Pectin methylesterase inhibitors GhPMEI53 and AtPMEI19 improve seed germination by modulating cell wall plasticity in cotton and Arabidopsis

The germination process of seeds is influenced by the interplay between two opposing factors,pectin methylesterase(PME)and pectin methylesterase inhibitor(PMEI),which collectively regulate patterns of pectin methylesterification.Despite the recognized importance of pectin methylesterification in seed germination,the specific mechanisms that govern this process remain unclear.In this study,we demonstrated that the overexpression of GhPMEI53is associated with a decrease in PME activity and an increase in pectin methylesterification.This leads to seed cell wall softening,which positively regulates cotton seed germination.AtPMEI19,the homologue in Arabidopsis thaliana,plays a similar role in seed germination to GhPMEI53,indicating a conserved function and mechanism of PMEI in seed germination regulation.Further studies revealed that GhPMEI53 and AtPMEI19 directly contribute to promoting radicle protrusion and seed germination by inducing cell wall softening and reducing mechanical strength.Additionally,the pathways of abscicic acid(ABA)and gibberellin(GA)in the transgenic materials showed significant changes,suggesting that GhPMEI53/AtPMEI19-mediated pectin methylesterification serves as a regulatory signal for the related phytohormones involved in seed germination.In summary,GhPMEI53 and its homologs alter the mechanical properties of cell walls,which influence the mechanical resistance of the endosperm or testa.Moreover,they impact cellular phytohormone pathways(e.g.,ABA and GA)to regulate seed germination.These findings enhance our understanding of pectin methylesterification in cellular morphological dynamics and signaling transduction,and contribute to a more comprehensive understanding of the PME/PMEI gene superfamily in plants.

Arginine promotes seed energy metabolism,increasing wheat seed germination at low temperature

Low temperatures during germination inhibit seed growth,lead to small and weak seedlings,and significantly reduce the wheat yield.Alleviating the adverse effects of low temperature on wheat seed germination is highly important for achieving high and stable wheat yields.In this study,Tongmai 6(insensitive)and Zhengmai 113(sensitive),which have different low-temperature sensitivities during germination were treated with low temperature during germination.The transcriptome,metabolome and physiological data revealed that low temperature decreased the germination rate,downregulated the expression of a large number of genes involved in regulating glycometabolism,and inhibited carbon,nitrogen(especially amino acids)and energy metabolism in the seeds.Arginine content increased at low temperature,and its increase in the low-temperature-tolerant variety was significantly greater than that in the sensitive variety.Arginine priming experiment showed that treatment with an appropriate concentration of arginine improved the seed germination rate.The conversion of starch to soluble sugar significantly increased under exogenous arginine conditions,the content of key metabolites in energy metabolism increased,and the utilization of ATP in the seeds increased.Taken together,arginine priming increased seed germination at low temperature by relieving inhibition of seed carbon and nitrogen metabolism and improving seed energy metabolism.

Genome-wide association study reveals that JASMONATE ZIM-DOMAIN 5 regulates seed germination in rice

Seed germination is a complex trait regulated by multiple genes in rice.However,the regulators of rice seed germination have yet to be sufficiently determined.Here,a quantitative trait locus(QTL)for rice seed germination was identified in a genome-wide association study.The candidate gene JASMONATE ZIM-DOMAIN 5(OsJAZ5)of the QTL was verified that positively regulates seed germination.OsJAZ5 regulation of seed germination involves an OsABI3-mediated abscisic acid pathway.Overexpression of OsJAZ5 facilitated seed germination.The application of OsJAZ5 might be useful for increasing seed germination for rice direct seeding.

