Xylem ion balance in tomato plants under alkali stress

Abstract In many areas of China, alkalinity (high pH) had strongly limit crops productivity. Control of ion loading into the xylem has been repeatedly named as a crucial factor determining plant salt tolerance. To investigate the role of roots in alkali tolerance of tomato, we tested the ion balance in root xylem of alkali stressed tomato plants. Two alkaline salts (NaHCO 3 and Na 2 CO 3 ) were mixed in a 9:1 molar ratio as the alkali stress treatments. Under alkali stress condition or control condition, xylem sap samples were collected by cutting plant stems near to cotyledon vestige, and then all mineral elements in excreted xylem sap were measured. The results showed that alkali stress decreased the concentrations of K ; however, under both stresses ion concentrations in the xylem sap were similar, indicating that the uptakes of inorganic ions were inhibited by high-pH but not by Na +

Comparison of Ion Balance and Nitrogen Metabolism in Old and Young Leaves of Alkali-Stressed Rice Plants

BACKGROUND: Alkali stress is an important agricultural contaminant and has complex effects on plant metabolism. The aim of this study was to investigate whether the alkali stress has different effects on the growth, ion balance, and nitrogen metabolism in old and young leaves of rice plants, and to compare functions of both organs in alkali tolerance. METHODOLOGY/PRINCIPAL FINDINGS: The results showed that alkali stress only produced a small effect on the growth of young leaves, whereas strongly damaged old leaves. Rice protected young leaves from ion harm via the large accumulation of Na(+) and Cl(-) in old leaves. The up-regulation of OsHKT1;1, OsAKT1, OsHAK1, OsHAK7, OsHAK10 and OsHAK16 may contribute to the larger accumulation of Na(+) in old leaves under alkali stress. Alkali stress mightily reduced the NO(3)(-) contents in both organs. As old leaf cells have larger vacuole, under alkali stress these scarce NO(3)(-) was principally stored in old leaves. Accordingly, the expression of OsNRT1;1 and OsNRT1;2 in old leaves was up-regulated by alkali stress, revealing that the two genes might contribute to the accumulation of NO(3)(-) in old leaves. NO(3)(-) deficiency in young leaves under alkali stress might induce the reduction in OsNR1 expression and the subsequent lacking of NH(4)(+), which might be main reason for the larger down-regulation of OsFd-GOGAT and OsGS2 in young leaves. CONCLUSIONS/SIGNIFICANCE: Our results strongly indicated that, during adaptation of rice to alkali stress, young and old leaves have distinct mechanisms of ion balance and nitrogen metabolism regulation. We propose that the comparative studies of young and old tissues may be important for abiotic stress tolerance research

A newly formed hexaploid wheat exhibits immediate higher tolerance to nitrogen-deficiency than its parental lines

Abstract Background It is known that hexaploid common wheat (Triticum aestivum L.) has stronger adaptability to many stressful environments than its tetraploid wheat progenitor. However, the physiological basis and evolutionary course to acquire these enhanced adaptabilities by common wheat remain understudied. Here, we aimed to investigate whether and by what means tolerance to low-nitrogen manifested by common wheat may emerge immediately following allohexaploidization. Results We compared traits related to nitrogen (N) metabolism in a synthetic allohexaploid wheat (neo-6×, BBAADD) mimicking natural common wheat, together with its tetraploid (BBAA, 4×) and diploid (DD, 2×) parents. We found that, under low nitrogen condition, neo-6× maintained largely normal photosynthesis, higher shoot N accumulation, and better N assimilation than its 4× and 2× parents. We showed that multiple mechanisms underlie the enhanced tolerance to N-deficiency in neo-6×. At morphological level, neo-6× has higher root/shoot ratio of biomass than its parents, which might be an adaptive growth strategy as more roots feed less shoots with N, thereby enabling higher N accumulation in the shoots. At electrophysiological level, H+ efflux in neo-6× is higher than in its 4× parent. A stronger H+ efflux may enable a higher N uptake capacity of neo-6×. At gene expression level, neo-6× displayed markedly higher expression levels of critical genes involved in N uptake than both of its 4× and 2× parents. Conclusions This study documents that allohexaploid wheat can attain immediate higher tolerance to N-deficiency compared with both of its 4× and 2× parents, and which was accomplished via multiple mechanisms

Efficient learning-based blur removal method based on sparse optimization for image restoration.

