scholarly journals (139) A Capacity for Mannitol Biosynthesis is a Critical Component of Salt Tolerance in Celery

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1057B-1057
Author(s):  
Wayne H. Loescher ◽  
Paolo Sabbatini ◽  
Guo-Qing Song ◽  
Kenneth Sink ◽  
James Flore

Mannitol, a sugar alcohol that appears to serve as an osmoprotectant/compatible solute to cope with salt stress, is synthesized in celery (Apium graveolens L.) via the action of a NADPH dependent mannose-6-phosphate reductase (M6PR). To evaluate the abiotic stress effects of mannitol biosynthesis, we transformed celery with an antisense construct of the celery leaf M6PR gene under control of the CaMV 35S promoter. Unlike wild type (WT) celery, independent antisense M6PR transformants did not accumulate significant amounts of mannitol in any tissue, with or without salt stress. In the absence of NaCl, and despite the lack of any significant accumulation of mannitol that is normally the major photosynthetic product, antisense transformants were mostly phenotypically similar to the WT celery. However, in the presence of NaCl, mature antisense transgenic plants were significantly less salt-tolerant, with reduced growth and photosynthetic rates, and some transformant lines were killed at 200 mM NaCl, a concentration that WT celery can normally withstand. Although mannitol biosynthesis is normally enhanced in salt-treated WT celery, no such increase was observed in the antisense transformants. Like our previous gain of function results showing enhanced salt tolerance in Arabidopsis plants transgenic for a sense M6PR construct, these loss of function results, using an antisense construct in celery, demonstrate a major role for mannitol biosynthesis in developing salt-tolerant plants.

2020 ◽  
Vol 71 (18) ◽  
pp. 5589-5602
Author(s):  
Shasha Liu ◽  
Rui Yang ◽  
Miao Liu ◽  
Shizhong Zhang ◽  
Kang Yan ◽  
...  

Abstract Although the salt overly sensitive (SOS) pathway plays essential roles in conferring salt tolerance in Arabidopsis thaliana, the regulatory mechanism underlying SOS gene expression remains largely unclear. In this study, AtPLATZ2 was found to function as a direct transcriptional suppressor of CBL4/SOS3 and CBL10/SCaBP8 in the Arabidopsis salt stress response. Compared with wild-type plants, transgenic plants constitutively overexpressing AtPLATZ2 exhibited increased sensitivity to salt stress. Loss of function of PLATZ2 had no observed salt stress phenotype in Arabidopsis, while the double mutant of PLATZ2 and PLATZ7 led to weaker salt stress tolerance than wild-type plants. Overexpression of AtPLATZ2 in transgenic plants decreased the expression of CBL4/SOS3 and CBL10/SCaBP8 under both normal and saline conditions. AtPLATZ2 directly bound to A/T-rich sequences in the CBL4/SOS3 and CBL10/SCaBP8 promoters in vitro and in vivo, and inhibited CBL4/SOS3 promoter activity in the plant leaves. The salt sensitivity of #11 plants constitutively overexpressing AtPLATZ2 was restored by the overexpression of CBL4/SOS3 and CBL10/SCaBP8. Salt stress-induced Na+ accumulation in both the shoots and roots was more exaggerated in AtPLATZ2-overexpressing plants than in the wild type. The salt stress-induced Na+ accumulation in #11 seedlings was also rescued by the overexpression of CBL4/SOS3 and CBL10/SCaBP8. Furthermore, the transcription of AtPLATZ2 was induced in response to salt stress. Collectively, these results suggest that AtPLATZ2 suppresses plant salt tolerance by directly inhibiting CBL4/SOS3 and CBL10/SCaBP8, and functions redundantly with PLATZ7.


HortScience ◽  
1997 ◽  
Vol 32 (2) ◽  
pp. 296-300 ◽  
Author(s):  
M.R. Foolad ◽  
G.Y. Lin

Seed of 42 wild accessions (Plant Introductions) of Lycopersicon pimpinellifolium Jusl., 11 cultigens (cultivated accessions) of L. esculentum Mill., and three control genotypes [LA716 (a salt-tolerant wild accession of L. pennellii Corr.), PI 174263 (a salt-tolerant cultigen), and UCT5 (a salt-sensitive breeding line)] were evaluated for germination in either 0 mm (control) or 100 mm synthetic sea salt (SSS, Na+/Ca2+ molar ratio equal to 5). Germination time increased in response to salt-stress in all genotypes, however, genotypic variation was observed. One accession of L. pimpinellifolium, LA1578, germinated as rapidly as LA716, and both germinated more rapidly than any other genotype under salt-stress. Ten accessions of L. pimpinellifolium germinated more rapidly than PI 174263 and 35 accessions germinated more rapidly than UCT5 under salt-stress. The results indicate a strong genetic potential for salt tolerance during germination within L. pimpinellifolium. Across genotypes, germination under salt-stress was positively correlated (r = 0.62, P < 0.01) with germination in the control treatment. The stability of germination response at diverse salt-stress levels was determined by evaluating germination of a subset of wild, cultivated accessions and the three control genotypes at 75, 150, and 200 mm SSS. Seeds that germinated rapidly at 75 mm also germinated rapidly at 150 mm salt. A strong correlation (r = 0.90, P < 0.01) existed between the speed of germination at these two salt-stress levels. At 200 mm salt, most accessions (76%) did not reach 50% germination by 38 days, demonstrating limited genetic potential within Lycopersicon for salt tolerance during germination at this high salinity.


