Based on surface observations, response of corn (Zea mays L.) to climate warming in the Hexi Corridor in the arid northwest of China was investigated. Results show that in the last 20 yr and more the response of corn to climate warming took the form that its growing season came in advance and its growth period became shorter period. And such response is related to the critical temperature. In case the mean temperature during the corn’s growth period was less than the critical temperature, an increase in temperature shortened its growth period. When the mean temperature was higher than the critical temperature, then a rise in temperature no longer showed a tendency of shortening. The continuous increase in temperature in future may cause the mean temperature of corn’s growth period to exceed the critical temperature, thus leading to lengthening of corn’s growth period. In addition, response of corn to climate warming varied in its different growing stages. An increase in temperature shortened corn’s phase of vegetative growth prior to the tasselling phase, prolonged the generative growth phase in the tasselling-milk stage, and cut down the generative growth phase in the milk-maturity stage. These characteristics may correlate with the climatic condition in the arid areas in the northwestern of China, the crop’s physiological properties, and the variation of temperature increase in various seasons.
Physiological and xeromorphic responses and adaptation of Populus euphratica Oliv. to artificial water-recharge of the lower reaches of Tarim River in Xinjiang Uygur Autonomous Region were investigated. Measurements were made of groundwater table, salt concentration in groundwater, as well as the contents of proline, soluble sugars, plant endogenous hormone (abscisic acid, ABA and cytokinin, CTK), and anatomic structure in P. euphratica leaves along 15 transects in three areas before and after the water-recharge. Results showed that, following the events of water-recharge, the groundwater table raised, which reduced the physiological stresses of P. euphratica. With the rising groundwater table, the groundwater salinity increased by 1.76 to 2.47 folds; the thickness of cuticular of epidermis cell, the vessel diameter and wall thickness of vascular bundle of mesophyll cell in P. euphratica leaves were reduced; but the developmental state of palisade tissue of leaves were not affected. The effect of water-recharge was at the optimum to the recovery and restoration of ecological environment in this region when groundwater table was raised to a range from -3.15 to -4.12 m below soil surface, and salt concentration of groundwater maintained in a range from 67.15 to 72.65 mmol/L.
Having been held in 10 mL/L 1-methylcyclopropene (1-MCP) or air for 18 h, seedless watermelon (Citrullus lanatus Thunb. Mansfeld, cv. Millionaire) fruit was cut to obtain pericarp cylinders (7 mm in diameter, 40 mm thick), which were rinsed with 2% CaCl2 or deionized water and then stored at 10 ℃. Tissue firmness, electrolyte leakage and activities of phospholipase C (PLC), phospholipase D (PLD) and lipoxygenase (LOX) were determined. Results suggested that 2% CaCl2 stimulated activities of phospholipase C (PLC), phospholipase C (PLD) and lipoxygenase (LOX), but maintained tissue firmness throughout storage. CaCl2 alone may not be sufficient to maintain quality of fresh-cut watermelon and even would exert negative effects for stimulating lipolytic enzymes. 1-MCP counteracted CaCl2 in regulation of PLC, PLD and LOX. Combination of 1-MCP and CaCl2 retarded the ripening process, as illustrated by higher firmness and lower activities of lipolytic enzymes in relative to the control.
Fructokinase (FRK) is of primary importance in phosphorylation of fructose in plants. Two genomic DNA fragments encoding putative fructokinase gene were isolated from Citrus unshiu Marc. using PCR, which were named Cufrk1 and Cufrk2. A cDNA sequence same to the exons’ sequences of Cufrk1 was amplified by RT-PCR and the full-length cDNA sequences of this gene was isolated using rapid amplifi-cation of cDNA ends (RACE) from mature fruit, named CuFRK1 (GenBank number: AY561840). Sequenc-ing analysis showed that the amino acid sequences were 68% identical between Cufrk1 and Cufrk2. The full-length cDNA of CuFRK1 was 1 459 bp in length and contained a complete ORF from 168 to 1 220 bp, encoding 350 amino acids with a calculated molecular weight of 37.5 kD and a predicted pI of 5.03. The deduced amino acids of CuFRK1 possessed two sugar-binding domains, three ATP-binding domains and were 62% to 78% identical to the previously characterized fructokinase genes of other plants. Northern analysis showed that transcripts of CuFRK1 (Cufrk1) and Cufrk2 were detected at a high level in leaves, fruit at early developmental stages, but undetectable in peels and stems. Their expression patterns were distinct in petals and mature fruit. Enzymatic analysis showed that the activity of citrus fructokinase was decreasing with the fruit development, coincided with the accumulation of fructose in fruit. There was a significantly negative correlation between the decreasing fructokinase activity and the increasing fructose content during fruit development.
Cre/lox -mediated gene excision in commercial rice (Oryza sativa L.) plants was studied with a recombination-reporter gene system, in which the selectable marker hygromycin phosphotransferase gene (hpt) flanking by two directly oriented lox sites was located between the rice actin1 promoter and a promoterless gusA gene. This system allows visualization of GUS expression by activating promoterless gusA after site-specific recombination. The crossing strategy was used to introduce the cre gene into the lox plants. In 30 hybrid plants from four crosses made from T0 actin1 promoter-lox -hpt -lox -gusA plant with T0 cre plant, 12 expressed GUS and 9 showed hygromycin-sensitive. We furthermore demonstrated the utility of the Cre/lox in excision of hpt marker gene in an elite indica rice restorer Minghui 86 transformed with both insecticidal modified cowpea trypsin inhibitor gene sck and Bacillus thuringiensis endotoxin gene cryIAc. In 77 hybrid plants from nine crosses made from T2 homozygous lox -hpt -lox -sck -cryIAc plant with T2 homozygous cre plant, 56 showed hygromycin-sensitive. Molecular analyses confirmed the excision of hpt in all hygromycin-sensitive plants.
