|MURA, JYOSTNA DEVI - North Carolina State University|
|SINCLAIR, TOM - North Carolina State University|
Submitted to: Environmental and Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2015
Publication Date: 2/1/2016
Citation: Mura, J., Taliercio, E.W., Sinclair, T. 2016. Silver and zinc inhibitors influence transpiration rate and aquaporin transcript levels in intact soybean plants. Journal of Euphytica. 122:168–175.
Interpretive Summary: Two slow wilting soybeans, PI416937 and PI471938, and two fast wilting soybeans, Benning and A5959 were used to investigate the effect silver and zinc treatments have on the transpiration rate of soybean plants. Silver and zinc are thought to block specific classes the water channels or aquaporins that transport water in a soybean plant and play an important role in replenishing water lost through transpiration. Compared to the fast-wilting genotypes, slow-wilting PI416937 and PI471938 as had lower inhibition if transpiration after being fed silver or zinc. Treatment with silver or zinc substantially affected aquaporin gene expression in all genotypes. Aquaporins that were differentially regulated in the slow wilting genotypes upon treatment with silver or zinc were identified. These differentially regulated aquaporin are excellent candidates to begin to explain the molecular and physiological basis of the slow wilting and water conserving phenotypes observed in PI416937 and PI471938.
Technical Abstract: Some soybean (Glycine max (L.) Merr.) have been identified that expressed limited transpiration rate (TR) above a threshold vapor pressure deficit (VPD). Restriction of TR at high VPD conditions is considered a water conservation trait that allows water to be retained in the soil to benefit of crop growth later in the season if water-deficit conditions develop. Previous studies have identified that the limited-TR trait was associated with low leaf hydraulic conductance, which may reflect differences in aquaporin (AQP) populations as evidenced by genotypic differences in responses to feeding de-rooted shoots AQP inhibitors. The objective of the present study was to assess and correlate the differences in TR responses under high VPD conditions and AQP transcriptional profiles using intact plants which offer understanding the involvement of AQPs in water flux when roots are part of the water flow pathway. Changes in TR were observed for intact soybean plants after being fed AQP inhibitors silver and zinc. Four genotypes were studied: slow-wilting genotypes PI 416937 and PI 471938 and fast-wilting cultivars Benning and A 5959. Slow-wilting PI 416937 and PI 471938 as compared to the fast-wilting genotypes had lower inhibition in TR after being fed silver (P<0.01) and zinc (P<0.01). An induced expression of AQP genes was identified in all the genotypes in response to treatment with silver and zinc measured in roots and shoots after short (15 min) and prolonged (180 min) treatment. Some of the AQP genes were differentially regulated among the genotypes following inhibitor treatment. These results document differences in intact plant responses to silver and zinc AQP inhibition, and corroborate the possible role of AQPs in differential TR responses under high VPD environments in slow- and fast-wilting soybean cultivars.