ЭлБиб

T O T IP O T E N C Y A N D M O R P H O G E N E S IS OF P L A N T C E L L S

IN V IT R O

INFLUENCE OFNITROGEN SOURCESANDPHOSPHORUS ONTHE

GROWTHANDMORPHOTYPE OFEMBRYOGENIC CALLUS OF

SORGHUM

L.A .Elkonin,N.V.Pakhomova

Volga-RegionInstitute o fBiotechnology, 410020Saratov

Embryogenic cultures in a number of cereal species are characterized

by two different morphotypes o f embryogenic callus (EC): the compact EC

(type I) and the friable one (type II). The friable EC is less differentiated, it is

characterized by a higher growth rate and has more value for experiments

on gene and cell engineering and mutant selection. However, formation of

friable EC is genotype-specific; the factors governing its growth has been

poorly studied.

To optimize conditions for somatic embryogenesis and growth of friable

EC in sorghum, the fragments of young panicles and immature embryos

were cultured on the modified MS and N6 media supplemented with

asparagine (1 g/l) and proline (2g/l) and contained different concentrations

o f N 03 - and/or NH4+ or P043- ions. Phosphorus ions fo rthe first time were

shown to be effective inductor of somatic embryogenesis in tissue culture of

higher plants. 3-4 times increase of the frequency of embryogenic cultures

induction and 1.5-2 times increase of EC mass were observed on the modified

MS and N6 media with increased level o f P043- (up to 8.8-14.2 mM). An

elevated level of inorganic nitrogen sources - N 03 - and NH4+ ions - in the

media with organic nitrogen (amino acids) significantly reinforced induction

and growth o f sorghum EC. М2 media contained 62.5 mM NH4+ and 72.4

mM N 03 - was proved to be favorable for different genotypes, exceeding all

other media which were shown previously to be effective fo r obtaining

embryogenic cultures in sorghum. The level of N 03 - and N03- / NH4+ ratio

were established to be the critical factors of formation of friable EC in sorghum.

A high NH4+ level (20.6 mM) with a comparatively low N03- -level (39.9 mM)

resulted in formation of the compact EC. A high N03- level (79.5-82.4 mM)

or a high N03- / NH4+ ratio (4:1) under a low N03- level (28,0 mM) induced

formation of friable EC. Different sorghum genotypes need different level of

N 03 - ions for proliferation o f friable EC.

188

Научная электронная библиотека ЦНСХБ