The persistence of Cry1 Ac protein in the soil and its effect on soil microbial communities are a core issue in assessing the ecological risk of transgenic Bacillus thuringiensis(Bt) cotton. In this study a field expe...The persistence of Cry1 Ac protein in the soil and its effect on soil microbial communities are a core issue in assessing the ecological risk of transgenic Bacillus thuringiensis(Bt) cotton. In this study a field experiment was conducted on the cultivation of transgenic Bt cotton(Jin 26 and BtJ i 668) with the immediate returning of residues to the fields, in order to quantify the Cry1 Ac protein content in the fields and investigate its effects on the functional diversity of soil microbial communities. Cry1 Ac protein in the residue-soil mixture was gradually degraded in the transgenic Bt cotton fields. After transgenic Bt cotton straw was returned to the fields for 30 d, 63.73%and 58.33% of the initial amounts of Cry1 Ac protein were degraded in the Jin 26 and BtJ i 668 fields, respectively. Before the crops were sown in the following year(180 d after returning the straw), no Cry1 Ac protein was detected in the fields. After returning the cotton straw to the fields for 30 d, the Shannon-Wiener and McIntosh indices of soil microbial communities in the transgenic Bt cotton fields were significantly higher than those in the non-transgenic cotton fields. Meanwhile, the utilization of carbon sources including amino acids, amines, and carbohydrates by the soil microbial communities significantly increased. Both the McIntosh index and the utilization of carbohydrates increased until 180 d. Principal component analysis revealed that amino acids, amides, and carbohydrates were the main carbon sources distinguishing the two principal component factors. These findings indicated that Cry1 Ac protein did not accumulate in the fields after transgenic Bt cotton was planted for one year and the residues were immediately returned to the fields; however, the original functional diversity of soil microbial communities was affected continuously.展开更多
Significant achievements have been made in breeding programs for the heavy-panicle-type(HPT)rice(Oryza sativa) in Southwest China. The HPT varieties now exhibit excellent lodging resistance,allowing them to overcome t...Significant achievements have been made in breeding programs for the heavy-panicle-type(HPT)rice(Oryza sativa) in Southwest China. The HPT varieties now exhibit excellent lodging resistance,allowing them to overcome the greater pressures caused by heavy panicles. However, the genetic mechanism of this lodging resistance remains elusive. Here, we isolated a major quantitative trait locus, Panicle Neck Diameter 1(PND1), andidentified the causal gene as GRAIN NUMBER 1 A/CYTOKININ OXIDASE 2(Gn1 A/Os CKX2). The null gn1 a allele from rice line R498(gn1 aR498) improved lodging resistance through increasing the culm diameter and promoting crown root development.Loss-of-function of Gn1 a/Os CKX2 led to cytokinin accumulation in the crown root tip and accelerated the development of adventitious roots. Gene pyramiding between the null gn1 aR498 allele with two gain-of-function alleles, STRONG CULM 2(SCM2)and SCM3, further improved lodging resistance.Moreover, Gn1 a/Os CKX2 had minimal influence on overall rice quality. Our research thus highlights the distinct genetic components of lodging resistance of HPT varieties and provides a strategy for tailormade crop improvement of both yield and lodging resistance in rice.展开更多
基金supported by the Shanxi Provincial Natural Science Foundation of China (No. 2012011030-2)181 Cultivate Foundation of National Natural Science from Shanxi Agricultural University (No. 2017GPY07)
文摘The persistence of Cry1 Ac protein in the soil and its effect on soil microbial communities are a core issue in assessing the ecological risk of transgenic Bacillus thuringiensis(Bt) cotton. In this study a field experiment was conducted on the cultivation of transgenic Bt cotton(Jin 26 and BtJ i 668) with the immediate returning of residues to the fields, in order to quantify the Cry1 Ac protein content in the fields and investigate its effects on the functional diversity of soil microbial communities. Cry1 Ac protein in the residue-soil mixture was gradually degraded in the transgenic Bt cotton fields. After transgenic Bt cotton straw was returned to the fields for 30 d, 63.73%and 58.33% of the initial amounts of Cry1 Ac protein were degraded in the Jin 26 and BtJ i 668 fields, respectively. Before the crops were sown in the following year(180 d after returning the straw), no Cry1 Ac protein was detected in the fields. After returning the cotton straw to the fields for 30 d, the Shannon-Wiener and McIntosh indices of soil microbial communities in the transgenic Bt cotton fields were significantly higher than those in the non-transgenic cotton fields. Meanwhile, the utilization of carbon sources including amino acids, amines, and carbohydrates by the soil microbial communities significantly increased. Both the McIntosh index and the utilization of carbohydrates increased until 180 d. Principal component analysis revealed that amino acids, amides, and carbohydrates were the main carbon sources distinguishing the two principal component factors. These findings indicated that Cry1 Ac protein did not accumulate in the fields after transgenic Bt cotton was planted for one year and the residues were immediately returned to the fields; however, the original functional diversity of soil microbial communities was affected continuously.
基金supported by the National Natural Science Foundation of China(92535301)Sichuan Science and Technology Program(2021YJ0501)。
文摘Significant achievements have been made in breeding programs for the heavy-panicle-type(HPT)rice(Oryza sativa) in Southwest China. The HPT varieties now exhibit excellent lodging resistance,allowing them to overcome the greater pressures caused by heavy panicles. However, the genetic mechanism of this lodging resistance remains elusive. Here, we isolated a major quantitative trait locus, Panicle Neck Diameter 1(PND1), andidentified the causal gene as GRAIN NUMBER 1 A/CYTOKININ OXIDASE 2(Gn1 A/Os CKX2). The null gn1 a allele from rice line R498(gn1 aR498) improved lodging resistance through increasing the culm diameter and promoting crown root development.Loss-of-function of Gn1 a/Os CKX2 led to cytokinin accumulation in the crown root tip and accelerated the development of adventitious roots. Gene pyramiding between the null gn1 aR498 allele with two gain-of-function alleles, STRONG CULM 2(SCM2)and SCM3, further improved lodging resistance.Moreover, Gn1 a/Os CKX2 had minimal influence on overall rice quality. Our research thus highlights the distinct genetic components of lodging resistance of HPT varieties and provides a strategy for tailormade crop improvement of both yield and lodging resistance in rice.
