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Changes in Activities of Key Enzymes for Starch Synthesis and Glutamine Synthetase in Grains of Progenies from a Rice Cross During Grain Filling
Rice Science, 2010, 17(3): 243–246 Copyright © 2010, China National Rice Research Institute. Published by Elsevier BV. All rights reserved DOI: 10.1016/S1672-6308(09)60023-8
Changes in Activities of Key Enzymes for Starch Synthesis and Glutamine Synthetase in Grains of Progenies from a Rice Cross During Grain Filling LI Xiao-guang1, 2, LIU Hai-ying3, JIN Zheng-xun1, LIU Hong-liang1, HUANG Xing1, XU Mei-lan1, ZHANG Feng-zhuan1 (1College of Agriculture, Northeast Agricultural University, Harbin 150030, China; 2Tonghua Academy of Agricultural Sciences, Hailong 135007, China; 3Jilin Province Ping’an Seeds Company, Changchun 133000, China)
Abstract: The progenies differed in amylose and protein contents in grains, which derived from a rice cross, Dongnong 423×Toukei 180, were used to study changes in the activities of ADP-glucose pyrophosphorylase (AGPP), soluble starch synthetase (SSS), starch branching enzyme (SBE) and glutamine synthetase (GS) in rice grains during grain filling. The activities of AGPP, SSS and SBE gradually increased and then declined as a single-peak curve with the process of grain filling in the progenies with high and low amylose contents in grains. The progenies with high amylose content peaked earlier in the AGPP, SSS and SBE activities and had higher AGPP, SSS and SBE activities at the early grain filling stage than those with low amylose content. The GS activity peaked earlier and was higher at the late stage of grain filling in the progenies with high protein content than in those with low protein content. It is suggested that the activities of key enzymes for starch synthesis and glutamine synthetase could be changed in oriented breeding for amylose and protein contents in grains. Key words: rice; hybrid progeny; grain filling; enzyme activity
Amylose and protein contents in grains are immanent factors for rice cooking and eating qualities. Synthesis and accumulation of amylose and protein are the most principal processes during rice grain filling. Therefore, the activities of key enzymes involved in carbohydrate and nitrogen metabolism are closely related with rice grain quality. In recent years, ADP-glucose pyrophosphorylase (EC 2.7.7.21, AGPP), soluble starch synthetase (EC 2.4.1.21, SSS) and starch branching enzyme (EC 2.2.1.18, SBE) have been proved to be key enzymes in starch synthesis in rice grains, which regulate the synthesis and accumulation of amylose in grains (Kato, 1995; Umemoto et al, 1995; Peng et al, 1997). Glutamine synthetase (GS) is a key enzyme that functions in protein synthesis when nitrogen compounds enter into the developing grains in the forms of amino acid and amide etc. from vegetative organs (Liu et al, 2001; Rong et al, 2003). There are lots of reports home and abroad on the activities of key enzymes in the synthesis and accumulation of amylose and protein, and on the activity of glutamine synthetase (GS) during rice grain filling. In our study, the changes of key enzyme activities involved in carbon and nitrogen metabolism during rice grain filling and the relationships between key enzyme activities and amylose content or protein content were investigated with hybrid progenies and their parents by directional selection in amylose and protein contents. Our study aimed to clarify the effects of amylose and protein content selection on key enzyme activities Received: 4 August 2009; Accepted: 7 January 2010 Corresponding author: JIN Zheng-xun ([email protected])
in hybrid progenies and to lay a foundation for understanding the genetic mechanism of key enzymes involved in carbon and nitrogen metabolism.
