Replication proteinAsubunit 3 and the iron efficiency response in soybean

Abstract

In soybean [Glycine max (L.) Merr.], iron deficiency results in interveinal chlorosis and decreased photosynthetic capacity, leading to stunting and yield loss. In this study, gene expression analyses investigated the role of soybean replication protein A (RPA) subunits during iron stress. Nine RPA homologs were significantly differentially expressed in response to iron stress in the near isogenic lines (NILs) Clark (iron efficient) and Isoclark (iron inefficient). RPA homologs exhibited opposing expression patterns in the two NILs, with RPA expression significantly repressed during iron deficiency in Clark but induced in Isoclark. We used virus induced gene silencing (VIGS) to repress GmRPA3 expression in the iron inefficient line Isoclark and mirror expression in Clark. GmRPA3-silenced plants had improved IDC symptoms and chlorophyll content under iron deficient conditions and also displayed stunted growth regardless of iron availability. RNA-Seq comparing gene expression between GmRPA3-silenced and empty vector plants revealed massive transcriptional reprogramming with differential expression of genes associated with defense, immunity, aging, death, protein modification, protein synthesis, photosynthesis and iron uptake and transport genes. Our findings suggest the iron efficient genotype Clark is able to induce energy controlling pathways, possibly regulated by SnRK1/TOR, to promote nutrient recycling and stress responses in iron deficient conditions.

Virus-induced gene silencing is a versatile tool for unraveling the functional relevance of multiple abiotic-stress-responsive genes in crop plants

“…In a soybean ( Glycine max ) iron-inefficient line, Isoclark, a Bean pod mottle virus (BPMV)-based VIGS vector was used to silence a REPLICATION PROTEIN A ( GmRPA3 ) gene. GmRPA3 -silenced plants had smaller leaves, decreased internode length and higher chlorophyll content, and failed to respond to increased iron nutrition, suggesting a role of the GmRPA3 gene in iron acquisition (Atwood et al, 2014). Using a satellite DNA (DNAmβ) virus system with TYLCCNV, the function of FERRIC CHELATE REDUCTASE gene ( FRO1 ) was studied in tomato roots (He et al, 2008).…”

Soybean Functional Genomics: Bridging the Genotype-to-Phenotype Gap

“…Gene silencing or mutagenesis would yield easily measurable phenotypic differences. For example, functional genomics approaches were used to target candidate genes for resistance (Meyer et al 2009;Pandey et al 2011;Liu et al 2012;Cook et al 2014), abiotic stress tolerance (Atwood et al 2014), silencing (Curtin et al 2011), or chlorophyll content ). The reference genome was also used to develop a comparative genome hybridization (CGH) array for soybean that could be used to identify structural variants within ) and between soybean accessions (McHale et al 2012;Anderson et al 2014).…”

“…Arikit et al (2014) generated an atlas of small RNAs developed from 69 libraries representing vegetative and reproductive tissues. These studies paved the way for soybean researchers studying gene expression changes in response to abiotic stress (Peiffer et al 2012;Atwood et al 2014;Moran Lauter et al 2014), biotic stress Tremblay et al 2013;Lin et al 2014;Wong et al 2014), and throughout soybean development (Zabala et al 2012;Cho et al 2013;Jones and Vodkin 2013;Kour et al 2014).…”

“…The BPMV system has been mainly applied to studying traits involved in interactions with biotic and abiotic stresses (Atwood et al 2014;Liu et al 2015). VIGS candidate genes used in these studies have been identified based on a number sources including transcriptome profiling, proteomics, homologs from model systems like Arabidopsis thaliana, and genetic mapping.…”

“…In addition, the BPMV system can be used to silence genes in the roots (Juvale et al 2012), and protocols have been developed that enable identification of genes involved in soybean-SCN interactions (Liu et al 2012;Kandoth et al 2013). With regard to abiotic stresses, the BPMV system has been used to assess functions of genes in iron-deficiency chlorosis and salt stress (Rao et al 2013;Atwood et al 2014).…”