Heterogeneous dwarf plant(tT) can exist?

Question

There are 2 types of pea plant according to Mendel:

1)Tall(TT or Tt)

2)Dwarf(tt)

Can there exist a dwarf pea plant with genotype tT, if there can exist a heterogeneous tall pea plant?

Answer 1

If you find a dwarf pea plant with heterozygous genotype tT, then you would have to conclude that there is new point mutation that disrupts the functional dominance of T allele and now it is unable to dominate recessive t allele. Instead, it is behaving like a recessive t allele. You need to check that out by:

 

a) Test cross: back crossing it with several homozygous tt plants: a test for classical genetics

 

b) Homozygosity: create homozygous plants to see if this new "T" allele homozygous plants have shorter height than TT plants or longer height than classical dwarf homozygous tt plants; another genetic test

 

c) Molecular Analysis: sequence that new T allele to characterize the mutation at molecular level and decide it it is variant of T that behaves like t. 

 

Hope this is clear, if not then please ask/post again. 

 

Best,

 

 

Answer 2

tT and Tt  are the same