Low Seed Germination Rate Research Articles

Characteristics of the Seed Germination and Seedlings of Six Grape Varieties (V. vinifera).

Intraspecific recurrent selection in V. vinifera is an effective method for breeding of high quality, disease-, cold-, and drought-resistance grapes. Exploring the optimal treatment methods for grape (V. vinifera) seeds can help to accelerate the process of intraspecific recurrent selection and improve breeding efficiency. In this study, seeds of six V. vinifera varieties were used as experimental materials, and the germination and seedling formation characteristics were studied by single factor treatment and orthogonal compound treatment, respectively. To do this, stratification, chemical substances, beak cutting, and pre-germination treatments were tested, and the optimal treatment combination was determined for each variety. The results indicated that the optimal conditions obtained in the orthogonal experiments were not completely consistent with those in the single-factor experiments. Single factor experiment results demonstrated that two stratification methods (chilling gauze-storage and chilling sand-storage) and two pre-germination methods (pre-germination in petri dishes and pre-germination in a bean sprouter) vary in effectiveness for different varieties. gibberellin acid (GA3) soaking and beak-cutting promote the germination and seedling rate of the tested varieties. Orthogonal test results demonstrate that, for Dunkelfelder and Cabernet Sauvignon, the optimal treatment combination was chilling sand-storage + GA3 soaking seed + beak cutting + pre-germination in petri dishes. For Meili, the optimal treatment combination was chilling sand-storage + acetic acid (HAc) soaking seed + beak cutting + pre-germination in petri dishes. For Ecolly, the optimal treatment combination was chilling sand-storage + GA3 soaking seed + beak cutting + pre-germination in a bean sprouter. For Garanior, the optimal treatment combination was chilling sand-storage + HAc soaking seed + no beak cutting + pre-germination in petri dishes. For Marselan, the optimal treatment combination was chilling gauze-storage + GA3 soaking seed + beak cutting + pre-germination in a bean sprouter. This study identified the optimal conditions for seed germination and seedling formation of six grape varieties, which will facilitate future work to characterize the seed germination and seedling formation of seeds obtained by intraspecific hybridization of these varieties. This work also provides a reference for addressing problems of low seed germination rate and suboptimal seedling formation for better utilization of grape germplasms.

Germinability and Seedling Growth Performance of Chilli (Capsicum annuum) Seeds in Response to Different Gibberellic Acid Concentrations Pre-Treatment

Chilli seeds are always associated with physiological dormancy characteristics or endogenous dormancy that has affected their germination potential. Problems noticed on the low seed germination rate, vigour growth, further may lead to the poor seedling growth pattern of chilli crop production. Gibberellic Acid (GA3) which is usually used as a treatment solution is not a new advent of seed dormancy breaking methods for chilli. But, looking forwards to a better GA3 concentration is still needed for the discovery of this treatment potential effect on chilli seed germinability and seedling growth. Thus, this study aimed to evaluate the effect of different GA3 concentrations on seed emergence and seedling growth performance in chilli. In this experiment, chilli seeds were imbibed with 25 mg/L, 75 mg/L and 125 mg/L concentration of GA3 with three replications each; for 24 hours at room temperature (32±4°C) and the untreated seeds as a control. The data collection on final germination percentage was taken daily for 21 days after sowing. While the 15 germinated seeds were directly planted on the 5 polybags arranged in the net house of Junaidy Jonik Farm, Sabah, Malaysia. The experiment was arranged in a completely randomized design with three replications. Data were subjected to analysis of variance with SAS version 9.4 and the significant means were separated by the least significant difference test at P<0.05. Significant differences were observed in the seed germinability measured; germination rate index (GRI), mean germination time (MGT) and final germination percentage (FGP), as well as on seedling vigour index (SVI) between treated and control seeds. Conversely, plant height, number of internodes, number of leaves and fresh weight of seedlings showed no significant differences among treatments. It was concluded that the use of GA3 was able to enhance chilli seeds germinability and could display a better SVI than the control. It is recommended to use GA3 treatment at 25 mg/L of concentration, as it may give an advantage to both economic and biological importance in producing higher germinability and seedling growth performance in chilli.