2020 ◽  
Author(s):  
Jingjing Wang ◽  
Cong An ◽  
Hailin Guo ◽  
Xiangyang Yang ◽  
Jingbo Chen ◽  
...  

Abstract Background: Areas with saline soils are sparsely populated and have fragile ecosystems, which severely restricts the sustainable development of local economies. Zoysia grasses are recognized as excellent warm-season turfgrasses worldwide, with high salt tolerance and superior growth in saline-alkali soils. However, the mechanism underlying the salt tolerance of Zoysia species remains unknown. Results: The phenotypic and physiological responses of two contrasting materials, Zoysia japonica Steud. Z004 (salt sensitive) and Z011 (salt tolerant) in response to salt stress were studied. The results show that Z011 was more salt tolerant than was Z004, with the former presenting greater K+/Na+ ratios in both its leaves and roots. To study the molecular mechanisms underlying salt tolerance further, we compared the transcriptomes of the two materials at different time points (0 h, 1 h, 24 h, and 72 h) and from different tissues (leaves and roots) under salt treatment. The 24-h time point and the roots might make significant contributions to the salt tolerance. Moreover, GO and KEGG analyses of different comparisons revealed that the key DEGs participating in the salt-stress response belonged to the hormone pathway, various TF families and the DUF family. Conclusions: Z011 may have improved salt tolerance by reducing Na+ transport from the roots to the leaves, increasing K+ absorption in the roots and reducing K+ secretion from the leaves to maintain a significantly greater K+/Na+ ratio. Twenty-four hours might be a relatively important time point for the salt-stress response of zoysiagrass. The auxin signal transduction family, ABA signal transduction family, WRKY TF family and bHLH TF family may be the most important families in Zoysia salt-stress regulation. This study provides fundamental information concerning the salt-stress response of Zoysia and improves the understanding of molecular mechanisms in salt-tolerant plants.


2019 ◽  
Author(s):  
Wenbin Ye ◽  
Taotao Wang ◽  
Wei Wei ◽  
Shuaitong Lou ◽  
Faxiu Lan ◽  
...  

ABSTRACTSpartina alterniflora (Spartina) is the only halophyte in the salt marsh. However, the molecular basis of its high salt tolerance remains elusive. In this study, we used PacBio full-length single molecule long-read sequencing and RNA-seq to elucidate the transcriptome dynamics of high salt tolerance in Spartina by salt-gradient experiments (0, 350, 500 and 800 mM NaCl). We systematically analyzed the gene expression diversity and deciphered possible roles of ion transporters, protein kinases and photosynthesis in salt tolerance. Moreover, the co-expression network analysis revealed several hub genes in salt stress regulatory networks, including protein kinases such as SaOST1, SaCIPK10 and three SaLRRs. Furthermore, high salt stress affected the gene expression of photosynthesis through down-regulation at the transcription level and alternative splicing at the post-transcriptional level. In addition, overexpression of two Spartina salt-tolerant genes SaHSP70-I and SaAF2 in Arabidopsis significantly promoted the salt tolerance of transgenic lines. Finally, we built the SAPacBio website for visualizing the full-length transcriptome sequences, transcription factors, ncRNAs, salt-tolerant genes, and alternative splicing events in Spartina. Overall, this study sheds light on the high salt tolerance mechanisms of monocotyledonous-halophyte and demonstrates the potential of Spartina genes for engineering salt-tolerant plants.


2020 ◽  
Author(s):  
Houda Chelaifa ◽  
Manikandan Vinu ◽  
Massar Dieng ◽  
Youssef Idaghdour ◽  
Ayesha Hasan ◽  
...  

