Institute of Agricultural Sciences of Jiangsu Coastal Area, Observation and Experimental Station of Saline Land of Costal Area, Ministry of Agriculture, Yancheng, P. R. China.
Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou, P. R. China.
PLoS One. 2018 Nov 7;13(11):e0207013. doi: 10.1371/journal.pone.0207013. eCollection 2018.
Insect-resistance of transgenic Bacillus thuringiensis (Bt) cotton varies among plants organs and with different environmental conditions. The objective of this study was to examine the influence of soil salinity on Bt protein concentration in cotton squares and to elucidate the potential mechanism of Bt efficacy reduction. Two cotton cultivars (NuCOTN 33B and CCRI 07, salt-sensitive and salt-tolerant) were subjected to salinity stress under four natural saline levels in field conditions in 2015 and 2016 and seven regimes of soil salinity ranged from 0.5 to 18.8 dS m-1 in greenhouse conditions in 2017. Results of field studies revealed that Bt protein content was not significantly changed at 7.13 dS m-1 salinity, but exhibited a significant drop at the 10.41 and 14.16 dS m-1 salinity. The greenhouse experiments further showed similar trends that significant declines of the insecticidal protein contents in squares were detected when soil salinity exceeded 9.1 dS m-1. Meanwhile, high salinity resulted in significant reduction in contents of soluble protein and total nitrogen, activities of nitrate reductase (NR), glutamine synthetase (GS) and glutamic-pyruvic transaminase (GPT), but increased amino acid content, activities of protease and peptidase in cotton squares. High salinity also decreased root vigor (RV), root total absorption area (RTA) and root active absorption area (RAA). The extent of decrease of Bt protein content was more pronounced in NuCOTN 33B than CCRI 07, and CCRI07 exhibited stronger enzymes activities involved in square protein synthesis and higher levels of RV, RTA and RAA. Therefore, the results of our present study indicated that insecticidal protein expression in cotton squares were significantly affected by higher salinity (equal to or higher than 9.1 dS m-1), reduced protein synthesis and increased protein degradation in squares and reduced metabolic activities in roots might lead to the decrease of Bt protein content in squares.
转 Bt 基因抗虫棉的抗虫性因植物器官而异，并受不同环境条件的影响。本研究旨在探讨土壤盐分对棉铃中 Bt 蛋白浓度的影响，并阐明其降低Bt 功效的潜在机制。在 2015 年和 2016 年田间条件下，采用 4 种天然盐度水平，以及 2017 年温室条件下 7 种土壤盐度水平（0.5 至 18.8 dS m-1）对两个棉花品种（NuCOTN 33B 和 CCRI 07，盐敏感和耐盐）进行盐胁迫处理。田间研究结果表明，在 7.13 dS m-1 盐度下，Bt 蛋白含量没有显著变化，但在 10.41 和 14.16 dS m-1 盐度下显著下降。温室试验进一步表明了类似的趋势，当土壤盐度超过 9.1 dS m-1 时，棉铃中杀虫蛋白含量显著下降。同时，高盐导致可溶性蛋白和总氮含量、硝酸还原酶（NR）、谷氨酰胺合成酶（GS）和谷氨酰胺-丙酮酸转氨酶（GPT）活性显著降低，而氨基酸含量、蛋白酶和肽酶活性显著升高。高盐还降低了根活力（RV）、根总吸收面积（RTA）和根活跃吸收面积（RAA）。Bt 蛋白含量的降低程度在 NuCOTN 33B 中比 CCRI 07 更为明显，而 CCRI07 表现出更强的参与棉铃蛋白合成的酶活性以及更高的 RV、RTA 和 RAA 水平。因此，本研究结果表明，较高的盐度（等于或高于 9.1 dS m-1）显著影响棉铃中杀虫蛋白的表达，棉铃中蛋白质合成减少、降解增加以及根系代谢活性降低可能导致棉铃中 Bt 蛋白含量降低。