Germinability and Seedling Growth Performance of Chilli (Capsicum annuum) Seeds in Response to Different Gibberellic Acid Concentrations Pre-Treatment

Chilli seeds are always associated with physiological dormancy characteristics or endogenous dormancy that has affected their germination potential. Problems noticed on the low seed germination rate, vigour growth, further may lead to the poor seedling growth pattern of chilli crop production. Gibberellic Acid (GA3) which is usually used as a treatment solution is not a new advent of seed dormancy breaking methods for chilli. But, looking forwards to a better GA3 concentration is still needed for the discovery of this treatment potential effect on chilli seed germinability and seedling growth. Thus, this study aimed to evaluate the effect of different GA3 concentrations on seed emergence and seedling growth performance in chilli. In this experiment, chilli seeds were imbibed with 25 mg/L, 75 mg/L and 125 mg/L concentration of GA3 with three replications each; for 24 hours at room temperature (32±4°C) and the untreated seeds as a control. The data collection on final germination percentage was taken daily for 21 days after sowing. While the 15 germinated seeds were directly planted on the 5 polybags arranged in the net house of Junaidy Jonik Farm, Sabah, Malaysia. The experiment was arranged in a completely randomized design with three replications. Data were subjected to analysis of variance with SAS version 9.4 and the significant means were separated by the least significant difference test at P<0.05. Significant differences were observed in the seed germinability measured; germination rate index (GRI), mean germination time (MGT) and final germination percentage (FGP), as well as on seedling vigour index (SVI) between treated and control seeds. Conversely, plant height, number of internodes, number of leaves and fresh weight of seedlings showed no significant differences among treatments. It was concluded that the use of GA3 was able to enhance chilli seeds germinability and could display a better SVI than the control. It is recommended to use GA3 treatment at 25 mg/L of concentration, as it may give an advantage to both economic and biological importance in producing higher germinability and seedling growth performance in chilli.

Identification and expression analyzes of CC-type glutaredoxin in cucumber (Cucumis sativus L.) under abiotic stress

Glutaredoxins (GRXs) are key regulators in the cellular redox state and play pivotal roles in both plant development and responses to stress stimuli. Here, we found 45 GRX gene members in cucumber, 16 of which were classified as CC-type. These CC-type GRXs were shown to be highly conserved among cucumber, Arabidopsis thaliana, and rice, according to our bioinformatic analyzes results. Cucumber CC-type GRX (CsGRX) genes showed varying expression levels in different plant organs and in response to different abiotic stresses. CsGRX1, CsGRX5, CsGRX9, CsGRX13, and CsGRX16 expression was induced from 3 to 6 h by salicylic acid (SA) treatments, whereas CsGRX1, CsGRX3, CsGRX8, CsGRX13, CsGRX14, and CsGRX17 expression was induced from 3 to 12 h with methyl jasmonate (MeJA) treatments. Moreover, CsGRX11 expression was strongly induced from 0 to 24 h by MeJA treatment, whereas CsGRX3 and CsGRX11 expression was strongly induced at the early stages of 42 °C treatments and at the later stages of the methyl viologen treatments. CsGRX4, CsGRX6, CsGRX7, CsGRX13 and CsGRX11 expression was induced by PEG and NaCl treatments. These results indicated the versatile roles of GRX genes in response to stress stimuli. The subcellular localization results for three CsGRX–green fluorescent protein (GFP) fusion proteins indicated that some orthologs were localized to the nucleus. CsGRX4 that responded to salt stress were heterologously expressed in Arabidopsis, and its transgenic lines demonstrated salt sensitivity, showing lower seed germination rate and shorter root length than their wild type counterparts under salt stress. Our results provide a foundation for future studies on GRX genes in cucumber.

Development of an embryo germination protocol for shy-seeded grape (Vitis vinifera L.)

