Characterization and Regulation of Aquaporin Genes of Sorghum [Sorghum bicolor (L.) Moench] in Response to Waterlogging Stress

Abstract

Waterlogging is a significant environmental constraint to crop production, and a better understanding of plant responses is critical for the improvement of crop tolerance to waterlogged soils. Aquaporins (AQPs) are a class of channel-forming proteins that play an important role in water transport in plants. This study aimed to examine the regulation of AQP genes under waterlogging stress and to characterize the genetic variability of AQP genes in sorghum (Sorghum bicolor). Transcriptional profiling of AQP genes in response to waterlogging stress in nodal root tips and nodal root basal regions of two tolerant and two sensitive sorghum genotypes at 18 and 96 h after waterlogging stress imposition revealed significant gene-specific pattern with regard to genotype, root tissue sample, and time point. For some tissue sample and time point combinations, PIP2-6, PIP2-7, TIP2-2, TIP4-4, and TIP5-1 expression was differentially regulated in tolerant compared to sensitive genotypes. The differential response of these AQP genes suggests that they may play a tissue specific role in mitigating waterlogging stress. Genetic analysis of sorghum revealed that AQP genes were clustered into the same four subfamilies as in maize (Zea mays) and rice (Oryza sativa) and that residues determining the AQP channel specificity were largely conserved across species. Single nucleotide polymorphism (SNP) data from 50 sorghum accessions were used to build an AQP gene-based phylogeny of the haplotypes. Phylogenetic analysis based on single nucleotide polymorphisms of sorghum AQP genes placed the tolerant and sensitive genotypes used for the expression study in distinct groups. Expression analyses suggested that selected AQPs may play a pivotal role in sorghum tolerance to water logging stress. Further experimentation is needed to verify their role and to leverage phylogenetic analyses and AQP expression data to improve waterlogging tolerance in sorghum.

Ectopic expression of a rice plasma membrane intrinsic protein (OsPIP1;3) promotes plant growth and water uptake

“…We identified the SNPs of OsPIP1;3 genes from two rice subspecies. In sorghum, hundreds of SNPs were identified from AQP loci among 50 sorghum accessions and most of the SNPs are related to the expression of AQP genes in response to waterlogging stress (Kadam et al , ).…”

Waterlogging affects plant morphology and the expression of key genes in tef (Eragrostis tef)

“…In sorghum, waterlogging‐tolerant genotypes showed differential regulation of PIP2‐6, PIP2‐7, TIP2‐2, TIP4‐4, and TIP5‐1. However, SbTIP4‐4 was downregulated in the sensitive genotypes (Kadam et al., ). TIP2 regulates the response to abiotic stresses (salt and drought) in bread wheat ( Triticum aestivum ) (Kayum et al., ) and tomato ( Solanum lycopersicum ) (Sade et al., ).…”

Investigation of the AQP Family in Soybean and the Promoter Activity of TIP2;6 in Heat Stress and Hormone Responses

“…AQPs extensively participated in plant physiological processes under variable environmental stresses [9,10]. Transcript profiles or gene function analyses of AQPs from many plant species, such as Arabidopsis , rice, barley, sorghum, cassava, soybean, and potato, demonstrated that they were associated with drought, cold, salt, silicon, or ABA stress [11,12,13,14,15,16,17]. Recently, several publications reported that AQPs were involved in response to heat stress.…”