In imaging systems, image blurs are a major source of degradation. This paper proposes a parameter estimation technique for linear motion blur, defocus blur, and atmospheric turbulence blur, and a nonlinear deconvolution algorithm based on sparse representation. Most blur removal techniques use image priors to estimate the point spread function (PSF); however, many common forms of image priors are unable to exploit local image information fully. In this paper, the proposed method does not require models of image priors. Further, it is capable of estimating the PSF accurately from a single input image. First, a blur feature in the image gradient domain is introduced, which has a positive correlation with the degree of blur. Next, the parameters for each blur type are estimated by a learning-based method using a general regression neural network. Finally, image restoration is performed using a half-quadratic optimization algorithm. Evaluation tests confirmed that the proposed method outperforms other similar methods and is suitable for dealing with motion blur in real-life applications

Legislative Documents

Also, variously referred to as: House bills; House documents; House legislative documents; legislative documents; General Court documents

Legislative Documents

Also, variously referred to as: House bills; House documents; House legislative documents; legislative documents; General Court documents

Legislative Documents

Also, variously referred to as: House bills; House documents; House legislative documents; legislative documents; General Court documents

Rapid and pervasive development- and tissue-specific homeolog expression partitioning in newly formed inter-subspecific rice segmental allotetraploids

Abstract Background In diverse plant taxa, whole-genome duplication (WGD) events are major sources of phenotypic novelty. Studies of gene expression in synthetic polyploids have shown immediate expression and functional partitioning of duplicated genes among different tissues. Many studies of the tissue-specific homeolog expression partitioning have focused on allopolyploids that have very different parental genomes, while few studies have focused on autopolyploids or allopolyploids that have similar parental genomes. Results In this study, we used a set of reciprocal F1 hybrids and synthetic tetraploids constructed from subspecies (japonica and indica) of Asian rice (Oryza sativa L.) as a model to gain insights into the expression partitioning of homeologs among tissues in a developmental context. We assayed the tissue-specific silencing (TSS) of the parental homeologs of 30 key genes in the hybrids and tetraploids relative to the in vitro “hybrids” (parental mixes) using Sequenom MassARRAY. We found that the parental mix and synthetic tetraploids had higher frequencies of homeolog TSS than the F1, revealing an instantaneous role of WGD on homeolog expression partitioning. Conclusions Our observations contradicted those of previous studies in which newly formed allopolyploids had a low TSS frequency, similar to that of F1 hybrids, suggesting that the impact of WGD on homeolog expression requires a longer time to manifest. In addition, we found that the TSS frequency in the tetraploids varied at different growth stages and that roots had a much higher frequency of TSS than leaves, which indicated that developmental and metabolic traits may influence the expression states of duplicated genes in newly formed plant polyploids

Transcriptomic Profiling and Physiological Responses of Halophyte Kochia sieversiana Provide Insights into Salt Tolerance

Halophytes are remarkable plants that can tolerate extremely high-salinity conditions, and have different salinity tolerance mechanisms from those of glycophytic plants. In this work, we investigated the mechanisms of salinity tolerance of an extreme halophyte, Kochia sieversiana (Pall.) C. A. M, using RNA sequencing and physiological tests. The results showed that moderate salinity stimulated the growth and water uptake of K. sieversiana and, even under 480-mM salinity condition, K. sieversiana maintained an extremely high water content. This high water content may be a specific adaptive strategy of K. sieversiana to high salinity. The physiological analysis indicated that increasing succulence and great accumulations of sodium, alanine, sucrose, and maltose may be favorable to the water uptake and osmotic regulation of K. sieversiana under high-salinity stress. Transcriptome data indicated that some aquaporin genes and potassium (K+) transporter genes may be important for water uptake and ion balance, respectively, while different members of those gene families were employed under low- and high-salinity stresses. In addition, several aquaporin genes were up-regulated in low- but not high-salinity stressed roots. The highly expressed aquaporin genes may allow low-salinity stressed K. sieversiana plants to uptake more water than control plants. The leaf K+/root K+ ratio was enhanced under low- but not high-salinity stress, which suggested that low salinity might promote K+ transport from the roots to the shoots. Hence, we speculated that low salinity might allow K. sieversiana to uptake more water and transport more K+ from roots to shoots, increasing the growth rate of K. sieversiana