AbstractAcquisition and germination of seeds are the most desired targets for the improvement of vegetatively propagated crops. In the present study, we developed a potential embryo germination protocol for the Red Globe grape cultivar having a low seed germination rate. Three grape berries at different developmental stages, viz. 50, 60 and 70 days after flowering (DAF), were selected for in-vitro embryo germination. Three growth media, namely Emershad and Ramming (ER), Nitsch and Nitsch (NN) and Murashige and Skoog (MS), and plant growth regulators (benzyl amino purine (BA), 0.5, 0.7 and 0.9 mg/l; indole butyric acid (IBA), 1.0, 1.5 and 2.0 mg/l; and gibberellic acid (GA), 0.1, 0.3 and 0.9 mg/l) were screened individually in different combinations with three amino acids, namely cysteine, glutamine and proline (2.0 μmol/l each). The maximum embryos germination percentage recorded at 70 DAF was 63.33, 47.78 and 45.56% in ER, NN and MS media, respectively, supplemented with 0.9 mg/l BA, 2.0 mg/l IBA, 0.9 mg/l GA and 2.0 μmol glutamine. Glutamine was found to have the most significant impact, and it improved the rescued embryos germination. The present study provides a potential recipe for a medium that can facilitate efficient germination of grape embryos.

The Effects of Leaf Extracts of Four Tree Species on Amygdalus pedunculata Seedlings Growth.

Vegetation reconstruction is an urgent problem in fragile environment like coal mine subsidence areas. Amygdalus pedunculata is an important eco-economic shrub species that promotes wind prevention, sand fixation as well as soil and water conservation. The natural regeneration of pure Amygdalus pedunculata forests is difficult to achieve because of its low seed germination rate and weak seedling growth. A stereo-complex ecosystem could potentially promote the germination and seedling growth of A. pedunculata and establish a steady mixed plantation consisting of trees and shrubs. Here, laboratory and pot experiments were conducted to assess the effect of four tree species on morphological and physiological indexes of A. pedunculata. The laboratory experiment showed that A. pedunculata seed germination and seedling growth from Yuyang County (YC-1) and Shenmu County (SC-6) were higher when plants were treated with the aqueous leaf extracts of Pinus sylvestris, Broussonetia papyrifera, and Pinus tabulaeformis compared with Populus simonii at concentrations of 2.5% (E2.5) and 5% (E5). Furthermore, the donor leaf extract was more sensitive to YC-1 than to SC-6. The pot experiment showed that the E2.5 and E5 treatments with the aqueous leaf extracts on the three tree species had strong promoting effects of seedling length, root length, seedling fresh weight, root fresh weight, and ground diameter for YC-1. The activity of catalase of A. pedunculata seedlings first increased and then decreased, while the activity of peroxidase, superoxide dismutase, roots, and the contents of soluble protein and chlorophyll decreased; the opposite patterns were observed for malondialdehyde, soluble sugar, cell membrane permeability, and proline were the opposite. Synthetical allelopathic effect index values of the leaf extracts of the three species on YC-1 were as follows: P. sylvestris > B. papyrifera > P. tabulaeformis (E2.5 to E20). Therefore, P. sylvestris and B. papyrifera could be used to promote the growth of A. pedunculata seedlings as well as for the construction of mixed plantations in coal mine degradation areas. Generally, this study provides new insight into the creation of stereo-complex ecosystems (P. sylvestris + A. pedunculata and B. papyrifera + A. pedunculata) in arid fragile environment.

OsRbohB-mediated ROS production plays a crucial role in drought stress tolerance of rice.

We found that a rice NADPH oxidase gene OsRbohB contributes drought tolerance and its functions are involved in the interaction of the OsRbohB-mediated ROS production and ABA signaling. The plasma membrane NADPH oxidases, also known as respiratory burst oxidase homologs, are the key producers of ROS under both normal and stress conditions in plants. However, their functions in rice development and stress tolerance are still under investigation. Here, we found that a rice NADPH oxidase gene OsRbohB, also named OsNOX1, is expressed in all tissues examined throughout the development stages with higher transcripts in leaves. The transcriptional expression of OsRbohB is also strongly stimulated by dehydration, salt and several phytohormonal treatments. Compared with wide-type and the OsRbohB-overexpressing transgenic plants, osrbohB, a Tos17 insertion knockout mutant of OsRbohB, shows lower ROS production, abscisic acid (ABA) content and transcripts of a series of stress-related genes. The osrbohB mutant also exhibits lower seed germination rate, organ size and thousand seed weight, but higher stomatal aperture and sensitivity to drought. Moreover, a number of genes involved in plant development, stress response, transcriptional regulation, and particularly ABA signaling are differentially expressed in osrbohB plants under both normal growth and drought conditions. All these results suggest the roles of OsRbohB in drought tolerance of rice, which probably performed through the interaction of the OsRbohB-mediated ROS production and ABA signaling.