MATERIALS AND METHODS Rice materials The field experiment was conducted at the Xiangfang Farm of Northeast Agricultural University, China in 2007. The progeny lines of F6 generation through directional selection in amylose and protein contents derived from a cross, Dongnong 423 × Toukei 180, were used. Seeds were sown on 6 April, and seedlings were transplanted on 21 May, at a spacing of 10 cm × 30 cm with two seedlings per hill. A tested progeny line or parent was planted in a 5-m long row with three replications. The conventional field management was applied. The panicles that grew synchronously and headed on the same day were marked at the heading stage. Samples were collected since the 10th day after heading at a 5-day interval. The marked panicles were collected at 9:00–9:30 a.m., immediately frozen in liquid nitrogen and kept in a refrigerator at –20ºC. Determination of enzyme activities and amylose and protein contents Grains at the middle of panicles were used for determination of enzyme activities and amylose and protein contents. The activities of ADP-glucose pyrophosphorylase, soluble starch
Rice Science, Vol. 17, No. 3, 2010
244 synthetase and starch branching enzymes were measured by the method of Nakamura et al (1989), and the activity of glutamine synthetase by the method of Jin et al (2007). The amylose content was determined by iodine colorimetry (He, 1981). The nitrogen content was measured by the semi-micro Kjeldahl method (Shanghai Institute of Plant Physiology et al, 1999). The protein content was estimated by the nitrogen/protein conversion coefficient of 5.95.
RESULTS Grain amylose and protein contents in hybrid progeny Analysis of variance showed that the F values of the amylose and protein contents were 97.6 and 116.3, respectively, suggesting significant genetic differences in the amylose and protein contents of grains among the rice materials. As shown in Table 1, amylose contents of HS10 and HS12 were 20.3% and 21.6%, respectively, significantly higher than those of LS25 and LS26 (9.0% and 9.4%, respectively). Protein contents of HP70 and HP74 were 9.3% and 9.2%, respectively, significantly higher than those of LP46 and LP90 (5.5% and 4.9%, respectively). The results indicate that continuous directional selection in the amylose and protein contents could significantly alter the amylose and protein contents in grains of hybrid progeny. Activities of AGPP, SSS and SBE during grain filling In our study, the changes of AGPP, SSS and SBE activities in the tested lines showed a similar tendency. The activities of AGPP, SSS and SBE increased to a peak and then declined as a single-peak curve during rice grain filling (Fig. 1). However, the peak values and time were different in progeny lines with different amylose contents. There was no significant difference in the time for AGPP activity to reach the peak between the progeny lines with different amylose contents. However, SSS and SBE activities in the progeny
Table 1. Amylose and protein contents in grains of Dongnong 423, Toukei 180 and their progenies. Parent and progeny
Amylose content (%)
Parent and progeny
Protein content (%)
Dongnong 423 16.0 cC Dongnong 423 9.0 bB Toukei 180 10.0 dD Toukei 180 7.0 cC HS10 20.3 bB HP70 9.3 aA HS12 21.6 aA HP74 9.2 aAB LS25 9.0 eE LP46 5.5 dD LS26 9.4 eE LP90 4.9 eE HS, High amylose content; LS, Low amylose content; HP, High protein content; LP, Low protein content. Within a column, data followed by the same uppercase and lowercase letters indicate no significant difference at 0.01 and 0.05 levels, respectively.
lines with high amylose content peaked earlier than those in the progeny lines with low amylose content. The assays showed that the three enzyme activities in the lines with high amylose content were higher than those with low amylose content during early filling period, whereas the enzyme activities in the lines with high amylose content were lower than those in the lines with low amylose content during late filling period. The multiple comparison showed that the peak values of the three enzyme activities in the lines with high amylose content were significantly higher than those in the lines with low amylose content. This result indicates that there were genetic differences in the peak values of the three enzyme activities and the activities of the enzymes involved in starch synthesis could be changed through the selection for amylose content in rice grains. GS activity during grain filling The GS activity in the tested lines showed a similar tendency. The activities of GS increased to a peak and then declined as a single-peak curve during grain filling (Fig. 2). The GS activity in the progeny lines with high protein content peaked earlier than that in the progeny lines with low protein content. There was a significant difference in the GS activity between the progeny lines with high and low protein contents during different
Fig. 1. Changes in the activities of ADP-glucose pyrophosphorylase and soluble starch synthetase and starch branching enzymes in the progeny lines with high and low amylose contents in grains during grain filling. HS10 and HS12 are high amylose content lines; LS25 and LS26 are low amylose content lines.
