【作者】 马翠兰；

【导师】 刘星辉；

【作者基本信息】 福建农林大学 ， 果树学， 2002， 博士

【摘要】 本研究以坪山柚和琯溪蜜柚为材料，研究了NaCl胁迫对种子萌发与幼苗生长、矿质元素吸收、叶片及根细胞亚显微结构、叶片内源激素、内源多胺含量、蛋白质组分及含量、叶片光合作用、叶绿素荧光诱导动力学和若干生理特性等的影响。结果表明： 1 盐胁迫对柚幼苗生长及矿质元素吸收特性的影响 1．1 40mmolL^-1NaCl胁迫不影响坪山柚种子萌发率及生长，但萌发时间延长；NaCl浓度≥60mmol L^-1会降低种子萌发率、抑制胚根及芽的生长，且随着NaCl浓度的增加，抑制作用加强。同一浓度NaCl胁迫下，坪山柚种子萌发率高于福橘、胚根长度及芽长度受抑制程度比福橘低。 1．2 NaCl浓度≥80mmol L^-1，柚幼苗叶片及根细胞变形严重，质壁分离明显，细胞器结构混乱，甚至崩溃瓦解。幼苗株高、叶面积、地上部干重、根部干重显著下降。坪山柚生长受抑制程度比福橘小。 1．3 随NaCl胁迫程度的加强，坪山柚地上部及根部Na和Cl含量明显增加，但低于福橘，这与其对Na⁺、Cl^-的吸收量及吸收速率低、K_m值较大有关，因而具有比福橘更强的耐NaCl胁迫的能力。NaCl胁迫后，坪山柚地上部及根部K、Ca、Mg、P和Mn含量降低，Fe、Zn和Cu含量因器官而异。K／Na、Ca／Na及Mg／Na比值均显著下降，同一浓度NaCl胁迫，坪山柚K／Na、Ca／Na及Mg／Na比值均高于福橘。 1．4 NaCl胁迫后，坪山柚地上部和根部甜菜碱含量增加，是其对盐胁迫的一种适应。 2 盐胁迫对柚幼苗内源激素、多胺含量及蛋白质的影响 2．1 NaCl胁迫下，坪山柚幼苗叶片IAA、GA₃和CTK含量下降，ABA含量增加，ABA／IAA、ABA／GA₃、ABA／CTK及ABA／（IAA+GA₃+CTK）比值均增大，其中ABA含量、ABA／GA₃及ABA／CTK比值与耐盐性关系密切。坪山柚叶片ABA含量及上述各比值均比福橘高。 2．2 NaCl胁迫后，坪山柚叶片内源Put、Spd和Spm含量均增加。当NaCl浓度高于80mmol L^-1，Put／Spd及Put／Spm比值增大。坪山柚多胺福建农林大学博士学位论文——摘要 ＊ （PAs）总量、Put、Spd禾 Spin含量比福橘高，且 Put／Spd比值和 Put／Spm比值的增幅比福橘大。因此，Put含量及Put／Snd及Put／SPm 比值的增大是坪山抽对NaCI胁迫的一种适应。2．3 NaCI胁迫后，一些蛋白质的合成受阻，但亦产生一些新的蛋白质。坪 山抽幼苗经 NaCI胁迫后，80kD、67kD、54kD、32kD、28kD、18kD、 17kD和 16kD等8种蛋白质不受影响而稳定表达；35kD和 24kD两种 蛋白是新产生的特异蛋白，而58kD和 14kD两种蛋白质消夫。福橘叶 片中 80kD、67kD、32kD、28kD、21kD、18kD、17kD、16kD和 15kD等 9种蛋白为稳定表达的蛋白，72kD、43kD和 24kD三种蛋白 为新产生的特异蛋白，13kD蛋白在NaCI胁迫后消失。3盐胁迫对抽光合作用和叶绿素荧光特性的影响3．INaCI胁迫后，棺溪蜜抽叶片Chl、Chla、Chlb及Car含量明显下降， 下降幅度 Car＞Chlb＞Chla。随着 NaCI浓度的增加，Chl／Car及 Chla／Chlb比值增大，说明Car LL Chl，Chlb比Chla更易受高浓度 NaCI胁迫的影响。3．2 40mmol LI NaCI胁迫 60d，植溪蜜抽叶片光合速率（Pn）、气孔导 度（C S）及胞间 CO。浓度（Ci）均降低，而气孔限制值（LS）增加， 表明光合作用受抑制主要是气孔限制。120mmol－’NaCI胁迫 60d，王 官溪蜜抽叶片 Pn和 Cs下降的同时，Ci升高，Ls降低，表明光合作用 限制主要是非气孔因素。此时，蒸腾速率（Tr）、光饱和点（LSP）、表 观量子产量（AQY）及光合梭化效率（CE）明显降低，而光补偿点（LCP） 升高，说明叶肉细胞光能转换系统活性下降，COZ固定能力降低。3．3 120mmol－INaCI胁迫60d，抽叶片可变荧光产量（Fv）下降，半 驰豫时间（TllZ）减少；可变荧光衰减能力（八 FV）、光系统＊（PS 11） 潜在光化学活性（＊v”。）及＊Sll原初光能转换效率（＊v瓜＿）降低： 可变荧光比值（A FV／FS）下降，表明碳同化受到影响，积砧馆溪蜜抽 叶片上述参数降低的幅度均比抽砧馆溪蜜抽大。3．4 NaCI胁迫下，抽叶绿素光合电子传递受阻，光合磷酸化活性降低，乙 醇酸氧化酶（GO）活性升高。4 抽对盐胁迫的生理反应及适应性福建农林大学博士学位论文——摘要V4．1 ＊。0胁迫后，棺溪蜜抽根系活力下降，且＊。m浓度越高，胁迫时间 越长，根系活力下降幅度越大；地上部表现为叶片细胞膜透性（大分子 渗漏值）增大，相对含水量（RWC）降低，叶片萎蔫。4．2 NaCI胁迫降低抽叶片氨基酸含量和硝酸还原酶（NR）活性，而使游 离脯氨酸含量和可溶性蛋白质含量增加，短时间 NaCI胁迫，硝态氮含 量增加，长时间 NaCI胁迫，硝态氮含量减少。4．3 NaCI胁迫下，植溪蜜抽叶片 O。“产生速率和 H刃。含量增加，膜脂过 氧化产物MDA累积，体内抗氧化酶类和抗氧化物质有明显变化：SOD 和POD活性增强，CAT和ASA－POD活性减弱，抗氧化物质GSH和 ASA含量增加。更多还原

