Identification of Drought Tolerance Markers in a Diverse Population of Rice Cultivars by Expression and Metabolite Profiling

Abstract

Rice provides about half of the calories consumed in Asian countries, but its productivity is often reduced by drought, especially when grown under rain-fed conditions. Cultivars with increased drought tolerance have been bred over centuries. Slow selection for drought tolerance on the basis of phenotypic traits may be accelerated by using molecular markers identified through expression and metabolic profiling. Previously, we identified 46 candidate genes with significant genotype × environment interaction in an expression profiling study on four cultivars with contrasting drought tolerance. These potential markers and in addition GC-MS quantified metabolites were tested in 21 cultivars from both indica and japonica background that varied in drought tolerance. Leaf blades were sampled from this population of cultivars grown under control or long-term drought condition and subjected to expression analysis by qRT-PCR and metabolite profiling. Under drought stress, metabolite levels correlated mainly negatively with performance parameters, but eight metabolites correlated positively. For 28 genes, a significant correlation between expression level and performance under drought was confirmed. Negative correlations were predominant. Among those with significant positive correlation was the gene coding for a cytosolic fructose-1,6-bisphosphatase. This enzyme catalyzes a highly regulated step in C-metabolism. The metabolic and transcript marker candidates for drought tolerance were identified in a highly diverse population of cultivars. Thus, these markers may be used to select for tolerance in a wide range of rice germplasms.

Metabolite profiles of maize leaves in drought, heat and combined stress field trials reveal the relationship between metabolism and grain yield

“…There are some previously reported correlation analyses in field studies on metabolite levels that corroborate this statement (Robinson et al, 2007;Degenkolbe et al, 2013). That said, the coefficient values of most of the correlations discussed here range from 20.77 to 20.45 with P values lower than 0.05 or 0.001, which can be considered as highly reliable.…”

“…The accumulation of these metabolites was much lower in this field study than in the other greenhouse studies (Sicher and Barnaby, 2012;Witt et al, 2012;Barnaby et al, 2013), most likely depending on the severity of DS due to the soil structure and coincident rainfalls. As the accumulation of amino acids under DS has been reported in various plant species (Evers et al, 2010;Degenkolbe et al, 2013;Barchet et al, 2014;Hatzig et al, 2014;Suguiyama et al, 2014), it can be considered as a wellconserved and robust metabolic response to DS in plants. This response might be due to less dilution effect caused by the diminished growth under stress conditions (Génard et al, 2014).…”

“…In recent years, genetic and phenotypic markers have been searched extensively for drought tolerance of maize by high-throughput genomic and phenotyping approaches, respectively (Tuberosa and Salvi, 2006;Wen et al, 2011;Araus et al, 2012;Cairns et al, 2013;Prasanna et al, 2013;Araus and Cairns, 2014;Tsonev et al, 2014). Moreover, metabolic markers started to draw attention due to their close relationship with yield phenotypes (Fernie and Schauer, 2009;Redestig et al, 2011;Riedelsheimer et al, 2012aRiedelsheimer et al, , 2012bWitt et al, 2012;Degenkolbe et al, 2013). The accumulation of some metabolites has been reported to be directly related to the performance of potato (Solanum tuberosum) cultivars in beetle resistance in the field (Tai et al, 2014).…”

Protein and starch characteristics of milled rice from different cultivars affected by transplantation date

“…Accumulation of AAs under abiotic stress condition Table 2 Effect of transplanting dates on amino acids composition of milled rice from different cultivars was frequent process in plants which may occurred due to (1) heat-stable uptake of AAs (2) increased AAs biosynthesis from carbohydrates (3) decreased charging of free AAs to tRNA (4) stress-induced degradation of proteins over protein synthesis and was an adaptive mechanism (Glaubitz et al 2015). Degenkolbe et al (2013) also demonstrated that drought stress-induced accumulation of more asparagine in drought-sensitive rice cultivars. Accumulation of glutamic acid, glutamine, glycine, serine and threonine, organic acids such as erythronic acid, galactonic acid and threonic acid was several folds higher in drought sensitive cultivars as compared to the drought tolerant cultivars.…”

Heterosis analysis in relation to drought tolerance in rice land races and their genotypes

“…Rice has been cultivated in more than 100 countries in variety of ecosystems around 163 m ha worldwide annually (FAO, 2013) of the world's cultivated land (Degenkolbe et al, 2013). Among the rice growing countries, the larger area (about 42.5 million ha, (FAO 2013) under cultivation is in India (Utharasu and Anandakumar, 2013).…”