LI Xiao-guang, et al. Activity Changes of Key Enzymes for Starch Synthesis and Glutamine Synthetase during Grain Filling
Fig. 2. Changes in glutamine synthetase activity in the progeny lines with high and low protein contents in grains during rice grain filling. HP70 and HP74 are high protein content lines; LP46 and LP90 are low protein content lines.
filling stages. The GS activity in the lines with high protein content was higher than that in the lines with low protein content during early filling period and the result was opposite during late filling period, indicating that the protein in grains was mainly synthesized and accumulated at the early stage of grain filling.
DISCUSSION Brown rice consists mainly of starch (more than 90%). Therefore, the process of grain filling was closely related with synthesis and accumulation of starch. In pervious studies, the relationship between key enzyme activities and the content and structure of starch have been reported (Mizuno et al, 1992; Denyer et al, 1995; Smith et al, 1995), and the functions of the three key enzymes (AGPP, SSS and SBE) involved in starch synthesis were different. Zhao et al (2004) reported that amylose content was positively correlated with starch synthase activity at the early filling stage, but negatively correlated with the activities of starch synthase and starch branching enzyme at the middle and late filling stages. Cheng et al (2001) and Zhong et al (2003) reported that there was no significant difference in the changes of three key enzyme activities in rice varieties with different amylose contents. Lu et al (2008) reported that the key enzymes expressed at different stages in starch biosynthetic pathway and showed stage-specific expression. Rice is a typical ammonium-dependent plant. Glutamine synthetase is a multi-functional enzyme in nitrogen metabolism. Zhu et al (2001) reported that the glutamine synthetase activity in leaves of high-protein content varieties was significantly higher than low-protein content varieties. Tang et al (1999) reported that rice varieties with high protein content had higher glutamine synthetase activity in grains at late stage of maturity. Luo et al (2007) reported that glutamine synthetase activity in rice was higher under high application level of nitrogen fertilizer
245
than under low application level of nitrogen fertilizer. The progeny lines with similar genetic background and different amylose and protein contents from a cross between Dongnong 423 and Toukei 180 were used to study the changes in the activities of key enzymes during rice grain filling. The results showed that the AGPP, SSS and SBE activities peaked significantly earlier in the high amylose content progenies than those in the low amylose content progenies. The glutamine synthetase activity in the high protein content progenies was significantly higher than that in the low protein content progenies at the early grain filling stage, which is consistent with the reports of Zhong and Cheng (2003), Zhao et al (2004), Tang et al (1999) and Jin et al (2007). Therefore, there were significant differences in the activities of key enzymes involved in carbohydrate and nitrogen metabolism in high and low amylose and protein contents progenies during grain filling. The results in this study suggest that continuous directional selection on amylose and protein contents can significantly increase or decrease grain amylose and protein contents, and change the activities of key enzymes involved in carbon and nitrogen metabolism during grain filling. The effect of directional selection mainly depends on the cumulative effect of genes. Selection on amylose and protein contents will change the activities of key enzymes related with carbon and nitrogen metabolism during grain filling. Therefore, the activities of key enzymes participated in carbon and nitrogen metabolism are quantitative traits controlled by minor effect multi-genes. We could obtain superior lines through the cumulative effect of genes.
ACKNOWLEDGEMENTS This research was supported by the Program for Innovative Research Team of Northeast Agricultural University, China and the Project of the Department of Education of Heilongjiang Province, China (Grant No. 11531017).
