Plant dehydroascorbate reductase (DHAR) is a physiologically important reducing enzyme in the ascorbateglutathione recycling reaction. In this study, we cloned 6 DHAR genes from a hybrid pine species complex of Pinus densata, P. yunnanensis and P. tabulaeformis. P. densata originated by natural hybridization of P. yunnanensis and P. tabulaeformis. The 6 DHAR genes were divided into 2 types: DHAR1 and DHAR2. Phylogenetic analyses indicated that the 3 DHAR1 and 3 DHAR2 genes from the 3 Pinus species were 2 orthologous groups. DHAR1 and DHAR2 genes originated from an ancestral duplication event that occurred in the most recent common ancestor of the early land plants. P. densata contains a copy of DHAR1 similar to that of P. tabulaeformis and a copy of DHAR2 similar to that of P. yunnanensis. RT-PCR revealed that the 6 DHAR were constitutive expression genes in the 3 Pinus species. The recombinant Pinus DHAR proteins were overexpressed in E. coli and purified by Ni-affinity chromatography. P. densata and P. tabulaeformis DHAR1 proteins showed similar enzymatic activities, catalytic efficiency, thermal stabilities and optimal pH profiles towards substrate DHA but about 300-fold higher enzymatic activities than P. yunnanensis DHAR1 protein. The enzymatic activity and thermal stability of P. densata DHAR2 protein were higher than those of P. tabulaeformis DHAR2 protein. Joint analyses of sequence structure, phylogenetic relationships, expression patterns, enzymatic properties and protein 3-D structure revealed selective DHAR gene composition in the hybrid genome of P. densata. Such a combination of divergent copies of DHAR gene in P. densata may have adaptive implications for its colonization of novel habitats on the Tibetan Plateau.

Here we report on the cloning and characterization of BhC2DP1, a novel gene encoding a plant-specific small protein with a single C2 domain from the resurrection plant Boea hygrometrica. Phylogenic analysis of C2-domain proteins and sequence analysis revealed that BhC2DP1 belongs to the C2 elicitor responsive protein subfamily. Real-time PCR and histochemical study of a GUS reporter gene driven by the BhC2DP1 promoter in transgenic Arabidopsis showed BhC2DP1 transcripts increased at the early stage after dehydration and exposure to exogenous Ca²⁺ but decreased with prolonged treatment. Expression of BhC2DP1 was suppressed by abscisic acid (ABA) and Ca²⁺-chelating agent EGTA but was promoted by simultaneous exposure to ABA and EGTA, suggesting that the transcriptional regulation of BhC2DP1 by ABA is Ca²⁺ dependent. Constitutive overexpression of BhC2DP1 in Arabidopsis resulted in an ABA-hypersensitive phenotype, which was rescued by supplementing EGTA to growth media. Therefore, Ca²⁺ is necessary for the function of BhC2DP1 in responding to ABA. Our results provide new insights into the role of small C2-domain proteins and the fine-tuning regulation mechanism in response to drought stress.

Submergence tolerance during germination in rice is regulated by a complex molecular network, the molecular mechanism of which is different from that of submergence tolerance during seedling stage. Germinability under submergence (GS) considerably affects seedling establishment of direct-seeded rice. According to the GS of 256 accessions of the rice core collection, both japonica and indica have high genetic variation of GS with no significant difference in GS. We constructed a linkage map of 146 molecular markers from 170 advanced inbred lines from a backcross between R0380 (japonica) and RP2334 (indica) and used composite interval mapping to detect quantitative trait loci (QTL) associated with GS (coleoptile length under hypoxia). We found 4 QTLs on chromosome 2 (2 QTLs), 3 (1 QTL), and 8 (1 QTL). The positive allele of qGS2.2, which explained 17.34% of the phenotypic variation, was from RP2334, and alleles for the other 3 QTLs came from R0380, which explained 12.86%, 9.37% and 14.60%, respectively, of the phenotypic variation.