Physiological characteristics changes of Aesculus chinensis seeds during natural dehydration

A study was conducted to determine the physiological characteristics changes of Aesculus chinensis seeds during natural dehydration in 2003. The results showed that A. chinensis seeds were recalcitrant with being highly desiccation-sensitive. The seed moisture content of fresh fruits was higher than 60%. When the seeds were naturally dried for 30 days, their moisture content declined to 30.2% and their viability was completely lost. The seed germination percentage had a small increase at the beginning of desiccation and then decreased rapidly. The relative electrical conductivity of the A. chinensis seeds increased along with a decrease in seed moisture content. However, there was an abnormal increase in relative electrical conductivity when the seed moisture content was between 53.7% and 50.9%. Superoxide dismutase （SOD） activity decreased rapidly in the period of desiccation except for an abnormality when the seed moisture content was between 53.7% and 50.9%. Malondialdehyde （MDA） content increased slowly at the early stage of desiccation and then rose rapidly after the moisture content was below 50.9%. The soluble sugar content in seeds slowly increased with the increasing period of desiccation. The seed germination percentage was at the high level when seed moisture content was in range of 47%- 60%, which suggests that this was the optimum moisture content for maintaining A. chinensis seed viability.

Analysis of Amylase and Superoxide Dismutase Isozymes During the Germination Process of Emmenopterys henryi Oliv Seeds

[ Objective] The study was to understand the changes of amylase（AMY） and superoxide dismutase（SOD） isozymes during the ger- mination process of Emmenopterys henryi Oliv seeds. [ Metbod] By employing polyacrylamide gel electrophoresis method, the expressions of AMY and SOD isozymes during seed germination process were analyzed. ~ Result] The main AMY bands remained strong during the whole peri- od and a new band A2 appeared in the middle and late period of seed germination. Some new SOD bands occurred at the early stage, then be- came weak or disappeared in the middle period, and band S6 became intense in the late peried. [ Conclusion.] The expression of AMY and SOD isozyme gene has temporal difference during germination of E. henryi Oliv seeds.

Effects of Nitric Oxide on the Germination of Wheat Seeds and Its Reactive Oxygen Species Metabolisms Under Osmotic Stress

Effects of sodium nitroprusside (SNP), a nitric oxide (NO) donor, on the germination and metabolism of reactive oxygen species were surveyed in wheat (Triticum aestivum L.) seeds. Germination of wheat seeds and even the elongation of radicle and plumule were dramatically promoted by SNP treatments during the germination under osmotic stress. Meanwhile, activities of amylase and EP were enhanced, thus leading to the degradation of storage reserve in seeds. After osmotic stress was removed, higher viability of wheat seeds was also maintained. In addition, the activities of CAT, APX and the content of proline were increased by SNP treatment simultaneously, but activities of LOX were inhibited, and both of which were beneficial for improving the antioxidant capacity during the germination of wheat seeds under osmotic stress. It was also shown that the increase of the activity of amylase induced by SNP in embryoless half-seeds of wheat in the beginning period of germination (6 h) might be indirectly related to GA(3).

The Role of Polyamine Oxidative Degradation in the Process of Lettuce Seed Germination

[Objective]The aim of this study was to understand the role of polyamine oxidative degradation in the process of lettuce seed germination. [Method]After lettuce seed soaking treatments with aminoguanidine （AG,a specific inhibitor of polyamine oxidases）,seed germination rate,activities of polyamine oxidase （PAO） and diamine oxidase （DAO）,change of endogenous polyamine and H2O2 content were determined. [Result]Compared with the control,AG treatment strongly inhibited the seed germination,which also had an extremely significant difference in seed germination rate after incubation for 12 h. During the seed germination,activities of PAO and DAO significantly changed,while their activities firstly increased and then decreased,then DAO and PAO reached peaks at 24 h and 48 h respectively. AG treatment was strongly inhibitory for activities of DAO and PAO,whose activities even disappeared after incubation with AG for 24 h and 36 h. During the seed germination,endogenous Put reduced sharply in the first 24 h,then reduced slowly in 24-60 h,while Spd decreased slowly in the early stage of germination,and then sharply declined after 48 h. However,Spm content was low but slightly increased,and the total polyamine gradually decreased. AG treatment could significantly increase endogenous polyamines,especially Put and Spd contents. During the seed germination,H2O2 content gradually increased,and had a peak from 36 to 48 h,then kept a high level at last. AG treatment could significantly reduce H2O2 content. [Conclusion]During the seed germination,the changes of endogenous polyamine and H2O2 content correspond with the changes of PAO and DAO activities,which indicate that there is an active polyamine metabolism of oxidative degradation during the lettuce seed germination.

