The Wr + Vr graph for lycopene content inheritance shows   that   it   is   dominant.   The   parents   are   situated around  the  regression  line  (see  fig.)  according  to  their number of dominant or recessive genes. The  cultivars  Caro  red  (2)  and  Moneymaker  (4), which  have  a  low  lycopene  content,  posses  the  largest number of dominant genes, while L. cheesmanii typicus and the line Violet, the largest number of recessive genes. It is  evident  that  low  lycopene  content  is  controlled  by dominant genes. Breeding  for  lycopene  content  is  therefore  com- paratively   slow   and   a   component   having   a   larger number  of  additive  genes  with  high  lycopene  content should be included in the program. Falavigna,   A.,   and   G.   P.   Soressi   Birdsnest phenotypes   as   related   with   sundwarf genes. An    allelism    test    between    mimic    birdsnest phenotypes   from   different   sources   has   been made.    All    the    phenotypes    considered    are characterized by a progressive shortening of internodes strictly dependent upon the intensity of sun light as the original sundwarf (sd) mutant.   The obtained F1 data, together with those of the F2, F3 and F4 progenies of the cross 429 x 387, evidence  the  existence  of  two  sundwarf  genes  (sd-2,  sd-3),  the  first  of  which  is  incompletely recessive, interacting with each other and with sp and br Mendelian factors. As a consequence of the environment and genetic background influences, the segregating progenies bring  about  a  range  of phenotypes   going   from   the   rosette   to   the   nearly   normal   habit.   The   well   known   birdsnest phenotype (TGC, 1966) is then recognized due to the interaction of the genes sd-2, sp and br; the sd- 2 gene is likely to be the same or an allele of the original sundwarf (sd) mutant. The checking of the allelism between sd and sd-2 phenotypes and the screening of the segregating progenies is in progress. Methods.  In  most  experiments  the  lower  three leaves  of  plants  at  the  fourth  true  leaf  stage were inoculated with race 0 of the virus. After 24    h    the    plants    were    given    temperature treatments of 320 or 350C for Kopliovitch,    E.,    N.    Kedar,    and    Nira    Retig Genotypic   and   environmental   effects   on heat-necrosis of heterozygous TMV- "resistant" lines. 24 or 48 h. The disease index (D.I.) reflected the number of plants infected and the severity of infection, where O=healthy, 1=1 to 10 systemic necrotic spots, 2=more than 10 necrotic spots,

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