RNA editing analysis of ATP synthase genes in the cotton cytoplasmic male sterile line H276A

BACKGROUND: Pollen development is an energy-consuming process that particularly occurs during meiosis. Low levels of adenosine triphosphate (ATP) may cause cell death, resulting in CMS (cytoplasmic male sterility). DNA sequence differences in ATP synthase genes have been revealed between the N- and S-cytoplasms in the cotton CMS system. However, very few data are available at the RNA level. In this study, we compared five ATP synthase genes in the H276A, H276B and fertile F1 (H276A/H268) lines using RNA editing, RNA blotting and quantitative real time-PCR (qRT-PCR) to explore their contribution to CMS. A molecular marker for identifying male sterile cytoplasm (MSC) was also developed. RESULTS: RNA blotting revealed the absence of any novel orf for the ATP synthase gene sequence in the three lines. Forty-one RNA editing sites were identified in the coding sequences. RNA editing showed that proteins had 32.43% higher hydrophobicity and that 39.02% of RNA editing sites had proline converted to leucine. Two new stop codons were detected in atp6 and atp9 by RNA editing. Real-time qRT-PCR data showed that the atp1, atp6, atp8, and atp9 genes had substantially lower expression levels in H276A compared with those in H276B. By contrast, the expression levels of all five genes were increased in F1 (H276A/H268). Moreover, a molecular marker based on a 6-bp deletion upstream of atp8 in H276A was developed to identify male sterile cytoplasm (MSC) in cotton. CONCLUSIONS: Our data substantially contributes to the understanding of the function of ATP synthase genes in cotton CMS. Therefore, we suggest that ATP synthase genes might be an indirect cause of cotton CMS. Further research is needed to investigate the relationship among ATP synthase genes in cotton CMS.

Impact of transgenic cotton varieties on activity of enzymes in their rhizosphere.

The impact of five Bacillus thuringiensis (Bt) cotton varieties and their respective isogenic non-Bt(NBt) isolines (ANKUR-2534, MECH-6304, RCH-317, ANKUR-651 and MECH-6301) was assessed on the key soil enzymes i.e., dehydrogenase, alkaline phosphatase and urease in their rhizosphere at four growth stages of the crop, namely vegetative, flowering, bolling and harvesting. These varieties were grown on farmer’s field in villages 22 miles and 24 miles of Ganganagar District of Rajasthan State in India. Results showed that dehydrogenase, alkaline phosphatase and urease activities were higher in rhizosphere of Bt isolines as compared to NBt isolines of all the varieties. Except phosphatase, differences in dehydrogenase and urease activities in rhizosphere of Bt and NBt isolines of all five varieties were significant (P<0.05). Maximum enhancement in the three enzymes activities was observed in MECH-6304 Bt isoline rhizosphere. Maximum and minimum activities of dehydrogenase and urease were observed in MECH-6304 and RCH-317 Bt isolines, respectively, whereas phosphatase activity was maximum and minimum in MECH-6304 and ANKUR-651 Bt isolines, respectively. Maximum dehydrogenase and urease activities were observed at boll formation and minimum at flowering and harvesting stage, respectively, while maximum phosphatase activity was observed at vegetative stage and minimum at harvesting stage. In conclusion, all the studied Bt isolines of cotton varieties showed no adverse effect on dehydrogenase, alkaline phosphatase and urease activities in the rhizosphere.

Efecto ambiental de agroquímicos y maquinaria agrícola en cultivos transgénicos y convencionales de algodón / Environmental effects of agrochemicals and agricultural machinery in transgenic and conventional crops cotton

La producción de alimentos se basa en el uso de diferentes tecnologías agrícolas, que pueden derivar en conflictos entre medioambiente y agricultura. Es significativo estudiar el impacto ambiental de las nuevas tecnologías aplicadas a la agricultura, la más importante de las cuales es la transgénesis. Este trabajo se realizó en la zona algodonera del municipio del Espinal, departamento del Tolima, para la cosecha de algodón del primer semestre de 2009, usando las metodologías de Brookes y Barfoot (2006) y Kovach y colaboradores (1992). Se estudió el efecto ambiental de la aplicación de agroquímicos y el uso de maquinaria agrícola en cultivos de algodón transgénico y convencional. Se recogió información mediante encuestas en veinte fincas productoras de algodón. El análisis de las encuestas se realizó de forma descriptiva, determinando diferencias de tipo cuantitativo y cualitativo para los predios que utilizan la tecnología convencional o la tecnología transgénicas (doble gen, Bt/RR), para luego realizar una correlación con el “Enviromental Index Quotient” (EIQ). No se encontraron diferencias entre el EIQ de campo de las dos tecnologías, aunque la tecnología transgénica tiene ventajas ambientales en el control de algunas plagas de lepidópteros. En relación con el uso de maquinaria agrícola, se encontró que la tecnología convencional genera menor liberación de CO2, gas de efecto invernadero. La metodología de Brookes y Barfoot puede adaptarse para estudios comparativos de tecnologías agrícolas en países tropicales.

Food production is based on the use of various agricultural technologies, which can lead to conflicts between environment and agriculture. It is important to study the environmental impact of new technologies applied to agriculture, the most important of which is transgenesis. This work was carried out in the cotton belt of the town of Espinal, Tolima Department for the cotton crop in the first half of 2009, through methodologies Brookes & Barfoot (2006) and Kovach et al (1992). We studied the environmental impact of pesticide application and use of agricultural machinery for cultivation of transgenic and conventional cotton. Information was collected through surveys of 20 farms producing cotton. The analysis of the survey was conducted descriptively, by determining differences in quantitative and qualitative for the sites that use conventional technology, and transgenic (Bt gene and double RR / RR), and then make a correlation with the Environmental Index Quotient (EIQ). No differences were found between the fields EIQ the two technologies, although transgenic technology has environmental advantages in the control of some lepidopteran pests. In connection with the use of agricultural machinery, was found to conventional technology generates less release of CO2, greenhouse gas. The Brookes and Barfoot methodology could be adapted in comparative studies of agricultural technologies in tropical countries.

Bio-indicators of soil fertility in cotton rotation

The correlation assessment of the bioindicators and classical chemical indicators of soil fertility can help in testing the practical application of the bioindicators as alternative approach for soil fertility evaluations. The relationship between enzyme activities and some soil properties under the cotton rotation at three governorates was studied to find out whether or not the enzyme activities can be taken as bioindicator to soil fertility. The results showed that there were differences in soil enzyme activities [dehydrogenase, invertase, phosphatase and urease] at the different sites within the three governorates according to its soil fertility level. Also, a significant positive correlation was found between the enzyme activities and soil organic matter content and clay fraction%. Significant positive correlations were also established between the activity of each of the studied enzyme and the microbial population, which are the functions of the essential nutrients of the soil