EFFECTS OF Bt TRANSGENIC COTTONS PLANTING ON RHIZOSPHERE SOIL MICROORGANISMS AT DIFFERENT GROWTH STAGES

doi:10.3773/j.issn.1005-264x.2008.01.023

Abstract

Abstract:

Aims Ecological risk assessments have paid increasing attention to the field release of transgenic Bt crops. Some studies have reported that Bt protein could enter the soil ecosystem through root exudates, crop residues, crop decomposition and pollen. Protein from transgenic Bt crops is a potential hazard for soil non-target organisms and biodiversity, and this may affect soil ecological function and soil nutrients. This study aims to evaluate the soil ecological risk of transgenic Bt cotton.
Methods A pot experiment with two types of transgenic Bt cotton, ‘BtXincai1’ and ‘BtJi668’, was conducted to study the effects of transgenic Bt cotton planting on rhizosphere soil microorganisms. The plant was carefully removed from the pot at seedling, budding, flowering, bolling and boll-opening stages. Rhizosphere soil approximately 0-5 mm in diameter was separated from bulk soil by gently shaking the root system. Samples were frozen at -20 ℃ after sieving for subsequent Bt protein analyses, or stored at 4 ℃ for microorganism analyses, which were begun within a day of sampling. Bt protein was analyzed by ELISA BOX. The populations of three main microorganism groups and some functional groups were measured by cultivation.
Important findings The content of Bt protein exuded by different transgenic Bt cottons and the degradation rate of Bt protein in different rhizosphere soils were different. Compared with the controls, transgenic Bt cottons seemed to stimulate the reproduction of rhizosphere soil bacteria and fungi. However, no significant effects on the populations of actinomycete, aerobic nitrogen fixing bacteria and kalium-solubilizing bacteria were observed. Transgenic Bt cottons increased the population of ammonifying bacteria and decreased that of inorganic phosphorus-solubilizing bacteria significantly at seedling and flowering stages, whereas they increased the population of aerobic cellulose-decomposing bacteria and decreased that of organic phosphorus-solubilizing bacteria significantly only at the flowering stage. ‘BtJi668’ also enhanced the population of aerobic cellulose-decomposing bacteria significantly at the seedling stage. The abundance of aerobic cellulose-decomposing bacteria and organic and inorganic phosphorus-solubilizing bacteria in transgenic Bt cottons rhizosphere soils changed. Although the total population of functional groups in transgenic Bt cottons rhizosphere soils was higher than in control cultivars, community diversity (H) and evenness (J) decreased and dominance concentration (C) increased. The change range of diversity indexes and population of functional groups in transgenic Bt cottons rhizosphere soils at the flowering stage was higher than at the seedling stage.

Key words: transgenic Bt cotton, Bt protein, microorganisms, diversity

ZHANG Mei-Jun, YANG Wu-De, LI Yan-E. EFFECTS OF Bt TRANSGENIC COTTONS PLANTING ON RHIZOSPHERE SOIL MICROORGANISMS AT DIFFERENT GROWTH STAGES[J]. Chin J Plant Ecol, 2008, 32(1): 197-203.

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Figures/Tables 4

References 22

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微生物 Microorganisms	处理 Treatments	苗期 Seedling	蕾期 Budding	花期 Flowering	盛铃期 Bolling	吐絮期 Boll-opening
细菌Bacteria (×10⁶ cfu·g^-1)	‘Bt新彩1’BtXincai1	93.30±2.63^b	418.60±3.77^a	1078.63±9.70^b	749.28±4.77^b	356.20±7.11^b
	‘新彩1’Xincai1	92.77±4.54^b	237.87±8.24^b	678.10±9.46^d	466.50±7.34^d	251.10±8.55^c
	‘Bt冀668’BtJi668	116.10±7.08^a	433.62±6.76^a	1209.73±8.04^a	884.27±6.34^a	457.73±5.51^a
	‘冀668’Ji668	114.57±7.78^a	219.70±9.37^c	828.20±7.59^c	528.18±6.26^c	237.77±6.09^c
放线菌Actinomycete (×10⁵ cfu·g^-1)	‘Bt新彩1’BtXincai1	20.83±4.57	28.34±9.17	34.39±2.51	31.14±4.97	19.90±2.04
	‘新彩1’Xincai1	24.26±2.14	26.36±2.33	35.41±4.04	32.46±5.63	18.90±3.21
	‘Bt冀668’BtJi668	21.27±5.11	22.81±5.28	34.94±9.19	32.85±5.47	21.30±1.15
	‘冀668’Ji668	25.72±3.14	26.19±1.17	35.04±3.68	31.87±6.68	20.81±2.69
真菌Fungi (×10³ cfu·g^-1)	‘Bt新彩1’BtXincai1	4.32±0.48	11.57±1.15^ab	28.50±1.97^a	15.25±1.23^a	7.24±0.42^b
	‘新彩1’Xincai1	4.23±0.56	10.77±1.01^bc	18.76±1.10^c	9.17±0.20^b	6.86±0.79^ab
	‘Bt冀668’BtJi668	4.21±0.49	13.15±1.46^a	25.74±1.90^b	16.42±1.16^a	9.58±1.00^a
	‘冀668’Ji668	4.14±0.42	9.24±1.01^c	16.53±1.16^c	10.27±0.32^b	6.18±0.87^b

