Receptor-like proteins (RLPs) are involved in both plant defense and developmental processes. Previous genetic and biochemical studies show that the leucine-rich repeat (LRR) receptor-like protein CLAVATA2 (CLV2) functions together with CLAVATA1 (CLV1) and CORYNE (CRN) in Arabidopsis to limit the stem cell number in shoot apical meristem, while in root it acts with CRN to trigger a premature differentiation of the stem cells after sensing the exogenously applied peptides of CLV3p, CLE19p or CLE40p. It has been proposed that disulfide bonds might be formed through two cysteine pairs in the extracellular LRR domains of CLV1 and CLV2 to stabilize the receptor complex. Here we tested the hypothesis by replacing these cysteines with alanines and showed that depletions of one or both of the cysteine pairs do not hamper the function of CLV2 in SAM maintenance. In vitro peptide assay also showed that removal of the cysteine pairs did not affect the perception of CLV3 peptides in roots. These observations allow us to conclude that the formation of disulfide bonds is not needed for the function of CLV2.

Song X, Guo P, Li C, Liu CM (2010) The cysteine pairs in CLV2 are not necessary for sensing the CLV3 peptide in shoot and root meristems. J. Integr. Plant Biol. 52(9), 774–781.

The ¹H nuclear magnetic resonance (¹H NMR) fingerprints of fractionated non-polar and polar extracts (control substance for plant drug [CSPD] A and B) from the roots of 12 specimens of Saposhnikovia divaricata (Turcz.) Schischk were achieved with Fourier Transform (FT)-NMR spectrometer and assigned by comparison to each other and to the ¹H NMR spectra of the isolated individual compounds. These fingerprints were found to be uniform in terms of the specificity for the implication of all 12 specimens being systematically of the same origin. The uniformity was further affirmed by high performance liquid chromatography (HPLC), which also revealed exactly identical specificity for the identified S. divaricata species with the ¹H NMR appearances of corresponding CSPD on the part of the composition of characteristic constituents when comparing to corresponding individual compounds. This investigation unambiguously shows that the specific signals from the chemotaxonomically significant compounds of chromones and coumarins in S. divaricata are exhibited distinctively in the composite features of both ¹H NMR fingerprints and HPLC profiles. The ¹H NMR and HPLC profiles established can successfully be used as reference for the authentication of the origin of S. divaricata species as well as for chemotaxonomic studies.  

Xin YY, Deng AJ, Du GH, Zhang JL, Qin HL (2010) Fingerprinting analysis of Saposhnikovia divaricata using ¹H nuclear magnetic resonance spectroscopy and high performance liquid chromatography. J. Integr. Plant Biol. 52(9), 782–792.

Purification of photosystem II (PSII) core complexes is a time-consuming and low-efficiency process. In order to isolate pure and active PSII core complexes in large amounts, we have developed a fast method to isolate highly active monomeric and dimeric PSII core complexes from spinach leaves by using sucrose gradient ultracentrifugation. By using a vertical rotor the process was completed significantly faster compared with a swing-out rotor. In order to keep the core complexes in high activity, the whole isolation procedure was performed in the presence of glycine betain and pH at 6.3. The isolated pigment-protein complexes were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, absorption spectroscopy, 77 K fluorescence spectroscopy and high performance liquid chromatography. Our results show that this method is a better choice for quick and efficient isolation of functionally active PSII core complexes.

Wang ZG, Xu TH, Liu C, Yang CH (2010) Fast isolation of highly active photosystem II core complexes from spinach. J. Integr. Plant Biol. 52(9), 793–800.

Plants are equipped to recognize invading pathogenic microbes and activate innate immune responses by sensing pathogen-associated molecular patterns (PAMPs). PAMP-triggered immunity (PTI) is critical for plant resistance to potential pathogens. Although the mechanism by which PTI is activated has been intensively studied, how plants prevent unregulated immune responses is less well understood. Here we provide evidence that AHL20, an AT-hook containing DNA-binding protein, negatively regulates PTI. Overexpression of AHL20 as a stable transgene suppressed PAMP-induced NHO1 and FRK1 expression in Arabidopsis plants. Similarly, transient expression of the closely related family members AHL19, AHL15, and AHL27 in protoplasts also blocked PAMP-induced gene expression. The AHL20 overexpression plants displayed greater susceptibility to virulent P. syringae bacteria. These results indicate that AHL proteins play an important role in plant immunity.

Lu H, Zou Y, Feng N (2010) Overexpression of AHL20 negatively regulates defenses in Arabidopsis. J. Integr. Plant Biol. 52(9), 801–808.

Ligustrum vicaryi L. is a hybrid of Ligustrum ovalifolium Hassk. var. aureo-marginatum and Ligustrum
vulgale L., and displays a chlorophyll-less phenotype. Therefore it is widely used as a horticultural shrub
because of its golden-color leaves. Its putative mechanism, light responses, chlorophyll synthesis and
plastid development were studied. L. vicaryi has a higher level of 5-aminolevulinic acid (ALA), but lower
levels of chlorophylls compared with L. quihoui. The yellowish phenotype of L. vicaryi upper leaves could
be attributed to their hampered conversion from chlorophyllide into chlorophyll a. Despite the enhanced
ALA level and the decreased thylakoid stacking in plastids, L. vicaryi golden leaves contain normal
levels of Lhcb transcripts and photosystem apoproteins. Furthermore, reactive oxygen species (ROS)
accumulation is almost the same in L. vicaryi and L. quihoui. The golden leaves often turn green and
the contents of chlorophylls increase with decreasing light intensity. Dynamic changes of chlorophyll-synthesis-
system under the light transition were also analyzed.

Yuan M, Xu MY, Yuan S, Chen YE, Du JB, Xu F, Zhang ZW, Guo ZC, Zhao ZY, Lin HH (2010) Light regulation to chlorophyll synthesis and plastid development of the chlorophyll-less golden-leaf privet. J. Integr. Plant Biol. 52(9), 809–816.

The natural hybridization that occurs between two sympatric species of Rhododendron subgenus Hymenanthes in Yunnan, China, was investigated. In field observations, it was noted that the putative hybrids between R. delavayi Franch. and R. cyanocarpum (Franch.) Franch. ex W.W. Sm. had intermediate morphologies. On the basis ofmorphology, chloroplast DNA (trnL-rpl32) and nuclear DNA (waxy), hybrids and parental species were identified. Hybridization occurred in both directions, but was asymmetrical, with R. delavayi as the major maternal parent. Reciprocal hand pollination treatments showed that either species, as pollen donor or pollen receiver, could produce fruits. It was noted that fruit set varied among treatments. The same pollinators (bumblebees) were shared in both parental species. From these results, we conclude that individuals with intermediate morphologies are indeed of hybrid origin from natural hybridization between R. cyanocarpum and R. delavayi. Furthermore, we presume the hybridization at the study site could have been initiated by habitat disturbance in the 1950s, and we may hence witness the early stages of hybrid swarm formation.

Ma YP, Zhang CQ, Zhang JL, Yang JB (2010) Natural hybridization between Rhododendron delavayi and R. cyanocarpum (Ericaceae), from morphological, molecular and reproductive evidence. J. Integr. Plant Biol. 52(9), 844–851.