REFERENCES Cheng F M, Jiang D A, Wu P, Shi C H. 2001. The dynamic change of starch synthesis enzymes during the grain filling and effects of temperature upon it. Acta Agron Sin, 27(2): 201–206. (in Chinese with English abstract) Denyer K H, Hylton C M, Jenner C F, Smith A M. 1995. Identification of multiple isoform of soluble and granule-bound starch synthase in developing wheat endosperm. Plant Physiol, 196: 256–261. He Z F. 1981. Test methods of straight, branched-chain and total starch dual-wavelength in grain. Prog Biochem Biophys, (1): 70– 72. (in Chinese with English abstract) Jing Z X, Qian C R, Yang J, Liu H Y, Piao Z Z. 2007. Changes in activities of glutamine synthetase during grain filling and their relation to rice quality. Rice Sci, 14(3): 211–214.
Rice Science, Vol. 17, No. 3, 2010
246 Kato T. 1995. Change of sucrose synthase activity in developing endospem of cultivars. Crop Sci, 35: 827–839. Liu Q, Rong X M, Zhu H M, Peng J W, Lu X Y, Chen J B. 2001. Nitrogen metabolism of different rice cultivars under different cultivations. J Hunan Agric Univ: Nat Sci, 27(6): 415–420. (in Chinese with English abstract) Lu B, Guo Z G, Liang J S. 2008. Starch synthesis-related enzyme activity changes in rice endosperm to amylopectin fine structure effect. Sci China: Life Sci, 38(8): 766–773. (in Chinese) Luo L F, Zheng S X, Liao Y L, Nie J, Xie J, Xiang Y W. 2007. Effect of controlled release nitrogen fertilizer on protein quality
Shanghai Institute of Plant Physiology, the Chinese Academy of Sciences, Shanghai Society for Plant Physiology. 1999. Laboratory Guide for Modern Plant Physiology. Beijing: Science Press: 133–134. (in Chinese) Smith A M, Denyer K, Martin C. 1995. What controls the amount and structure of starch in storage organ? Plant Physiol, 107: 673–677. Tang X R, Guan C Y, Yu T Q. 1999. Study on material metabolism of yield and quality of different genotypic rice. J Hunan Agric Univ, 25(4): 279–282. (in Chinese with English abstract) Umemoto T, Nakamura Y, Ishikura N. 1995. Activity of starch synthase
of brown rice and key enzyme activity involved in nitrogen
and the amylose content in rice endosperm. Phytochemistry,
metabolism in hybrid rice. Chin J Rice Sci, 21(4): 403–410. (in
40(6): 1613–1616.
Chinese with English abstract) Mizuno K, Kimura K, Arai Y. 1992. Starch branching enzymes from immature rice seeds. J Biochem, 112: 643–651. Nakamura Y, Yuki K, Park S. 1989. Carbohydrate metabolism in the developing endosperm of rice grain. Plant Cell Physiol, 30(6): 833–839. Peng J S, Zheng Z R, Liu D, Hu Z B. 1997. Starch biosynthesis and
Zhao B H, Zhang W J, Chang E H, Wang Z Q, Yang J C. 2004. Changes in activities of the key enzymes related to starch synthesis in rice grain during grain filling and their relationships with the filling rate and cooking quality. Sci Agric Sin, 37(8): 1123–1129. (in Chinese with English abstract) Zhong L J, Cheng F M. 2003. Varietal differences in amylose accumulation and activities of major enzymes associated with
its key enzymes. Plant Physiol Comm, 33(4): 297–303. (in
starch synthesis during grain filling in rice. Acta Agron Sin,
Chinese with English abstract)
29(3): 452–456. (in Chinese with English abstract)
Rong X M, Liu Q, Zhu H M, Chen J B, Peng J W, Mo L L, Xie G
Zhu H M, Rong X M, Liu Q, Peng J W. 2001. Differences in
X. 2003. Effects of plant growth regulators on activities of key
contents of grain protein of different genotype rice varieties. J
enzymes of rice nitrogen metabolism. J Hunan Agric Univ: Nat
