Effect on Root Length of the Overexpression of Arabidopsis VHA-c4 and VHA-c5 Genes

To study the role of vacuole H⁺-ATPase subunit c genes on plant growth and development, over-expression vectors of VHA-c4 and VHA-c5 from Arabidopsis thaliana were constructed and introduced into wild-type A. thaliana, and 9 and 7 homozygous T2 generations of VHA-c4 and VHA-c5 overexpressed transgenic lines were obtained, respectively. Semi-quantitative RT-PCR methods were used for identification of the positive VHA-c4 and VHA-c5 transgenic homozygotes, and their corresponding transcript levels were increased in every transgenic line. When cultivated under different light conditions, the VHA-c4 transgenic plants exhibited a reduction in primary root length compared with that of the wild-type when cultivated in the dark, whereas the VHA-c5 transgenic plants showed reduced primary root length under normal light conditions. These results indicated that VHA-c4 and VHA-c5 affected the growth of roots during light/dark cycles. Following ABA and sugar (glucose and sucrose) treatment, no significant differences were found between the transgenic homozygote phenotype and wild type, indicating that VHA-c4 and VHA-c5 overexpression did not affect the response of Arabidopsis to ABA or sugar.