Glossary Plant Breeding

chromosome number. Thus, it maintains chromosome number of sexually
reproducing species.
Meiospores. Products of meiosis in plants.
Meiotic Drive. Any mechanism that affects the genetic composition of a population
through unequal contribution of gene(s) [and thus chromosome(s)] to the gametes
during meiosis. This preferential segregation makes a disproportionate contribution to
the gene pool of the next generation. It is an exception to the rule of 1:1 recovery of
segregating alleles in heterozygous organism. This unequal or preferential segregation
has also been termed segregation distortion.
Melting. Denaturation of DNA.
Melting Pot Technique. A modified polycross method as in sugar cane. It consists of
placing arrows from a number of prospective parents in small containers (added with
preservative solution) and effecting random intermating by changing the position of
containers (along with arrows) in relation to each other every day. Seeds so obtained
include selfs and all possible crosses including reciprocals.
Mendelian Inheritance. Inheritance of chromosomal genes in contrast to extrachromosomal
inheritance, which deals with cytogenes.
Mendelian Ratio. A ratio of progeny phenotypes based on Mendel’s laws of inheritance.
Mendelian Variation. The diverse types resulting from gene mutations as well as
recombinations following hybridization between types carrying these mutations. This
is the major kind of variation exploited by plant breeders.
Meristem. An area of rapidly dividing plant cells. It may be a single cell (as in lower
plants) or it may include many cells (as in higher plants).
Meristem Tip Culture. The in vitro culturing of plant tissue from the meristem tip
region for the purpose of regenerating pathogen-free plants.
Mesolithic Age. The cultural period between the Paleolithic and Neolithic Ages;
appearance of the bow and cutting tools.
Metabolism. The chemical reactions occurring in a living cell.
Metabolite. A product of metabolism.
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