Full-length DNA, cDNA and promoter sequences of nodulin-like gene have been isolated and characterized by isocaudarner inverse PCR (Ⅱ-PCR) and rapid isolating cDNA 5'' unknown sequence and promoter (RICUP) methods from cotton. Sequence analysis indicated that nodulin-like gene was 2 353 bp in size, including five introns and six exons. Its full-length cDNA was 1 480 bp, containing an 1 125-bp ORF structure, which encoded a 40.23-kD polypeptide with predicted isoelectric point of 8.433. A check against nr database in GenBank indicated that no DNA sequence was found to share homology with it. Searched in EST database, a 733-bp EST sequence of Gossypium arboreum L. (GenBank asscession number BF271235) was found to share 92% homology with it. Promoter of nodulin-like gene was 1 969 bp in length with several typical sequences, such as initiator, TATA box, CAAT-like box and AT-rich sequence. Southern blotting analysis suggested that one copy of nodulin-like gene was integrated into cotton genome. Northern blotting analysis showed that nodulin-like gene expressed preferentialy in fiber and reproductive organs of cotton, such as bud, flower and boll. Our work provides researchers with candidate genes to improve agronmic traits of cotton and also provide efficient expression elements for problem solving in transgenic Bt cotton, namely resistance to bollworm declining dramatically at late developmental stage of cotton.
The developmental morphology of the obturator and micropyle and the pathway of the pollen tubes in the ovarian locule in Phellodendron amurense Rupr. have been investigated by scanning electron microscopy and light microscopy. The obturator of the ovule is of funicular origin. As the ovule is fully developed, the obturator becomes considerably large and closely covers the micropyle. When the pistillate flower reaches the receptive phase, the morphology of the obturator is greatly modified, and its cells on the surface are radially expanded and appear to be columnar, semi-papillar or papillar. Following fertilization the obturator reduces in size and degenerates. The pollen tubes need not necessarily traverse the obturator. Whether the pollen tubes pass the obturator or not depends on the sites at which they enter the ovarian locule. This observation does not support the idea that the obturator mainly serves the function of mechanical guidance for the growth of pollen tubes. Our investigations indicate that the structure of the micropyle changes with the different stages of the reproductive process, and becomes asymmetrical during pollination. The development of the obturator and the micropyle correlates with that of the female gametophyte in P. amurense.
Pectinase activity was localized at the ultrastructural level in pollen mother cells of tobacco (Nicotiana tabacum L.) during meiotic prophaseⅠto elucidate its role in the biogenesis of secondary plasmodesma (sPD) and cytoplasmic channel (CC). At the leptotene stage the enzyme was mainly present in the cisternae of smooth endoplasmic reticulum (SER) and their derived vesicles, but absent in the Golgi body and Golgi vesicles. Later at the zygotene stage, when sPDs and CCs were actively formed, strong pectinase activity was observed not only in the SER cisternae and their derived vesicles but also in the cell wall, especially in the vicinity of or within both simple and branched plasmodesmata, notably along the middle lamellae, which also characterized the sites of CCs being formed. The presence of exocytotic vesicles containing reaction products suggests that pectinase shares the same excretive pathway as that used by cellulase for its delivery into the wall, i.e. in active form via smooth endoplasmic reticulum (ER) and its derived vesicles by exocytosis. In combination with cellulase, pectinase also promotes the secondary formation of plasmodesmata and CCs by specifically digesting the pectin in middle lamella.
A new monoterpene glycoside, hemiphroside C (1), along with seven known compounds were isolated from the whole plants of Hemiphragma heterophyllum Wall. By spectral evidence, the structure of the new compound was elucidated as (4S)-a-terpineol 8-O-b-D-xylopyranosyl-(1→6)-b-D-glucopyranoside. The known compounds were identified to be globularin (2), (2S, 3S, 4R, 9E)-1, 3, 4-trihydroxy-2-[(2''R)-hydroxytetracosanoylamino]-9-octadecene (3), b-amyrin (4), oleanolic acid (5), cinnamic acid (6), b-sitosterol (7) and daucosterol (8). All compounds except compound 2 were firstly isolated from H. heterophyllum.
Eighty-five rice (Oryza sativa L.) varieties, including 82 rice landraces collected from 17 villages in Yunnan Province of China and three standard varieties representing typical Indica and Japonica ecotypes, were studied using simple sequence repeat (SSR) markers to estimate their genetic diversity for the purpose of strategic conservation. Nineteen selected SSR primer pairs amplified a total of 83 SSR alleles, with molecular weight ranging from 100 to 500 bp, from the 85 rice varieties. An UPGMA dendro-gram based on the cluster analysis of genetic similarity of the SSR alleles showed a significant genetic variation among the included rice varieties, with the similarity coefficients varying between 0.152 and 0.900. However, genetic diversity of the rice varieties collected from Yunnan was unevenly distributed over their geographical locations. Two distinct groups were identified from the cluster analysis of the 85 rice varieties at the similarity coefficient level of 0.152, with one group that included almost all accessions of Indica ecotype and another group that contained all accessions of Japonica ecotype. Varieties that shared the same names but collected from different villages did not always show a close genetic relationship, indicating misidentification of some varieties by local farmers. It is concluded from this study that conser-vation of genetic diversity in rice landraces is urgently necessary in Yunnan, given their high level of diversity, but an appropriate strategy needs to be followed to guarantee the effectiveness of conservation activities. Properly selected SSR primer pairs might provide an ideal method for identifying Indica and Japonica ecotypes for rice conservation and breeding programs.
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