Efficient production and characterization for maize inbred lines with low-phosphorus tolerance

Embryogenic calli derived from the young embryo of maize inbred line Qi-319, were subcultured for half a year and screened continuously on the medium without phosphate. Low-P tolerant cell lines were obtained and the regenerated plants (R0) were self-pollinated to harvest seeds. The progeny (R1) of 21% regenerated plants showed low-P tolerance traits. Low-P tolerant R1 plants and their progeny were self-pollinated for 5 generations, and a number of low-P tolerant inbred lines including 99038 were obtained. Comparison of response of 99038 and Qi-319 to P nutrition indicated that under P deficiency the growth of 99038 plants were less influenced, especially roots, indicating that low-P tolerance was improved significantly. Inbred line 99038 had larger root systems with modification and capability of P acquisition improved significantly compared to Qi-319, and a larger proportion of P was retained in roots of 99038, so P concentration in roots was obviously higher, which improved root growth under P deficiency. Comparison of 2-DE gel maps of proteins isolated from roots treated with P deficiency suggested that more than 13% of the proteins were different in 99038 and Qi-319, which supported the general viewpoint that the P-efficiency of plant was a trait controlled by multi-gene. We concluded that maize mutants with low-P tolerance could be obtained efficiently by cellular engineering and the low-P tolerance of maize inbred lines 99038 appeared to be a complicated metabolism process controlled by major genes.