Natural variation in the cytochrome c oxidase subunit 5B OsCOX5B regulates seed vigor by altering energy production in rice

Seed vigor is a crucial trait for the direct seeding of rice.Here we examined the genetic regulation of seed vigor traits in rice,including germination index(GI)and germination potential(GP),using a genome-wide association study approach.One major quantitative trait locus,qGI6/qGP6,was identified simultaneously for both GI and GP.The candidate gene encoding the cytochrome c oxidase subunit 5B(OsCOX5B)was validated for qGI6/qGP6.The disruption of OsCOX5B caused the vigor traits to be significantly lower in Oscox5b mutants than in the japonica Nipponbare wild type(WT).Gene co-expression analysis revealed that OsCOX5B influences seed vigor mainly by modulating the tricarboxylic acid cycle process.The glucose levels were significantly higher while the pyruvic acid and adenosine triphosphate levels were significantly lower in Oscox5b mutants than in WT during seed germination.The elite haplotype of OsCOX5B facilitates seed vigor by increasing its expression during seed germination.Thus,we propose that OsCOX5B is a potential target for the breeding of rice varieties with enhanced seed vigor for direct seeding.

Direct-Seeded Rice: Genetic Improvement of Game-Changing Traits for Better Adaption

The sustainability of rice production continues to be a subject of uncertainty and inquiry attributed to shifts in climatic conditions. In light of the impending climate change crisis and the high labor and water costs accompanying it, direct-seeded rice(DSR) is unquestionably one of the most practical solutions. Despite its resource and climate-friendly advantages, early maturing rice faces weed competitiveness and seedling establishment challenges. Resolving these issues is crucial for promoting its wider adoption among farmers, presenting it as a more effective sustainable rice cultivation method globally. Diverse traditional and contemporary breeding methods are employed to mitigate the limitations of the DSR approach, leveraging advanced techniques such as speed breeding and genome editing. Focusing on key traits like mesocotyl length elongation, early seedling vigor, root system architecture, and weed competitiveness holds promise for transformative improvements in DSR adaptation at a broader scale within farming communities. This review aims to summarize how these features contribute to increased crop production in DSR conditions and explore the research efforts focusing on enhancing DSR adaptation through these traits. Emphasizing the pivotal role of these game-changing traits in DSR adaptation, our analysis sheds light on their potential transformative impact and offers valuable insights for advancing DSR practices.

Investigation of GhFAT Genes Related to Seed Oil Content and Fatty Acid Composition in Gossypium hirsutum L.

Fatty Acyl-ACP thioesterase(FAT)is a key enzyme controlling oil biosynthesis in plant seeds.FATs can be divided into two subfamilies,FATA and FATB according to their amino acid sequences and substrate specificity.The Upland cotton genome contains 20 GhFAT genes,amongst which 6 genes were of the GhFATA subfamily and 14 of the GhFATB subfamily.The 20 GhFAT genes are unevenly distributed on 14 chromosomes.The GhFATA genes have 5 or 7 exons and the GhFATB genes have 6 or 7 exons.All GhFAT proteins have the conserved Acyl-ACP_TE domain and PLN02370 super family,the typical characteristics of plant thioesterases.Analyses of the expression level of GhFATs and the compositions of fatty acid in 5-60 days-post-anthesis seeds showed that the ratio of saturated fatty acids to unsaturated fatty acids was consistent with the expression profile of GhFATB12,GhFATB3,and GhFATB10;the ratio of monounsaturated fatty acid to polyunsaturated fatty acids was consistent with the expression profile of GhFATA3.The oil contents of mature cottonseeds were positively correlated with the contents of palmitic acid and linolenic acid as well as seed vigor.These results provide essential information for further exploring the role(s)of the specific GhFATs in determining oil biosynthesis and cottonseed compositions.

Effects of Different Seed Coating Agents on the Quality of"Grey-matter"Hybrid Rice Seeds

[Objectives]This study was conducted to select suitable mixed seed coating agents for improving the quality of"grey-matter"hybrid rice seeds.[Methods]Three different mixed seed coating agents(A,B,C)were used to coat the seeds of two varieties(Taiyou 390 and Zhenliangyou 8612)of hybrid rice with different"grey-matter"content(5%,15%,25%),and the results were investigated and compared.[Results]The combinations of treatment B(seed coating agent A+Linong)and treatment C(Manshijin+seed coating agent A)could significantly improve indexes including seed germination potential,germination rate,seed vigor,seedling height,fibrous roots and fresh weight of the two varieties with a"grey-matter"content greater than 15%,but had no significant effects on main root length,dry weight,leaf number and tiller number,and the effects of treatment B was better than those of treatment C.That is to say,mixed seed coating agent B(seed coating agent A+Linong)was suitable for use as a seed coating agent to improve the quality of"grey-matter"seeds.[Conclusions]This study provides a reference plan for the safe use of mixed seed batches with"grey-matter"deterioration.