Seed Germination of Eggplant (Solanum melongena L.) Luba 2 Treated with Hydrogen Peroxide

[Objective] This study aimed to investigate the effect of hydrogen peroxide on the seed germination of eggplant （Solanum melongena L.） Luba 2.[Method] The seeds of Luba 2 were separately soaked in 20％,40％,60％ and 80％ hydrogen peroxide solution for 2,5 and 10 min before seed germination.The germination rate and days to reach the maximum germination rate were calculated.[Result] Treatment with low concentrations （20％） of hydrogen peroxide for 2 and 5 min made eggplant Luba 2 germinate in advance,and shortened the time to reach the maximum germination rate.Treatment with high concentrations （60％ and 80％） of hydrogen peroxide solution for longer time （10 min） caused significant damage to the seeds,delayed seed germination,and reduced the germination rate.[Conclusion] This study will provide theoretical references for the production practices of eggplant.

Effect of Different Treatment on Seed Germination of Echinochloa crus-galli

The effect of different treatment on seed germination of Echinochloa crusgalli was investigated in this study. The results showed that GA3, concentrated sulfuric acid, KNO3, NaOH and temperature treatments all could promote the germination of E. crus-galli seeds, but there were great differences in the promoting effect. Seed soaking with 1 000-1 500 mg/L of GA3 for 24 h and seed soaking with concentrated sulfuric acid for 15-20 min all maintained the germination rate of E. crusgalli seeds higher than 70.0%; 1.5% NaOH made the germination rate of E. crusgalli seeds up to 93.7%, but higher-concentration NaOH significantly reduced the germination rate of E. crus-galli seeds; KNO3 treatment showed certain promoting effect on germination of E. crus-galli seeds, but the effect was not ideal, i.e., the germination rate was lower than 35.5%; 20-25 ℃ temperature treatment could effectively promote the germination of E. crus-galli seeds, and the germination rate ranged from 68.2% to 75.8%.

Effects of Cadmium Stress on Seed Germination and Seedling Growth of Brassica napus L.

To investigate the effects of the heavy metal cadmium （Cd） on seed ger- mination and seedling growth of Brassica napus L., 25 B. napus lines with different genetic background were treated with four concentrations （0, 1, 5 and 10 mg/L） of Cd, and then, their germination potential, germination rate, seedling length, main root length, seedling fresh weight, and seedling dry weight were measured. The re- sults showed that the response of the B. napus lines to Cd stress was different. With the increase of Cd concentration, the relative germination potential and relative seedling rate increased first and then decreased, and reached the maximum levels when the Cd concentration was 5 rag/L. The inhibitory effects of Cd stress on seedling growth indices in a decreasing order were root length〉seedling length〉 seedling fresh weight〉seedling water content. There were extremely significant differ- ences in the relative root length, relative seedling length, relative seedling fresh weight and relative seedling water content among the B. napus lines treated by dif- ferent concentrations of Cd, while there were no significant differences in the rela- tive germination potential and relative seedling rate among the lines, except that the relative seedling rate was significantly different among the lines treated by 5 mg/L Cd. The results suggested that seedling growth was more sensitive than seed ger- mination to heavy metal stress.

