Differentiation of the High Night Temperature Response in Leaf Segments of Rice Cultivars with Contrasting Tolerance

Abstract

High night temperatures (HNT) affect rice yield in the field and induce chlorosis symptoms in leaves in controlled chamber experiments. However, little is known about molecular changes in leaf segments under these conditions. Transcript and metabolite profiling were performed for leaf segments of six rice cultivars with different HNT sensitivity. The metabolite profile of the sheath revealed a lower metabolite abundance compared to segments of the leaf blade. Furthermore, pre-adaptation to stress under control conditions was detected in the sheath, whereas this segment was only slightly affected by HNT. No unique significant transcriptomic changes were observed in the leaf base, including the basal growth zone at HNT conditions. Instead, selected metabolites showed correlations with HNT sensitivity in the base. The middle part and the tip were most highly affected by HNT in sensitive cultivars on the transcriptomic level with higher expression of jasmonic acid signaling related genes, genes encoding enzymes involved in flavonoid metabolism and a gene encoding galactinol synthase. In addition, gene expression of expansins known to improve stress tolerance increased in tolerant and sensitive cultivars. The investigation of the different leaf segments indicated highly segment specific responses to HNT. Molecular key players for HNT sensitivity were identified.

Spatially resolved gene regulatory networks in Asian rice (Oryza sativa cv. Nipponbare) leaves

“…Additional environmental factors, including abiotic stressors, are also predicted to influence transcriptome to varying degrees according to position along the leaf blade. Rice leaves grown with high night temperatures have higher amplitude metabolomic and transcriptomic changes in the tip and middle of the leaf than in the base (Schaarschmidt et al., 2021) and rice coleoptiles have distinct responses in the tip and base in hypoxic conditions (Narsai et al., 2015). Moreover, there is evidence that biological functions can shift along the length of the leaf in response to environmental stress.…”

Temperature‐smart plants: A new horizon with omics‐driven plant breeding

“…Metabolite profiling of rice leaf segments from six cultivars sensitive to high‐night temperatures revealed the accumulation of several metabolites, including sugars, organic acids, amino acids, and unknown analytes, in response to HS (Schaarschmidt et al, 2021). In another study, intermediates of the lignin biosynthetic pathway, including caffeate and coniferaldehyde, increased in Populus spp.…”