Constitutive expression of aldose reductase 1 from Zea mays exacerbates salt and drought sensitivity of transgenic Escherichia coli and Arabidopsis

Aldose reductases (ARs) have been considered to play important roles in sorbitol biosynthesis, cellular detoxification and stress response in some plants. ARs from maize are capable of catalyzing the oxidation of sorbitol to glucose. However, little is known how maize ARs response to abiotic stresses. In this work, we cloned one isoform of maize ARs (ZmAR1), and furthermore we analyzed the roles of ZmAR1 in response to salt and drought stresses at both prokaryotic and eukaryotic levels. ZmAR1 encodes a putative 35 kDa protein that contains 310 amino acids. Under normal growth conditions, ZmAR1 was expressed in maize seedlings, and the highest expression level was found in leaves. But when seedlings were subjected to drought or salt treatment, the expression levels of ZmAR1 were significantly reduced. The constitutive expression of ZmAR1 increased the sensitivity of recombinant E. coli cells to drought and salt stresses compared with the control. Under salt and drought stresses, transgenic Arabidopsis lines displayed lower seed germination rate, shorter seedling root length, lower chlorophyll content, lower survival rate and lower antioxidant enzyme activity than wild type (WT) plants, but transgenic Arabidopsis had higher relative conductivity, higher water loss rate, and more MDA content than WT. Meanwhile, the introduction of ZmAR1 into Arabidopsis changed the expression levels of some stress-related genes. Taken together, our results suggested that ZmAR1 might act as a negative regulator in response to salt and drought stresses in Arabidopsis by reducing the sorbitol content and modulating the expression levels of some stress-related genes.

Arabidopsis MDN1 Is Involved in the Establishment of a Normal Seed Proteome and Seed Germination.

Seed germination and formation are the beginning and ending, respectively, of a plant life cycle. These two processes are under fine regulation by the internal genetic information. Previously, we demonstrated that Arabidopsis MIDASIN 1 (MDN1) is required for ribosome biogenesis, and its dysfunction leads to pleiotropic developmental phenotypes, including impaired embryogenesis and slow seed germination. In this study, we further found that the weak mutant of MDN1, mdn1-1, exhibits an increased seed size phenotype. Seed proteomic analysis reveals that a number of proteins involved in seed development and response to external environments are mis-regulated by the MDN1 dysfunction. Many 2S seed storage proteins (SSPs) and late embryogenesis abundant (LEA) proteins are over-accumulated in the dry seeds of mdn1-1. Further, some genes encoding seed storage reserves are also upregulated in mdn1-1 seedlings. More interestingly, abscisic acid-insensitive 5 (ABI5) is over-accumulated in mdn1-1 seeds, and the loss of its function partially rescues the low seed germination rate of mdn1-1. Together, this study further demonstrates that MDN1 is essential for establishing a normal seed proteome, and its mutation triggers ABI5-mediated repression of seed germination.

The Stimulating Effects of Imazalil and Carbendazim Fungicides on in Vitro Propagation and ex Situ conservation of the Medicinal Balkan Range-Restricted Sideritis Raeseri Boiss & Heldr. Subsp. Raeseri

Sideritis raeseri Boiss & Heldr. subsp. raeseri, known in Greece as Mountain tea of Parnassus or Velouchi is a range restricted medicinal plant of the Balkan peninsula. Conventional propagation methods did not allow the mass production of plant material in a short period of time due to both low seed germination rate and rooting of cuttings. Therefore, the aim of this study was to establish a reliable, reproducible and efficient regeneration protocol for mass and large-scale micropropagation, germplasm and ex situ conservation of S. raeseri Boiss & Heldr. using Imazalil and Carbendazim fungicides. After 9 weeks, 2.5-10 mg/l Imazalil stimulated root length by 1 cm but diminished root number and rooting percentage. Optimum shoot number (5.58), shoot length (24.91 mm), shoot multiplication (100%), root number (20.63) and rooting (66.67%) were recorded with 0.5 mg/l kinetin (KN) + 0.05 mg/l ?-napthaleneacetic acid (NAA) (Imazalil-free). After 4 ½ weeks, 1 mg/l Carbendazim + 0.5 mg/l 6-benzyladenine (BA) yielded 5.77 shoots/explant, 16.1 mm shoot length and 100% shoot multiplication. However, Carbendazim did not result in rooting. The ex vitro survival percentage of rooted shoot-tip explants derived from Imazalil experiment was 95%. Carbendazim proved useful in shoot proliferarion and Imazalil in root elongation of S. raeseri Boiss & Heldr. subsp. raeseri micropropagation system.