Effects of Pb Stress on Seed Germination and Seedling Growth of Two Weed Species Seeds

Objective] The aim was to investigate the effects of Pb stress on seed germination and seedling growth of Chenopodium glaucum and Chenopodium serot-inum L. [Method] With C. glaucum and C. serotinum as the study objects, the ef-fects of different concentrations of Pb on their seed germination and seedling growth, as wel as on the leaf SOD, POD and CAT activity were studied primarily. [Result] The germination potential of both the two kinds of weed seeds increased first and then decreased with the increase of Pb concentration. The germination po-tential of C. serotinum and C. glaucum seeds reached the peak at Pb concentration of 25 and 50 mg/L, respectively. With the increase of Pb treatment concentration, the germination rate, germination index and vigor index of C. serotinum and C. glaucum seeds decreased, and their bud length and root length also reduced gradu-al y. ln overal , the leaf SOD, POD and CAT activity of C. glaucum and C. serot-inum_ seedlings increased first and then decreased with the increased treatment concentration of Pb. The leaf SOD and POD activity of C. glaucum and C. serot-inum seedlings reached the maximum at Pb concentration of 200 and 100 mg/L, respectively, and the leaf CAT activity reached the maximum at Pb concentration of 100 mg/L. [Conclusion] The two Chenopodium species had strong tolerance to Pb stress, and they could be used as alternative accumulator plants of soil Pb contami-nation.

Effect of trace elements on growth of Pinus tabulaeformis seedling

The stimulative effect of trace elements on seed germination and seedling growth of Pinus tabulaeformis was tested. The experiments were carried out on seed soak and topdressing with different trace elements and varied concentrations at the nursery of Gardens Research Institute, Harbin, in 2000-2001. The experimental results showed that soaking seed with 1% and 0.2% concentrations of Mn element produced best result for seed germination, and the germination rate was increased by 9%~19% for the seeds treated with 1% concentration and 12%~14% for the seeds treated with 0.2% concentration compared with the control group. The seeds treated with boron element had lowest germination rate. For trace element topdressing, Mn and Mo elements presented good result for seedling growth and the treatment with low concentration was even better. The height or chlorophyll content of the seedlings with spray of low-concentration Mn and Mo element was much higher than that of untreated ones. In the contrast to the treating method of seed soak, topdressing (application of spraying on foliage) had evident effect on seedling growth.

Effects of Magnetized Water on Seed Germination of Welsh Onion (Allium fistulosum L.)

With Welsh Onion seeds employed as materials, effects of magnetized water on seed Germination were studied. The results showed the treatment of magnetized water soaking for 4 h promoted water absorption rate and amylase ac- tivities of seeds significantly, which accelerated the transformation process of en- dosperm starch to soluble sugar, resulting in emergence of 36 hours in advance under low temperature condition. Germination rate and germination potential of magnetized water soaking were higher than the contrast by 6.7% and 10.0%, which helped cultivate vigorous seedling.

Effects of Liquid Seaweed Bio-organic Fertilizer on Seed Germination and Seedling Growth of Vegetables

[Objective] This study aimed to investigate the effects of liquid seaweed bio-organic fertilizer on seed germination and seedling growth of different vegetables. [Method] Serial dilution concentrations of liquid seaweed bio-organic fertilizer were prepared for seed soaking and pot incubation of cucumber, tomato and chili, to ob- serve the effects of liquid seaweed bio-organic fertilizer on seed germination and seedling growth of vegetables. [Result] Compared with the control, germination rate of cucumber and tomato seeds applied with 600-fold liquid seaweed bio-organic fer- tilizer varied significantly; germination rate of chili seeds applied with 400-fold liquid seaweed bio-organic fertilizer varied significantly; germination energy and germination index of chili seeds applied with different dilution concentrations of liquid seaweed bio-organic fertilizer presented no significant differences. In addition, 200-fold and 400-fold liquid seaweed bio-organic fertilizer significantly improved the root length, plant height, plant fresh weight, plant dry weight, chlorophyll content and leaf area of cucumber, tomato and chili seedlings; after treated with 600-fold liquid seaweed bio-organic fertilizer, root length, chlorophyll content and leaf area of cucumber seedlings varied significantly compared with the control, but no significant differences were observed in plant height, plant fresh weight and plant dry weight; after treated with 600-fold liquid seaweed bio-organic fertilizer, root length, chlorophyll content, plant height, plant fresh weight and plant dry weight of chili and tomato varied sig- nificantly compared with the control, but no significant differences were observed in leaf area. [Conclusion] Soaking vegetable seeds with liquid seaweed bio-organic fer- tilizer can significantly improve seed generation rate and seedling growth.

