Xiangbo Duan

MicroRNA319 positively regulates cold tolerance by targeting OsPCF6 and OsTCP21 in rice (Oryza sativa L.).

The microRNA319 (miR319) family is conserved among diverse plant species. In rice (Oryza sativa L.), the miR319 gene family is comprised of two members, Osa-miR319a and Osa-miR319b. We found that overexpressing Osa-miR319b in rice resulted in wider leaf blades and delayed development. Here, we focused on the biological function and potential molecular mechanism of the Osa-miR319b gene in response to cold stress in rice. The expression of Osa-miR319b was down-regulated by cold stress, and the overexpression of Osa-miR319b led to an enhanced tolerance to cold stress, as evidenced by higher survival rates and proline content. Also, the expression of a handful of cold stress responsive genes, such as DREB1A/B/C, DREB2A, TPP1/2, was increased in Osa-miR319b transgenic lines. Furthermore, we demonstrated the nuclear localization of the transcription factors, OsPCF6 and OsTCP21, which may be Osa-miR319b-targeted genes. We also showed that OsPCF6 and OsTCP21 expression was largely induced by cold stress, and the degree of induction was obviously repressed in plants overexpressing Osa-miR319b. As expected, the down-regulation of OsPCF6 and OsTCP21 resulted in enhanced tolerance to cold stress, partially by modifying active oxygen scavenging. Taken together, our findings suggest that Osa-miR319b plays an important role in plant response to cold stress, maybe by targeting OsPCF6 and OsTCP21.

GsSKP21 , a Glycine soja S-phase kinase-associated protein, mediates the regulation of plant alkaline tolerance and ABA sensitivity

Plant SKP1-like family proteins, components of the SCF complex E3 ligases, are involved in the regulation of plant development and stress responses. Little is known about the precise function of SKP genes in plant responses to environmental stresses. GsSKP21 was initially identified as a potential stress-responsive gene based on the transcriptome sequencing of Glycine soja. In this study, we found that GsSKP21 protein contains highly conserved SKP domains in its N terminus and an extra unidentified domain in its C terminus. The transcript abundance of GsSKP21, detected by quantitative real-time PCR, was induced under the treatment of alkali and salt stresses. Overexpression of GsSKP21 in Arabidopsis dramatically increased plant tolerance to alkali stress. Furthermore, we found that overexpression of GsSKP21 resulted in decreased ABA sensitivity during both the seed germination and early seedling growth stages. GsSKP21 mediated ABA signaling by altering the expression levels of the ABA signaling-related and ABA-induced genes. We also investigated the tissue expression specificity and subcellular localization of GsSKP21. These results suggest that GsSKP21 is important for plant tolerance to alkali stress and plays a critical regulatory role in the ABA-mediated stress response.

GsERF6, an ethylene-responsive factor from Glycine soja, mediates the regulation of plant bicarbonate tolerance in Arabidopsis.

AbstractMain conclusionThis is an original study focus on ERF gene response to alkaline stress. GsERF6functions as transcription factor and significantly enhanced plant tolerance to bicarbonate (HCO3−) in transgenic Arabidopsis. Alkaline stress is one of the most harmful, but little studied environmental factors, which negatively affects plant growth, development and yield. The cause of alkaline stress is mainly due to the damaging consequence of high concentration of the bicarbonate ion, high-pH, and osmotic shock to plants. The AP2/ERF family genes encode plant-specific transcription factors involved in diverse environmental stresses. However, little is known about their physiological functions, especially in alkaline stress responses. In this study, we functionally characterized a novel ERF subfamily gene, GsERF6 from alkaline-tolerant wild soybean (Glycine soja). In wild soybean, GsERF6 was rapidly induced by NaHCO3 treatment, and its overexpression in Arabidopsis enhanced transgenic plant tolerance to NaHCO3 challenge. Interestingly, GsERF6 transgenic lines also displayed increased tolerance to KHCO3 treatment, but not to high pH stress, implicating that GsERF6 may participate specifically in bicarbonate stress responses. We also found that GsERF6 overexpression up-regulated the transcription levels of bicarbonate-stress-inducible genes such as NADP-ME, H+-Ppase and H+-ATPase, as well as downstream stress-tolerant genes such as RD29A, COR47 and KINI. GsERF6 overexpression and NaHCO3 stress also altered the expression patterns of plant hormone synthesis and hormone-responsive genes. Conjointly, our results suggested that GsERF6 is a positive regulator of plant alkaline stress by increasing bicarbonate ionic resistance specifically, providing a new insight into the regulation of gene expression under alkaline conditions.

