Principles of Plant Genetics and Breeding

(a) (b)
PLANT REPRODUCTIVE SYSTEMS 67
Tr16L Satellite
Figure 3 (a) The satellite region of Tr16L (arrow), which confers apomixis in the V31 apomictic line. No normal or
intact Tr16 is present in this line. (b) An enlargement of the isochromosome-appearing entity with the nucleolusorganizing
region (NOR) and satellite regions identified.
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Constraints of sexual biology
in plant breeding
Some constraints of sexual biology are exploited as tools
for breeding plants. They were previously mentioned
and will be discussed in detail, including how they are
NOR
exploited in plant breeding. These include dioecy,
monoecy, self-incompatibility, and male sterility.
As previously indicated, crossing is a major procedure
employed in the transfer of genes from one parent to
another in the breeding of sexual species. A critical
aspect of crossing is pollination control to ensure that