail me @ jonhorridge(at)live.co.uk



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posted 16-10-2014

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