The role of low soil temperature in the inhibition of growth and PSII function during dark chilling in soybean genotypes of contrasting tolerance

Abstract

Dark chilling affects growth and yield of warm-climate crops such as soybean [Glycine max (L.) Merr.]. Several studies have investigated chilling-stress effects on photosynthesis and other aspects of metabolism, but none have compared effects of whole-plant chilling (WPC; shoots and roots) with that of aboveground chilling in legumes. This is important because low root temperatures might induce additional constraints, such as inhibition of N(2) fixation, thereby aggravating chilling-stress symptoms. Effects of dark chilling on PSII, shoot growth, leaf ureide content and photosynthetic capacity were studied in two soybean genotypes, Highveld Top (chilling tolerant) and PAN809 (chilling sensitive), in experiments comparing effects of WPC with that of shoot chilling (SC). Both treatments inhibited shoot growth in PAN809 but not Highveld Top. Also, WPC in PAN809 caused a decrease in leaf ureide content followed by severe chlorosis and alterations in O-J-I-P fluorescence-rise kinetics, distinct from SC. A noteworthy difference was the appearance of a Delta K peak in the O-J-I-P fluorescence rise in response to WPC. These genotypic and treatment differences also reflected in the degree of inhibition of CO(2) assimilation rates. The appearance of a Delta K peak, coupled with growth inhibition, reduced ureide content, chlorosis and lower CO(2) assimilation rates, provides mechanistic information about how WPC might have aggravated chilling-stress symptoms in PAN809. We introduce a model explaining how chilling soil temperatures might trigger N-limitation in sensitive genotypes and how characteristic changes in O-J-I-P fluorescence-rise kinetics are linked to changes in carbon and nitrogen metabolism.

Identification and physiological characterization of two sister lines ofindicarice (Oryza sativaL.) with contrasting levels of cold tolerance

“…Results from chlorophyll fluorescence studies suggest that the reaction center of photosystem II (PSII) is one of the main targets of low temperature stress (Strauss et al 2007). When rice seedlings are chilled, the superstructure of chloroplasts is altered and the electron transfer activity is decreased (Guo-Li and Zhen-Fei 2005).…”

Physiological adaptive mechanisms of plants grown in saline soil and implications for sustainable saline agriculture in coastal zone

“…1). O-J-I-P transient has been accepted as a reliable and popular tool in photosynthetic research, especially to study PSII behavior in recent years (Wen et al 2005;Strauss et al 2007;Toth et al 2007;Yang et al 2007;Chen et al 2008;Rapacz et al 2008;Yan et al 2008Yan et al , 2011Li et al 2009;Mehta et al 2010;Rapacz et al 2010;Jedmowski et al 2013). O, J, I and P are a sequence of phases in the kinetics of fast fluorescence rise, and environmental stress often provokes the occurrence of K phase in this transient, suggesting the damage to oxygen-evolving complex in donor side of PSII (Strasser et al 2004).…”

Regulation of Respiration and the Oxygen Diffusion Barrier in Soybean Protect Symbiotic Nitrogen Fixation from Chilling-Induced Inhibition and Shoots from Premature Senescence

“…We have previously characterized the adverse effects of dark chilling on soybean leaf photosynthesis and carbon metabolism (Van Heerden et al, 2003) as well as the respective roles of shoots and root parameters (Strauss et al, 2006(Strauss et al, , 2007. Exposure to dark chilling had a direct effect on photosynthesis, as determined by the polyphasic (OKJIP, the letters denoting the positions of various peaks) rise in chlorophyll a fluorescence.…”

“…Exposure to dark chilling had a direct effect on photosynthesis, as determined by the polyphasic (OKJIP, the letters denoting the positions of various peaks) rise in chlorophyll a fluorescence. Specifically, dark chilling resulted in the appearance of a J-peak (Strauss et al, 2006(Strauss et al, , 2007. However, the J-peak was induced by dark chilling in all of the 30 soybean genotypes that were screened under conditions in which root temperatures were maintained at optimal values (shoot chilling treatment), regardless of their relative sensitivities to dark chilling (Strauss et al, 2006).…”

“…However, when the roots and the shoots were exposed simultaneously to dark chilling (whole plant chilling), the OKJIP kinetic change induced in PAN was absent from HT. The typical J-peak that formed in PAN was accompanied by the generation of a K-peak that appeared as leaf ureide contents fell (Strauss et al, 2007). Since to date only heat stress (Lazár et al, 1997;Lazár, 2006) and nitrogen limitation have been implicated in the formation of the K peak in the OKJIP transient, the observation of this kinetic change in PAN, in combination with a greater inhibition of CO 2 assimilation rates, suggested that chilling sensitivity in the shoot results more from a dark chilling-dependent inhibition of symbiotic nitrogen fixation (SNF) than a direct effect on shoot parameters per se.…”