微生物 Microorganisms	处理 Treatments	苗期 Seedling	蕾期 Budding	花期 Flowering	盛铃期 Bolling	吐絮期 Boll-opening
细菌Bacteria (×10⁶ cfu·g^-1)	‘Bt新彩1’BtXincai1	93.30±2.63^b	418.60±3.77^a	1078.63±9.70^b	749.28±4.77^b	356.20±7.11^b
	‘新彩1’Xincai1	92.77±4.54^b	237.87±8.24^b	678.10±9.46^d	466.50±7.34^d	251.10±8.55^c
	‘Bt冀668’BtJi668	116.10±7.08^a	433.62±6.76^a	1209.73±8.04^a	884.27±6.34^a	457.73±5.51^a
	‘冀668’Ji668	114.57±7.78^a	219.70±9.37^c	828.20±7.59^c	528.18±6.26^c	237.77±6.09^c
放线菌Actinomycete (×10⁵ cfu·g^-1)	‘Bt新彩1’BtXincai1	20.83±4.57	28.34±9.17	34.39±2.51	31.14±4.97	19.90±2.04
	‘新彩1’Xincai1	24.26±2.14	26.36±2.33	35.41±4.04	32.46±5.63	18.90±3.21
	‘Bt冀668’BtJi668	21.27±5.11	22.81±5.28	34.94±9.19	32.85±5.47	21.30±1.15
	‘冀668’Ji668	25.72±3.14	26.19±1.17	35.04±3.68	31.87±6.68	20.81±2.69
真菌Fungi (×10³ cfu·g^-1)	‘Bt新彩1’BtXincai1	4.32±0.48	11.57±1.15^ab	28.50±1.97^a	15.25±1.23^a	7.24±0.42^b
	‘新彩1’Xincai1	4.23±0.56	10.77±1.01^bc	18.76±1.10^c	9.17±0.20^b	6.86±0.79^ab
	‘Bt冀668’BtJi668	4.21±0.49	13.15±1.46^a	25.74±1.90^b	16.42±1.16^a	9.58±1.00^a
	‘冀668’Ji668	4.14±0.42	9.24±1.01^c	16.53±1.16^c	10.27±0.32^b	6.18±0.87^b

生育期 Growth Stages	处理 Treatments	好气固氮菌 Aerobic nitrogen fixing bacteria	氨化细菌 Ammonifying bacteria	好气纤维分解菌 Aerobic cellulose- decomposing bacteria	有机溶磷菌 Organic phosphorus- solubilizing bacteria	无机溶磷菌 Inorganic phosphorus- solubilizing bacteria	钾细菌 Kalium- solubilizing bacteria
苗期	‘Bt新彩1’BtXincai1	0.16±0.02	42.17±2.89^b	14.10±1.72^ab	0.99±0.10	10.58±1.16^b	14.74±0.79^ab
Seedling	‘新彩1’Xincai1	0.15±0.02	30.37±0.74^c	12.31±1.19^b	1.08±0.09	16.92±2.68^a	13.29±2.10^a
	‘Bt冀668’BtJi668	0.14±0.03	57.27±3.67^a	14.55±1.18^a	1.12±0.12	12.25±1.50^b	17.53±1.03^a
	‘冀668’Ji668	0.15±0.01	45.30±2.62^b	8.74±0.37^c	1.16±0.20	18.78±2.46^a	16.70±1.95^ab
花期	‘Bt新彩1’BtXincai1	0.70±0.17	95.43±7.67^b	35.81±1.78^b	2.51±0.57^d	16.34±3.09^c	31.49±0.97
Flowering	‘新彩1’Xincai1	0.81±0.14	51.93±2.38^d	25.25±2.22^c	7.49±0.59^b	28.23±2.00^b	32.75±2.08
	‘Bt冀668’BtJi668	0.75±0.14	111.53±3.47^a	46.42±2.29^a	3.50±0.58^c	21.65±2.53^c	33.47±2.09
	‘冀668’Ji668	0.87±0.09	63.30±4.13^c	23.48±1.61^c	8.48±0.54^a	35.82±2.29^a	32.99±2.26

