, Volume 39, Issue 1, pp 193–208 | Cite as

Chlorophyll variegation caused by unstable behavior of an alien chromosome in hybrid derivatives ofNicotiana species

  • S. B. Gupta


The hybrid derivatives ofNicotiana tabacum (2n=48) (female parent) andN. plumbaginifolia (2n=20) carried a variable number ofN. plumbaginifolia (pbg) chromosomes inN. tabacum (tbc) nuclei. Onepbg chromosome carried a gene for chlorophyll (Ws, pbg) and thetbc genome was homozygous recessive for the white seedling lociws1,ws1,ws2.ws2. The hybrid derivatives showed chlorophyll variegation. Thepbg chromosome, carrying the geneWs (pbg) for chlorophyll production, also carried information for a particular intensity of variegation. The alien chromosome formed anaphase bridges in the somatic tissue and led to subsequent loss of chromatin material having theWs pbg gene, resulting in leaf-color variegation. The intensity of this variegation was determined by information contained in this same chromosome. Either a chromatid type of breakage-fusion-bridge cycle, or formation of independent mitotic bridges by allocyclic segments ofpbg chromosomes, followed by their unequal breakage and restitution of the broken ends, has been hypothesized to be the cause of loss of chromatin material and subsequently of chlorophyll variegation.


Chlorophyll Variable Number Female Parent Somatic Tissue Subsequent Loss 
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Copyright information

© Martinus Nijhoff 1968

Authors and Affiliations

  • S. B. Gupta
    • 1
  1. 1.Department of GeneticsUniversity of CaliforniaBerkeleyUSA

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