Screening And Idenfication Of Salt-tolerant Mutants From Diploid And Tetraploid Of Paulownia Tomentosa

Soil salinization is an important environmental factor for inhibited plant growth and reduce crop yield, and with the development of irrigated agriculture, the expansion of greenhouses area and soil secondary salinization, it becoming increasingly serious restrictions on agriculture and forestry production as a worldwide problem. Paulownia is suitable for loose, fertile loam and sandy loam, pH values greater than 8.0, salt content more than 0.05% in the soil is constraints of Paulownia distributed in the plain areas (Henan Forest, 2000). Salt limit of Paulownia seedlings is 0.2% -0.3%, salt limi tof root cuttings seedlings is 0.25% (Jiang Jianping, 1990). Salt stress has very serious impact on Paulownia growth and wood yield, so it is very important that carry out the study of salt tolerant breeding of Paulownia to the development of Paulownia industry and the utilization of saline land.In this study, we used MMS treatment induced embryo callus of diploid and tetraploid of Paulownia tomentosa separately, targeted screening the salt-tolerant mutant of diploid and tetraploid of P. tomentosa. With SSR and AFLP molecular markers identify the authenticity of the salt-tolerant mutants, laid the foundation for creating new germplasm resources and breeding new varieties for Paulownia. The results were be summarized as follows:(1) MMS treatment was significantly affected growth of leaves embryogenic callus of diploid and tetraploid of P. tomentosa: with MMS concentrations increaseing and treatment time extending, the survival rate of callus decreasing. The survival rate of leaves embryogenic callus of diploid of P. tomentosa by MMS treatment was higher than tetraploid of P. tomentosa's. It determined suitable half lethal combination of concentration and time of MMS treatment on leaves embryogenic callus of diploid and tetraploid of P. tomentosa were 120 mg·L^-1 +4 h and 80 mg·L^-1 +4 h.(2) NaCl stress was significantly affected growth of leaves embryogenic callus of diploid and tetraploid of P. tomentosa: with NaCl concentrations increaseing and culture time extending, the survival rate of callus decreasing. The survival rate of leaves embryogenic callus of tetraploid of P. tomentosa by NaCl stress treatment was higher than diploid of P. tomentosa's. It determined suitable half lethal concentration of NaCl stress on leaves embryogenic callus of diploid and tetraploid of P. tomentosa was 0.6%.(3) Nine salt-tolerant mutants of diploid of P. tomentosa and twelve salt-tolerant mutants of tetraploid of P. tomentosa were obtained from the medium containing 0.6% NaCl. Salt-tolerant mutants were selected in medium containing 0.6% NaCl grow normally, robust and growing minor slower than control plants in medium without salt. Salt-tolerant mutants was significantly different form the natural plantlet in morphologic, its representation was discribed as stuned, easily sprouted axillary buds, roots stout, thick leaves smaller, lighter leaf color and other traits.(4) The differences of the number and size of DNA fragments between diploid and tetraploid of Paulownia tomentosa and control were detected in the SSR and AFLP level.