High night temperature strongly impacts TCA cycle, amino acid and polyamine biosynthetic pathways in rice in a sensitivity-dependent manner.

Ulrike Glaubitz,Joachim Kopka,Alexander Erban,Ellen Zuther,Dirk K Hincha

doi:10.1093/jxb/erv352

Abstract

Global climate change combined with asymmetric warming can have detrimental effects on the yield of crop plants such as rice (Oryza sativa L.). Little is known about metabolic responses of rice to high night temperature (HNT) conditions. Twelve cultivars with different HNT sensitivity were used to investigate metabolic changes in the vegetative stage under HNT compared to control conditions. Central metabolism, especially TCA cycle and amino acid biosynthesis, were strongly affected particularly in sensitive cultivars. Levels of several metabolites were correlated with HNT sensitivity. Furthermore, pool sizes of some metabolites negatively correlated with HNT sensitivity under control conditions, indicating metabolic pre-adaptation in tolerant cultivars. The polyamines putrescine, spermidine and spermine showed increased abundance in sensitive cultivars under HNT conditions. Correlations between the content of polyamines and 75 other metabolites indicated metabolic shifts from correlations with sugar-phosphates and 1-kestose under control to correlations with sugars and amino and organic acids under HNT conditions. Increased expression levels of ADC2 and ODC1, genes encoding enzymes catalysing the first committed steps of putrescine biosynthesis, were restricted to sensitive cultivars under HNT. Additionally, transcript levels of eight polyamine biosynthesis genes were correlated with HNT sensitivity. Responses to HNT in the vegetative stage result in distinct differences between differently responding cultivars with a dysregulation of central metabolism and an increase of polyamine biosynthesis restricted to sensitive cultivars under HNT conditions and a pre-adaptation of tolerant cultivars already under control conditions with higher levels of potentially protective compatible solutes.

Highlights

Environmental changes have an increasing influence on crop yields all over the world due to the reduced availability of agricultural land and water resources, and especially accelerating global climate change (Lobell et al, 2011)
To investigate the impact of high night temperature (HNT) on central metabolism, 12 previously characterized rice cultivars from either the japonica or indica subspecies (Supplementary Table S1) with different HNT tolerance were investigated under HNT (30°C day/28°C night) and control conditions (28°C day/21°C night)
Already under control conditions metabolic differences were observed between the cultivars that lead to a separation of the subspecies indica and japonica in a Principal component analysis (PCA) analysis

Summary

Introduction

Environmental changes have an increasing influence on crop yields all over the world due to the reduced availability of agricultural land and water resources, and especially accelerating global climate change (Lobell et al, 2011). With a greater increase in night compared to day temperatures, resulting in a broad decline in the diurnal temperature range (Karl et al, 1991; Easterling et al, 1997; Vose et al, 2005). Possible causes for this trend are an increased cloud development resulting in reduced back radiation The interactive effects of HNT and exogenously applied ascorbic acid were investigated (Shah et al, 2011)

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Conclusion