Thermogenesis is a process of heat production in living organisms. It is rare in plants, but it does occur in some species of angiosperm. The heat is generated via plant mitochondrial respiration. As possible involvement in thermogenesis of mitochondrial factors, alternative oxidases (AOXs) and plant uncoupling mitochondrial proteins (PUMPs) have been well studied. AOXs and PUMPs are ubiquitously present in the inner membrane of plant mitochondria. They serve as two major energy dissipation systems that balance mitochondrial respiration and uncoupled phosphorylation by dissipating the H⁺ redox energy and proton electrochemical gradient (ΔμH⁺) as heat, respectively. AOXs and PUMPs exert similar physiological functions during homeothermic heat production in thermogenic plants. AOXs have five isoforms, while PUMPs have six. Both AOXs and PUMPs are encoded by small nuclear multigene families. Multiple isoforms are expressed in different tissues or organs. Extensive studies have been done in the area of thermogenesis in higher plants. In this review, we focus on the involvement and regulation of AOXs and PUMPs in thermogenesis.

Zhu Y, Lu J, Wang J, Chen F, Leng F, Li H (2011) Regulation of thermogenesis in plants: the interaction of alternative oxidase and plant uncoupling mitochondrial protein. J. Integr. Plant Biol. 53(1), 7–13.

Rad21 and its meiotic counterpart Rec8, the key components of the cohesin complex, are essential for sister chromatid cohesion and chromosome segregation in mitosis and meiosis, respectively. In contrast to yeast and vertebrates, which have only two RAD21/REC8 genes, the rice genome encodes four Rad21/Rec8 proteins. Here, we report on the cloning and characterization of OsRAD21-2 from rice (Oryza sativa L.). Phylogenetic analysis of the full-length amino acids showed that OsRad21-2 was grouped into the plant-specific Rad21 subfamily. Semi-quantitative reverse transcription-polymerase chain reaction revealed OsRAD21-2 preferentially expressed in premeiotic flowers. Further RNA in situ hybridization analysis and promoter::β-glucuronidase staining indicated that OsRAD21-2 was mainly expressed in actively dividing tissues including premeiotic stamen, stem intercalary meristem, leaf meristem, and root pericycle. Ectopic expression of OsRAD21-2 in fission yeast resulted in cell growth delay and morphological abnormality. Flow cytometric analysis revealed that the OsRAD21-2-expressed cells were arrested in G2 phase. Our results suggest that OsRad21-2 functions in regulation of cell division and growth.

Gong C, Li T, Li Q, Yan L, Wang T (2011) Rice OsRAD21-2 is expressed in actively dividing tissues and its ectopic expression in yeast results in aberrant cell division and growth. J. Integr. Plant Biol. 53(1), 14–24.

In mid-May 2008 a serious green tide caused mainly by floating Ulva prolifera (Müller) J. Agardh (Chlorophyta, Ulvales) thalli struck the coastal area of Qingdao, China. To understand the present physiological conditions of the floating alga, in this work both laboratory and field investigations were conducted on the floating U. prolifera thalli in comparison with the attached U. prolifera thalli collected from the area. The floating thalli of three distinctively different colors and attached thalli at three different stages of sporangium formation process were characterized under a microscope, while their photosynthetic parameters were determined with chlorophyll fluorescence technology. On the other hand, the sporangium formation status of the floating U. prolifera thalli was surveyed both in the laboratory and in the field. Comparisons showed that both of the paired morphological characteristics and the paired physiological parameters of the floating and attached U. prolifera thalli were consistent. Furthermore, some spores were confirmed in the field and some motile particles were found within the floating thalli. These results suggest that the floating U. prolifera thalli with different colors could be at different stages of sporangium formation. However, our results also showed that the floating alga thalli have only a limited reproductive potential. This might limit the duration and the further geographic expansion of the green algal bloom.

Lin A, Shen S, Wang G, Yi Q, Qiao H, Niu J, Pan G (2011) Comparison of chlorophyll and photosynthesis parameters of floating and attached Ulva prolifera. J. Integr. Plant Biol. 53(1), 25–34.

The tau class glutathione S-transferases (GSTs) have important roles in stress tolerance and the detoxification of herbicides in crops and weeds. Structural investigations of a wheat tau GST (TaGSTU4) show two subunit interactions: a hydrogen bond between the Tyr93 and Pro65 from another subunit of the dimer, and two salt bridges between residues Glu78 and side chains of Arg95 and Arg99 in the opposite subunit. By investigating enzyme activities, kinetic parameters and structural characterizations, this study showed the following results: (i) the hydrogen bond interaction between the Tyr93 and Pro65 was not essential for dimerization, but contributed to the enzyme's catalytic activity, thermal stability and affinity towards substrates glutathione and 1-chloro-2, 4-dinitrobenzene; and (ii) two salt bridges mainly contributed to the protein structure stability and catalysis. The results of this study form a structural and functional basis for rational design of more selective and environmentally friendly herbicides.

Wang CL, Yang HL (2011) Conserved residues in the subunit interface of tau glutathione S-transferase affect catalytic and structural functions. J. Integr. Plant Biol. 53(1), 35–43.

