In agriculture, shattering is the
dispersal of a crop's seeds upon their becoming ripe. From an agricultural perspective this is generally an undesirable process, and in the history of
crop domestication several important advances have involved a
mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, ...
in a crop plant that reduced shattering—instead of the seeds being dispersed as soon as they were ripe, the mutant plants retained the seeds for longer, which made harvesting much more effective. Non-shattering
phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological propert ...
is one of the prerequisites for
plant breeding especially when
introgressing valuable traits from wild varieties of domesticated crops.
A particularly important mutation that was selected very early in the history of agriculture removed the "brittle rachis" problem from wheat. A ripe head ("ear") of wild-type wheat is easily shattered into dispersal units when touched, or blown by the wind, because during ripening a series of
abscission layers forms that divides the
rachis
In biology, a rachis (from the [], "backbone, spine") is a main axis or "shaft".
In zoology and microbiology
In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the ''rachi ...
into short segments, each attached to a single
spikelet
A spikelet, in botany, describes the typical arrangement of the inflorescences of grasses, sedges and some other monocots.
Each spikelet has one or more florets. The spikelets are further grouped into panicles or spikes. The part of the sp ...
(which contains 2–3 grains along with
chaff).
A different class of shattering mechanisms involves
dehiscence of the mature fruit, which releases the seeds.
Rapeseed and the shattering types of
sesame are harvested before the seed is fully mature, so that the pods do not split and drop the seeds.
Harvesting shattering types of sesame involves wrapping the cut plants before processing.
[
Current research priorities to understand the genetics of shattering include the following crops:
* ]Barley
Barley (), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains; it was domesticated in the Fertile Crescent around 9000 BC, giving it nonshattering spikele ...
* Buckwheat
Buckwheat (''Fagopyrum esculentum'') or common buckwheat is a flowering plant in the knotweed family Polygonaceae cultivated for its grain-like seeds and as a cover crop. Buckwheat originated around the 6th millennium BCE in the region of what ...
* Amaranth grain
Species belonging to the genus ''Amaranthus'' have been cultivated for their grains for 8,000 years. Amaranth plants are classified as pseudocereals that are grown for their edible starchy seeds, but they are not in the same Family (biology), bo ...
* Oilseed rape (''Brassica napus
Rapeseed (''Brassica napus'' subsp. ''napus''), also known as rape and oilseed rape and canola, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed, which naturall ...
'')
References
{{Wheat
History of agriculture
Mutation