【Abstract】 Pingshan pomelo (citrus grandis Osbeck>> and Guanxi pomelo were used as materials in the experiment. Effects of NaCl stress on seed germination, the growth of seedlings, mineral elements absorption, cytoultrastructure of leaves and roots, contents of endogenous hormones and endogenous polyamines, contents and components of protein, photosynthesis, chlorophyll a fluorescence induction kinetics and changes in physiological characteristics were studied. The main results were as follows: 1 Effects of NaCI stress on seedling growth and ion absorption characteristics of pomelo1.1 Seed germination percentage and seedling growth of Pingshan pomelo were not affected when the treated concentration of NaCl up to 40mmoL"1, but the time needed to complete germination was lengthened. NaCl concentration higher than 60mmoL~1 decreased final germination percentage, inhibited the growth of radicle and sprout, the inhibition was strengthened along with the increasing of NaCl concentration, Germination percentage of Pingshan pomelo was higher than Fuju and the inhibited extent of radicle sprout , and the inhibition was strengthened , along with the increasing of NaCl concentration. Germination percentage of Pingshan pomelo was higher than Fuju and the inhibited extent of radicle and sprout was lower than Fuju under the same NaCl concentration.1.2 The changes in celluar ultrastructure of leaves and roots of Pingshan pomelo were significant at NaCl concentration up to SOmnioLT1, the cell deformed severely, plasmolysis distinctly and the structure of organelle was destroyed or even collapsed when NaCl concentration was higher than SOmmoL"1. At the same time, NaCl salinity decreased drastically seedling plant height, leaf area, shoot dry weight and root dry weight of Pingshan pomelo, the decrements were higher in Fuju than in Pingshan pomelo.1.3 As NaCl concentration increased, Na and Cl contents in both root and the above ground parts of Pingshan pomelo seedlings were remarkably increased, but they are lower than the contents of Na and Cl in Fuju seedling, This was related to smaller Na+and Cl~ absorption amount and absorption rate with lower affinity of Pingshan pomelo seedlings. So the salt tolerance of Pignshan pomelo was stronger than Fuju. NaCl salinity decreased contents of K^ Ca%Mg, P and Mn in both root and the above ground parts of Pingshan pomelo,96the contents of Fe -, Zn and Cu varied with organ. In addition, the value of K/T^^ Ca/Na and Mg/Na reduced remarkably with increasing NaCl salinity. the values of K/Nax Ca/Na and Mg/Na were higher in Pingshan pomelo than in Fuju under the same NaCl concentration.1 .4 NaCl salinity was showed to result in the increase of glycinebetaine contentin seedling shoots and roots of Pingshan pomelo, which was good at adaptation to NaCl stress.2 Effects of NaCl stress on endogenous hormones N endogenous polyamines and content and component of protein in leaves of pomelo2.1 Under NaCl stress, the contents of endogenous IAA,GAs and CTK in seedling leaves of Pingshan pomelo decreased, whereas the content of ABA and the ratios of ABA/IAA, ABA/GA3 , ABA/CTK and ABA/( lAA+GAs+CTK ) increased, which the ABA content, the ratios of ABA/GAs and ABA/CTK were closely related to salt tolerance. The content of ABA and the ratios above were higher in Pingshan leaves than in Fuju.2.2 The contents of endogenous Pu^ Spd and Spm and the ratios of Put /Spd* Put/Spm increased under 80mmol/L~1NaCl stress. The increasing ranges of total polyamines ^ Put> Spd and Spm as well as the ratios of Put/Spd and Put/Spm in Pingshan pomelo were much than those in Fuju. therefore, the increment in Put content and in ratios of Put/Spd and Put/Spm were an adaptive response of Pingshan pomelo to NaCl stress.2.3 The composition of some proteins were obstructed and some new proteins were induced under NaCl stress. 80^67^54^32^28^ 18^ 16 kilodaltons proteins exhibited unchangeable and expressed stably, 35 and 24 kD were prese更多还原