Abstract
Rice is an important grain that is the staple food for most of the world’s population. Drought is one of the major stresses that negatively affects rice yield. The nature of drought tolerance in rice is complex as it is determined by various components and has low heritability. Therefore, to ensure success in breeding programs for drought tolerant rice, QTLs (quantitative trait loci) of interest must be stable in a variety of plant genotypes and environments. This study identified stable QTLs in rice chromosomes in a variety of backgrounds and environments and conducted a meta-QTL analysis of stable QTLs that have been reported by previous research for use in breeding programs. A total of 653 QTLs for drought tolerance in rice from 27 genetic maps were recorded for analysis. The QTLs recorded were related to 13 traits in rice that respond to drought. Through the use of BioMercartor V4.2, a consensus map containing QTLs and molecular markers were generated using 27 genetic maps that were extracted from the previous 20 studies and meta-QTL analysis was conducted on the consensus map. A total of 70 MQTLs were identified and a total of 453 QTLs were mapped into the meta-QTL areas. Five meta-QTLs from chromosome 1 (MQTL 1.5 and MQTL 1.6), chromosome 2 (MQTL2.1 and MQTL 2.2) and chromosome 3 (MQTL 3.1) were selected for functional annotation as these regions have high number of QTLs and include many traits in rice that respond to drought. A number of genes in MQTL1.5 (268 genes), MQTL1.6 (640 genes), MQTL 2.1 (319 genes), MQTL 2.2 (19 genes) and MQTL 3.1 (787 genes) were annotated through Blast2GO. Few major proteins that respond to drought stress were identified in the meta-QTL areas which are Abscisic Acid-Insensitive Protein 5 (ABI5), the G-box binding factor 4 (GBF4), protein kinase PINOID (PID), histidine kinase 2 (AHK2), protein related to autophagy 18A (ATG18A), mitochondrial transcription termination factor (MTERF), aquaporin PIP 1-2, protein detoxification 48 (DTX48) and inositol-tetrakisphosphate 1-kinase 2 (ITPK2). These proteins are regulatory proteins involved in the regulation of signal transduction and gene expression that respond to drought stress. The meta-QTLs derived from this study and the genes that have been identified can be used effectively in molecular breeding and in genetic engineering for drought resistance/tolerance in rice.
Highlights
Rice (Oryza sativa L.) is one of the most important cereals in the world
Collected quantitative trait loci (QTL) include QTLs related to properties that respond to drought stress
Since the current study is to find meta-QTL related to drought tolerance in rice, only the QTLs expressed in drought condition were taken into account
Summary
Rice (Oryza sativa L.) is one of the most important cereals in the world. It is a major food source for more than half of the world’s population. More than 90% of rice is grown and eaten by Asians, who make up 60% of the world’s population. The Southeast Asian Region (SEA) has become the world’s economic center of rice [2]. In 2016, the Asian region produced 453.2 million tons of rice, representing 90% of the world’s rice production [3]. Rice has the potential to produce a yield of 10 tons per hectare. The average rice yield produced by local farmers is only between 4–5 tonnes per hectare [4]. In order to achieve food security status in rice production by 2050, the development of high yielding rice varieties with tolerance to both biotic and abiotic stresses is crucial [5]
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