AbstractSoil salinity is an increasing threat to global food production systems. As such, there is a need for salt tolerant plant model systems in order to understand salt stress regulation and response. Salicornia bigelovii, a succulent obligatory halophyte, is one of the most salt tolerant plant species in the world. It possesses distinctive characteristics that make it a candidate plant model for studying salt stress regulation and tolerance, showing promise as an economical non-crop species that can be used for saline land remediation and for large-scale biofuel production. However, available S. bigelovii genomic and transcriptomic data are insufficient to reveal its molecular mechanism of salt tolerance. We performed transcriptome analysis of S. bigelovii flowers, roots, seeds and shoots tissues cultivated under desert conditions and irrigated with saline aquaculture effluent. We identified a unique set of tissue specific transcripts present in this non-model crop. A total of 66,943 transcripts (72.63%) were successfully annotated through the GO database with 18,321 transcripts (27.38%) having no matches to known transcripts. Excluding non-plant transcripts, differential expression analysis of 49,914 annotated transcripts revealed differentially expressed transcripts (DETs) between the four tissues and identified shoots and flowers as the most transcriptionally similar tissues relative to roots and seeds. The DETs between above and below ground tissues, with the exclusion of seeds, were primarily involved in osmotic regulation and ion transportation. We identified DETs between shoots and roots implicated in salt tolerance including SbSOS1, SbNHX, SbHKT6 upregulated in shoots relative to roots, while aquaporins (AQPs) were up regulated in roots. We also noted that DETs implicated in osmolyte regulation exhibit a different profile among shoots and roots. Our study provides the first report of a highly upregulated HKT6 from S. bigelovii shoot tissue. Furthermore, we identified two BADH transcripts with divergent sequence and tissue specific expression pattern. Overall, expression of the ion transport transcripts suggests Na+ accumulation in S. bigelovii shoots. Our data led to novel insights into transcriptional regulation across the four tissues and identified a core set of salt stress-related transcripts in S. bigelovii.


2018 ◽  
Author(s):  
Reza Shokri-Gharelo ◽  
Pouya Motie-Noparvar

Canola (Brassica napus L.) is widely cultivated around the world for the production of edible oils and biodiesel fuel. Despite many canola varieties being described as ‘salt-tolerant’, plant yield and growth decline drastically with increasing salinity. Although many studies have resulted in better understanding of the many important salt-response mechanisms that control salt signaling in plants, detoxification of ions, and synthesis of protective metabolites, the engineering of salt-tolerant crops has only progressed slowly. Genetic engineering has been considered as an efficient method for improving the salt tolerance of canola but there are many unknown or little-known aspects regarding canola response to salinity stress at the cellular and molecular level. In order to develop highly salt-tolerant canola, it is essential to improve knowledge of the salt-tolerance mechanisms, especially the key components of the plant salt-response network. In this review, we focus on studies of the molecular response of canola to salinity to unravel the different pieces of the salt response puzzle. The paper includes a comprehensive review of the latest studies, particularly of proteomic and transcriptomic analysis, including the most recently identified canola tolerance components under salt stress, and suggests where researchers should focus future studies.


2020 ◽  
Vol 8 (10) ◽  
pp. 1565 ◽  
Author(s):  
Abraham Mulu Oljira ◽  
Tabassum Hussain ◽  
Tatoba R. Waghmode ◽  
Huicheng Zhao ◽  
Hongyong Sun ◽  
...  

Soil salinity is one of the most important abiotic stresses limiting plant growth and productivity. The breeding of salt-tolerant wheat cultivars has substantially relieved the adverse effects of salt stress. Complementing these cultivars with growth-promoting microbes has the potential to stimulate and further enhance their salt tolerance. In this study, two fungal isolates, Th4 and Th6, and one bacterial isolate, C7, were isolated. The phylogenetic analyses suggested that these isolates were closely related to Trichoderma yunnanense, Trichoderma afroharzianum, and Bacillus licheniformis, respectively. These isolates produced indole-3-acetic acid (IAA) under salt stress (200 mM). The abilities of these isolates to enhance salt tolerance were investigated by seed coatings on salt-sensitive and salt-tolerant wheat cultivars. Salt stress (S), cultivar (C), and microbial treatment (M) significantly affected water use efficiency. The interaction effect of M x S significantly correlated with all photosynthetic parameters investigated. Treatments with Trichoderma isolates enhanced net photosynthesis, water use efficiency and biomass production. Principal component analysis revealed that the influences of microbial isolates on the photosynthetic parameters of the different wheat cultivars differed substantially. This study illustrated that Trichoderma isolates enhance the growth of wheat under salt stress and demonstrated the potential of using these isolates as plant biostimulants.


2018 ◽  
Vol 19 (10) ◽  
pp. 3108 ◽  
Author(s):  
Hongxia Miao ◽  
Peiguang Sun ◽  
Juhua Liu ◽  
Jingyi Wang ◽  
Biyu Xu ◽  
...  

