|Kim, Woojae - Rural Development Administration - Korea|
|Bui, Liem - Cuu Long Delta Rice Research Institute|
|Chun, Jae-buhm - Rural Development Administration - Korea|
Submitted to: Plant Breeding and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2018
Publication Date: 12/1/2018
Citation: Kim, W., Bui, L., Chun, J., McClung, A.M., Barnaby, J.Y. 2018. Correlation between methane (CH4) emissions and root aerenchyma of rice varieties. Plant Breeding and Biotechnology. 6:381-390.
Interpretive Summary: Methane is one of the main greenhouse gases known to be a major cause of global warming. Rice cultivation areas continue to expand with population growth, and methane emissions are expected to increase accordingly. Therefore, the development of technologies to reduce methane from paddy rice production is a key research goal that can minimize global warming. Rice has a well-developed aerenchyma as an oxygen supply to adapt to anaerobic, flooded field conditions. This study demonstrated that the amount of aerenchyma was different among rice varieties and was related to varietal differences in methane emissions. Previous studies suggested that breeding high yield rice cultivars with a reduced methane transport capacity as a means of developing low methane-emitting rice cultivars. Our study revealed that there was a strong positive correlation between root transverse section (RTS) area and methane emissions as well as with aerenchyma area; however, percent aerenchyma area is not a major trait affecting methane emissions.
Technical Abstract: Percentage of aerenchyma area has been closely linked with amounts of methane emitted by rice. A diversity panel of 39 global rice varieties were examined to determine genetic variation for root transverse section (RTS), aerenchyma area, and percent aerenchyma. RTS and aerenchyma area showed a strong positive correlation while there existed no significant correlation between RTS area and percent aerenchyma. Five varieties previously shown to differ in methane emissions under field conditions were found to encompass the variation found in the diversity panel for RTS and aerenchyma area. These five varieties were evaluated in a greenhouse study to determine the relationship of RTS, aerenchyma area, and percent aerenchyma with methane emissions. Methane emissions at physiological maturity were the highest for ‘Rondo’, followed by 'Jupiter', while 'Sabine', 'Francis' and 'CLXL745' emitted the least. The same varietal rank, ‘Rondo’ being the largest and ‘CLXL745’ the smallest, was observed with RTS and aerenchyma areas. RTS and aerenchyma area were significantly correlated with methane emissions, r=0.61 and r=0.57, respectively (p<0.001), however there was no relationship with percent aerenchyma. Our results demonstrated that varieties with a larger root area also developed a larger aerenchyma area, which serves as a gas conduit, and as a result, methane emissions were increased. This study suggests that root transverse section area could be used as a means of selecting germplasm with reduced CH4 emissions.