[Changes of wheat seed vigor at different development stages and their response to environmental temperature]. / ä¸åŒå‘è‚²æ—¶æœŸå°éº¦ç§å­æ´»åŠ›çš„å˜åŒ–åŠå ¶å¯¹çŽ¯å¢ƒæ¸©åº¦çš„å“åº”.

Two wheat cultivars (Jimai 22 and Shannong 23) were selected to investigate the changes of seed vigor at different development stages in different years by standard germination test, and the effect of environmental temperature on it was also analyzed, which would provide a theoretical basis for the utilization of early wheat seeds and the production of high vigor seeds. The results showed that the germination ability of fresh seeds appeared around 26 d after anthesis, and then the germination rate of fresh seeds displayed an overall upward trend with the development of wheat seeds. The germination energy, germination rate and germination index of dry seeds rapidly increased from 5 d to 8 d after anthesis, and then remained relatively stable, while the vigor index increased continually and reached the peak 4-6 days before the end of ripening due to the increase of seedling dry mass. The dry seeds at different developmental stages were also studied by field-plan-ting and the seed vigor of their progenies was also determined. For Jimai 22, the results indicated that the field emergence of dry seeds at 17 d after anthesis was higher and the plant could form grains, there were no significant differences in germination rate and vigor index among different samples of progeny seeds. In addition, the changes of seed vigor at different development stages were significantly affected by the environmental temperature. In the year with the high mean daily average temperature, high mean daily maximum temperature, high mean daily minimum temperature after anthesis, and large mean daily temperature difference after anthesis, the seed development time was shorter, but the 100-grain mass and seed vigor reached the peak earlier; Otherwise, the seed development time was longer, but the accumulated temperature of ripe stage was higher, and the seed vigor was higher.

[Relationships of wheat seed vigor with enzyme activities and gene expression related to seed germination under stress conditions.] / é€†å¢ƒæ¡ä»¶ä¸‹å°éº¦ç§å­æ´»åŠ›ä¸Žç§å­èŒå‘ç›¸å ³é ¶æ´»æ€§åŠå ¶åŸºå› è¡¨è¾¾çš„å ³ç³».

This study aimed to analyze the enzyme activities and gene expression differences related to seed germination in different wheat genotypes, and to clarify the relationship between seed vigor and the related enzyme activities as well as gene expression under stress germination conditions. We measured seed vigor, total soluble sugar content, soluble protein content, α-amylase activity, cysteine protease activity and gene expression of the related enzymes of four wheat cultivars under drought, artificial aging and cold soaking stress. Results showed that drought, artificial aging and cold soaking stress affected seed vigor to some extent. Under different germination conditions, total soluble sugar content showed an increasing trend with small amplitude at first and then decreased with small amplitude and after that increased rapidly again, while soluble protein content in the four cultivars gradually decreased with germination time. The α-amylase activity of the four cultivars showed a rising trend on the whole, but that of Yunong 949 and Lunxuan 061 declined after germinating for 60 hours after cold soaking stress. Cysteine protease activity decreased at first and then increased as a whole. However, under drought stress condition, cysteine protease activity of Yunong 949, Yumai 49-198 and Lunxuan 061 increased at first and then decreased and finally increased again. The α-AMY (α-amylase gene) expression levels increased at first and then decreased as a whole under different germination conditions. The expression level of α-AMY in Lunxuan 061 after cold soaking stress was higher than that of CK, while the α-AMY expression levels in four cultivars under other stress germination conditions were lower than that of CK. The expression level of CP (cysteine protease gene) showed an increasing trend. No significant difference of CP expression level was found in Chang 4738 between artificial aging treatment and CK. The CP expression levels in the four cultivars under other stress conditions were higher than that of CK. The results demonstrated that there was no direct relationship between the enzyme activities and gene expression levels of α-amylase and cysteine protease under different germination conditions. The α-amylase activity and total soluble sugar content had an extremely significant positive correlation, but the correlation between cysteine protease activity and soluble protein content was not significant. The α-amylase activity significantly positively correlated with vigor index under standard germination condition. However, the α-amylase activity had no significant correlation with vigor index under stress conditions. After cold soaking stress, cysteine protease activity significantly positively correlated with vi-gor index during seed germination, but the correlation was not significant under standard germination, drought stress and artificial aging.

[Seed vigor evaluation based on adversity resistance index of wheat seed germination under stress conditions.] / 基于小麦种子发芽逆境抗逆指数的种子活力评价.

