Dawuda Mohammed Mujitaba, Liao Weibiao, Hu Linli, Yu Jihua, Xie Jianming, Calderón-Urrea Alejandro, Jin Xin, Wu Yue
Department of Horticulture, Faculty of Agriculture, University for Development Studies, Tamale, Ghana.
College of Horticulture, Gansu Agricultural University, Lanzhou, China.
PeerJ. 2019 Aug 22;7:e7530. doi: 10.7717/peerj.7530. eCollection 2019.
This study was conducted to determine the root tolerance and biochemical responses of four Chinese L. genotypes ( and ) to cadmium (Cd) stress. Twenty-eight days old seedlings were exposed to Hoagland's nutrient solution supplied with or without 100 µM CdCl and monitored for seven days in a climate controlled room. The 100 µM CdCl significantly ( < 0.001) decreased all the root morphological indexes of the four genotypes. However, , which possessed the smallest root system, exhibited greater root tolerance to Cd by having the highest tolerance indexes for root volume (46%), surface area (61%), projected area (74%) and numbers of root forks (63%) and root tips (58%). Moreover, Cd stress also caused increases in HO contents in the roots but the increase was least in which showed greater root tolerance to Cdstress. The effect of Cd stress on the contents of hormones in the roots depended on the genotypes. Under Cd stress, abscisic acid correlated positively with indole-3-acetic acid ( = 0.669*), gibberellic acid ( = 0.630*) and cytokinin ( = 0.785**). The antioxidant enzyme activities and proline responses of the four genotypes to Cd stress were similar. The SOD activity was decreased whiles the CAT and POD activities, as well as the contents of proline increased in all the genotypes under the stress condition. These results suggest that lettuce genotypes with smaller root systems could be more tolerant to Cd stress compared to those with larger root systems.
本研究旨在确定四种中国生菜基因型（和）对镉（Cd）胁迫的根系耐受性及生化响应。将28日龄的幼苗置于添加或不添加100 µM CdCl₂的霍格兰营养液中，并在气候控制室中监测7天。100 µM CdCl₂显著（<0.001）降低了这四种基因型的所有根系形态指标。然而，根系最小的，通过对根体积（46%）、表面积（61%）、投影面积（74%）、根叉数（63%）和根尖数（58%）具有最高的耐受指数，对Cd表现出更高的根系耐受性。此外，Cd胁迫还导致根系中HO含量增加，但在中增加最少，其对Cd胁迫表现出更高的根系耐受性。Cd胁迫对根系激素含量的影响取决于基因型。在Cd胁迫下，脱落酸与吲哚-3-乙酸（=0.669*）、赤霉素（=0.630*）和细胞分裂素（=0.785**）呈正相关。四种基因型对Cd胁迫的抗氧化酶活性和脯氨酸响应相似。在胁迫条件下，所有基因型的超氧化物歧化酶（SOD）活性降低，而过氧化氢酶（CAT）和过氧化物酶（POD）活性以及脯氨酸含量增加。这些结果表明，与根系较大的生菜基因型相比，根系较小的生菜基因型对Cd胁迫的耐受性可能更强。