The female sterile mutant FS-M₁ was isolated from spontaneous mutation of Brassica napus ‘Ningyou10’. To understand the cellular mechanism of female sterility, we investigated the pollination response and ultrastructure of FS-M₁ papilla cells by fluorescence microscope, scanning electron and transmission electron microscopy. Pollen grains could adhere to and germinate to produce pollen tubes on FS-M₁ papilla cells, but the pollen tubes could not penetrate into papilla cells. FS-M₁ papilla cells became withered and degenerated quickly after flowering. During the degeneration, the number of organelles was significantly decreased; vacuolization was obvious; some organelles such as dictyosome, endoplasmic reticulum, and mitochondria gradually became misshapen and degenerated. Therefore, female sterility in FS-M₁ may have resulted from defects in papilla cells.

Resurrection plants are a valuable resource for understanding the mechanisms of dehydration tolerance and for mining candidate genes that can be used to improve drought tolerance in crops. Here, we determined the contents of galactinol, raffinose and stachyose in dehydrated and rehydrated leaves of a resurrection plant Boea hygrometrica. We cloned a dehydration-inducible gene encoding a raffinose synthase from B. hygrometrica and found that BhRFS was upregulated by cold (4°C), high salt (200 mmol·L^–1NaCl), and abscisic acid (ABA, 100 μmol·L^–1) but downregulated by high temperature (37°C) and not affected by H₂O₂ (200 μmol·L^–1). BhRFS may function in responce to various abiotic stresses, possibly regulated by ABA-dependent signal pathways, therefore it is a good candidate gene for plant breeding to enhance plant stress tolerance.

14-3-3 proteins are a highly conserved acidic protein family present in all eukaryotic cells. Different isoforms of 14-3-3 proteins have different specificities in cells and can interact with target proteins by recognizing specific phosphorylation sites in the targets; these are known as “bridge proteins”. In plant development, 14-3-3 proteins interacting with other proteins regulate phytohormone signal transduction, metabolism regulation, nutrient transportation and response to light signaling, for example. Here, we summarize recent studies of the roles of 14-3-3 proteins in regulating plant development, especially phytohormone signal transduction.

Maize is a typical monoecious plant, and the formation of a unisexual flower undergoes a complex process of sex determination. Monoecious and spatially separated unisexual flowers are produced by selective abortion of pistil primordia in both tassel floral and lower ear floral parts and arrest of all stamen primordia in tassel spikelets. Previous study of related mutants revealed that sex determination is a complex process involving selective cell death, cell protection and signal transduction. Phytohormones and their signal transduction play an important role. Recent studies indicated that gibberellins, cytokinin and jasmonic acid are involved in the regulation of sex determination in maize. In this paper, we summarize the latest advances in the roles and regulatory pathways of plant hormones in maize sex determination. We describe problems in research and future directions in the field.

Reactive oxygen species (ROS) are the byproducts of plant aerobic metabolism. ROS are considered to have double functions (harmful and beneficial) in many plant processes. Oxidative damage to cells and signal transduction in the induced protection response by ROS have been investigated intensively. ROS are increasingly thought to control plant growth and development in particular. Cell growth is the important component of plant development, and control of plant development by ROS is by regulating cell growth, so ROS is an important regulator of plant growth and development. Here, we review the research progress in the control and regulation of plant growth and development by hydroxyl radicals and their precursors, superoxide radical and hydrogen peroxide, and the mechanism, the generation pathway of ROS, the methods for detecting ROS, and prospects for future study.

Gramineous forage and turfgrass are critical to sustainable agriculture and contribute extensively to urban landscaping and ecological protection. In recent years, with the rapid development of biotechnology, significant progress has been made in androgenesis and haploid breeding research of gramineous forage and turfgrasses. This review describes the development of androgenesis systems for gramineous forage and turfgrass and summarizes the latest progress of some important influencing factors on androgenesis and haploid breeding. The genotype of experimental materials is the main factor influencing androgenesis efficiency. The optimal stage for efficient androgenesis of microspore development is between middle and late uninucleate. The ratio and quality of callus induction were improved after anthers were pretreated with low temperature or mannitol. Suitable varieties and ratios of hormone are also the key factors in androgenesis. We summarize the methods of ploidy determination and techniques of chromosome doubling and point out prospects for further research into double haploid breeding in forage and turfgrass.