A novel AP2/ERF family transcription factor from Glycine soja, GsERF71, is a DNA binding protein that positively regulates alkaline stress tolerance in Arabidopsis

AbstractKey messageHere we first found that GsERF71, an ERF factor from wild soybean could increase plant alkaline stress tolerance by up-regulating H+-ATPase and by modifing the accumulation of Auxin.AbstractAlkaline soils are widely distributed all over the world and greatly limit plant growth and development. In our previous transcriptome analyses, we have identified several ERF (ethylene-responsive factor) genes that responded strongly to bicarbonate stress in the roots of wild soybean G07256 (Glycine soja). In this study, we cloned and functionally characterized one of the genes, GsERF71. When expressed in epidermal cells of onion, GsERF71 localized to the nucleus. It can activate the reporters in yeast cells, and the C-terminus of 170 amino acids is essential for its transactivation activity. Yeast one-hybrid and EMSA assays indicated that GsERF71 specifically binds to the cis-acting elements of the GCC-box, suggesting that GsERF71 may participate in the regulation of transcription of the relevant biotic and abiotic stress-related genes. Furthermore, transgenic Arabidopsis plants overexpressing GsERF71 showed significantly higher tolerance to bicarbonate stress generated by NaHCO3 or KHCO3 than the wild type (WT) plants, i.e., the transgenic plants had greener leaves, longer roots, higher total chlorophyll contents and lower MDA contents. qRT-PCR and rhizosphere acidification assays indicated that the expression level and activity of H+-ATPase (AHA2) were enhanced in the transgenic plants under alkaline stress. Further analysis indicated that the expression of auxin biosynthetic genes and IAA contents were altered to a lower extent in the roots of transgenic plants than WT plants under alkaline stress in a short-term. Together, our data suggest that GsERF71 enhances the tolerance to alkaline stress by up-regulating the expression levels of H+-ATPase and by modifying auxin accumulation in transgenic plants.

A novel hybrid proline-rich type gene GsEARLI17 from Glycine soja participated in leaf cuticle synthesis and plant tolerance to salt and alkali stresses

Recent discoveries showed that hybrid proline rich type proteins were involved in plant responses to several environmental stresses. However, little is known about their roles in plant alkali stress adaptation, especially in wild soybean. Here, we isolated and characterized GsEARLI17, a novel the hybrid proline-rich protein type EARLI family gene from Glycine soja. Bioinformatic analysis showed that GsEARLI17 protein contained a conserved N-terminus hybrid proline-rich domain in and a C-terminus 8CM domain. Transcript abundance of GsEARLI17 was higher in young tissues than that in old tissues, and induced following exposure to salt and alkali treatments. GsEARLI17 overexpression in Arabidopsis influenced cuticles formation, as evidenced by thicker cuticles of transgenic lines, and enhanced plant tolerance to salt stress. Further observation was found that compared to the wild type Arabidopsis, overexpression of GsEARLI17 in Arabidopsis improved seed germination with higher leaf opening and greening rate during the early stages under alkali stress. GsEARLI17 exhibited enhanced alkaline tolerance with higher chlorophyll content, and lower malondialdehyde content at the adult developmental stage, and the expression levels of some alkali stress response marker genes NADP-ME, H+Ppase were higher in the GsEARLI17 overexpression lines than in wild-type plants. Taken together we suggest that GsEARLI17 reveal a positive role in enhancing plant tolerance of alkali stress in Arabidopsis.

