| Researches on cotton somatic embryogenesis would greatly promote cotton genetic engineering,now there were only a few reports about the molecule mechanisem of cotton somatic embryogenesis.W10,the line of Gossypium hirsutum CRI24 has 100% rate of redifferentiation in cotton tissue culture. The SSH library including the pools 1, 2, 3, 4, 5, 6, 7, 14, 21 day-old embryonic callus and 35 nonembryonic callus was constructed. Differentially expressed ESTs were enriched for about 20 times, the plaques of amplified library is 1×104pfu/ml,the rate of recombination is 99%. 368 ESTs were identified by reverse Northern Blot, sequencing results indicated that they represented 254 unigenes. Analysis revealed that the library included some new genes.Eight genes were selected from the library and their express patterns during the somatic embryogenesis were analyzed by RT-PCR. All of them showed up regulation at different stages.The callus were transferred to MSB medium with 0.1mg/L IAA and 0.1mg/L KT or MSB medium without any hormone as the control ,cultured for 15 and 30 days. The RNAs of different stages were pooled for dscDNA probe labling. By reverse Northern Blot screening, 220 hormone response clones were identified, which revealed 117 non-redundant unigenes. Whereafter, 19 ESTs with simple sequence repeat (SSR) were selected from the 254 unigenes by SSRIT program. Four pairs of them showed polymorphism in the F2 population of TM-1×W10. T test was used to find whether there was any linkage between the markers and the tissue culture phenotypes of F2 population of TM-1×W10 at the threshold level of 0.95. However, these markers did not have dominant relationships with embryogensis. More clones should be sequenced and screened to get the EST-SSR markers related to somatic embryogenesis.The quality of SSH library was good enough for research , would provide the material base for the isolation of researches on cotton somatic embryogenesis.
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