A total of 16 wheat cultivars were selected to detect seed vigor of different genotypes using standard germination test, seed germination test under stress conditions and field emergence test. The adversity resistance indices of seed vigor indices and field emergence percentage under different germination conditions were used as the indices to evaluate adversity resistance. Principal component analysis and cluster analysis were used for the comprehensive evaluation of seed vigor. Results showed that drought stress, artificial aging and cold soaking treatments affected seed vigor to some extent. The adversity resistance indices of the artificial aging and cold soaking tests were significantly positively correlated with the field emergence percentage, while the adversity resistance index of drought stress test had no significant correlation with the field emergence percentage. 16 wheat cultivars were classified as three groups based on the principal component analysis and cluster analysis. Yunong 949, Yumai 49-198, Luyuan 502, Zhengyumai 9987, Shimai 21, Shannong 23, and Shixin 828 belonged to high vigor seeds. Xunong 5, Yunong 982, Tangmai 8, Jimai 20, Jimai 22, Jinan 17, and Shannong 20 belonged to medium vigor seeds. The other two cultivars, Chang 4738 and Lunxuan 061, belonged to low vigor seeds.

Pollen flow of wheat under natural conditions in the Huanghuai River Wheat Region, China.

The transgenic pollen spread is the main pathway of transgenic plant gene flow. The maximum distance of pollen dispersal (horizontal), the spatial dynamics of pollen movement (vertical), and the patterns of pollen dispersal are important considerations in biosafety assessments of genetically modified crops. To evaluate wheat (Triticum aestivum) pollen dispersal, we measured the pollen suspension velocity and analyzed pollen dispersal patterns under natural conditions in the Huanghuai River wheat-growing region in 2009. The pollen suspension velocity was 0.3-0.4 m/s. The highest pollen densities were detected in the north, northwest, and south of the pollen source. Pollen was dispersed over distances greater than 245 m in the northwest and northeast directions. At the pollen source center, pollen density decreased with increasing vertical height. In the north of the pollen source, the pollen density from 65 m to 225 m showed a wave-mode decrease with increasing height. The horizontal transport of pollen over longer distances fitted polynomial equations. In the north, the pollen density was highest at 45 m from the pollen source, and decreased with increasing distance. In the northwest, the pollen density showed a double-peak trend. In the northeast, pollen density was highest from 45 m to 125 m from the source. Wind speeds greater than the pollen suspension velocity and the duration of continuous gusts were the main factors affecting pollen dispersal. This information will be useful for determining the spatial isolation distances for hybrid seed production and for the commercial production of transgenic wheat.

[Effects of different planting patterns on farmland soil quality in Yellow River alluvial plain of Shandong Province].

Taking Chiping County in the Yellow River alluvial plain of Shandong Province as study area, a systematical survey was conducted on the 20 parameters of farmland soil physical and chemical properties under wheat/corn rotation, open air vegetable planting, sunlight greenhouse vegetable planting, and plastic shed vegetable planting, aimed to evaluate the effects of different planting patterns on the farmland soil quality in the plain. Significant differences (P < 0.05 or P < 0.01) were observed in the soil pH, soil moisture content, and the contents of soil organic matter, N, P, K, available S and Zn, and total salt under different planting patterns. The soil available P under all tested planting patterns and the soil available S under sunlight greenhouse vegetable planting presented a comparatively higher variability. Different planting patterns had significant effects on the soil quality, with the trend of protected vegetable planting > open air vegetable planting > wheat/ corn rotation. The effects were higher on soil chemical properties than on soil physical properties, and higher on soil organic matter and macronutrients than on soil secondary nutrients. Soil micronutrients were less affected. The main causes for these were the straw-returning of wheat and corn, the application of sulfur-containing and zinc fertilizers, and the long-term high rate fertilization of protected vegetable planting.

The involvement of chloroplast HSP100/ClpB in the acquired thermotolerance in tomato.

The chloroplast HSP100/ClpB is a newly documented member of the ClpB family, but little was known about its role in imparting thermotolerance to cells. A cDNA coding for a HSP100/ClpB homolog has been cloned from Lycopersicon esculentum and termed as Lehsp100/ClpB (the cDNA sequence of Lehsp100/ClpB has been submitted to the GenBank database under accession number: AB219939). The protein encoded by the cDNA was most similar to the putative chloroplast HSP100/ClpBs in higher plants and the ClpB from Cyanobacterium Synechococcus sp. A 97 kDa protein, which matched the predicted size of mature LeHSP100/ClpB, was immunologically detected in chloroplast isolated from heat-treated tomato plants. In addition, the fusion protein, combining the transit sequence of LeHSP100/ClpB and GFP, was found to be located in chloroplast based on the observations of fluorescent microscope images. These results indicated the chloroplast-localization of LeHSP100/ClpB. Both the transcript and the protein of Lehsp100/ClpB were not detected under normal growth conditions, but they were induced by increasingly higher temperatures. An antisense Lehsp100/ClpB cDNA fragment was introduced into the tomato by Agrobacterium-mediated transformation. Antisense lines exhibited an extreme repression of heat-induced expression of Lehsp100/ClpB. The levels of chloroplast HSP60 and small HSP in antisense lines were identical to those of the control plants. After plants preconditioned at 38 degrees C for 2 h were exposed to a lethal heat shock at 46 degrees C for 2 h, the antisense lines were greatly impaired and withered in 21 days of the recovery phase, whereas the untransformed control plants and the vector-transformed plants survived. Furthermore, chlorophyll fluorescence measurements showed that PS II in antisense lines were more susceptible to the thermal irreversible inactivation than the untransformed and vector-transformed control plants. This work provides the first example that induction of chloroplast LeHSP100/ClpB contributes to the acquisition of thermotolerance in higher plants.