Reduced bioactive gibberellin content in rice seeds under low temperature leads to decreased sugar consumption and low seed germination rates

GA is important for rice seed germination, and seed embryo growth relies on sugar supplementation via starch hydrolysis in the endosperm. Low temperature reduces the seed germination rates of rice; however, the mechanism of GA metabolism and its impact on sugar utilization of germinating seeds under low temperature conditions remain poorly understood. In this study, low-temperature (15 °C) treatment delayed rice (Oryza sativa L.) seed germination, promoted GA deactivation, inhibited GA signal transduction, and increased ABA synthesis in the seed compared with normal treatment (30 °C). Under low temperature conditions, the soluble sugar content in endosperm was reduced along with depression of the specific activity levels of α-amylase (EC 3.2.1.1) and β-amylase (EC 3.2.1.2), but the soluble sugar content was increased in the embryo compared with the control treatment. Low temperature treatment promoted sugar transportation from endosperm to embryo and reduced the activity levels of enzymes involved in glycolysis and the tricarboxylic acid cycle, which participated in sugar consumption. Exogenous GA3 application (10 μM) prompted GA signal transduction and inhibited ABA synthesis, while enhancing starch hydrolysis and sugar consumption to boost rice seed germination under low temperature conditions. In conclusion, a deficiency of bioactive GAs in rice seeds exposed to low temperature led to a decrement in starch hydrolysis and sugar consumption, thus inhibit seed germination.

Transcriptomic approach to address low germination rate in Cyclobalnopsis gilva seeds

Cyclobalnopsis gilva is a woody plant with lower seed germination rate in its natural habitats as compared with other plants. The regulation at transcriptional level to of seed germination in C.gilva is yet to be discovered. Illumina HiSeq 2500 platform was performed to investigate the transcriptome of germinated and non-germinated seeds of C.gilva. A total of 40,782 differentially expressed unigenes (DEGs) were identified in germinated and non-germinated seeds and compared with the control. Carbohydrate metabolisms were enriched significantly through the analysis of KEGG pathways of DEGs. The physiological parameters and mRNA expression levels relevant to carbohydrate metabolisms including glycolysis and TCA cycle, and sucrose and starch metabolism were found to be poor in non-germinated seeds. The consistent results of the transcriptomic data, physiological analyses, and mRNA expression levels suggest that C.gilva seeds fail to germinate due to the lower activity of carbohydrate metabolism. Our findings will expand the knowledge on the transcriptional responses of respiratory pathways, sucrose, and starch metabolism related to lower seed germination rate of C.gilva.

Exogenous gibberellin weakens lipid breakdown by increasing soluble sugars levels in early germination of zanthoxylum seeds

Zanthoxylum is a precious medicinal woody plant with a very low seed germination rate in China. The gibberellin (GA) treatment extremely increased the germination rate of zanthoxylum seeds. Our previous transcriptome data showed that exogenous GA played a negative role in the expression levels of genes involved in lipid metabolism during imbibition. Our present data indicated that compared with the GA-treated seeds, the soluble sugars were more quickly consumed and lipid breakdown was prematurely and actively initiated in the water-treated seeds during the early germination. However, the application of sucrose could improve the germination of water-treated seeds and significantly inhibit lipid breakdown. Both the application of sucrose and exogenous GA could significantly reduce the catalytic activities of sugar–dependent 1 (SDP1) and isocitratelyase (ICL), the expressions of SDP1 and ICL genes, and decrease the products of lipid breakdown as well during the early germination. We suggested that exogenous GA might enhance starch hydrolysis by promoting the catalytic activity of ɑ–amylase to supplement metabolically consumed soluble sugars, thus the increased sugars levels would help to inhibit the lipid breakdown to mitigate oxidative damages in the early germination of zanthoxylum seeds. In the end, we summarized the possible molecular mechanism on the exogenous GA weakening lipid breakdown by increasing soluble sugars levels in the early germination of zanthoxylum seeds.

