Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2014
Publication Date: 12/22/2014
Citation: Burke, J.J., Payton, P.R., Chen, J., Xin, Z., Burow, G.B., Hayes, C.M. 2015. Metabolic responses of two contrasting sorghums to water-deficit stress. Crop Science. 55:344-353.
Interpretive Summary: Pre-flowering drought tolerant sorghums tend to be post-flowering drought sensitive and senesce their leaves during grain-fill. Post-flowering drought sensitive sorghums tend to be pre-flowering drought sensitive and exhibit symptoms of water-deficit stress. This study determined the response of pre- and post-flowering sorghum to the onset of water-deficit stress. The pre-flowering line SC1211-11E induced abscisic acid and proline accumulation earlier and to a greater level than the post-flowering drought tolerant line BTx642. These results help to explain the visual stress responses observed between these sorghum lines.
Technical Abstract: This study investigated metabolic responses of the stay-green line BTx642 and the senescent line SC1211-11E to the onset of water-deficit stress in the greenhouse and field. Because of the reported differences in osmotic potential among stay-green and senescent lines we examined whether BTx642 and SC1211-11E responded differently to the onset of stress. We hypothesized that the elevated sucrose and higher cyanogenic glucoside (dhurrin) levels in stay-green sorghums result in higher cellular osmotic levels compared with senescent lines. To determine if the pre-flowering drought sensitivity of stay-green lines may result from an inability to either sense or respond the soil drying until the rate of drying is too great for the stay-green lines to compensate, we evaluated ABA and proline accumulation in response to the onset of water deficit stress of senescent and stay-green sorghums under greenhouse and field environments. Differential accumulation of proline and ABA between senescent and stay-green lines was observed suggesting that lines having lower cellular osmotic levels may be able to detect small changes in soil water levels, thereby allowing the plants to respond more rapidly to the stress as it develops. Information from this study provides insight into the ability of pre-flowering drought tolerant (senescent) and post-flowering drought tolerant (stay-green) sorghum to respond to the onset of water-deficit stress.