生育期 Growth Stages	处理 Treatments	好气固氮菌 Aerobic nitrogen fixing bacteria	氨化细菌 Ammonifying bacteria	好气纤维分解菌 Aerobic cellulose- decomposing bacteria	有机溶磷菌 Organic phosphorus- solubilizing bacteria	无机溶磷菌 Inorganic phosphorus- solubilizing bacteria	钾细菌 Kalium- solubilizing bacteria
苗期	‘Bt新彩1’BtXincai1	0.16±0.02	42.17±2.89^b	14.10±1.72^ab	0.99±0.10	10.58±1.16^b	14.74±0.79^ab
Seedling	‘新彩1’Xincai1	0.15±0.02	30.37±0.74^c	12.31±1.19^b	1.08±0.09	16.92±2.68^a	13.29±2.10^a
	‘Bt冀668’BtJi668	0.14±0.03	57.27±3.67^a	14.55±1.18^a	1.12±0.12	12.25±1.50^b	17.53±1.03^a
	‘冀668’Ji668	0.15±0.01	45.30±2.62^b	8.74±0.37^c	1.16±0.20	18.78±2.46^a	16.70±1.95^ab
花期	‘Bt新彩1’BtXincai1	0.70±0.17	95.43±7.67^b	35.81±1.78^b	2.51±0.57^d	16.34±3.09^c	31.49±0.97
Flowering	‘新彩1’Xincai1	0.81±0.14	51.93±2.38^d	25.25±2.22^c	7.49±0.59^b	28.23±2.00^b	32.75±2.08
	‘Bt冀668’BtJi668	0.75±0.14	111.53±3.47^a	46.42±2.29^a	3.50±0.58^c	21.65±2.53^c	33.47±2.09
	‘冀668’Ji668	0.87±0.09	63.30±4.13^c	23.48±1.61^c	8.48±0.54^a	35.82±2.29^a	32.99±2.26

特征参数 Parameter of trait	功能类群 Functional groups	苗期 Seedling				花期 Flowering
特征参数 Parameter of trait	功能类群 Functional groups	‘Bt新彩1’ BtXincai1	‘新彩1’ Xincai1	‘Bt冀668’ BtJi668	‘冀668’ Ji668	‘Bt新彩1’ BtXincai1	‘新彩1’ Xincai1	‘Bt冀668’ BtJi668	‘冀668’ Ji668
多度 Abundance (P_i)	好气固氮菌 Aerobic nitrogen fixing bacteria	0.002	0.002	0.001	0.002	0.004	0.006	0.003	0.006
	氨化细菌 Ammonifying bacteria	0.510	0.410	0.557	0.499	0.523	0.355	0.513	0.383
	好气纤维分解菌 Aerobic cellulose-decomposing bacteria	0.170	0.166	0.142	0.095	0.131	0.172	0.213	0.143
	有机溶磷菌Organic phosphorus-solubilizing bacteria	0.012	0.015	0.011	0.013	0.080	0.051	0.016	0.051
	无机溶磷菌Inorganic phosphorus- solubilizing bacteria	0.128	0.228	0.119	0.207	0.090	0.193	0.101	0.217
	钾细菌 Kalium-solubilizing bacteria	0.178	0.179	0.170	0.184	0.173	0.224	0.154	0.200
总数量 Total individual No. (N)		84.74	74.11	102.86	90.83	182.29	146.47	217.33	164.93
群落多样性 Community diversity (H)		1.279	1.384	1.164	1.277	1.309	1.506	1.274	1.483
均匀度 Evenness (J)		0.714	0.772	0.650	0.713	0.730	0.840	0.711	0.828
优势集中性 Concentration (C)		0.337	0.280	0.373	0.335	0.335	0.246	0.342	0.257