Effects of Sunflower Artificial Aging on Seed Vigor and Physiological Characteristics

[Objective]The aim was to study the effects of sunflower artificial aging on seed vigor and physiological characteristics.[Method] The varieties of seed germination capacity,vigor of germination,germination index,vigor index,peroxidase（POD） activity,superoxide dismutase（SOD） activity and malondialdehyde（MDA） content for four sunflower germplasms such as＇SunM20＇,＇Deep Purple Minle＇,＇Da San Kui Hua 4＇and＇Ji Kui 24＇were studied under high temperature and high humidity conditions（100% RH,45 ℃） for different days（0 d,2 d,4 d,6 d,8 d,10 d）.[Result]The result showed that the germination capacity,vigor of germination,germination index,vigor index,POD activity,SOD activity declined gradually with the increase of seed aging days,whereas MDA content enhanced by degrees;The diggerences of resistance to artifical aging existed among the four accessions,＇SunM20＇was the most resistant one,and exhibited the strongest seed vigor,highest activities of two protective enzyme（POD,SOD） and lowest content of MDA at the uniform condition,moreover,the seed vigor and protective enzyme activities of＇SunM20＇changed slowest among the four materials during the aging process.[Conclusion]The distinct reduction of POD,SOD activities maybe the main reasons for the decrease of sunflower seed vigor at the artificial aging,and the gradual accumulation of a few MDA accelerated seeds aging.

Effects of Concentration of NO_3^--N on Root Vigor and Rhizosphere pH of Winter Wheat Seedlings

[Objective] The aim was to research the effect of concentration of NO-3-N on root vigor and rhizosphere pH of winter wheat seedlings under water culture.[Method]By selecting Hoagland's nutritional solution as cultural medium and winter wheat as material of experiment,on the basis,testing root vigor,nutrient solution NO-3 and change of pH values under the different level of disposal,such as high(containing NO-3-N 15 mmol/L),medium(containing NO-3-N 7.5 mmol/L)and lower(containing NO-3-N 2.5 mmol/L).[Result]The results of this research showed that the effect of different nitrogen level on the wastage of nutrient solution NO-3,the changes of pH values and root vigor is obvious under the hydroponics condition.[Conclusion]Though NO-3 is a safe nitrogen sources when it was supplied to plants too more,it would restrain assimilation on nitrate nitrogen farther,but when it was supplied to plants too little,it would lead to deficiency of NO-3 that plants uptake and decrease of root activity,so it isn't useful to wheat young seedling to absorb nitrogen nutrition.

The Effects of UV-B Radiation on Maize at the Seedling Stage

In this study, maize plant seedlings were grown in soilless cultures, with and without ^-B radiation at a close of 5.4 kJt（m2-d）. Three clays later, it was found that the treatment of UV-B radiation significantly reduced such characteristics as biomass, plant height, leaf area, and so on. Also, the photosynthesis of the maize was inhabited, the anti-oxid activity decreased, and the MDA concentration increased with the UV-B radiation exposure. The maize presented visible hybrid vigor under the control condition, while the hybrid vigor under UV-B radiation barely emerged in biomass, plant height, leaf area, and physiological metabolic index.

Identification of Quantitative Trait Loci for Cold Response of Seedling Vigor Traits in Rice

The quantitative trait loci （QTLs） for the seedling vigor traits under 12℃ cold water irrigation, such as the seedling height, the seedling fresh weight, the seedling dry weight, and their cold response index, were identified using an F2：3 population including 200 individuals and lines derived from a cross of indica and japonica ＂Milyang 23/Jileng 1＂ with microsatellite markers. All seedling vigor traits exhibited a continuous distribution near normal in F3 lines; these traits were quantitative traits controlled by multiple genes. Twelve QTLs conferring the seedling vigor traits under cold water irrigation were detected on chromosomes 1, 2, 7, 8, and 12, which explained the observed phenotypic variance from 5.2% to 17.9%. Among them, qCSH2 and qCSH12 were located in RM262-RM263 on chromosome 2 and RM270-RM17 on chromosome 12, respectively, which were associated with the seedling height, qSDW12 and qCSDW1 were located in RM19-RM270 on chromosome 12 and RM 129-RM9 on chromosome 1, respectively, which were correlated with the seedling dry weight and its cold response index, and the explained 16.6%, 17.9%, 15.9%, and 16.2% of the observed phenotypic variation, respectively. These QTLs alleles were derived from cold-tolerant parent Jileng 1; the gene actions of the two front genes showed their additive effect, and the two genes belind showed dominant and over dominant effects, respectively.