Hunan Agric Univ, 27(1): 13–16. (in Chinese with English
Sci, 29(3): 327–375. (in Chinese with English abstract)
abstract)
Changes in Activities of Key Enzymes for Starch Synthesis and Glutamine Synthetase in Grains of Progenies from a Rice Cross During Grain Filling LI Xiao-guang1, 2, LIU Hai-ying3, JIN Zheng-xun1, LIU Hong-liang1, HUANG Xing1, XU Mei-lan1, ZHANG Feng-zhuan1 (1College of Agriculture, Northeast Agricultural University, Harbin 150030, China; 2Tonghua Academy of Agricultural Sciences, Hailong 135007, China; 3Jilin Province Ping’an Seeds Company, Changchun 133000, China)
Abstract: The progenies differed in amylose and protein contents in grains, which derived from a rice cross, Dongnong 423×Toukei 180, were used to study changes in the activities of ADP-glucose pyrophosphorylase (AGPP), soluble starch synthetase (SSS), starch branching enzyme (SBE) and glutamine synthetase (GS) in rice grains during grain filling. The activities of AGPP, SSS and SBE gradually increased and then declined as a single-peak curve with the process of grain filling in the progenies with high and low amylose contents in grains. The progenies with high amylose content peaked earlier in the AGPP, SSS and SBE activities and had higher AGPP, SSS and SBE activities at the early grain filling stage than those with low amylose content. The GS activity peaked earlier and was higher at the late stage of grain filling in the progenies with high protein content than in those with low protein content. It is suggested that the activities of key enzymes for starch synthesis and glutamine synthetase could be changed in oriented breeding for amylose and protein contents in grains. Key words: rice; hybrid progeny; grain filling; enzyme activity
Amylose and protein contents in grains are immanent factors for rice cooking and eating qualities. Synthesis and accumulation of amylose and protein are the most principal processes during rice grain filling. Therefore, the activities of key enzymes involved in carbohydrate and nitrogen metabolism are closely related with rice grain quality. In recent years, ADP-glucose pyrophosphorylase (EC 2.7.7.21, AGPP), soluble starch synthetase (EC 2.4.1.21, SSS) and starch branching enzyme (EC 2.2.1.18, SBE) have been proved to be key enzymes in starch synthesis in rice grains, which regulate the synthesis and accumulation of amylose in grains (Kato, 1995; Umemoto et al, 1995; Peng et al, 1997). Glutamine synthetase (GS) is a key enzyme that functions in protein synthesis when nitrogen compounds enter into the developing grains in the forms of amino acid and amide etc. from vegetative organs (Liu et al, 2001; Rong et al, 2003). There are lots of reports home and abroad on the activities of key enzymes in the synthesis and accumulation of amylose and protein, and on the activity of glutamine synthetase (GS) during rice grain filling. In our study, the changes of key enzyme activities involved in carbon and nitrogen metabolism during rice grain filling and the relationships between key enzyme activities and amylose content or protein content were investigated with hybrid progenies and their parents by directional selection in amylose and protein contents. Our study aimed to clarify the effects of amylose and protein content selection on key enzyme activities Received: 4 August 2009; Accepted: 7 January 2010 Corresponding author: JIN Zheng-xun ([email protected])
in hybrid progenies and to lay a foundation for understanding the genetic mechanism of key enzymes involved in carbon and nitrogen metabolism.
