The characterization of senescence-associated endopeptidase (EP) isoenzymes in wheat (Triticum aestivum L. cv. Yangmai 158) leaves during dark-induced senescence was performed. It was found that there was much higher ...The characterization of senescence-associated endopeptidase (EP) isoenzymes in wheat (Triticum aestivum L. cv. Yangmai 158) leaves during dark-induced senescence was performed. It was found that there was much higher endoproteolytic activity in dark-induced wheat leaves than in control. Six endopeptidase isoenzymes (EP1-EP6) were identified by natural gradient-polyacrylamide gel electrophoresis (PAGE) co-polymerized gelatin in the gel, five of which (EP1, EP2, EP4, EP5 and EP6) were only detected in senescing leaves. Treatment with 6-benzyl aminopurine (6-BA) delayed the expression of these EP isoenzymes and abscisic acid (ABA) accelerated it. The activity of EP3 could be detected at a wider range of pH and temperature levels while EP4, EP5 and EP 6 could be only detected at pH 4-5 and 30 -45 degreesC, EP1 and EP2 at pH 3-5 and 30-45 degreesC. All of the EP isoenzymes showed high thermal stability, especially EP3, EP5 and EP6 which still had activitiy even by incubation at 55 degreesC for 1 h. By using different class-specific inhibitors, EP1 and EP2 were characterized as metal-dependent cysteine-proteases, EP4 as a serine-protease.展开更多
Sugarcane leaf shows the classical arrangement of cells, which defines a C4 species. Vascular bundles consist of xylem, phloem and fibres, surrounded by an outer layer ofsclereids and an inner ring of stone cells asso...Sugarcane leaf shows the classical arrangement of cells, which defines a C4 species. Vascular bundles consist of xylem, phloem and fibres, surrounded by an outer layer ofsclereids and an inner ring of stone cells associated with the phloem. Some sclereids located below and above the vascular bundles act as docking cells and connect the vascular bundle to the internal surfaces of upper and lower layers of the epidermis. A compact mass ofsclereids occupies the total internal volume of the leaf edge. Neither docking cells nor the internal mass of sclereids in the edge were markedly coloured by phloroglucinol, indicating the absence of lignin in their cell walls. However, such staining indicated that fibres of the vascular bundle and the external layer of sclereids were strongly lignified. Incubation of leaf discs with an virulence factors produced by the pathogen Sporisorium scitamineum increased the thickness of the lignified cell walls of sclereids as well as the mid and small xylem vessels, as a possible mechanical defence response to the potential entry of the pathogen. This mechanism was mainly revealed for the resistant cv. Mayari 55-14, whereas lignification decreased for the susceptible cv. B 42231.展开更多
Byrsonima intermedia A. Juss. is a species from the Brazilian Cerrado that produces edible fruits and, in common with other species from the Byrsonima genus, has pharmacological potential. Previous attempts to propaga...Byrsonima intermedia A. Juss. is a species from the Brazilian Cerrado that produces edible fruits and, in common with other species from the Byrsonima genus, has pharmacological potential. Previous attempts to propagate the species through conventional methods showed difficulties. Thus, the purpose of this work was to characterize pro-embryogenic masses of Byrsonima intermedia callus, aiming for their in vitro propagation through somatic embryogenesis. Leaf segments from in vitro germinated seedlings were employed as explants for callus production. The calli were then subcultured and exposed to dyes to fulfill their embryogenic potential. Digitalizations of the cytological preparations were made in order to measure the area that was stained by both Aceto-Carmine and Evans-Blue, using image tool software. Somatic embryos were induced after treatments with l-naphthaleneacetic acid （NAA）. The percentages of double-colored areas （by Aceto-Carmine and Evans-Blue） were calculated and the data were analyzed by using the Skott-Knott test （P ≤ 0.05） and, the embryogenic callus, as well as the formation of somatic embryos were analyzed by using the Krsuskal-Wallis rank test （P ≤0.05）. The results show that double coloration is effective at identifying cells showing embryogenic potential. Early callus subculture phases show a larger percentage ofembryogenic area （83%） Somatic embryos were induced by using high auxin level.展开更多
