Abstract
Drought stress affects crop quality and productivity. The challenge of increasing food availability for a growing worldwide demand relies on the development of tolerant cultivars that will need to be adapted to arid and semi-arid areas. In order to help the understanding of rice response to stress, the phenotypic response of 6 Brazilian rice cultivars and 2 different crosses between them were characterized under drought conditions. Since gene regulation is an important part of root morphological responses to stressful conditions, 4 genes related to auxin response and root modifications (OsGNOM1 CRL4, OsIAA1, OsCAND1 and OsRAA1) were evaluated. The expression of these genes was analyzed in stressed rice using public available microarray data and then through real-time quantitative polymerase chain reaction (RT-qPCR), in the 6 phenotypically evaluated Brazilian genotypes under standard conditions (absence of stress). Our results show that all genotypes lengthened its roots in response to drought, specially the 2 hybrids. The expression of these genes is modified in response to stress, and OsRAA1 has a very special behavior, constituting a target for future studies. Further steps include the study of polymorphisms in these genotypes in order to understand if differences in these genes or in regulatory regions can be associated with differences in root system architecture and/or stress tolerance.
Highlights
Rice (Oryza sativa L.) is the second most cultivated cereal in the world and a primary source of food for about two-thirds of the world’s population (Pirdashti et al 2009)
Significant differences (p < 0.05) between genotypes were observed for shoot length (SL) and root length (RL), as well as for shoot dry weight (SDW) and root dry weight (RDW), under control and stressful conditions (Figure 1)
When analyzing RDW (Figure 1d), genotypes with well-developed root systems showed the highest values under stress, along with BRS Ligeirinho
Summary
Rice (Oryza sativa L.) is the second most cultivated cereal in the world and a primary source of food for about two-thirds of the world’s population (Pirdashti et al 2009). The cultivation of rice faces many different challenges, according to region, climate and cultivation system, i.e. upland or lowland. Water deficit can become a primary limiting factor for productivity and its importance is increasing due to climate changes (Datta et al 2012). In Asia, rice cultivation areas go through dry periods of varying intensity affecting different stages of the crop cycle (Dixit et al 2012)
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