MATERIALS AND METHODS Rice materials The field experiment was conducted at the Xiangfang Farm of Northeast Agricultural University, China in 2007. The progeny lines of F6 generation through directional selection in amylose and protein contents derived from a cross, Dongnong 423 × Toukei 180, were used. Seeds were sown on 6 April, and seedlings were transplanted on 21 May, at a spacing of 10 cm × 30 cm with two seedlings per hill. A tested progeny line or parent was planted in a 5-m long row with three replications. The conventional field management was applied. The panicles that grew synchronously and headed on the same day were marked at the heading stage. Samples were collected since the 10th day after heading at a 5-day interval. The marked panicles were collected at 9:00–9:30 a.m., immediately frozen in liquid nitrogen and kept in a refrigerator at –20ºC. Determination of enzyme activities and amylose and protein contents Grains at the middle of panicles were used for determination of enzyme activities and amylose and protein contents. The activities of ADP-glucose pyrophosphorylase, soluble starch
Rice Science, Vol. 17, No. 3, 2010
244 synthetase and starch branching enzymes were measured by the method of Nakamura et al (1989), and the activity of glutamine synthetase by the method of Jin et al (2007). The amylose content was determined by iodine colorimetry (He, 1981). The nitrogen content was measured by the semi-micro Kjeldahl method (Shanghai Institute of Plant Physiology et al, 1999). The protein content was estimated by the nitrogen/protein conversion coefficient of 5.95.
RESULTS Grain amylose and protein contents in hybrid progeny Analysis of variance showed that the F values of the amylose and protein contents were 97.6 and 116.3, respectively, suggesting significant genetic differences in the amylose and protein contents of grains among the rice materials. As shown in Table 1, amylose contents of HS10 and HS12 were 20.3% and 21.6%, respectively, significantly higher than those of LS25 and LS26 (9.0% and 9.4%, respectively). Protein contents of HP70 and HP74 were 9.3% and 9.2%, respectively, significantly higher than those of LP46 and LP90 (5.5% and 4.9%, respectively). The results indicate that continuous directional selection in the amylose and protein contents could significantly alter the amylose and protein contents in grains of hybrid progeny. Activities of AGPP, SSS and SBE during grain filling In our study, the changes of AGPP, SSS and SBE activities in the tested lines showed a similar tendency. The activities of AGPP, SSS and SBE increased to a peak and then declined as a single-peak curve during rice grain filling (Fig. 1). However, the peak values and time were different in progeny lines with different amylose contents. There was no significant difference in the time for AGPP activity to reach the peak between the progeny lines with different amylose contents. However, SSS and SBE activities in the progeny
Table 1. Amylose and protein contents in grains of Dongnong 423, Toukei 180 and their progenies. Parent and progeny
Amylose content (%)
Parent and progeny
Protein content (%)
Dongnong 423 16.0 cC Dongnong 423 9.0 bB Toukei 180 10.0 dD Toukei 180 7.0 cC HS10 20.3 bB HP70 9.3 aA HS12 21.6 aA HP74 9.2 aAB LS25 9.0 eE LP46 5.5 dD LS26 9.4 eE LP90 4.9 eE HS, High amylose content; LS, Low amylose content; HP, High protein content; LP, Low protein content. Within a column, data followed by the same uppercase and lowercase letters indicate no significant difference at 0.01 and 0.05 levels, respectively.
lines with high amylose content peaked earlier than those in the progeny lines with low amylose content. The assays showed that the three enzyme activities in the lines with high amylose content were higher than those with low amylose content during early filling period, whereas the enzyme activities in the lines with high amylose content were lower than those in the lines with low amylose content during late filling period. The multiple comparison showed that the peak values of the three enzyme activities in the lines with high amylose content were significantly higher than those in the lines with low amylose content. This result indicates that there were genetic differences in the peak values of the three enzyme activities and the activities of the enzymes involved in starch synthesis could be changed through the selection for amylose content in rice grains. GS activity during grain filling The GS activity in the tested lines showed a similar tendency. The activities of GS increased to a peak and then declined as a single-peak curve during grain filling (Fig. 2). The GS activity in the progeny lines with high protein content peaked earlier than that in the progeny lines with low protein content. There was a significant difference in the GS activity between the progeny lines with high and low protein contents during different
Fig. 1. Changes in the activities of ADP-glucose pyrophosphorylase and soluble starch synthetase and starch branching enzymes in the progeny lines with high and low amylose contents in grains during grain filling. HS10 and HS12 are high amylose content lines; LS25 and LS26 are low amylose content lines.
