生物炭调控盐胁迫下水稻幼苗耐盐性能

土壤盐渍化降低土壤生产力.探索生物炭对盐胁迫下水稻幼苗耐盐性能的影响,对调控盐渍区水稻生产潜力具有重要意义.本研究通过生物炭介入盐胁迫稻田土壤的盆栽试验,调查了生物炭对盐胁迫下土壤环境和水稻幼苗耐盐性能的影响.盐胁迫设置4个水平,分别为0 g NaCl·kg-1土(S0),1 g NaCl·kg-1土(S1),2 g ...     

Expression of a calcineurin gene improves salt stress tolerance in transgenic rice

Calcineurin is a Ca²⁺- and calmodulin-dependent serine/threonine phosphatase and has multiple functions in animal cells including regulating ionic homeostasis. We generated transgenic rice plants that not only expressed a truncated form of the catalytic subunit of mouse calcineurin, but also were able to grow and fertilize normally in the field. Notably, the expression of the mouse calcineurin gene in rice resulted in its higher salt stress tolerance than the non-transgenic rice. Physiological studies have indicated that the root growth of transgenic plants was less inhibited than the shoot growth, and that less Na⁺ was accumulated in the roots of transgenic plants after a prolonged period of salt stress. These findings imply that the heterologous calcineurin plays a significant role in maintaining ionic homeostasis and the integrity of plant roots when exposed to salt. In addition, the calcineurin gene expression in the stems of transgenic plants correlated with the increased expression of the Rab16A gene that encodes a group 2-type late-embryogenesis-abundant (LEA) protein. Altogether our findings provide the first genetic and physiological evidence that expression of the mouse calcineurin protein functionally improves the salt stress tolerance of rice partly by limiting Na⁺ accumulation in the roots.     

Silencing of the SlZF-31 gene decreases the salt stress tolerance and drought tolerance of tomato

Plant Cell, Tissue and Organ Culture (PCTOC) - Sceletium tortuosum is a South African protected species with tremendous value in traditional and modern medicine. The plants’ mesembrine-type...     

Enhanced tolerance to salt stress in transgenic rice that overexpresses chloroplast glutamine synthetase

The potential role of photorespiration in the protection against salt stress was examined with transgenic rice plants. Oryza sativa L. cv. Kinuhikari was transformed with a chloroplastic glutamine synthetase (GS2) gene from rice. Each transgenic rice plant line showed a different accumulation level of GS2. A transgenic plant line, G39-2, which accumulated about 1.5-fold more GS2 than the control plant, had an increased photorespiration capacity. In another line, G241-12, GS2 was almost lost and photorespiration activity could not be detected. Fluorescence quenching analysis revealed that photorespiration could prevent the over-reduction of electron transport systems. When exposed to 150 mM NaCl for 2 weeks, the control rice plants completely lost photosystem II activity, but G39-2 plants retained more than 90% activity after the 2-week treatment, whereas G241-12 plants lost these activities within one week. In the presence of isonicotinic acid hydrazide, an inhibitor of photorespiration, G39-2 showed the same salt tolerance as the control plants. The intracellular contents of NH₄ ⁺ and Na⁺ in the stressed plants correlated well with the levels of GS2. Thus, the enhancement of photorespiration conferred resistance to salt in rice plants. Preliminary results suggest chilling tolerance in the transformant.     

