Glossary Plant Breeding

called it synthetic horizontal resistance or population resistance. It is only a concept;
now-a-days, it is not used practically.
Multilineal Hybrids (Borlaug 1965). A mixture of several modified single crosses that
differ in relation to a single gene for resistance to a specific race of the pathogen. In
this approach, the advantages of multilines and of heterosis are exploited
simultaneously. At first, two parents A and B are chosen to produce a hybrid. One
resistant gene along with cytoplasmic male sterility is incorporated in parent A. Other
resistant genes are separately incorporated in the parent A to produce component
lines. The last resistant gene along with the fertility restorer one is combined in the
parent B. Other steps are as follows:
A B Component of multilineal
hybrids
↓
[{A 1 (S) × A 2 } × B 8 (F)] 1
[{A 1 (S) × A 3 } × B 8 (F)] 2
[{A 1 (S) × A 4 } × B 8 (F)] 3
[{A 1 (S) × A 5 } × B 8 (F)] 4
[{A 1 (S) × A 6 } × B 8 (F)] 5
[{A 1 (S) × A 7 } × B 8 (F)] 6
_____________________________________________________________________
Seeds of above six hybrids are mixed to form a multilineal hybrid variety. Note that subscript number
indicates the presence of particular resistance genes. The letter S and F in the parenthesis represents
sterility and fertility conditions, respectively of the lines concerned.
Multiline Variety. A variety developed through a composite of isolines. The term
“multilines” sometimes is applied to mixtures of genetically diverse lines produced in
various ways to buffer against environmental stresses. More accurately, these
populations should be called composites instead. Such a variety is now rare in
cultivation.
Multimer. A protein consisting of two or more subunits (monomers or polypeptides).
152