LI Xiao-guang, et al. Activity Changes of Key Enzymes for Starch Synthesis and Glutamine Synthetase during Grain Filling
Fig. 2. Changes in glutamine synthetase activity in the progeny lines with high and low protein contents in grains during rice grain filling. HP70 and HP74 are high protein content lines; LP46 and LP90 are low protein content lines.
filling stages. The GS activity in the lines with high protein content was higher than that in the lines with low protein content during early filling period and the result was opposite during late filling period, indicating that the protein in grains was mainly synthesized and accumulated at the early stage of grain filling.
DISCUSSION Brown rice consists mainly of starch (more than 90%). Therefore, the process of grain filling was closely related with synthesis and accumulation of starch. In pervious studies, the relationship between key enzyme activities and the content and structure of starch have been reported (Mizuno et al, 1992; Denyer et al, 1995; Smith et al, 1995), and the functions of the three key enzymes (AGPP, SSS and SBE) involved in starch synthesis were different. Zhao et al (2004) reported that amylose content was positively correlated with starch synthase activity at the early filling stage, but negatively correlated with the activities of starch synthase and starch branching enzyme at the middle and late filling stages. Cheng et al (2001) and Zhong et al (2003) reported that there was no significant difference in the changes of three key enzyme activities in rice varieties with different amylose contents. Lu et al (2008) reported that the key enzymes expressed at different stages in starch biosynthetic pathway and showed stage-specific expression. Rice is a typical ammonium-dependent plant. Glutamine synthetase is a multi-functional enzyme in nitrogen metabolism. Zhu et al (2001) reported that the glutamine synthetase activity in leaves of high-protein content varieties was significantly higher than low-protein content varieties. Tang et al (1999) reported that rice varieties with high protein content had higher glutamine synthetase activity in grains at late stage of maturity. Luo et al (2007) reported that glutamine synthetase activity in rice was higher under high application level of nitrogen fertilizer
245
than under low application level of nitrogen fertilizer. The progeny lines with similar genetic background and different amylose and protein contents from a cross between Dongnong 423 and Toukei 180 were used to study the changes in the activities of key enzymes during rice grain filling. The results showed that the AGPP, SSS and SBE activities peaked significantly earlier in the high amylose content progenies than those in the low amylose content progenies. The glutamine synthetase activity in the high protein content progenies was significantly higher than that in the low protein content progenies at the early grain filling stage, which is consistent with the reports of Zhong and Cheng (2003), Zhao et al (2004), Tang et al (1999) and Jin et al (2007). Therefore, there were significant differences in the activities of key enzymes involved in carbohydrate and nitrogen metabolism in high and low amylose and protein contents progenies during grain filling. The results in this study suggest that continuous directional selection on amylose and protein contents can significantly increase or decrease grain amylose and protein contents, and change the activities of key enzymes involved in carbon and nitrogen metabolism during grain filling. The effect of directional selection mainly depends on the cumulative effect of genes. Selection on amylose and protein contents will change the activities of key enzymes related with carbon and nitrogen metabolism during grain filling. Therefore, the activities of key enzymes participated in carbon and nitrogen metabolism are quantitative traits controlled by minor effect multi-genes. We could obtain superior lines through the cumulative effect of genes.
ACKNOWLEDGEMENTS This research was supported by the Program for Innovative Research Team of Northeast Agricultural University, China and the Project of the Department of Education of Heilongjiang Province, China (Grant No. 11531017).
