It is known that cytoskeleton-dependent trafficking of cell wall and membrane components to apical plasma membrane （PM） coupled with ion transport across pollen PM is crucial for maintaining polar pollen tube growth...It is known that cytoskeleton-dependent trafficking of cell wall and membrane components to apical plasma membrane （PM） coupled with ion transport across pollen PM is crucial for maintaining polar pollen tube growth. To elucidate whether plant hormones are involved in these processes, the effects of exogenous phytohormones, indole-3-acetic acid （IAA）, abscisic acid （ABA）, gibberellin A3 （GA3） and cytokinin （kinetin） on the growth, PM polarization, actin cytoskeleton （AC） organization and cytoplasmic pH （pile） of in vitro 4 h-growing petunia pollen tubes were investigated. IAA, ABA and GA3 displayed the growth-stimulating effects and these were accompanied by orthovanadate-sensitive hyperpolarization of the PM. Fluorescent labeling the enzyme with H＋-ATPase antibodies exhibited IAA- and ABA-induced lateral PM redistribution of it into the subapical zone of pollen tube PM. Pollen cultivation on the medium with latrunculin B, the inhibitor of actin polymerization, resulted in inhibition of pollen tube growth and simultaneously in the drop of endogenous IAA content. The IAA-growth stimulating effect was correlated with increased content of actin filaments （AF） in both apical and subapical zones of tubes, while ABA and GA3 exerted the same effect but it was accompanied by redistributing F-actin only to apical zone. In contrast, kinetin decreased the total F-actin content and inhibited pollen tube growth. It has been shown that the pHe of growing pollen tubes is sensitive to the plant hormones. In the case of male gametophyte growing for 1, 2 and 4 h, IAA induced alkalinization of the cytosol, while ABA and GA3 exerted qualitatively similar effect only after its growth for 1 h and 4 h, respectively. Kinetin, in contrast, resulted in acidification of the cytosol. All these results, taken together, indicate, for the first time, potential targets of the phytohormone action in pollen tubes.展开更多
It was reported that exogenous hydrogen peroxide （H2O2） can induce primary root bend in Arabidopsis and pea. However, the mechanism remains unclear. Here we explored the mechanism underlying this phenomenon by using...It was reported that exogenous hydrogen peroxide （H2O2） can induce primary root bend in Arabidopsis and pea. However, the mechanism remains unclear. Here we explored the mechanism underlying this phenomenon by using the pea （Pisum sativum L.） variety ＂longwan No. 1＂ The results showed that the endogenous indole-3-acetic acid （IAA） content decreased and gibberellin A3 （GA3） content increased in the curving primary pea root induced by H2O2. Meanwhile, both of the two hormones asymmetrically distributed in the inside and outside parts of the curving root. Also, the starch content decreased due to the increased a-amylase activity in this process. However, exogenous Ca2＋ can relieve the horizontal bending of pea root induced by H2O2 and altered the contents of endogenous IAA and GA3. A working model was proposed： Exogenous H2O2 causes the increase in GA3 content, and GA3 stimulates the activity of or-amylase, which leads to the hydrolysis of starch, and then the root lost the gravity perceiving. The asymmetric distribution of IAA and GA3 in two sides of curving root may cause the horizontal bending.Exogenous Ca^2＋ can relieve root bending through altering the endogenous IAA and GA3 contents.展开更多
文摘It is known that cytoskeleton-dependent trafficking of cell wall and membrane components to apical plasma membrane （PM） coupled with ion transport across pollen PM is crucial for maintaining polar pollen tube growth. To elucidate whether plant hormones are involved in these processes, the effects of exogenous phytohormones, indole-3-acetic acid （IAA）, abscisic acid （ABA）, gibberellin A3 （GA3） and cytokinin （kinetin） on the growth, PM polarization, actin cytoskeleton （AC） organization and cytoplasmic pH （pile） of in vitro 4 h-growing petunia pollen tubes were investigated. IAA, ABA and GA3 displayed the growth-stimulating effects and these were accompanied by orthovanadate-sensitive hyperpolarization of the PM. Fluorescent labeling the enzyme with H＋-ATPase antibodies exhibited IAA- and ABA-induced lateral PM redistribution of it into the subapical zone of pollen tube PM. Pollen cultivation on the medium with latrunculin B, the inhibitor of actin polymerization, resulted in inhibition of pollen tube growth and simultaneously in the drop of endogenous IAA content. The IAA-growth stimulating effect was correlated with increased content of actin filaments （AF） in both apical and subapical zones of tubes, while ABA and GA3 exerted the same effect but it was accompanied by redistributing F-actin only to apical zone. In contrast, kinetin decreased the total F-actin content and inhibited pollen tube growth. It has been shown that the pHe of growing pollen tubes is sensitive to the plant hormones. In the case of male gametophyte growing for 1, 2 and 4 h, IAA induced alkalinization of the cytosol, while ABA and GA3 exerted qualitatively similar effect only after its growth for 1 h and 4 h, respectively. Kinetin, in contrast, resulted in acidification of the cytosol. All these results, taken together, indicate, for the first time, potential targets of the phytohormone action in pollen tubes.
基金supported by the National Natural Science Foundation of China(31160304)Gansu Provincial Key Laboratory of Aridland Crop Science,Gansu Agricultural University,China
文摘It was reported that exogenous hydrogen peroxide （H2O2） can induce primary root bend in Arabidopsis and pea. However, the mechanism remains unclear. Here we explored the mechanism underlying this phenomenon by using the pea （Pisum sativum L.） variety ＂longwan No. 1＂ The results showed that the endogenous indole-3-acetic acid （IAA） content decreased and gibberellin A3 （GA3） content increased in the curving primary pea root induced by H2O2. Meanwhile, both of the two hormones asymmetrically distributed in the inside and outside parts of the curving root. Also, the starch content decreased due to the increased a-amylase activity in this process. However, exogenous Ca2＋ can relieve the horizontal bending of pea root induced by H2O2 and altered the contents of endogenous IAA and GA3. A working model was proposed： Exogenous H2O2 causes the increase in GA3 content, and GA3 stimulates the activity of or-amylase, which leads to the hydrolysis of starch, and then the root lost the gravity perceiving. The asymmetric distribution of IAA and GA3 in two sides of curving root may cause the horizontal bending.Exogenous Ca^2＋ can relieve root bending through altering the endogenous IAA and GA3 contents.