Hydrogen peroxide (H₂O₂) is a key reactive oxygen species (ROS) in signal transduction pathways leading to activation of plant defenses against biotic and abiotic stresses. In this study, we investigated the effects of H₂O₂ pretreatment on aluminum (Al) induced antioxidant responses in root tips of two wheat (Triticum aestivum L.) genotypes, Yangmai-5 (Al-sensitive) and Jian-864 (Al-tolerant). Al increased accumulation of H₂O₂ and O₂^•− leading to more predominant lipid peroxidation, programmed cell death and root elongation inhibition in Yangmai-5 than in Jian-864. However, H₂O₂ pretreatment alleviated Al-induced deleterious effects in both genotypes. Under Al stress, H₂O₂ pretreatment increased the activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and monodehydroascorbate reductase, glutathione reductase and glutathione peroxidase as well as the levels of ascorbate and glutathione more significantly in Yangmai-5 than in Jian-864. Furthermore, H₂O₂ pretreatment also increased the total antioxidant capacity evaluated as the 2, 2-diphenyl-1-picrylhydrazyl-radical scavenging activity and the ferric reducing/antioxidant power more significantly in Yangmai-5 than in Jian-864. Therefore, we conclude that H₂O₂ pretreatment improves wheat Al acclimation during subsequent Al exposure by enhancing the antioxidant defense capacity, which prevents ROS accumulation, and that the enhancement is greater in the Al-sensitive genotype than in the Al-tolerant genotype.

Xu FJ, Jin CW, Liu WJ, Zhang YS, Lin XY (2011) Pretreatment with H₂O₂ alleviates aluminum-induced oxidative stress in wheat seedlings. J. Integr. Plant Biol. 53(1), 44–53.

Flavin monooxygenases (FMOs) play critical roles in plant growth and development by synthesizing auxin and other signaling molecules. However, the structure and function relationship within plant FMOs is not understood. Here we defined the important residues and domains of the Arabidopsis YUC1 FMO, a key enzyme in auxin biosynthesis. We previously showed that simultaneous inactivation of YUC1 and its homologue YUC4 caused severe defects in vascular and floral development. We mutagenized the yuc4 mutant and screened for mutants with phenotypes similar to those of yuc1 yuc4 double mutants. Among the isolated mutants, five of them contained mutations in the YUC1 gene. Interestingly, the mutations identified in the new yuc1 alleles were concentrated in the two GXGXXG motifs that are highly conserved among the plant FMOs. One such motif presumably binds to flavin adenine dinucleotide (FAD) cofactor and the other binds to nicotinamide adenine dinucleotide phosphate (NADPH). We also identified the Ser₁₃₉ to Phe conversion in yuc1, a mutation that is located between the two nucleotide-binding sites. By analyzing a series of yuc1 mutants, we identified key residues and motifs essential for the functions of YUC1 FMO.

Hou X, Liu S, Pierri F, Dai X, Qu LJ, Zhao Y (2011) Allelic analyses of the Arabidopsis YUC1 locus reveal residues and domains essential for the functions of YUC family of flavin monooxygenases. J. Integr. Plant Biol. 53(1), 54–62.

Mungbean (Vigna radiata (L.) Wilczek) is a unique species in its ability to fix atmospheric nitrogen, with early maturity, and relatively good drought resistance. We used 454 sequencing technology for transcriptome sequencing. A total of 150 159 and 142 993 reads produced 5 254 and 6 374 large contigs (≥500 bp) with an average length of 833 and 853 for Sunhwa and Jangan, respectively. Functional annotation to known sequences yielded 41.34% and 41.74% unigenes for Jangan and Sunhwa. A higher number of simple sequence repeat (SSR) motifs was identified in Jangan (1 630) compared with that of Sunhwa (1 334). A similar SSR distribution pattern was observed in both varieties. A total of 8 249 single nucleotide polymorphisms (SNPs) and indels with 2 098 high-confidence candidates were identified in the two mungbean varieties. The average distance between individual SNPs was ∼860 bp. Our report demonstrates the utility of transcriptomic data for implementing a functional annotation and development of genetic markers. We also provide large resource sequence data for mungbean improvement programs.

Moe KT, Chung JW, Cho YI, Moon JK, Ku JH, Jung JK, Lee J, Park YJ (2011) Sequence information on simple sequence repeats and single nucleotide polymorphisms through transcriptome analysis of mungbean. J. Integr. Plant Biol. 53(1), 63–73.

In flowering plants, the exine components are derived from tapetum. Despite its importance to sexual plant reproduction, little is known about the translocation of exine materials from tapetum to developing microspores. Here we report functional characterization of the arabidopsis WBC27 gene. WBC27 encodes an adenosine tri-phosphate binding cassette (ABC) transporter and is expressed preferentially in tapetum. Mutation of WBC27 disrupted the exine formation. The wbc27 mutant microspores began to degenerate once released from tetrads and most of the microspores collapsed at the uninucleate stage. Only a small number of wbc27-1 microspores could develop into tricellular pollen grains. These survival pollen grains lacked exine and germinated in the anther before anthesis. All of these results suggest that the ABC transporter, WBC27 plays important roles in the formation of arabidopsis exine, possibly by translocation of lipidic precursors of sporopollenin from tapetum to developing microspores.

Dou XY, Yang KZ, Zhang Y, Wang W, Liu XL, Chen LQ, Zhang XQ, Ye D (2011) WBC27, an adenosine tri-phosphate-binding cassette protein, controls pollen wall formation and patterning in Arabidopsis. J. Integr. Plant Biol. 53(1), 74–88.