文摘The characterization of senescence-associated endopeptidase (EP) isoenzymes in wheat (Triticum aestivum L. cv. Yangmai 158) leaves during dark-induced senescence was performed. It was found that there was much higher endoproteolytic activity in dark-induced wheat leaves than in control. Six endopeptidase isoenzymes (EP1-EP6) were identified by natural gradient-polyacrylamide gel electrophoresis (PAGE) co-polymerized gelatin in the gel, five of which (EP1, EP2, EP4, EP5 and EP6) were only detected in senescing leaves. Treatment with 6-benzyl aminopurine (6-BA) delayed the expression of these EP isoenzymes and abscisic acid (ABA) accelerated it. The activity of EP3 could be detected at a wider range of pH and temperature levels while EP4, EP5 and EP 6 could be only detected at pH 4-5 and 30 -45 degreesC, EP1 and EP2 at pH 3-5 and 30-45 degreesC. All of the EP isoenzymes showed high thermal stability, especially EP3, EP5 and EP6 which still had activitiy even by incubation at 55 degreesC for 1 h. By using different class-specific inhibitors, EP1 and EP2 were characterized as metal-dependent cysteine-proteases, EP4 as a serine-protease.
基金Department of Science and Technology of Yunnan Province,China (No . 2007PY01-24)the national science founda-tion of China (No . 30560033, No .30960077)
文摘Sugarcane leaf shows the classical arrangement of cells, which defines a C4 species. Vascular bundles consist of xylem, phloem and fibres, surrounded by an outer layer ofsclereids and an inner ring of stone cells associated with the phloem. Some sclereids located below and above the vascular bundles act as docking cells and connect the vascular bundle to the internal surfaces of upper and lower layers of the epidermis. A compact mass ofsclereids occupies the total internal volume of the leaf edge. Neither docking cells nor the internal mass of sclereids in the edge were markedly coloured by phloroglucinol, indicating the absence of lignin in their cell walls. However, such staining indicated that fibres of the vascular bundle and the external layer of sclereids were strongly lignified. Incubation of leaf discs with an virulence factors produced by the pathogen Sporisorium scitamineum increased the thickness of the lignified cell walls of sclereids as well as the mid and small xylem vessels, as a possible mechanical defence response to the potential entry of the pathogen. This mechanism was mainly revealed for the resistant cv. Mayari 55-14, whereas lignification decreased for the susceptible cv. B 42231.
文摘Byrsonima intermedia A. Juss. is a species from the Brazilian Cerrado that produces edible fruits and, in common with other species from the Byrsonima genus, has pharmacological potential. Previous attempts to propagate the species through conventional methods showed difficulties. Thus, the purpose of this work was to characterize pro-embryogenic masses of Byrsonima intermedia callus, aiming for their in vitro propagation through somatic embryogenesis. Leaf segments from in vitro germinated seedlings were employed as explants for callus production. The calli were then subcultured and exposed to dyes to fulfill their embryogenic potential. Digitalizations of the cytological preparations were made in order to measure the area that was stained by both Aceto-Carmine and Evans-Blue, using image tool software. Somatic embryos were induced after treatments with l-naphthaleneacetic acid （NAA）. The percentages of double-colored areas （by Aceto-Carmine and Evans-Blue） were calculated and the data were analyzed by using the Skott-Knott test （P ≤ 0.05） and, the embryogenic callus, as well as the formation of somatic embryos were analyzed by using the Krsuskal-Wallis rank test （P ≤0.05）. The results show that double coloration is effective at identifying cells showing embryogenic potential. Early callus subculture phases show a larger percentage ofembryogenic area （83%） Somatic embryos were induced by using high auxin level.
