Rice SVP-group MADS-box proteins, OsMADS22 and OsMADS55, are negative regulators of brassinosteroid responses

Most short vegetative phase (SVP)-group MADS-box genes control meristem identity and flowering time. Among the three SVP-group genes in rice, OsMADS47 has been reported as a negative regulator of brassinosteroid (BR) responses. Here, we investigated the functional roles of two close homologs, OsMADS22 and OsMADS55, by generating single, double and triple RNAi lines and overexpression lines. Analyses of the plants showed that their roles in regulating meristem identity are well conserved; however, the involvement of these genes in determining flowering time has diversified. Most importantly, OsMADS55 works as a major negative regulator of BR responses, and OsMADS22 functions to support OsMADS55. Whereas single OsMADS55 RNAi plants display weak BR responses in the lamina joint (LJ), OsMADS22 - OsMADS55 double and OsMADS22 - OsMADS47 - OsMADS55 triple RNAi plants manifest dramatic BR responses with regard to LJ inclination, coleoptile elongation and senescence. Stem elongation is also notably reduced in the double and triple RNAi plants, probably because of BR oversensitivity. Expression analyses indicate the diversified roles in age-dependent BR responses. Altogether, our study demonstrates that all three rice SVP-group genes work as negative regulators of BR responses, but that their spatial and temporal roles are diversified.     

Graphene Oxide Regulates Root Development and Influences IAA Concentration in Rice

Researchers have found that graphene oxide (GO) has significant effects on plant growth and development. The effects of GO on plants are variable and influenced by many factors, including GO concentration and genotype. Five rice varieties, Huanghuazhan (HHZ), Jinghuazhan (JHZ), Shenyou9521 (SY9521), Jingyouhuazhan (JYHZ), and Jingchuxiang (JCX), were treated with different concentrations of GO (0, 5, 15, 25, and 50 mg/L), and their physiological response was measured. The results demonstrate that GO had significant effects on the development of HHZ, JCX, JHZ, JYHZ, and SY9521 roots, but the effect varied by GO concentration and rice variety. The highest concentration of GO (50 mg/L) reduced the root length, fresh weight, and dry weight for all five rice species. The GO treatment also affected the levels of abscisic acid (ABA), indole-3-acetic acid (IAA), and malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) and catalase (CAT) enzymes. The correlation analysis indicates that GO could affect the IAA content to modulate rice root growth.

     

植物防御素调控水稻镉积累的新机制

镉是我国农产品的主要重金属污染物之一。随着我国土壤重金属污染问题日益突出, 包括稻米在内的农产品重金属超标时常发生。如何防控重金属在作物可食部位的积累, 在保证农产品安全的同时将农田重金属进行移除修复, 已成为我国农业生产急需解决的问题。最近, 中科院上海生命科学院植物生理生态所龚继明研究组和中国水稻所钱前研究组克隆到1个特异调控镉在水稻(Oryza sativa)叶片中积累的主效QTL基因CAL1。CAL1编码1个植物防御素类似蛋白, 通过与镉进行螯合, 将镉从维管束木质部薄壁细胞中分泌出来, 进入木质部参与长距离转运, 从而定向调控镉在水稻叶片等营养器官的积累而不影响籽粒镉的积累。该研究加深了人们对重金属镉在植物体内的转运和再分配机理的认识, 同时也为培育秸秆镉高积累而籽粒镉含量达标的“修复型”水稻品种提供有价值的新基因。研究成果具有重要的理论意义和应用价值。     

沙棘hrh-miR319e靶向转录因子AP4调控种子发育的研究

为探讨沙棘hrh-miR319e与转录因子AP4间的靶向关系,并分析其在种子发育过程中的表达,以不同发育期的种子为材料,运用RNAhybrid软件预测hrh-miR319e成熟体序列与其候选靶基因AP4的3′-UTR区的结合位点,构建pcDNA3.1+pmirGLO-AP4和pcDNA3.1-hrh-mir319e+pmirGLO-AP4载体,用双荧光素酶报告基因检测方法验证hrh-miR319e与候选靶基因AP4间的靶向关系,并采用qRT-PCR方法分析hrh-miR319e与AP4基因在沙棘不同发育期种子中的表达变化。结果显示：(1)生物信息学预测AP4-3′-UTR区与hrh-miR319e成熟体序列完全互补。(2)荧光检测显示pcDNA3.1-hrh-mir319e+pmirGLO-AP4质粒显著抑制荧光素酶活性(P<0.001)。(3)不同发育期种子中hrh-miR319e的表达量总体呈现出先明显上升后明显降低的变化趋势,而AP4基因的表达量则呈现出先降低后上升的趋势;当hrh-miR319e的表达量在花后80 d达到最高水平时,‘新俄3号’种子中为3.146、‘绥棘1...     

