The Arabidopsis vacuolar Na+/H+ antiporter gene,AtNHX1,was introduced into soybean by Agrobacterium-mediated transformation.Four independent kanamycin resistant lines were obtained.The result of PCR,Southern blotting and Northern blotting analyses demonstrated that the AtNHX1 gene was successfully inserted into the soybean genome and stably expressed in these kanamycin resistant lines.The stability of AtNHX1 expression and salt resistance were evaluated in the soybean transformants for over 6 generations.Two independently derived transgenic lines with high expression level of AtNHX1 were selected,and propagated to generation T5 in the absence of selection pressure.PCR and RT-PCR examinations revealed that AtNHX1 was highly expressed in all investigated transgenic T5 progenies.Furthermore,all transgenic T5 plants showed resistant to salt stress,same as those of homozygous T2 plants.Taken together,our results indicated that constitutive expression of AtNHX1 enhanced salt tolerance in soybean for over 6 generations,suggesting a great potential use of AtNHX1 for improving salt tolerance in plants by genetic engineering.
LI TianXingZHANG YueLIU HuaWU YuTingLI WenBinZHANG HongXia
The demand for high quality rice represents a major issue in rice production. The primary components of rice grain quality include appearance, eating, cooking, physico-chemical, milling and nutritional qualities. Most of these traits are complex and controlled by quantitative trait loci （QTLs）, so the genetic characterization of these traits is more difficult than that of traits controlled by a single gene. The detection and genetic identification of QTLs can provide insights into the genetic mechanisms underlying quality traits. Chromosome segment substitution lines （CSSLs） are effectivetools used in mapping QTLs. In this study, we constructed 154 CSSLs from backcross progeny （BC3F2） derived from a cross between ＇Koshihikari＇ （an Oryza sativa L. ssp. japonica variety） as the recurrent parent and ＇Nona Bokra＇ （an O. sativa L. ssp. indica variety） as the donor parent. In this process, we carried out marker-assisted selection by using 102 cleaved amplified polymorphic sequence and simple sequence repeat markers covering most of the rice genome. Finally, this set of CSSLs was used to identify QTLs for rice quality traits. Ten QTLs for rice appearance quality traits were detected and eight QTLs concerned physico-chemical traits. These results supply the foundation for further genetic studies and breeding for the improvement of grain quality.
Wei Hao Mei-Zhen Zhu Ji-Ping Gao Shi-Yong Sun Hong-Xuan Lin
