Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, College of Resources and Environmental Sciences, Hunan Agricultural University, Changsha, China.
Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, College of Resources and Environmental Sciences, Hunan Agricultural University, Changsha, China; National Engineering Laboratory of High Efficiency Utilization of Soil and Fertilizer Resources, Hunan Agricultural University, Changsha, China.
Plant Sci. 2019 Jul;284:57-66. doi: 10.1016/j.plantsci.2019.04.003. Epub 2019 Apr 5.
The transmembrane transport of NO and Cd into plant cell vacuoles relies on the energy from their tonoplast proton pumps, V-ATPase and V-PPase. If the activity of these pumps is reduced, it results in less NO and Cd being transported into the vacuoles, which contributes to better nitrogen use efficiency (NUE) and lower Cd tolerance in plants. The physiological mechanisms that regulate the balance between NUE and Cd tolerance remain unknown. In our study, two Brassica napus genotypes with differential NUEs, xiangyou 15 and 814, and Atclca-2 mutant and AtCAX4 over-expression line (AtCAX4-OE) of Arabidopsis thaliana, were used to investigate Cd stress responses. We found that the Brassica napus genotype, with higher NUE, was more sensitive to Cd stress. The AtCAX4-OE mutant, with higher Cd vacuolar sequestration capacity (VSC), limited NO sequestration into root vacuoles and promoted NUE. Atclca-2 mutants, with decreased NO VSC, enhanced Cd sequestration into root vacuoles and conferred greater Cd tolerance than the WT. This may be due to the competition between Cd andNO in the vacuoles for the energy provided by V-ATPase and V-PPase. Regulating the balance between Cd and NO vacuolar accumulation by inhibiting the activity of CLCa transporter and increasing the activity of CAX4 transporter will simultaneously enhance both the NUE and Cd tolerance of Brassica napus, essential for improving its Cd phytoremediation potential.
NO 和 Cd 通过植物液泡膜进入液泡的跨膜运输依赖于液泡膜质子泵 V-ATPase 和 V-PPase 的能量供应。如果这些泵的活性降低，进入液泡的 NO 和 Cd 就会减少，这有助于提高植物的氮利用效率（NUE）和降低 Cd 耐性。调节 NUE 和 Cd 耐性之间平衡的生理机制尚不清楚。在我们的研究中，使用具有不同 NUE 的两种甘蓝型油菜（xiangyou 15 和 814）和拟南芥 Atclca-2 突变体和 AtCAX4 过表达系（AtCAX4-OE）来研究 Cd 胁迫响应。我们发现，具有较高 NUE 的甘蓝型油菜基因型对 Cd 胁迫更敏感。具有较高 Cd 液泡区隔化能力（VSC）的 AtCAX4-OE 突变体，限制了 NO 进入根液泡区隔化，并促进了 NUE。Atclca-2 突变体，由于 NO VSC 减少，增强了 Cd 进入根液泡区隔化的能力，并赋予了比 WT 更高的 Cd 耐性。这可能是由于 Cd 和 NO 在液泡中竞争 V-ATPase 和 V-PPase 提供的能量所致。通过抑制 CLCa 转运体的活性和增加 CAX4 转运体的活性来调节 Cd 和 NO 液泡积累之间的平衡，将同时提高油菜的 NUE 和 Cd 耐性，这对于提高其 Cd 植物修复潜力至关重要。