[Molecular cloning of tomato LeHsp110/ClpB gene and its effect on the thermotolerance in plant].

The heat shock protein ClpB is a member of the Clp family and functions as molecular chaperones. ClpB is related to the acquired thermotolerance in organisms. A cDNA of 3144 bp was screened out of a tomato cDNA library. The polypeptide deduced from the longest ORF contains 980 amino acid residues, and was classified into HSP100/ClpB family based on the result of molecular phylogenesis analysis. Thus it was named as LeHSP110/ClpB according to its calculated molecular weight. LeHSP110/ClpB was characteristic of heat-inducibility but no constitutive expression, and was demonstrated to locate in chloroplastic stroma. An antisense cDNA fragment of LeHsp110/ClpB under the control of CaMV 35S promoter was introduced into tomato by Agrobacterium tumefactions-mediated method. At high temperature, the mRNA levels of LeHsp110/ClpB in antisense transgenic plants were lower than those in control plants. The PS II of transgenic plants is more sensitive to high temperature than that of control plants according to data of Fv/Fm. These results clearly showed that HSP110/ClpB plays an important role in thermotolerance of high plants.

Cloning and molecular characteristic of the metalloprotease gene LeftsH6 from tomato.

The full-length 2213-bp ftsH (filamentation temperature-sensitive H) cDNA was cloned from the cDNA library of heat-shocked tomato leaves. According to an open reading frame of 2019-bp, the deduced protein precursor was predicted to target chloroplast. The putative AAA (ATPases associated with diverse cellular activities) domain and the Zn(2+)-binding domain, characteristic of FtsH metalloproteases family, were found in the FtsH-like protein. Most similar to the FtsH6 of Arabidopsis thaliana, the tomato ftsH-like gene was named as Lycopersicon esculentum filamentation temperature-sensitive H6 (LeftsH6). Purified FtsH degraded casein but not BSA in vitro, whereas a FtsH mutant with the Glu(472) in the zinc-binding motif replaced by Gln had lost the protease activity. A single copy of LeftsH6 was detected in tomato genome by Southern blot analysis. Northern and Western blot analyses revealed consistently the heat-inducible character of the LeftsH6 gene. No LeftsH6 expression was detected after cold, salt, drought or light stress. The results provided the first experimental evidence of the existence of heat-inducible ftsH gene in higher plants.

Differential regulation of Lehsp23.8 in tomato plants: Analysis of a multiple stress-inducible promoter.

Small heat shock proteins (sHSPs) are the major family of HSP induced by heat stress in plants. In this report, an approximately 1.9kb of Lehsp23.8 5'-flanking sequence was isolated from tomato genome. By using the ß-glucuronidase (GUS) reporter gene system, the developmental and tissue specific expression of the gus gene controlled by the Lehsp23.8 promoter was characterized in transgenic tomato plants. Strong GUS staining was detected in the roots, leaves, flowers, fruits and germinated seeds after heat shock. The heat-induced GUS activity was different in the floral tissues at various developmental stages. Fluorometric GUS assay showed that the heat-induced GUS activity was higher in the pericarp than in the placenta, and it was the lowest in the locular gel. The heat-shock induction of the Lehsp23.8 promoter depended on the different stages of fruit development. The optimal heat-shock temperatures leading to the maximal GUS activity in the pericarp of green, breaker, pink and red fruits were 42, 36, 39 and 39°C, respectively. The heat-induced GUS activity in tomato fruits increased gradually within 48h of treatment and weakened during tomato fruit ripening. Obvious GUS activities under cold, exogenous ABA and heavy metal (Cd(2+), Cu(2+), Pb(2+) or Zn(2+)) stress conditions were also detected. These results show that the Lehsp23.8 promoter is characterized as strongly heat-inducible and multiple-stress responsive.