Improving Nitrogen Use Efficiency in Rice through Enhancing Root Nitrate Uptake Mediated by a Nitrate Transporter,NRT1.1B

<正>Nitrogen(N)is one of most important nutrients for crop production,which makes up 1%-5%of total plant dry matter(Marschner,2012).Due to the limited availability of N in soil,application of N fertilizers has been an important agronomic practice to increase crop yield.However,over-application of N fertilizers has caused pollution of N in soil,water and air.It     

Nanosilver-Promoted Lateral Root Development in Rice is Mediated through Hydrogen Peroxide

Nanosilver (10⁻⁹ m) refers to particles comprising 20–15,000 silver atoms, exhibiting high stability and specific surface area. At present, nanosilver has been used in agricultural cultivation and production. This study examined the effects of nanosilver on growth and development of rice root systems. Study results showed that fresh weight of rice belowground organs and root length both increased significantly by 5% and 25%, respectively, after rice radicles were treated with 2 ppm of nanosilver for three days. However, the H₂O₂ level reached its peak at 2 days from treatment, but the activities of the antioxidant enzymes CAT, APX, and GR were inhibited by 2 ppm of nanosilver treatment. The results showed that nanosilver treatment inhibited the antioxidant enzyme activity of rice roots. The treatment of rice radicles with 5 μM H₂O₂ promoted root development and the same was observed when nanosilver was used for treatment. Moreover, ascorbic acid (AsA) is a H₂O₂ scavenger and therefore rice root development was inhibited when AsA was added to rice radicles together with either treatment of nanosilver or H₂O₂. In summary, nanosilver treatment of rice radicles promoted root growth and development via the regulation of H₂O₂ and not the O₂^•− pathway.     

The Proto-oncogene Transcription Factor Ets1 Regulates Neural Crest Development through Histone Deacetylase 1 to Mediate Output of Bone Morphogenetic Protein Signaling

The neural crest (NC) is a transient, migratory cell population that differentiates into a large variety of tissues including craniofacial cartilage, melanocytes, and peripheral nervous system. NC is initially induced at the border of neural plate and non-neural ectoderm by balanced regulation of multiple signaling pathways among which an intermediate bone morphogenetic protein (BMP) signaling is essential for NC formation. ets1, a proto-oncogene playing important roles in tumor invasion, has also been implicated in delamination of NC cells. In this study, we investigated Ets1 function in NC formation using Xenopus. Overexpression of ets1 repressed NC formation through down-regulation of BMP signaling. Moreover, ets1 repressed the BMP-responsive gene id3 that is essential for NC formation. Conversely, overexpression of id3 can partially rescue the phenotype of NC inhibition induced by ectopic ets1. Mechanistically, we found that Ets1 binds to id3 promoter as well as histone deacetylase 1, suggesting that Ets1 recruits histone deacetylase 1 to the promoter of id3, thereby inducing histone deacetylation of the id3 promoter. Thus, our studies indicate that Ets1 regulates NC formation through attenuating BMP signaling epigenetically.     

甘薯MADS-box转录因子IbMADS11-Like的克隆及胁迫响应分析

MADS-box蛋白在植物生长发育及抗逆等过程中均发挥重要功能。本实验室根据甘薯近缘野生种I.trifida基因组序列,在甘薯栽培种徐薯22（Ipomoea batatas（L.） Xu22）中克隆到一个STMADS11亚家族MADS-box基因,命名为IbMADS11-Like。实时定量RT-PCR分析表明,IbMADS11-Like基因在甘薯根中大量表达,并且随着块根的形成和膨大表达量逐渐降低,表明该基因可能参与了甘薯块根的发育过程。胁迫处理分析表明,IbMADS11-Like基因的表达受干旱、盐和高温的诱导,而低温则抑制其表达。此外,IbMADS11-Like基因对ABA、IAA、ZT、BR、ACC、JA及GA等激素的处理也有不同程度的响应,暗示IbMADS11-Like基因可能参与了甘薯生长发育及胁迫的调控过程。这些结果为进一步分析IbMADS11-Like基因在甘薯块根发育和胁迫响应中的功能奠定了基础。