Shifts in functional trait-species abundance relationships over secondary subalpine meadow succession in the Qinghai-Tibetan Plateau.

Although trait-based processes of community assembly during secondary succession invokes multiple factors that ultimately determine the presence or absence of a species, little is known regarding the impacts of functional traits on species abundance in successional plant communities. Here in species-rich subalpine secondary successional meadows of the Qinghai-Tibetan Plateau, we measured photosynthesis rate and leaf proline content that are related to plant growth and abiotic stress resistance, respectively, and seed germination rate that is closely correlated with plant germination strategy to test their influence on species abundance during succession. We used a linear mixed effects model framework to examine the shifts in trait-abundance relationships and the correlations among these three traits in successional communities. We observed significant shifts in trait-abundance relationships during succession, e.g., abundant species in early-successional meadows exhibited relatively high photosynthesis rates and leaf proline content, but showed low seed germination rates, whereas the converse were true in late successional communities. However, the correlations among the three traits were insignificant in most meadow communities. Our results show that functional traits associated with plant growth, stress resistance, and reproduction impose strong influence on species abundance during secondary subalpine meadow succession in the Qinghai-Tibetan Plateau.

Habitat fragmentation, low seed germination rates, and herbivory impede conservation efforts for a prairie relict wildflower

Fire exclusion, agriculture, and the extirpation of large herbivores have contributed to the loss of early successional plant communities and species across the southeast USA. Georgia aster (Symphyotrichum georgianum (Alexander) G.L. Nesom), a wildflower endemic to the southeast Piedmont, is one species that is thought to have experienced a notable decline. To document the status of S. georgianum in an area in which Piedmont prairie plant communities were historically present (Clemson Experimental Forest, Central, SC), we inventoried patches and flowers and collected seeds for a germination study. We found 37 patches across this 7,082-ha forested landscape, with an average of 25 flowers/patch. Seed germination rates were low, averaging 11%. In addition to fragmentation and low seed-germination rates, camera traps suggest herbivory from eastern cottontail rabbits (Sylvilagus floridanus J.A. Allen) further constrains the population. We conclude that forest management that creates, maintains, and connects early successional habitat is crucial in the conservation of S. georgianum.

DEPRESI SILANG DALAM BIJI DAN SEMAI Melaleuca alternifolia

Tea tree (Melaleuca alternifolia) is known as an essential oil producer. This species is commercially important as a source of essential oil especially in Australia. To improve its oil quality, research on artificial pollination between plus trees were carried out. The information about self-incompatibility and inbreeding depression due to self-pollination should be ascertained to support the pollination success. This study was aimed at examining the self-incompatibility of tea tree by conducting controlled self-pollination and cross-pollination. Controlled cross and self-pollination were carried out at a seedling seed orchard of tea tree, using four mother trees as experimental samples. Natural self-pollination was undertaken by bagging nopened flowers, without emasculation and counting the number of capsule set. Open pollination was used as a control treatment, of which the number of unopened flowers and the number of capsule set were counted. Observations revealed that no capsule was found from controlled self pollination (with the index self-incompatibility = 0), even though natural self-pollination produced low number of capsules (with the index self-incompatibility = 0.24). Therefore, it can be assumed that high level of self-incompatibility was took place in tea tree. Inbreeding depression also existed in this species, revealed by the decreased number of capsul set, lower seed germination rate of self-pollinated seeds than cross pollinated seeds. The slower growth of self-pollinated seedlings than cross pollinated seedlings in the nursery also indicated that inbreeding depression occured.

Proteomic approach to address low seed germination in Cyclobalnopsis gilva.

Seeds play essential roles in plant life cycle and germination is a complex process which is associated with different phases of water imbibition. Upon imbibition, seeds begin utilization of storage substances coupled with metabolic activity and biosynthesis of new proteins. Regeneration of organelles and emergence of radicals lead to the establishment of seedlings. All these activities are regulated in coordinated manners. Translation is the requirement of germination of seeds via involvements of several proteins like beta-amylase, starch phosphorylase. Some important proteins involved in seed germination are discussed in this review. In the past decade, several proteomic studies regarding seed germination of various species such as rice, Arabidopsis have been conducted. We face A paucity of proteomic data with respect to woody plants e.g. Fagus, Pheonix etc. With particular reference to Cyclobalnopsis gilva, a woody plant having low seed germination rate, no proteomic studies have been conducted. The review aims to reveal the complex seed germination mechanisms from woody and herbaceous plants that will help in understanding different seed germination phases and the involved proteins in C. gilva.