Effects of Exogenous Vc on Seed Germination and Physiological Properties of Oil Sunflower(Helianthus annuus) under Salt Stress

[Objective] This study aimed to provide the theoretical and technical basis for alleviating salt damages in production practice of oil sunflower （Helianthus annuus）. [Method] Seeds of oil sunflower were used as experimental materials and treated with 120 mmol/L NaCI solution and 0-200 mg/L Vc solution during the germina- tion process, to investigate the effects of exogenous Vc on seed germination and physiological properties of oil sunflower under salt stress. [Result] Under salt stress, with the increase of Vc concentration, germination potential and germination rate of oil sunflower seeds, superoxide dismutase （SOD） and peroxidase （POD） activities and proline （Pro） content of oil sunflower seedlings increased first and then declined, which reached the maixmum in 80 mg/L Vc treatment, 120 mg/L Vc treatment and 80 mg/L Vc treatment, respectively; malondialdehyde （MDA） content of oil sunflower seedlings declined first and then increased, which reached the minimum in 160 mg/L Vc treatment. [Conclusion] To varying degrees, Vc could improve germination potential and germination rate of oil sunflower seeds and promote seedling growth under salt stress, thus alleviating the damages of salt stress to seed germination and seedling growth of oil sunflower.

Construction and Quality Analysis of Full-length cDNA Library of Phyllostachys heterocycla Germinating Seeds

[Objective] This study aimed to construct the full-length cDNA library for ger- minating seeds of Phyllostachys heterocycla [Method] Germinating seeds of P. hetero- cycla were used as experimental materials to construct the full-length cDNA library by using Oligo-capping method. [Result] The constructed library has a total capacity of 6.5×10^6 recombinant clones, and a low proportion of clones without inserted frag- ments; the size of inserted fragments ranges between 0.3-5.0 kb, with strict classifi- cation and ideal consistency. Furthermore, the proportion of clones harboring long in- serted fragments （1.0-5.0 kb） is as high as 30%, achieving the standard for high- quality full-length cDNA library. [Conclusion] The full-length cDNA library of germinat- ing seeds of P. heterocycla was successfully constructed, which laid important foun- dation for the functional genomics research of bamboo plants.

Effects of Bamboo Vinegar on Seed Germination and Seedling Growth of Different Flue-cured Tobacco Varieties

[Objective] The present experiment was conducted to study the effects of bamboo vinegar on seed germination and seedling growth of different flue-cured to- bacco varieties, so as to provide some references for its application in tobacco pro- duction. [Method] By using indoor culture dish method and greenhouse seedling- raising plate culture,four different concentrations of bamboo vinegar dilution （50, 100, 200 and 400 times）were designed and clean water was used as the control （CK）. The germination indices of Yunyan 97, Guiyan 2, Jiucaiping 2 and Bina 1 were de- termined after seed germinating. The seedling growth indices of Yunyan 97 were investigated after 10 days of spaying bamboo vinegar on seedling leaves at the 3r~ time. [Result] Compared with CK, different bamboo vinegar dilutions could inhibit the seed germination and seedling growth of all flue-cured tobacco varieties. The seed germination rate and index, vigor index, whole length, root length, stem length and fresh weight of seedlings of all varieties presented decreasing trend to varying de- grees, moreover, most of them reached significant level. Compared with CK, spray- ing different concentrations of bamboo vinegar dilution at the seedling stage could improve the quality of seedlings. In all bamboo vinegar treatments, the plant height, the maximum leaf length and root volume under 100 times dilution treatment were the highest with 3.36 and 10.14 cm, and 0.92 ml, respectively. And the stem girth, dry weight and the maximum leaf width of seedlings under 400 times dilution treat- ment also showed the highest with 1.82 cm, 0.262 g and 5.74 cm, respectively. [Conclusion] Supplying different concentrations of bamboo vinegar solution on culture dish could inhibit the seed germination and seedling growth of flue-cured tobacco, while spraying 100-400 times bamboo vinegar solution to leaves could promote the seedling growth and improve the quality of Yunyan 97 to varying degrees.