Rho-like GTPases from plants (ROPs) are plant-specific molecular switches that are crucial for plant survival when subjected to abiotic stress. We identified and characterized 17 novel ROP proteins from Musa acuminata (MaROPs) using genomic techniques. The identified MaROPs fell into three of the four previously described ROP groups (Groups II–IV), with MaROPs in each group having similar genetic structures and conserved motifs. Our transcriptomic analysis showed that the two banana genotypes tested, Fen Jiao and BaXi Jiao, had similar responses to abiotic stress: Six genes (MaROP-3b, -5a, -5c, -5f, -5g, and -6) were highly expressed in response to cold, salt, and drought stress conditions in both genotypes. Of these, MaROP5g was most highly expressed in response to salt stress. Co-localization experiments showed that the MaROP5g protein was localized at the plasma membrane. When subjected to salt stress, transgenic Arabidopsis thaliana overexpressing MaROP5g had longer primary roots and increased survival rates compared to wild-type A. thaliana. The increased salt tolerance conferred by MaROP5g might be related to reduced membrane injury and the increased cytosolic K+/Na+ ratio and Ca2+ concentration in the transgenic plants as compared to wild-type. The increased expression of salt overly sensitive (SOS)-pathway genes and calcium-signaling pathway genes in MaROP5g-overexpressing A. thaliana reflected the enhanced tolerance to salt stress by the transgenic lines in comparison to wild-type. Collectively, our results suggested that abiotic stress tolerance in banana plants might be regulated by multiple MaROPs, and that MaROP5g might enhance salt tolerance by increasing root length, improving membrane injury and ion distribution.


Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 569
Author(s):  
Annick Bertrand ◽  
Craig Gatzke ◽  
Marie Bipfubusa ◽  
Vicky Lévesque ◽  
Francois P. Chalifour ◽  
...  

Alfalfa and its rhizobial symbiont are sensitive to salinity. We compared the physiological responses of alfalfa populations inoculated with a salt-tolerant rhizobium strain, exposed to five NaCl concentrations (0, 20, 40, 80, or 160 mM NaCl). Two initial cultivars, Halo (H-TS0) and Bridgeview (B-TS0), and two populations obtained after three cycles of recurrent selection for salt tolerance (H-TS3 and B-TS3) were compared. Biomass, relative water content, carbohydrates, and amino acids concentrations in leaves and nodules were measured. The higher yield of TS3-populations than initial cultivars under salt stress showed the effectiveness of our selection method to improve salinity tolerance. Higher relative root water content in TS3 populations suggests that root osmotic adjustment is one of the mechanisms of salt tolerance. Higher concentrations of sucrose, pinitol, and amino acid in leaves and nodules under salt stress contributed to the osmotic adjustment in alfalfa. Cultivars differed in their response to recurrent selection: under a 160 mM NaCl-stress, aromatic amino acids and branched-chain amino acids (BCAAs) increased in nodules of B-ST3 as compared with B-TS0, while these accumulations were not observed in H-TS3. BCAAs are known to control bacteroid development and their accumulation under severe stress could have contributed to the high nodulation of B-TS3.


Plants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 287 ◽  
Author(s):  
Ibrahim Al-Ashkar ◽  
Ali Alderfasi ◽  
Walid Ben Romdhane ◽  
Mahmoud F. Seleiman ◽  
Rania A. El-Said ◽  
...  

Salinity is a major obstacle to wheat production worldwide. Salt-affected soils could be used by improving salt-tolerant genotypes depending upon the genetic variation and salt stress response of adapted and donor wheat germplasm. We used a comprehensive set of morpho-physiological and biochemical parameters and simple sequence repeat (SSR) marker technique with multivariate analysis to accurately demonstrate the phenotypic and genetic variation of 18 wheat genotypes under salinity stress. All genotypes were evaluated without NaCl as a control and with 150 mM NaCl, until the onset of symptoms of death in the sensitive plant (after 43 days of salinity treatment). The results showed that the relative change of the genetic variation was high for all parameters, heritability (>60%), and genetic gain (>20%). Stepwise regression analysis, noting the importance of the root dry matter, relative turgidity, and their respective contributions to the shoot dry matter, indicated their relevance in improving and evaluating the salt-tolerant genotypes of breeding programs. The relative change of the genotypes in terms of the relative turgidity and shoot dry matter during salt stress was verified using clustering methods. For cluster analysis, the genotypes were classified into three groups: tolerant, intermediate, and sensitive, representing five, six, and seven genotypes, respectively. The morphological and genetic distances were significantly correlated based on the Mantel test. Of the 23 SSR markers that showed polymorphism, 17 were associated with almost all examined parameters. Therefore, based on the observed molecular marker-phenotypic trait association, the markers were highly useful in detecting tolerant and sensitive genotypes. Thus, it considers a helpful tool for salt tolerance through marker-assisted selection.


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