Analysis of Nutritional Characteristics of Boletus edulis Mycelium

This study aimed to investigate the nutritional characteristics of Boletus edulis mycelium. The results showed that the optimal carbon source was glucose;the optimal nitrogen source was peptone; the optimal inorganic salt was KH2PO4;the optimal vitamin was VB1. The optimal medium, in which B. edulis mycelium in-cubated at 28 ℃ and pH 5.5 exhibited the strongest growth vigor and the rapidest growth rate, contained 3.0% glucose, 0.20% peptone, 0.60% KH2PO4, 0.20% Mg-SO4＆#183;7H2O and 0.000 50% VB1.

Effects of Different Cultivation Methods on Growth, Yield and Quality of Cassava

The research explored effects of cultivation methods on growth, yield and quality of cassava. The results showed that the mulching treatment by direct seed- ing, the mulching treatment by transplanting, and the exposed treatment by trans- planting performed excellently in bringing seedling stage forward, improving germina- tion rate, yield and quality. For example, seedling emergence stages were 36, 31 and 31 d earlier; germination rates improved by 19.24%, 14.29% and 14.29%; yields grew by 41.98%, 26.72% and 11.45%; starch contents increased by 3.50%, 2.10% and 1.40%, respectively. Therefore, cassava in the mulching treatment by direct seeding is characterized by earlier seedling emergence stage, high germination rate, high yield and quality.

Study on Seed Vigor of Rice Photo-ThermoSensitive Genic Male Sterile(PTGMS) Line with Low Temperature Storage

To explore the change rule of seed vigor and seed application technology of rice PTGMS lines with low temperature storage,Zhun S,Y58S,Feng S and Guangzhan 63-4S stored in the seed bank with the temperature of 8-10 ℃ and with the relative humidity of 55% for different years were used as the materials to study the properties of seed vigor,growth and development in the field, etc. The re- sults showed that the germination potential, germination rate, germination index and vigor index of rice PTGMS lines seeds showed downward trends as the time of low temperature storage prolonged,and all of the germination rates of the seeds within five years were over 60%. The conductivity in the soaked solution of seeds was significantly increased with the prolonged low temperature storage time. Seedling rate,root length,white root number,base stem width and seedling dry weight of seeds showed downward trends as the time of low temperature storage prolonged. There was no significant difference between two integral seedling qualities of seeds within 4-6 years in low temperature storage. Compared with the germination rate of low temperature storage seeds soaking for 6,12 and 24 h,the appropriate soak time of long time low temperature storage or low vigor seeds was 12 h. A serious natural aging phenomenon occurred in low temperature storage seeds after out of the storage. The germination rate of seeds placed under natural condition for 50 d decreased obviously. The duration from seeding to heading of Zhun S,Y58S and Feng S shortened as the time of low temperature storage prolonged, while the vari- ation of panicle duration of all PTGMS lines was not obvious. In conclusion, rice PTGMS line seeds with low temperature storage in 5 years could still be used nor- mally. However.seeds after low temperature storage should be sowed as soon as possible, and the soaking time of low vigor seeds should be shortened,and the possibility that the decreased duration from seeding to heading should also be con- sidered.

Relationship Between Heterosis and Endogenous Plant Hormones in Liriodendron

To investigate the possible involvement of endogenous plant hormones in heterosis of Liriodendron interspecific hybrid, growth traits and contents of endogenous GA 1/3 (gibberellin A 1, A 3), IAA (indole_3_acetic acid) and iPA (isopentenyl adenine) of tulip tree ( L. chinense (Hemsl.) Sarg.), yellow poplar ( L. tulipifera L.) and their interspecific hybrid ( L. chinense × L. tulipifera ) were examined. Results showed that: (1) the heterosis in height growth trait of the interspecific hybrid was mainly caused by the reletively greater elongation of internodes. Although the uppermost three internodes had the potential of elongation, the first one, which had the greatest elongation amount, contributed to the heterosis of the height growth trait; (2) the contents of endogenous GA 1/3 , IAA and iPA were greatly different among tulip tree, yellow poplar and their interspecific hybrid. All of the three interspecific hybrid families studied significantly contained higher amount of endogenous GA 1/3 and iPA in the uppermost first internode than their parental species. And thus, a correlation between the contents of endogenous GA 1/3 and iPA, and hybrid vigor for height growth trait in Liriodendron was observed; (3) the rankings of endogenous GA 1/3 and iPA contents in the uppermost first internode of three hybrid families studied were not similar to the ranking for height of 3_year_old trees. Therefore, the contents of endogenous GA 1/3 and iPA in the uppermost first internode could not be used in predicting hybrid vigor among hybrid families.