Resistance to Soybean Cyst Nematode: Rhg1

The genes underlying rhg1 lie at a sometimes dominant sometimes co-dominant locus, necessary for resistance to all Hg types of the soybean (Glycine max (L.) Merr.) cyst nematode (Heterodera glycines). Genomic research identified; nucleotide changes within a candidate gene encoding a receptor like kinase (RLK) that were capable of altering root development and thereby part of the resistance to Hg types 0 (race 3); changes in a laccase that are capable of altering cyst development; and genes underlying changes in membrane biology. This set of three genes are subject to co-selection with a modifier locus on another linkage block. Root development is slowed in the resistant seedling and results in end of season yield loss when SCN is not present. However, in the presence of SCN resistant seedling roots grow just as vigorously as the now slower growing parasitized susceptible roots and therefore show little loss to SCN parasitism. In some genotypes but not others the RLK can act alone to confer resistance. Functional paralogs of the three gene cluster have been found on other linkage groups including A1, B1, G, and O and these can be functional in different sources of resistance like G. soja, PI 437654 and PI438489B. At rhg1 the allele differences change the structure, interacting partners and activity of the LRR protein and the laccase. The changes between the alleles result in about 30 other proteins (judged by 2 Dgels), 112 metabolites (by FTICRMS) and 8 metabolites (by GCMS) to increase in abundance in roots during SCN infection in the resistant NILs. Understanding the basis of root stunting by resistance alleles will be used to improve methods for developing new nematode resistant soybean cultivars that do not suffer from the yield suppression and low seed germination rates of existing cultivars.

In silico Structural and Functional Analysis of Arabidopsis thaliana’s XPB Homologs

Arabidopsis thaliana has two homologs of the corresponding human xeroderma pigmentosum group B (XPB) helicase protein. The proteins namely AtXPB1 and AtXPB2, which are 95% similar, participate in transcription and Nucleotide Excision Repair. We used bioinformatic tools to investigate the phylogeny, structure, domains, docking site, and interactome of the two paralogs in order to reveal their functional differences. This study suggests that AtXPB1 interacts with Farnesyl Pyrophosphate Synthase 2 (FPS2), a rate-limiting enzyme in the synthesis of brassinosteroids, and Heat Shock Protein 90 (AtHSP90), such interactions were absent from the AtXPB2 interactome. AtXPB1 may be required to regulate the activity of Farnesyl Pyrophosphate Synthase 2, which controls the levels of brassinosteroids, phytohormones that control multiple physiological processes required for normal plant growth and development. In addition, AtXPB1 may have better oxidative stress tolerance than AtXPB2 as AtHSP90 seems to stabilize and protect the former from the proteasomal degradation induced by oxidative stress. These results were applied to the previously observed phenotypic characteristics of atxpb1-/- mutants which show great sensitivity to the oxidative stress-inducing agent hypochlorous acid, and experience absence of germination synchrony, lower seed germination rate, and delay in organ differentiation Keywords: AtHSP90, brassinosteroids, FPS2, oxidative stress, XPB.

Seed Gravity, Germination, and Optimum Seeding Rate for Machine Transplanting in Colored Rice Varieties