REFERENCES Cheng F M, Jiang D A, Wu P, Shi C H. 2001. The dynamic change of starch synthesis enzymes during the grain filling and effects of temperature upon it. Acta Agron Sin, 27(2): 201–206. (in Chinese with English abstract) Denyer K H, Hylton C M, Jenner C F, Smith A M. 1995. Identification of multiple isoform of soluble and granule-bound starch synthase in developing wheat endosperm. Plant Physiol, 196: 256–261. He Z F. 1981. Test methods of straight, branched-chain and total starch dual-wavelength in grain. Prog Biochem Biophys, (1): 70– 72. (in Chinese with English abstract) Jing Z X, Qian C R, Yang J, Liu H Y, Piao Z Z. 2007. Changes in activities of glutamine synthetase during grain filling and their relation to rice quality. Rice Sci, 14(3): 211–214.
Rice Science, Vol. 17, No. 3, 2010
246 Kato T. 1995. Change of sucrose synthase activity in developing endospem of cultivars. Crop Sci, 35: 827–839. Liu Q, Rong X M, Zhu H M, Peng J W, Lu X Y, Chen J B. 2001. Nitrogen metabolism of different rice cultivars under different cultivations. J Hunan Agric Univ: Nat Sci, 27(6): 415–420. (in Chinese with English abstract) Lu B, Guo Z G, Liang J S. 2008. Starch synthesis-related enzyme activity changes in rice endosperm to amylopectin fine structure effect. Sci China: Life Sci, 38(8): 766–773. (in Chinese) Luo L F, Zheng S X, Liao Y L, Nie J, Xie J, Xiang Y W. 2007. Effect of controlled release nitrogen fertilizer on protein quality
Shanghai Institute of Plant Physiology, the Chinese Academy of Sciences, Shanghai Society for Plant Physiology. 1999. Laboratory Guide for Modern Plant Physiology. Beijing: Science Press: 133–134. (in Chinese) Smith A M, Denyer K, Martin C. 1995. What controls the amount and structure of starch in storage organ? Plant Physiol, 107: 673–677. Tang X R, Guan C Y, Yu T Q. 1999. Study on material metabolism of yield and quality of different genotypic rice. J Hunan Agric Univ, 25(4): 279–282. (in Chinese with English abstract) Umemoto T, Nakamura Y, Ishikura N. 1995. Activity of starch synthase
of brown rice and key enzyme activity involved in nitrogen
and the amylose content in rice endosperm. Phytochemistry,
metabolism in hybrid rice. Chin J Rice Sci, 21(4): 403–410. (in
40(6): 1613–1616.
Chinese with English abstract) Mizuno K, Kimura K, Arai Y. 1992. Starch branching enzymes from immature rice seeds. J Biochem, 112: 643–651. Nakamura Y, Yuki K, Park S. 1989. Carbohydrate metabolism in the developing endosperm of rice grain. Plant Cell Physiol, 30(6): 833–839. Peng J S, Zheng Z R, Liu D, Hu Z B. 1997. Starch biosynthesis and
Zhao B H, Zhang W J, Chang E H, Wang Z Q, Yang J C. 2004. Changes in activities of the key enzymes related to starch synthesis in rice grain during grain filling and their relationships with the filling rate and cooking quality. Sci Agric Sin, 37(8): 1123–1129. (in Chinese with English abstract) Zhong L J, Cheng F M. 2003. Varietal differences in amylose accumulation and activities of major enzymes associated with
its key enzymes. Plant Physiol Comm, 33(4): 297–303. (in
starch synthesis during grain filling in rice. Acta Agron Sin,
Chinese with English abstract)
29(3): 452–456. (in Chinese with English abstract)
Rong X M, Liu Q, Zhu H M, Chen J B, Peng J W, Mo L L, Xie G
Zhu H M, Rong X M, Liu Q, Peng J W. 2001. Differences in
X. 2003. Effects of plant growth regulators on activities of key
contents of grain protein of different genotype rice varieties. J
enzymes of rice nitrogen metabolism. J Hunan Agric Univ: Nat
Hunan Agric Univ, 27(1): 13–16. (in Chinese with English
Sci, 29(3): 327–375. (in Chinese with English abstract)
abstract)