Structure and Expression Analyses of a Gene Encoding Fructose-6-Phosphate, 2-Kinase/Fructose-2,6-Bisphosphatase from Maize

A full-length cDNA encoding fructose-6-phosphate, 2-kinase/fructose-2,6-bisphosphatase from maize (Zea mays L.) was cloned by the methods of reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE), and designated as mF2KP. The encoded protein is composed of two regions. Its COOH-terminal region is catalytic region and homologous to the enzymes from other eukaryotes; and its NH 2-terminal region is common and special region only in plant. A truncated fragment of mF2KP covering integrated catalytic region was expressed in Escherichia coli. The fusion protein had the activities of fructose-6-phosphate, 2-kinase as well as fructose-2,6-bisphosphatase. Northern blot showed that the transcript level of mF2KP in seedlings initiated from strong-vigor seeds is lower than that from weak-vigor seeds.

A Comparative Study on the Leaf Characteristics and Root Vigor of Bowl Lotus under Hydroponics and Soil Culture

[Objective] The experiment aimed to study the growth characteristics of hydroponic bowl lotus. [Method] The lotus variety Hongxia was chosen as the experimental material. Two treatments, hydroponics and soil culture were set to measure their photosynthetic indices, chlorophyll content and root vigor, and to observe their leaf tissue structure and stomatal characteristics. [Result] The findings indicated that there are no differences in the leaf physiological indices between bowl lotus under hydroponics and soil culture, while the leaf stomata of hydroponic bowl lotus is bigger and its amount is larger than that of soil-culture bowl lotus. At the same time, the ratio of the palisade tissue thickness to spongy tissue thickness is small,and its leaf tissue structure is loose. The root vigor of hydroponic bowl lotus reached its summit earlier, then began to drop. Whereas, the root activity of soil-culture lotus sustained increasing, with vigorous growth. [Conclusion] Therefore, it indicated that hydroponic bowl lotus can adapt to the aquatic-culture environment well and quickly, meanwhile, it also enters into its aging period quickly and its growth cycle gets shorter.

Study on Vigor of Kenaf Seeds Stored with Different Packaging Methods for 31 Years

This study was conducted to investigate the effects of different packaging methods on seed germination and vigor under a long-term bank storage condition, selecting suitable packaging materials and methods, and comprehensively estimate changes in seed vigor of seeds stored with different packaging materials. Hibiscus cannabinus L. seeds were stored in aluminium box, seed box, glass bottle, POlyethylene film bag, sack and kraft paper bag as packaging materials in a, long-term bank and tested for their seeds germinability, electrical conductivity and field seedling rate after 31 years. The results showed that the kenaf seeds with an initial germination rate of 88% exhibited the germination rates over 79.7% after being stored in the 6 packaging materials for 31 years, the germination rates of seeds packaged with paper bag and sack and of those sealed in film bag and aluminium box showed significantly decreased germination rates, while the seeds sealed in seed boxes and glass bottles exhibited non-significant decreases in seed germination rate, and their germination rates were still above 85%. Seed box and glass bottle were the packaging materials most suitable for long-term safe storage of kenaf seeds with a safe storage period long than 31 years.

Physiological Responses of Paspalum vaginatum Sw. to Cd Stress and Its Cd Accumulation Characteristics

The physiological responses of Paspalum vaginatum Sw. to Cd stress and its Cd accumulation characteristics were studied by investigating the effects of different concentrations of Cd on the growth, root vigor, leaf membrane permeability, membrane lipid peroxidation, protective enzyme activity and Cd accumulation of P. vaginatum. When the Cd concentration was over 50.00 mg/kg, with the increased Cd concentration, the CAT activity declined significantly, the synergistic effect between SOD and CAT was weakened, the MDA content increased greatly, and the root vigor decreased, leading to inhibited growth of P. vaginatum. When the Cd concentration was in the range of 0-50 mg/kg, the root vigor of P. vaginatum did not decline obviously, the activity of protective enzymes （SOD and CAT） was enhanced, and the MDA accumulation and cell membrane permeability did not increase significantly, thus the damage of Cd to P. vaginatum was lighter. Roots of P. vaginatum showed strong enrichment capacity for Cd. When the Cd concentration was up to 200.00 mg/kg, the Cd contents in shoot and root of P. vaginatum reached 39.15 and 1 097.38 mg/kg, respectively. It suggests that in the concentration range of 0-50.00 mg/kg, P. vaginatum can make effective responses to Cd stress and grow normally, and it can be planted as a candidate material to remediate Cd-contaminated soil.

