Identification and Characterization of the EXO70 Gene Family in Polyploid Wheat and Related Species

Abstract

The EXO70 gene family is involved in different biological processes in plants, ranging from plant polar growth to plant immunity. To date, analysis of the EXO70 gene family has been limited in Triticeae species, e.g., hexaploidy Triticum aestivum and its ancestral/related species. By in silico analysis of multiple Triticeae sequence databases, a total of 200 EXO70 members were identified. By homologue cloning approaches, 15 full-length cDNA of EXO70s were cloned from diploid Haynaldia villosa. Phylogenetic relationship analysis of 215 EXO70 members classified them into three groups (EXO70.1, EXO70.2, and EXO70.3) and nine subgroups (EXO70A to EXO70I). The distribution of most EXO70 genes among different species/sub-genomes were collinear, implying their orthologous relationship. The EXO70A subgroup has the most introns (at least five introns), while the remaining seven subgroups have only one intron on average. The expression profiling of EXO70 genes from wheat revealed that 40 wheat EXO70 genes were expressed in at least one tissue (leaf, stem, or root), of which 25 wheat EXO70 genes were in response to at least one biotic stress (stripe rust or powdery mildew) or abiotic stress (drought or heat). Subcellular localization analysis showed that ten EXO70-V proteins had distinct plasma membrane localization, EXO70I1-V showed a distinctive spotted pattern on the membrane. The 15 EXO70-V genes were differentially expressed in three tissue. Apart from EXO70D2-V, the remaining EXO70-V genes were in response to at least one stress (flg22, chitin, powdery mildew, drought, NaCl, heat, or cold) or phytohormones (salicylic acid, methyl jasmonate, ethephon, or abscisic acid) and hydrogen peroxide treatments. This research provides a genome-wide glimpse of the Triticeae EXO70 gene family and those up- or downregulated genes require further validation of their biological roles in response to biotic/abiotic stresses.

OsExo70B1 Positively Regulates Disease Resistance to Magnaporthe oryzae in Rice

“…Then, in order to examine the subcellular localization of OsExo70B1 , the OsExo70B1 fused with the green fluorescent protein (GFP) was expressed under the control of the 35S promoter in N. benthamiana leaves by agrobacterium-mediated genetic transformation. We observed clear fluorescence signals in the cytoplasm, nucleus, and plasma membrane (PM) ( Figure 2 ), indicating that OsExo70B1 distributed throughout the whole cell, which is similar to some Exo70 members in Arabidopsis and H. villosa , such as AtExo70B1, Exo70D1-V and Exo70F2-V [ 20 , 39 ]. Interestingly, OsExo70B1 formed some strong dotted fluorescence in the cytoplasm and plasma membrane, which is similar to Exo70A1, Exo70B1 and Exo70E2 in Arabidopsis [ 24 , 30 , 40 ].…”

“…Among them, Exo70 is a key member of the exocyst complex and has been found to be widely present in yeast, mammals and plants [ 13 , 14 ]. In yeast and mammals, there is one Exo70 gene, while there are multiple copies of Exo70 genes in plants [ 15 ] ranging from 21 to 47 Exo70 members in potatoes, Arabidopsis, Populus trichocarpa, wheat and rice [ 16 , 17 , 18 , 19 , 20 ]. Exo70 genes have been duplicated independently in the moss, lycophyte and angiosperm lineages, and in the subsequent lineage-specific multiplications which are represented by nine subgroups (Exo70A–Exo70I) [ 15 ] and their function ranges from growth, development to biotic and abiotic stresses [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

Genome-Wide Association Study (GWAS) Analysis of Camelina Seedling Germination under Salt Stress Condition

“…EXO70 family proteins were reported to be responsible for vesicular trafficking, regulation of actin polarity and vesicle transportation [62]. Some genes in this family were found to be upregulated by salt stress [63], but the exact function of the exocyst complex in plants against abiotic stress is not clear. Our study might indicate the indirect relationship between exocyst complex SEC8 and salt stress tolerance in C. sativa.…”

Characterization of the Heavy-Metal-Associated Isoprenylated Plant Protein (HIPP) Gene Family from Triticeae Species

“…Subcellular localization was performed as described by Zhao et al [ 66 ] with the following modifications. The ORFs of the HIPP-V genes (without stop codons) were cloned into vector pCambia1305-GFP to produce the fusion expression construct 1305-GFP: HIPP-V.…”