Breed not at risk
In AnGR: A breed where the total number of breeding females and males is greater than
1000 and 20 respectively; or the population size approaches 1000 and the percentage of pure­bred females is close to 100%, and the overall population size is increasing. cf breed at risk.
Broad-host-range plasmid
A plasmid that can replicate in a number of different bacterial species

BSE
Bovine spongiform encephalopathy. See proteinaceous infectious particle.

BST
See bovine somatotrophin.

Bt
See Bacillus thuringiensis.

Bud
A region of meristematic tissue with the potential for developing into leaves, shoots, flowers or combinations; generally protected by modified scale leaves. A terminal (or apical) bud exists at the tip of a stem or branch, while auxillary (or lateral) buds develop in the axils of leaves

Bud scar
A scar left on a shoot when the bud or bud scales drop.

Bud sport
A somatic mutation arising in a bud and different shoot. Bud sports, includes changes due to gene mutation, somatic reduction, chromosome deletion or polyploidy.

Budding
1. A method of asexual reproduction in which a new individual is derived from an outgrowth (bud) that becomes detached from the body of the parent.
2. Among fungi, budding is characteristic of the yeast      Saccharomyces cerevisiae.
3. A form of grafting in which a single vegetative  bud is taken from one plant and inserted to stem tissue of another plant so that the  two will grow together. The inserted but develops into a new shoot. See grafting