Effects of Different-concentration EMS on Germination of Tarary Buckwheat [Fagopyrum tataricum(L.) Gaertn] Seeds

[Objective] This study aimed to determine the optimum ethyl methane sulfonate（EMS） concentration for germination of tarary buckwheat seeds so as to lay a solid foundation for obtaining excellent traits of tarary buckwheat and breeding new varieties that meet the requirements by EMS mutation breeding. [Method] The seeds of Jinqiaomai No.4, a local tarary buckwheat variety [Fagopyrum tataricum（L.） Gaertn] in Shanxi Province, were used as the material. They were mutagenized by different concentrations（0.3%, 0.5%, 0.7%, 1.0%, 1.5%, 1.7%） of EMS for different times（4, 8, 12 h）. Then the germination rate and germination vigor were analyzed. [Result] With the increase of EMS mutagenic agent concentration, the germination vigor, relative germination vigor, germination rate and relative germination rate are all trended to be decreased. When the EMS concentrations ranged from 0.3%to 1.0%, there were no significant differences between treatment and control groups（P〉0.05）. When the EMS concentrations were 1.5% and 1.7%, significant differences were shown between treatment and control groups（P〈0.01）. The 4 and 8 h treatment of EMS all had no significant effects on germination rate and relative germination rate of Jinqiaomai No.4, but the 12 h treatment of EMS showed significant effects. Among the three treatment times, there were still no significant differences in germination vigor and relative germination vigor between treatment and control groups. [Conclusion] The optimum median lethal dose and treatment time of EMS for mutagenizing Jinqiaomai No.4 were 1.7% and 12 h, respectively.

Preliminary Discussion on Stigma Vitality of Sterile Line Rong 18A and Its Application in Seed Production

Rong 18A is an Indica three-line sterile line bred with M5B×D Xing B, and has the characteristics of stable sterility, high outcrossing rate, good combining ability and good quality. With Rong 18A as an experimental material and Ⅱ-32A, Jin 23A and Gang46 A as the CK materials, a seed setting rate estimation method by daily pollination was used for measuring its stigma vigor, to comparatively analyze the decreasing rates and lasting time of stigma vigor of various materials under natural condition. According to experimental results and combining with field breeding practice, the application of stigma vigor of sterile lines on hybrid rice seed production was discussed.

Effects of Specific Gravity-based Seed Grading on Seed Germination, Seedling Emergence and Grain Yield of Hybrid Rice

Using the commercial seeds of two hybrid rice varieties including Lu- liangyou 996 and Liangyoupeijiu as the materials, four specific gravity-based seed grading treatments, Le., the specific gravity of 〈1.0 （T1）, 1.0-1.09 （T2）, 1.1-1.19（T3） and ≥1.2 （T4）, by selection with different saline solutions, and the control without seed grading （CK） were designed to study the effects of seed grading on seed germination, seedling emergence, seedling quality and grain yield. The results showed that the treatments of T2, T3 and T4 had higher or significantly higher seed germination rate, germination index and vigor index, seedling emergence rate and adult seedling rate than the CK, while T1 had significantly lower values of these traits than the CK. Compared with the CK, the number of spikelets per pani- cle was found to be the main reason for the yield increase of these treatments with high seed viability.

Effects of Induced Concentration and Time of EMS on Seed Germination of Common Buckwheat

[Objective] This study aimed to investigate the effects of induced concen- tration and time of EMS on seed germination of common buckwheat. [Method] The seeds of Jinqiaomai No.3, a common buckwheat cultivar, were used as the test material, and their germination was induced by different concentrations of EMS un- der different induced times. The germination rate, germination vigor, relative germi- nation rate and relative germination vigor of Jinqiaomai No.3 were measured. [Re- sult] With increased induced concentration and time of EMS, the germination rate, germination vigor, relative germination rate and relative germination vigor of Jinqiao- mai No.3 were all trended to be decreased. For Jinqiaomai No.3, the optima in- duced concentration and time of EMS was 1.0% and 4 h, respectively, and the lethal concentration was 1.7%. [Conclusion] The induced concentration and time of EMS all showed significant effects on seed germination of Jinqiaomai No.3.