【作者】 张鹤；

【导师】 张新忠； 韩振海； 王忆；

【作者基本信息】 中国农业大学 ， 果树学， 2013， 博士

【摘要】 嫁接不但使园艺作物具有更强适应性和抗性,同时也改变了接穗的生长发育特性。M9作自根砧或中间砧使苹果树体矮化、丰产,已在苹果生产中广泛应用,但致矮机理尚未完全揭示。随着研究的深入,越来越多的研究表明是由接穗与砧木间相互作用导致了树体内激素的改变而引起,其作用机制尚待深入研究。本试验以3年生M9、八棱海棠、富士/M9、富士/M9/八棱海棠和富士/八棱海棠为试材,筛选了苹果中IAA极性运输蛋白PIN和LAX家族成员,采用qRT-PCR方法测定了不同试材茎段韧皮部的PIN、LAX基因家族表达特性。富士/M9和富士/M9/八棱海棠接穗和根系分别外施100mg/L NAA和BA；富士/八棱海棠茎段环剥后涂抹NPA。检测处理后树体内IAA.NAA.Z.BA含量和PIN基因表达的动态变化及树体年新梢生长量的差异。苹果中PIN基因家族成员为13个,LAX基-因家族成员为8个,依据与拟南芥的亲缘关系命名MdPIN1-13、MdLAX1-8。在MdPIN的13个成员中,MdPIN8、MdPIN10和MdPIN13在M9、八棱海棠、富士/M9、富士/M9/八棱海棠和富士/八棱海棠茎韧皮部中表达量均高于其他家族成员,且在富士/M9/八棱海棠的中间砧段MdPIN8表达量显著低于接穗和基砧,而富士/八棱海棠在接穗和基砧茎段韧皮部中MdPIN8、MdPIN10和MdPIN13表达量无显著差异,这表明M9中间砧段限制IAA下运是由于MdPIN8的表达量弱。而M9中MdPIN8、MdPIN10和MdPIN13的表达量均显著低于八棱海棠。在MdLAX的8个成员中,MdLAX1、MdLAX8在不同材料茎韧皮部中表达量均显著高于其他家族成员。MdLAX1、MdLAX8在不同砧穗复合体的接穗、基砧(中间砧)茎韧皮部中表达量无差异,这表明MdLAX不是M9中间砧段限制IAA下运的关键因素。在富士/M9接穗叶面喷施或根系滴灌NAA后1天,即检测到根系IAA+NAA含量持续上升,7天内维持高含量水平,随后下降。茎韧皮部MdPIN8、MdPIN10基因表达量变化规律与IAA+NAA规律一致,但根系玉米素含量和新梢年生长量与未施用NAA的对照无显著差异,表明IAA供应不足不是M9根系z含量低的原因。富士/M9接穗叶面喷施或根系滴灌BA,提高了叶片的Z+BA含量,根系IAA含量持续上升,至处理后3周分别为初始值的2.5和2.4倍,新梢年生长量显著增加,为对照的3.1倍。这表明外源BA可抵消M9自根砧的致矮作用,Z含量低与致矮性密切相关。富士/M9/八棱海棠根系滴灌NAA,叶片和根系IAA+NAA含量在处理后1天急剧增加,7天内维持高含量水平,随后下降。根系和叶片Z含量自处理后持续上升,直至第2周分别达到106.31和141.04ng/gFW,与0天相比差异显著,新梢年生长量显著增加,为对照的2.9倍。这表明根系Z含量低与根系IAA供应不足密切相关。但富十/M9/八棱海棠接穗叶面喷施NAA,叶片、接穗皮和中间砧皮IAA+NAA含量在1-7天内维持高含量水平,基砧皮和根中IAA+NAA含量始终基本保持稳定,同时在M9中间砧段IAA+NAA的含量高于接穗和基砧。叶片和根系的Z含量在处理后3周内未见显著变化,生长势的恢复弱于NAA根施。MdPIN8、 MdPIN10表达量变化规律与IAA+NAA基本一致,但接穗韧皮部MdPIN8、MdPIN10相对表达量显著高于中间砧和基砧。NPA处理富士/八棱海棠茎皮后第1天,根系IAA含量显著下降,叶片和根系z含量在处理后第3天持续下降,削弱了新梢生长,表明根系IAA供应不足与M9中间砧IAA极性运输受阻密切相关。因此认为,M9在作自根砧和中间砧时致矮机理不同。M9自根砧致矮是由于根系Z含量低所致；而M9中间砧致矮是由中间砧段韧皮部PIN8表达量低,限制1AA下运,根系获得IAA不足所致。更多还原

