Azoarcus sp. strain KH32C affects rice plant growth and the root-associated soil bacterial community in low nitrogen input paddy fields

Figures & data

Table 1. Total carbon and total nitrogen in paddy field soil. Eg, early growth stage; Pf, panicle formation stage; Fh, full heading stage; Hv, harvesting stage

		C (g/kg)		N (g/kg)
		KH32C	Control	KH32C	Control
PF4
	Eg	54.8 ± 1.6	53.2 ± 0.8	4.85 ± 0.20	4.68 ± 0.12
Nipponbare	Pf	51.9 ± 0.6	53.5 ± 2.2	4.61 ± 0.14	4.78 ± 0.20
	Hv^§	58.1 ± 0.5	51.4 ± 0.7	5.46 ± 0.14	4.75 ± 0.11
	Eg	52.6 ± 0.4	51.5 ± 0.4	4.71 ± 0.11	4.54 ± 0.12
Takanari	Pf	55.0 ± 1.2	53.8 ± 0.9	4.87 ± 0.23	4.89 ± 0.22
	Hv^§	59.1 ± 1.3	62.4 ± 1.1	5.37 ± 0.11	5.63 ± 0.09
	Eg	54.4 ± 2.5	57.0 ± 0.1	4.84 ± 0.31	5.02 ± 0.09
IR64	Pf	58.5 ± 0.8	54.2 ± 2.0	5.22 ± 0.22	4.95 ± 0.22
	Hv^§	55.8 ± 0.4	58.0 ± 6.0	5.25 ± 0.09	5.34 ± 0.57
PF2
	Eg	67.5 ± 0.3	67.5 ± 0.5	5.46 ± 0.06	5.41 ± 0.12
Nipponbare	Pf	66.3 ± 0.2	67.3 ± 0.7	5.44 ± 0.10	5.63 ± 0.09
	Fh	67.2 ± 0.2	67.2 ± 0.1	5.48 ± 0.13	5.46 ± 0.13
	Hv	66.7 ± 0.8	67.4 ± 0.3	5.60 ± 0.00	5.56 ± 0.03
	Eg	67.3 ± 0.0	65.5 ± 0.2	5.54 ± 0.06	5.37 ± 0.09
Takanari	Pf	67.0 ± 1.5	65.4 ± 1.1	5.58 ± 0.14	5.48 ± 0.08
	Fh	67.1 ± 0.1	66.1 ± 0.2	5.46 ± 0.16	5.35 ± 0.14
	Hv	68.2 ± 0.3	67.0 ± 0.2	5.26 ± 0.13	5.31 ± 0.01
	Eg	66.3 ± 0.4	64.8 ± 0.5	5.46 ± 0.17	5.25 ± 0.16
IR64	Pf	66.5 ± 0.4	65.8 ± 0.0	5.67 ± 0.02	5.61 ± 0.02
	Fh	67.3 ± 0.5	65.6 ± 0.5	5.42 ± 0.18	5.29 ± 0.09
	Hv	67.6 ± 0.3	66.9 ± 0.1	5.42 ± 0.01	5.29 ± 0.02

Mean ± SE.

^§, Mean ± SD.

Figure 1. Growth rates of Nipponbare, Takanari, and IR64 at (a) early growth stage and (b) panicle formation stage. Error bars mean SE. *; Significantly higher comparing between KH32C inoculation and control in the same cultivar and year (paired t-test, p-value<0.05)