최근 소비자들의 건강에 대한 관심이 증가함에 따라 건강기능성 성분이 다량 함유 되어 있는 유색벼 품종의 안전 육묘를 위한 종자의 발아특성, 적정 침종기간 및 적정 파종량을 구명하기 위한 시험결과는 다음과 같다. 1. 현미색이 흑색인 조생흑찰 및 신명흑찰은 비중이 1.0이하의 물에 뜨는 종자가 85.7~86.3%로 대부분을 차지하였고, 비중이 1.06이상 충실한 종자 비율은 1.0~1.3%로 다른 흑미에 비해 상대적으로 낮았다. 한편 신토흑미, 흑진주, 흑설, 흑남, 흑광은 비중이 1.0이하가 15.3~43.7%, 1.0~1.06이 24.6~39.4%, 1.0이상이 25.5~55.7%로 다양한 무게의 종자가 분포해 있었다. 그러나 적미인 홍진주, 적진주, 건강홍미는 일반벼인 일미벼와 같이 충실한 종자인 1.06이상의 비율이 84.0~86.6%로 높았고, 반면 비중이 1.0~1.06은 2.5~4.1%, 비중이 1.0이하의 물에 뜨는 종자의 비율은 9.3~12.1%로 낮았다. 2. 흑미는 일반적으로 물온도에 관계없이 발아율이 적미보다 낮았고 발아속도가 느렸으며 평균발아일수도 길었고 수분흡수율도 낮았다. 그 결과 80%이상 발아하기 까지 침종기간이 적미나 일반벼 보다 2~4일 가량 더 결렸다. 이것은 흑미는 비중이 1.0이하의 가벼운 종자가 적미보다 훨씬 높았기 때문이다. 3. 상자육묘시 흑미의 출아율은 10일묘에서 75.2~82.2%, 30일묘에서 85.3~90.9%로 적미보다 10일묘에서는 4.5~8.0%, 30일묘에서는 0~3.3% 낮았는데 이것은 미출아율 종자가 많았기 때문이었다. 4. 기계이앙 육묘시 유색벼의 안전 육묘를 위한 적정 파종량은 관행 일미벼 어린모 및 중묘의 상자당 성묘개체수를 기준으로 흑미의 경우 어린모는 200~220g, 중묘는 110~130g이었고 적미는 일반벼와 같이 어린모 220g, 중묘 130g이었다. Seeds of colored rice generally have high anthocyanin and flavonoid content but some cultivars have low seed germination rate. This defect poses unstable seedling establishment in nursery bed. The seed gravity variations of 10 colored rice varieties and its effect on germination, seed soaking duration and their optimum seeding rates for seedling raising in machine transplanting were investigated in the experiment. Based on seed gravity distribution of the 7 black- and 3 red-colored rice varieties at three levels of seed gravity (1.0<, 1.0~1.06, 1.06>), the black colored seeds such as Josaengheugchal and Sinmyungheugchal had high amount of specific gravity of below 1.0 ranging from 86~ 96%, while they had only 3~13% of seeds in specific gravity above 1.06. Sintoheugmi, Heugjinju, Heugnam, Heugkwang had various mass of seeds, showing 29~44% for specific gravity of below 1.0, 24~39% for 1.0~1.06 and 25~45% for above 1.06. On the other hand, the red colored rice such as Hongjinju, Jeogjinju and Geonkanghongmi had high percentage of specific gravity of above 1.06 with 84~86% while they had only 9~12% of specific gravity below 1.0 similar to Ilmibyeo of noncolored rice. The black colored seed generally showed low germination percentage, slow germination speed and long mean germination time, and low water absorption rate as compared with seed of the red colored rice which was similar to those of Ilmibyeo used as a control cultivar. The black colored seeds took 2~4 days longer seed soaking duration than the red colored rice before germination. This was related to high seed amount of specific gravity below 1.0 in black colored rices. The high amount of seed gravity above 1.06 in the colored rice seeds was positively correlated with percentage of germination, germination speed and mean germination time, ripened grain ratio and water absorption. Seed gravity distribution effect were less pronounced between back- and red- colored seeds in seedling emergence. The black colored rice has slightly lower normal seedling emergence rate than the red colored rice and Ilmibyeo in the seedbed soil due to high percentage of ungerminated seed. Normal seedling emergence rate of the black colored rice in the seedbed was 75.2~82.2% for 10-day old seedling and 85.3~ 90.9% for 30-day old seedling which was lower by 4.5~ 8.0% and 0~3.3%, respectively, than the red colored rice. Based on the normal seedling number per tray of Ilmibyeo for seeding rate of 10-day and 30-day old seedlings, the recommended seeding rate of black colored rice is 200~ 220g seeds for the 10-day old seedling and 110~130g for the 30-day old seedling in transplanting rice while the seeding rate of the red colored rice was 220g seeds for the 10-day old seedling and 130g for the 30-day old seedling.