甜菜M14品系BvM14-SAMS2基因的克隆及表达特异性分析

甜菜M14品系富含丰富的优质基因资源,对盐、寒冷、干旱等非生物胁迫具有极强的耐受性,是研究逆境胁迫极为难得的材料。课题组前期以甜菜M14品系为试验材料,在500mmol/L NaCl胁迫下,从蛋白质水平筛选获得了76个差异蛋白质点,在转录水平筛选获得了58个Unigenes序列,二者匹配得到了蛋白质点——BvM14-SAMS2。试验采用RACE技术,克隆获得甜菜M14品系BvM14-SAMS2基因cDNA全长1 538bp,包含最大开放阅读框ORF 1 182bp,编码393个氨基酸。采用实时荧光定量PCR(Real-time PCR)技术对甜菜M14品系BvM14-SAMS2基因的表达特异性进行分析,结果表明,在正常生长条件下,BvM14-SAMS2基因在甜菜M14品系根、茎、叶、花中的表达量大小依次为:根>叶>花>茎。受盐胁迫诱导,BvM14-SAMS2基因在甜菜M14品系叶片中的表达量随着盐浓度的增大而增大,根中的表达量随着盐浓度的增大无明显变化。研究结果表明,BvM14-SAMS2基因在甜菜M14品系叶片中受盐胁迫诱导表达,该基因在胁迫下的表达量增加可能有利于植物抵御盐胁迫损伤。

Cloning and Differential Gene Expression of Two Catalases in Suaeda salsa in Response to Salt Stress

Two different cDNA clones (Sscat1 and Sscat2) encoding catalase, the primary important H2O2-scavenging enzyme, were isolated from a AZap-cDNA library constructed from a 400 mmol/L NaCl-treated library of Suaeda salsa ( L.) Pall aerial tissue. Sscat1 (1.7 kb) contains a full open reading frame of 492 amino acids and Sscat2 (1.1 kb) is a partial clone. BLAST analysis indicates that the two clones share 71.9% identity in nucleotide sequence and 75% identity in deduced amino acid sequence within the last 287 amino acid residues of Sscat1. Southern blotting analysis showed that Sscat1 is multicopy in S. salsa genome, while Sscat2 is a single copy gene. Northern blotting analysis showed a rapid increase in the steady-level of both genes in roots after 48 It salt treatment, but only Sscat1 was induced in salinity treated leaves. Time-course analysis carried out in leaves confirmed that Sscat1 was induced by salt stress, in contrast to Sscat2. These implied that the expression of Sscat1 and Sscat2 genes are differentially regulated in S. salsa. The activity of total catalase is dramatically increased in response to salt stress.

Effect of salt stress on activity of superoxide dismutase （SOD） in Ulmus pumila L.

The injury tolerance of cell plasma membrane and the correlative enzymes activities of plasma-membrane protection system in the Ulmuspumila leaves treated by nine concentrations （0.3%, 0.6%, 0,9%, 1,2%, 1.5%, 1.8%, 2,1%, 2.4%, 3.0%） of Na2CO3 and NaHCO3 mixtures were studied in a greenhouse of Northeast Forestry University, Harbin, China. The rate of electrolyte leakage （REL） and SOD （Superoxide dismutase） activity in leaves of different samples were determined. Results showed that the REL in leaves of U. pumila presented a slowly increasing trend at the salt concentrations less than 1.5%, which indicated that cell plasma membrane of U. pumila leaves had rather strong resistance to the injury of salt ion, and had a significant increase at the salt concentrations more than 1.5%. The SOD activities in leaves of U, pumila presented an increased trend at salt concentrations less than 1.5%, the growth of seedlings did not decline, and tress and leaves had no symptom of injury, while the salt concentrations exceeded 1.5%, SOD activities sharply decreased and REL increased promptly.

Lipid Peroxidation and Antioxidative Enzymes of Two Turfgrass Species Under Salinity Stress

Salinity stress is a major factor limiting the growth of turfgrass irrigated with recycled wastewater. The change in lipid peroxidation in terms of malondialdehyde （MDA） content and the activities of superoxide dismutase （SOD）, catalase （CAT）, ascorbate peroxide （APX） and glutathione reductase （GR） in the shoots and roots of Kentucky bluegrass and tall rescue were investigated under salinity stress. Plants were subjected to 0, 50, 100, 150 and 200 mmol L-1 NaCl for 40 d. The MDA content under salinity stress was lower in tall fescue than in Kentucky bluegrass in both shoots and roots. Activities of SOD in the shoots of both species increased with salinity stress. The activities of CAT and APX decreased in Kentucky bluegrass, but no significant difference in the activities of CAT and APX was observed in tall rescue. The activities of SOD, CAT and APX in the shoots of tall fescue were higher than those in Kentucky bluegrass. In the roots of Kentucky bluegrass, SOD and GR activities increased and CAT and APX activities decreased in comparison with the control. In the roots of tall fescue, salinity increased the activities of SOD, CAT, and APX. These results suggested that tall fescue exhibited a more effective protection mechanism and mitigated oxidative stress and lipid peroxidation by maintaining higher SOD, CAT and APX activities than Kentucky bluegrass.

Advances in studies on ion transporters involved in salt tolerance and breeding crop cultivars with high salt tolerance

Soil salinity is a global major abiotic stress threatening crop productivity. In salty conditions, plants may suffer from osmotic, ionic, and oxidative stresses, resulting in inhibition of growth and development. To deal with these stresses, plants have developed a series of tolerance mechanisms, including osmotic adjustment through accumulating compatible solutes in the cytoplasm, reactive oxygen species(ROS) scavenging through enhancing the activity of anti-oxidative enzymes, and Na^+/K^+ homeostasis regulation through controlling Na^+ uptake and transportation. In this review, recent advances in studies of the mechanisms of salt tolerance in plants are described in relation to the ionome, transcriptome, proteome, and metabolome, and the main factor accounting for differences in salt tolerance among plant species or genotypes within a species is presented. We also discuss the application and roles of different breeding methodologies in developing salt-tolerant crop cultivars. In particular, we describe the advantages and perspectives of genome or gene editing in improving the salt tolerance of crops.