Cytoskeleton and plant salt stress tolerance

The plant cytoskeleton is a highly dynamic component of plant cells and mainly based on microtubules (MTs) and actin filaments (AFs). The important functions of dynamic cytoskeletal networks have been indicated for almost every intracellular activity, from cell division to cell movement, cell morphogenesis and cell signal transduction. Recent studies have also indicated a close relationship between the plant cytoskeleton and plant salt stress tolerance. Salt stress is a significant factor that adversely affects crop productivity and quality of agricultural fields worldwide. The complicated regulatory mechanisms of plant salt tolerance have been the subject of intense research for decades. It is well accepted that cellular changes are very important in plant responses to salt stress. Because the organization and dynamics of cytoskeleton may play an important role in enhancing plant tolerance through various cell activities, study on salt stress-induced cytoskeletal network has been a vital topic in the subject of plant salt stress tolerance mechanisms. In this article, we introduce our recent work and review some current information on the dynamic changes and functions of cytoskeletal organization in response to salt stress. The accumulated data point to the existence of highly dynamic cytoskeletal arrays and the activation of complex cytoskeletal regulatory networks in response to salt stresses. The important role played by cytoskeleton in mediating the plant cell''s response to salt stresses is particularly emphasized.Key words: cytoskeleton, microtubules (MTs), microfilaments (MFs), salt stress, response mechanisms, plant tolerance     

OsMPK4 promotes phosphorylation and degradation of IPA1 in response to salt stress to confer salt tolerance in rice

Salt stress adversely affects plant growth, development, and crop yield. Rice (Oryza sativa L.) is one of the most salt-sensitive cereal crops, especially at the early seedling stage. Mitogen-activated protein kinase (MAPK/MPK) cascades have been shown to play critical roles in salt response in Arabidopsis. However, the roles of the MPK cascade signaling in rice salt response and substrates of OsMPK remain largely unknown. Here, we report that the salt-induced OsMPK4-Ideal Plant Architecture 1 (IPA1) signaling pathway regulates the salt tolerance in rice. Under salt stress, OsMPK4 could interact with IPA1 and phosphorylate IPA1 at Thr180, leading to degradation of IPA1. Genetic evidence shows that IPA1 is a negative regulator of salt tolerance in rice, whereas OsMPK4 promotes salt response in an IPA1-dependent manner. Taken together, our results uncover an OsMPK4-IPA1 signal cascade that modulates the salt stress response in rice and sheds new light on the breeding of salt-tolerant rice varieties.     

Photosynthesis in rice under a salt stress

In four cultivars of Oryza sativa L., a gradual decrease in the activity of photosystems 1 and 2 as well as in chlorophyll (Chl) fluorescence transients and emission at 688 nm was observed with an increase in NaCl concentration. This decrease was more pronounced in salt-sensitive cultivars as compared to the tolerant ones. A drastic decrease in net photosynthetic rate was found in both cultivar types.     

Photosynthesis in rice under a salt stress

In four cultivars of Oryza sativa L., a gradual decrease in the activity of photosystems 1 and 2 as well as in chlorophyll (Chl) fluorescence transients and emission at 688 nm was observed with an increase in NaCl concentration. This decrease was more pronounced in salt-sensitive cultivars as compared to the tolerant ones. A drastic decrease in net photosynthetic rate was found in both cultivar types. This revised version was published online in June 2006 with corrections to the Cover Date.     

RFLP tagging of a salt tolerance gene in rice

A salt tolerant rice mutant (M-20) was obtained through selection in vitro. Its tolerance was stably inherited over eight generations and most traints between M-20 and its sensitive original 77–170 (Oryza sativa) were very similar. By deriving an F₂ population of M-20 × 77–170 and splitting every F₂ individual into two parts, with one part planted in normal conditions and another part in saline conditions, the inheritance of salt tolerance in rice was studied. Under normal conditions, there was no apparent segregation among F₂ individuals. Under saline conditions, however, the segregation of traits was obvious. According to our standards, the ratio of salt sensitive:moderately-tolerant:tolerant plants was 25:42:18, in accordance with a 1:2:1 ratio. It suggested that the improvement of salt tolerance in our materials was induced by the mutation of a major tolerant gene which showed incomplete dominance. By use of 130 RFLP probes distributed throughout the rice genome, the gene was tagged by a single copy DNA probe, RG4, which was located on chromosome 7. The genetic distance between the salt tolerant gene and RG4 was 7.0 ± 2.9 cM. Based on the split method, a method which could be currently used to evaluate the damage of salt stress in rice was proposed.     

