Phytosulfokine-α(PSK-α),a sulfated pentapeptide with the sequence YIYTQ,is encoded by a small precursor gene family in Arabidopsis.PSK-αregulates multiple growth and developmental processes as a novel peptide hormo...Phytosulfokine-α(PSK-α),a sulfated pentapeptide with the sequence YIYTQ,is encoded by a small precursor gene family in Arabidopsis.PSK-αregulates multiple growth and developmental processes as a novel peptide hormone.Despite its importance,functions of PSK-αin M.truncatula growth remains unknown.In this study,we identified five genes to encode PSK-αprecursors in M.truncatula.All of these precursors possess conserved PSK-αsignature motif.Expression pattern analysis of these MtPSK genes revealed that each gene was expressed in a tissue-specific or ubiquitous pattern and three of them were remarkably expressed in root.Treatment of M.truncatula seedlings with synthetic PSK-αpeptide significantly promoted root elongation.In addition,expression analysis of downstream genes by RNA-seq and qRT-PCR assays suggested that PSK-αsignaling might regulate cell wall structure via PMEI-PME module to promote root cell growth.Taken together,our results shed light on the mechanism by which PSK-αpromotes root growth in M.truncatula,providing a new resource for improvement of root growth in agriculture.展开更多
ABSTRACT Endo-l,4-β-glucanases （EGases） are involved in many aspects of plant growth. Our previous study found that an EGase, PtrCel9A6, is specifically expressed in differentiating xylem cells during Populus secon...ABSTRACT Endo-l,4-β-glucanases （EGases） are involved in many aspects of plant growth. Our previous study found that an EGase, PtrCel9A6, is specifically expressed in differentiating xylem cells during Populus secondary growth. In this study, the xylem-specific PtrCel9A6 was characterized for its role in xylem differentiation. The EGase is localized on the plasma membrane with catalytic domain toward the outside cell wall, hydrolyzing amorphous cellulose. Suppression of PtrCel9A6 expression caused secondary cell wall defects in xylem cells and significant cellulose reduction in Populus. Heterologous expression of PtrCelgA6 in Arabidopsis enhanced plant growth as well as increased fiber cell length. In addition, introduction of PtrCel9A6 into Arabidopsis resulted in male sterility due to defects in anther dehiscence. Together, these results demonstrate that PtrCel9A6 plays a critical role in remodeling the 1,4-β-glucan chains in the wall matrix and is required for cell wall thickening during Populus xylem differentiation.展开更多
A 63-year-old female suffered right upper quadrant pain for 5 days,and icteric sclera for 3 days.Her Laboratory examinations revealed a normal blood routine and abnormal bilirubin levels:total bilirubin 222.0μmol/L,d...A 63-year-old female suffered right upper quadrant pain for 5 days,and icteric sclera for 3 days.Her Laboratory examinations revealed a normal blood routine and abnormal bilirubin levels:total bilirubin 222.0μmol/L,direct bilirubin 131.8μmol/L.Stool occult blood was negative.Abdomen/pelvis CT(Panel A)and MRCP(Panel B)showed cholecystolithiasis and lower choledocholithiasis.展开更多
In this study, interstitial free （IF） steel plates were subjected to double-sided friction stir processing （FSP）. The fine-grained structure with an average grain size of about 12 μm was obtained in tbe processed...In this study, interstitial free （IF） steel plates were subjected to double-sided friction stir processing （FSP）. The fine-grained structure with an average grain size of about 12 μm was obtained in tbe processed zone （PZ）with a thickness of about 2.5mm. The yield strength （325 MPa） and ultimate tensile strength （451 MPa） of FSP IF steel were significantly higher than those of base material （BM） （192 and 314 MPa）, while the elongation （67.5%） almost remained unchanged compared with the BM （66.2%）. The average microhardness value of the PZ was about 130 HV, 1.3 times bigher than that of the BM. In addition, the FSP IF steel showed a more positive corrosion potential and lower corrosion current density than the BM, exhibiting lower corrosion tendency and corrosion rates in a 3.5 wt% NaCl solution. Furtbernlore, FSP IF steel exhibited higher fatigue life than the BM both in air and NaCl solution. Corrosion fatigue fracture surfaces of FSP IF steel mainly exhihited a typical transgranular fracture with fatigue striations, while the BM predominantly presented an intergranular fracture. Enhanced corrosion fatigue performance was mainly attributed to the increased resistance of nucleation and growth of fatigue cracks. The corrosion fatigue mechanism was primarily controlled by anodic dissolution under the combined effect of cyclic stress and corrosive solution.展开更多
基金This work is supported by the National Natural Science Foundation of China(31500197).