Table 2. Elemental composition in dried brown rice

		(%)			(ppm)
		C	N	Ash	Inorganic element
					K	P	Mg	Si	Ca	S	Zn	Mn	Fe	Cu	Rb	Mo
PF4
Nipponbare	KH32C	44.9 ± 0.5	1.48 ± 0.04	1.39 ± 0.04	5691 ± 75	4938 ± 191	1373 ± 175	1170 ± 78	260.9 ± 24.1	185.1 ± 34.5	113.1 ± 1.3*	75.38 ± 4.21	38.77 ± 3.00	10.46 ± 0.85	5.74 ± 0.59	0.58 ± 0.26
	Control	44.5 ± 0.4	1.53 ± 0.17	1.33 ± 0.18	5392 ± 569	4748 ± 585	1472 ± 177	1029 ± 416	238.4 ± 4.2	170.1 ± 57.9	85.2 ± 7.6	74.06 ± 2.58	39.72 ± 2.44	9.20 ± 0.12	6.56 ± 0.26	0.49 ± 0.18
Takanari	KH32C	44.9 ± 0.4	1.59 ± 0.04	1.48 ± 0.01	5916 ± 140	5720 ± 242	2024 ± 178	509 ± 76	273.8 ± 6.7	183.4 ± 78.0	98.2 ± 5.9*	68.02 ± 6.43	26.63 ± 1.05	9.64 ± 0.30	7.06 ± 1.30	1.45 ± 0.39
	Control	45.2 ± 0.3	1.62 ± 0.13	1.46 ± 0.04	6265 ± 222*	5437 ± 156	1735 ± 115	478 ± 166	275.2 ± 6.5	173.5 ± 24.2	77.0 ± 1.3	71.04 ± 4.48	40.88 ± 24.91	8.46 ± 0.38	9.25 ± 0.72*	1.25 ± 0.15
IR64	KH32C	44.7 ± 0.1	1.63 ± 0.09	1.50 ± 0.06	5803 ± 404	5726 ± 239	1867 ± 204	818 ± 250	370.1 ± 20.5*	249.4 ± 48.5	84.6 ± 11.7	73.68 ± 1.56*	36.39 ± 6.91	7.97 ± 0.24	7.28 ± 0.56	1.57 ± 0.07
	Control	45.4 ± 0.6	1.62 ± 0.04	1.47 ± 0.07	5571 ± 283	5810 ± 300	2095 ± 152	575 ± 92	258.9 ± 27.2	185.0 ± 25.2	90.2 ± 7.4	54.92 ± 4.40	44.24 ± 15.25	7.59 ± 0.66	8.13 ± 0.39	1.39 ± 0.14
PF2
Nipponbare	KH32C	44.9 ± 0.1	1.20 ± 0.04	1.50 ± 0.03*	5881 ± 176	5140 ± 172	1458 ± 99	1768 ± 223	268.6 ± 2.9	144.4 ± 13.9	186.5 ± 21.3	79.44 ± 5.23	28.48 ± 3.58	13.59 ± 0.76*	6.46 ± 0.17*	0.45 ± 0.09
	Control	44.5 ± 0.2	1.20 ± 0.07	1.41 ± 0.01	5509 ± 93	4817 ± 60	1443 ± 80	1610 ± 45	259.7 ± 10.9	139.4 ± 7.5	165.9 ± 4.2	76.90 ± 2.96	23.72 ± 1.28	12.35 ± 0.32	5.31 ± 0.18	0.32 ± 0.07
Takanari	KH32C	45.0 ± 0.4	1.29 ± 0.06	1.56 ± 0.10	6812 ± 368	5606 ± 400	1757 ± 94	677 ± 155	286.1 ± 42.6	136.9 ± 5.9	170.3 ± 8.3	84.44 ± 2.79	24.40 ± 2.40*	12.38 ± 0.76	8.09 ± 0.67	0.87 ± 0.22
	Control	45.3 ± 0.1	1.32 ± 0.07*	1.56 ± 0.02	6722 ± 73	5620 ± 93	1839 ± 36	680 ± 112	273.1 ± 30.4	140.4 ± 11.1	174.5 ± 16.9	82.46 ± 1.70	23.05 ± 2.41	12.25 ± 0.77	6.34 ± 0.56	1.10 ± 0.29
IR64	KH32C	45.2 ± 0.2	1.24 ± 0.09	1.43 ± 0.02	5685 ± 175	5110 ± 134	1737 ± 87	1055 ± 117	261.9 ± 8.2	132.3 ± 17.5	251.0 ± 4.3	66.71 ± 4.24	27.37 ± 0.96	12.47 ± 0.37	5.78 ± 0.38	1.03 ± 0.07
	Control	45.1 ± 0.3	1.22 ± 0.06	1.48 ± 0.05	5998 ± 217*	5308 ± 161	1766 ± 59	892 ± 79	311.4 ± 37.2	147.7 ± 4.5	248.7 ± 11.8	70.46 ± 5.35	23.37 ± 3.19	12.42 ± 0.53	5.99 ± 0.82	1.26 ± 0.36

Mean ± SD.

*; Significantly higher comparing between KH32C inoculation and control for the same element, cultivar, and year (paired t-test, p-value< 0.05).

Figure 2. Cluster analysis of the bacterial community in rice root-associated soil based on terminal restriction fragments profile in PF4. Eg, early growth stage; Pf, panicle formation stage; Hv, harvesting stage. Underlines indicate KH32C inoculation

Figure 3. Heatmap analysis based on the relative abundance of Alphaproteobacteria and Deltaproteobacteria at the family level in root-associated soil of Nipponbare plants. Color means Z-score. Eg, early growth stage; Pf, panicle formation stage; Hv, harvesting stage

Figure 4. Relative abundance of potential plant growth-promoting bacteria at the phylum level in root-associated soil of Nipponbare in PF4. Proteobacteria is shown at a class level. Eg, early growth stage; Pf, panicle formation stage; Hv, harvesting stage; ACC deaminase, 1-aminocyclopropane-1-carboxic acid deaminase; IAA, indole-3-acetic acid; PGP, plant growth-promoting