[Study on molecular identification and pre-harvest sprouting characteristic of the transgenic anti-trxs-gene wheat line 00T89].

Pre-harvest sprouting of wheat is caused by a series of enzymes, in which α-amylase plays a key role. Thioredoxin (trx) is an important protein capable of reducing S-S to -SH. The authors transferred the anti-trxs gene into wheat (Triticum aestivum L.) cultivar Wanmai 48 in 2000 in order to obtain a transgenic line with low activities of trx and α-amylase in wheat seeds to enhance their resistance to pre-harvest sprouting. In this work, a pair of specific anti-trxs primers were used in PCR test to validate the transgenic plants in T_4 lines. A pair of primers of a wheat actin gene cDNA and a pair of trxs gene primers were used in the reverse transcription PCR test to measure the relative content of trx mRNA in the transgenic positive lines. The experiments of pre-harvest sprouting were carried out to test the resistance to pre-harvest sprouting. The results showed that there were 13 positive lines with the anti-trxs gene among 18 transgenic lines. In the maturity stage, the 8 relative contents of the trx mRNA in the 13 positive lines were reduced evidently(P0.01). The trx mRNA was correlated with the sprouting parameters significantly(r=0.7181). 6 lines with low trx mRNA showed stronger resistance to pre-harvest sprouting during the period from 30 days after anthesis to 10 days after maturity. Compared with non-transgenic plant (Wanmai 48, CK), the average sprouting time of these lines was postponed by 2.7 days (P0.01), the sprouting ratio of seeds on spikes and the spike sprouting degree were reduced by 35.5%(P0.01) and 47.5%(P0.01), respectively. However, 25 days after maturity, the sprouting capacity of the positive lines recovered gradually, and no significant differences were found between them(P0.05). Thus, it can be concluded that the wheat pre-sprouting was controlled effectively in some 00T89 transgenic lines as a result of the expression of anti-trxs gene.