Transformation Of Brassica Carinata With Thlaspi Goesingense SAT Gene And The Effect On Nickel Tolerance

Brassica carinata is difficult to cross with edible B.napus under natural conditions,therefore is possible to be developed into a new industrial oil crop for phytoremediation of contaminated soils.Overexpression of exogenous serine acetyltransferase(SAT)in non-hyperaccumulating plants could significantly increase the GSH content and thus increase the tolerance to heavy metals.In this paper the gene for serine acetyltransferase(SAT)from Thlaspi goesingense was introduced into Brassica carinata by Agrobacterium-mediated genetic transformation method.After transformation new shoots were induced and then screened by kanamycin.Purple and white seedlings were removed while green healthy seedlings were kept and continued to be screened and finally transplanted into pots after rooting.Young leaves of the transplanted seedlings were taken for DNA extraction.After PCR using Npt II primers,putative transgenic seedlings were bagged while flowering to harvest T1 seeds.In the next year T1 seeds were sown and PCRs using Npt ? primers were carried out.The confirmed tansgenic T1 plants were bagged while flowering to harvest T2 seeds.In the T2 generation transgenic frequency exceeded 50%in lines 4-8,8-19,4-5,8-16,1-23,3-9,1-27 and 7-15,with the highest frequency of 67%.The seeds of Brassica carinata were treated with nickel sulfate to observe the seedling growth.The results showed that the germination rate of the transgenic lines was not significantly different from that of the wildtype;the relative survival rates of 3-9 and 6-10 were significantly higher than the wildtype;the relative root lengths of 4-5,6-10,1-23 and 8-18 were significantly higher than the wildtype;The relative seedling lengths of 6-10 and 6-17 were significantly higher than the wildtype,the relative fresh seedling weight in 7-15,4-8,6-10,7-11,4-5,6-17,1-27,3-9,1-23,8-18 and 8-16 was significantly higher than the wildtype;line 6-10 showed good resistance to nickel in terms of survival rate,root length,seedling length and fresh weight.Among 73 T2 seedlings 36 were found to be PCR-positive and have an average chlorophyll A content of 0.725,chlorophyll B content of 0.355,and chlorophyll A/B of 2.063;37 seedlings were found to be PCR-negative and have an average chlorophyll A content of 0.685,chlorophyll B content of 0.363,and chlorophyll A/B of 1.920.Compared with the non-transgenic group,in the transgenic group the chlorophyll A content showed 5.84%increase,chlorophyll B content showed 2.20%decrease,and chlorophyll A/B showed 7.45%increase,suggesting that introduction of Thlaspi goesingense SAT gene increased the nickel tolerance in B.carinata.