Effects of NaCl Stress on Seed Germination of Four Canavium album Raeuseh Cultivars

The effects of different concentrations of NaCl stresses on seed germina- tion and seedling growth of Canavium album （Lour.） Raeuseh. were investigated. In addition, the amylase activity was measured. The results showed that the four Canavium album Raeuseh cultivars were sensitive to NaCI stress in varying de- grees. When the NaCI concentration was less than 0.8%, the seed germination rates of the four Canavium album Raeuseh cultivars were all higher than 90%. However, with the increased NaCI concentration, the water intake by seed germina- tion was inhibited, the amylase activity was decreased, and the germination rate, germination index and vigor index were all trended to be decreased, which differed among the four test cultivars. When the NaCl concentration was less than 0.4%, the seedling growths of the four Canavium album Raeuseh cultivars were not af- fected. But when the NaCI concentration was increased, the critical salinities inhibit- ing radicle growth were different among the four cultivars （Huiyuan, 1.0%; Chayao No.1, 1.2%; Sanfang, 1.4%; Frantoio, 1.6%）. Among the four test cuttivars, the sen- sitivities to NaCl stress ranked as Huiyuan 〉 Chayao No.1 〉 Sanfang 〉 Frantoio.

Effects of Different Treatments on Seed Germination of Gagea nigra

According to different mechanisms of dormancy,seeds of Gagea nigra L.Z.Shue were treated with different methods so as to investigate the effects of different treatments on seed germination of G.nigra.The results showed that at 4 ℃,the seeds of G.nigra began to germinate on day 32 with germination period of 80 d and germination rate of 72%;room temperature（25 ℃） and acid and alkali treatments were all unsuitable for the germination of G.nigra seeds;no significant differences were found in germination rate of G.nigra seeds among warm water（50℃）,ultrasound and 200 mg/L GA_3treatments（P 0.05）;seed coat-removing treatment effectively promoted the germination of G.nigra seeds（P =0.002 0.01） with germination rate of 88%;seed coat piercing ＋ 200 mg/L GA_3 and 500 mg/L GA_3＋15% H_2O_2 treatments effectively promoted the germination of G.nigra seeds with germination rates of 84% and 82%,respectively（P0.05）;the germination vigor of G.nigra seeds in the seed coat piercing ＋ 200 mg/L GA_3 treatment was highest,and it was significantly higher than those in the other treatments.

Effects of Antibiotics on Seed Germination of Different Rape Cultivars

[Objective] The research aimed to study the seed germination and growth of different rape cultivars, including Brassica napus, Brassica juncea and Brassica rapa, treated with kanamycin or hygromycin at different concentrations. [Method] Brassica napus Chun K101, Brassica napus L0935 and Brassica rapa L0926 seeds were cultured on 1/2 MS medium supplemented with different concentrations of antibiotics. The hypocotyl and taproot changes of different rape cultivated were recorded and analyzed. [Result] It was shown that 50 mg/L kanamycin could stimulate rapeseed hypocotyl growth, but obviously restrain taproot development. Hygromycin apparently inhibited the growth of hypocotyl and taproot of all the three cultivars. [Conclusion] Kanamycin was suitable to screen the transformed seed of Brassica juncea. The optimal concentration of hygromycin to screen transgenic rapeseed was 40-60 mg/L.