文摘Phytosulfokine-α(PSK-α),a sulfated pentapeptide with the sequence YIYTQ,is encoded by a small precursor gene family in Arabidopsis.PSK-αregulates multiple growth and developmental processes as a novel peptide hormone.Despite its importance,functions of PSK-αin M.truncatula growth remains unknown.In this study,we identified five genes to encode PSK-αprecursors in M.truncatula.All of these precursors possess conserved PSK-αsignature motif.Expression pattern analysis of these MtPSK genes revealed that each gene was expressed in a tissue-specific or ubiquitous pattern and three of them were remarkably expressed in root.Treatment of M.truncatula seedlings with synthetic PSK-αpeptide significantly promoted root elongation.In addition,expression analysis of downstream genes by RNA-seq and qRT-PCR assays suggested that PSK-αsignaling might regulate cell wall structure via PMEI-PME module to promote root cell growth.Taken together,our results shed light on the mechanism by which PSK-αpromotes root growth in M.truncatula,providing a new resource for improvement of root growth in agriculture.
基金the National Key Basic Research Program of China，the National Natural Science Foundation of China，Shanghai Science and Technology Commission (11XD1405900) to L.L
文摘ABSTRACT Endo-l,4-β-glucanases （EGases） are involved in many aspects of plant growth. Our previous study found that an EGase, PtrCel9A6, is specifically expressed in differentiating xylem cells during Populus secondary growth. In this study, the xylem-specific PtrCel9A6 was characterized for its role in xylem differentiation. The EGase is localized on the plasma membrane with catalytic domain toward the outside cell wall, hydrolyzing amorphous cellulose. Suppression of PtrCel9A6 expression caused secondary cell wall defects in xylem cells and significant cellulose reduction in Populus. Heterologous expression of PtrCelgA6 in Arabidopsis enhanced plant growth as well as increased fiber cell length. In addition, introduction of PtrCel9A6 into Arabidopsis resulted in male sterility due to defects in anther dehiscence. Together, these results demonstrate that PtrCel9A6 plays a critical role in remodeling the 1,4-β-glucan chains in the wall matrix and is required for cell wall thickening during Populus xylem differentiation.
基金sponsorship from the National Natural Science Foundation of China under grant Nos.51404180,51274161 and U1360105
文摘In this study, interstitial free （IF） steel plates were subjected to double-sided friction stir processing （FSP）. The fine-grained structure with an average grain size of about 12 μm was obtained in tbe processed zone （PZ）with a thickness of about 2.5mm. The yield strength （325 MPa） and ultimate tensile strength （451 MPa） of FSP IF steel were significantly higher than those of base material （BM） （192 and 314 MPa）, while the elongation （67.5%） almost remained unchanged compared with the BM （66.2%）. The average microhardness value of the PZ was about 130 HV, 1.3 times bigher than that of the BM. In addition, the FSP IF steel showed a more positive corrosion potential and lower corrosion current density than the BM, exhibiting lower corrosion tendency and corrosion rates in a 3.5 wt% NaCl solution. Furtbernlore, FSP IF steel exhibited higher fatigue life than the BM both in air and NaCl solution. Corrosion fatigue fracture surfaces of FSP IF steel mainly exhihited a typical transgranular fracture with fatigue striations, while the BM predominantly presented an intergranular fracture. Enhanced corrosion fatigue performance was mainly attributed to the increased resistance of nucleation and growth of fatigue cracks. The corrosion fatigue mechanism was primarily controlled by anodic dissolution under the combined effect of cyclic stress and corrosive solution.
