Overcoming obstacles to interspecific hybridization between Gossypium hirsutum and G. turneri
Publication Overview
Abstract Gossypium turneri, a wild cotton species
(2n = 2X = 26, D10D10) originating from Mexico,
possesses invaluable characteristics unavailable in the
cultivated tetraploid cotton gene pool, such as
caducous involucels at anthesis, resistance to insects
and tolerance to abiotic stresses. However, transferring
desired characteristics from wild species into
cultivated cotton is often fraught with diverse obstacles.
Here, Gossypium hirsutum (as the maternal
parent) and G. turneri were crossed in the Hainan
Province of China, and the obtained hybrid seeds
(2n = 3X = 39, ADD10) were treated with 0.075%
colchicine solution for 48 h to double the chromosome
complement in order to overcome triploid F1 sterility
and to generate a fertile hexaploid. Chromosome
doubling was successful in four individuals. However,
the new synthetic hexaploids derived from these
individuals were still highly sterile, and no seeds were
generated by selfing or crossing. Therefore, an embryo
rescue technique was employed in an attempt to
produce progenies from the new synthetic hexaploids.
Consequently, a total of six large embryos were
obtained on MSB2K medium supplemented with
0.5 mg l-1 KIN and 250 mg l-1 CH using ovules
from backcrossing that were 3 days post-anthesis.
Four grafted surviving seedlings were confirmed to be
the progenies (pentaploids) of the new synthetic
hexaploids using cytological observations and molecular
markers. Eight putative fertile individuals derived
from backcrossing the above pentaploids were confirmed
using SSR markers and generated an abundance
of normal seeds. This research lays a foundation for transferring desirable characteristics from G.
turneri into upland cotton.
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