Polyamines as modulators of salt tolerance in rice cultivars

The effect of NaCl on the endogenous levels of diamine, putrescine and polyamines, spermidine and spermine, was studied in the shoot system of salt-tolerant and salt-sensitive lines of rice (Oryza sativa L.) cultivars during three growth stages. Salt stress increased the levels of diamine and polyamine in varying degrees among nine rice cultivars investigated. Salt tolerant AU1, Co43, and CSC1 were effective in maintaining high concentrations of spermidine and spermine, while the content of putrescine was not significantly altered in all the growth stages when plants were exposed to salinity. The salt sensitivity in rice was associated with excessive accumulation of putrescine and with low levels of spermidine and spermine in the shoot system of salt-sensitive cultivars Co36, CSC2, GR3, IR20, TKM4, and TKM9 under saline condition. One of the possible mechanisms of saline resistance was observed to be due to the highly increased polyamines against the low increase in diamines. Alternatively, the salt sensitivity could be due to high increase of diamines and an incapacity to maintain high levels of polyamines.     

A novel stress-associated protein SbSAP14 from Sorghum bicolor confers tolerance to salt stress in transgenic rice

We have characterized a member of the stress-associated protein (SAP) gene family from Sorghum bicolor (SbSAP14) with A20 and AN1 zinc-finger domains. Expression profiling revealed that SbSAP14 is specifically induced in response to dehydration, salt, and oxidative stress as well as abscisic acid treatment. During the early stage of salt stress, overexpression of SbSAP14 was able to prevent yellowing and withering of the leaf tip of rice plants. Measurements of malondialdehyde, ion leakage, and chlorophyll content demonstrated that transgenic rice had an enhanced tolerance to oxidative damage caused by salt stress. Under prolonged salt stress, transgenic rice plants had a higher seed germination rate and higher percentage seedling survival than wild-type (WT) plants. Importantly, in vivo and in situ assays revealed that the accumulation of reactive oxygen species in transgenic rice plants was significantly lower than that in WT plants. Among the six antioxidant genes tested, APX2, CatB, CatC, and SodA1 showed a higher expression level in transgenic rice than in WT rice. Based on these results, we propose that SbSAP14 may play a key role in antioxidant defense systems and possibly be involved in the induction of antioxidant genes in plants, suggesting a possible mechanism of the SAP gene family in stress defense response.     

CYSTM3 negatively regulates salt stress tolerance in Arabidopsis

Plant Molecular Biology - CYSTM3, a small mitochondrial protein, acts as a negative regulator in salt stress response by preventing Na+?efflux and disturbing reactive oxygen species (ROS)...     

A method for screening rice plants for salt tolerance

A number of varieties of rice, a halophyte, Sesuvium portulacastrum and a glycophyte, Phaseolus vulgaris were grown in culture solution containing a range of concentrations of NaCl. Growth of the plants and internal sodium concentrations of the roots were measured after 14 days. The electrical potential difference (PD) between the external solution and the vacuole of the outer cells of the root was also measured. This enabled the driving force on sodium at the cell membranes to be calculated using the Nernst equation. It was found that Sesuvium and those varieties of rice that had previously shown salt tolerance generated relatively negative PDs and large driving forces tending to exclude sodium from the root. This suggested that a simple measurement of PD for plants grown in a given concentration of NaCl over a given period of time would provide a fairly rapid screening method for salt tolerance in rice and possibly other species also. T J Flowers Section editor     

水稻耐盐响应中钾运输载体的研究进展北大核心CSCD

水稻是全球主要粮食作物之一，随着种植区盐渍化加剧，其产量及安全已受到严重威胁。土壤中过高的盐浓度使细胞内Na+过量累积，K/Na失衡，造成离子毒害和渗透胁迫。为减轻盐胁迫带来的生长抑制，水稻进化出一系列适应性机制，包括钾运输载体对K+的摄取或运输以及对Na+的区隔化或外排。水稻中介导这些过程的钾运输载体家族可划分为Shaker、TPK、KT/HAK/KUP、HKT和CPA五大家族。本文总结了上述水稻钾运输载体在盐胁迫下的功能作用及调控机制的研究进展，并对未来研究前景予以展望。