GsSLAH3, a Glycine soja slow type anion channel homolog, positively modulates plant bicarbonate stress tolerance

Alkaline stress is a major form of abiotic stress that severely inhibits plant growth and development, thus restricting crop productivity. However, little is known about how plants respond to alkali. In this study, a slow-type anion channel homolog 3 gene, GsSLAH3, was isolated and functionally characterized. Bioinformatics analysis showed that the GsSLAH3 protein contains 10 transmembrane helices. Consistently, GsSLAH3 was found to locate on plasma membrane by transient expression in onion epidermal cells. In wild soybeans, GsSLAH3 expression was induced by NaHCO3 treatment, suggesting its involvement in plant response to alkaline stress. Ectopic expression of GsSLAH3 in yeast increased sensitivity to alkali treatment. Dramatically, overexpression of GsSLAH3 in Arabidopsis thaliana enhanced alkaline tolerance during the germination, seedling and adult stages. More interestingly, we found that transgenic lines also improved plant tolerance to KHCO3 rather than high pH treatment. A nitrate content analysis of Arabidopsis shoots showed that GsSLAH3 overexpressing lines accumulated more NO3- than wild-type. In summary, our data suggest that GsSLAH3 is a positive alkali responsive gene that increases bicarbonate resistance specifically.

A potential efflux boron transporter gene GsBOR2, positively regulates Arabidopsis bicarbonate tolerance

Soil alkalization severely restricts agricultural production and economic development worldwide, this problem is far more serious in Songnen Plain, the largest commodity grain base of China. However, little research has been done concerning the mechanisms of plant responses to alkaline stress to date. In this study, we isolated an alkali inducible gene GsBOR2 from Glycine soja on the basis of RNA seq data. GsBOR2 sh high protein sequence similarity with the known boron transporters in other species. The expression of GsBOR2 was highly up-regulated by 50 mM NaHCO3 treatment and displayed tissue specificity. We then generated the transgenic Arabidopsis overexpressing GsBOR2 and found that the transgenic lines exhibited enhanced alkaline tolerance compared to wild type plants, as illustrated by longer roots and greater shoot biomass. Moreover, GsBOR2 overexpression was also capable of increasing plant resistance to KHCO3 treatment but not to high-pH stress. Functional complementation of Scbor1 mutant yeasts suggested that GsBOR2 could likely mediate the efflux of boron from cells. Taken together, the alkali responsive gene GsBOR2 is a positive regulator of plant bicarbonate tolerance.

Genome-Wide Analysis of Glycine soja Response Regulator GsRR Genes Under Alkali and Salt Stresses

Soil salt-alkalization is a dramatic challenging factor for plant growth. Wild soybean (Glycine soja) exhibits a favorable trait of superior tolerance to salt-alkali stress, and recent discoveries show that response regulator family genes are involved in diverse abiotic stresses. Genomic and transcriptomic analyses of all response regulator genes in wild soybean will provide insight into their function in plant stress response. In this study, we identified and characterized a total of 56 Glycine soja response regulator (GsRR) genes. Phylogenetic analysis suggested that GsRR genes could be classified into five subclasses (A1, A2, B1, B2, and C). We further investigated the chromosome locations, gene duplications and conserved domains of the GsRRs. Furthermore, the clustering analysis of GsRR transcript profiles revealed five different expression patterns under alkali stress. The A1 and A2 subclasses display significantly higher transcriptional levels than the B subclass. In addition, quantitative real-time PCR results verified that the GsRR genes were also significantly influenced by salt stress. Notably, GsRR2a in the A1 subclass showed opposite expression patterns under salt stress comparing with alkali stress. Moreover, overexpression of GsRR2a in Arabidopsis significantly improved the tolerance to alkali stress, but not salt stress. These results suggest the important roles of GsRR genes in response to salt and alkaline stresses, and also provide valuable clues for further functional characterization of GsRR family genes.

Additional file 2: Figure S3. of A novel Glycine soja homeodomain-leucine zipper (HD-Zip) I gene, Gshdz4, positively regulates bicarbonate tolerance and responds to osmotic stress in Arabidopsis

No difference in growth between the overexpression lines and WT plants in the normal condition. (TIF 3134 kb)