【Abstract】 Grafting makes the horticultural plants more torlerant to environmental and biotic stress, but also alters the growth and development of the scion. Apple trees grafted onto dwarfing rootstock M9produce dwarfing tree architecture with high yield and were widely used in production. However, there are different hypotheses to explain how to dwarf. After the intensive study, the changes of hormone between scion and rootstock would be the major reason in those increasing studies. The mechanisms whereby rootstocks induce dwarfing on their scion remain unclear.The experimental materials were3-year-old M9, Baleng Crab, Fuji/M9, Fuji/M9/Baleng Crab and Fuji/Baleng Crab. The expressions of gene families encoding auxin polar transporters, PIN and LAX, in the phloem of those rootstocks were detected by using qRT-PCR.100mg/L1-naphthaleneacetic acid (NAA) and6-benzylaminopurine (BA) were foliar or root applied to Fuji/M9and Fuji/M9/Baleng Crab or N-1-naphthylphthalamic acid acid (NPA) was applied in the stem of Fuji/Baleng Crab after gridling. Then the IAA, NAA, Z, BA contents, relative expressions of MdPINs and shoot growth were measured.There are13members in PIN gene familiy and8members in LAX gene familiy, and they were nominated as MdPIN1-13and LAX1-8respectively based on phylogenetic relationship with Arabidopsis. MdPIN8, MdPIN10and MdPIN13were preferentially and differently expressed in the phloem of M9, Baleng, Fuji/M9, Fuji/M9/Baleng and Fuji/Baleng Crab when compared with other MdPINs. MdPIN8showed a significantly lower expression in interstem than in scion and rootstock of Fuji/M9/Baleng Crab. However, the expression of MdPLN8, MdPIN10and MdPIN13did not change significantly in the scion and the rootstock of Fuji/Baleng Crab. These indicated that lower expression of MdPIN8in the M9interstem phloem limited IAA basipetal transport. Likewise, MdLAXl and MdLAX8were preferentially expressed in the phloem of scion.when compared whit those other MdLAXs. The expressions of MdLAXl and MdLAX8showed no significant change in phloem scion, interstem and rootstock, indicating the expression of MdLAXs was not a key factor that limited IAA basipetal transport in M9.In Fuji/M9, foliar or root application of NAA increased root auxin (NAA+IAA) levels on day1, maintained a high levels7days and then decreased in the following days, which have a consistent with the expression of MdPIN8and MdPIN10. But there were no significantly increase in root zeatin contents and shoot growth after NAA treatments compared to that in controls. These indicated the poor root IAA supply was not the reason of the lower Z content in root of M9. After foliar and root application of BA, leaf cytokinin (zeatin+BA) levels increased significantly, root IAA content increased to2.5-fold and2.4-fold respectively when compared to the original value and shoot growth has a significantly increasing to3.1-fold compared to the controls in both foliar and root BA treatments. The results indicated that exogenous BA compensated the lower zeatin contents and relieved the dwarfing effect of M9rootstock. When NAA was root-applied in Fuji/M9/Baleng Crab, the IAA+NAA contents in root and leaf increased on day1, maintained7days and decreased on the following days. the zeatin contents in root and leaf increased significantly up to106.31and141.04ng/g FW respectively on week2. The shoot growth increased significantly to2.9-fold when compared to the controls indicating the lower zeatin contents was closely related to the poor IAA supply in the root. When NAA was foliar sprayed in scion of Fuji/M9/Baleng Crab, IAA+NAA contents in the leaf, scion-bark and interstem-bark increased and maintained high levels, IAA+NAA contents in the rootstock-bark and root didn’t change significantly. While IAA+NAA contents in interstem were higher than in scion and rootstock of M9. The zeatin content in the root and leaf did not change significanty3weeks after treatment, but no recovering of shoot growth occurred than NAA root application. The expression of MdPIN8and MdPIN10was consistent with the changes of IAA+NAA content. But the expression of MdPIN8and MdPIN10in the phloem of scion was significantly higher than that in interstem and rootstock. After day1of NPA treatment the stem-bark of Fuji/Baleng Crab, the root IAA contents decreased. The zeatin contents in the root and leaf continuously decreased after day3of treatment and the shoot growth decreased there after. These data indicated that the poor IAA supply in the root was closely related with the limited IAA basipetal transport in M9.Taken together, the dwarfing mechanism differed between M9rootstock and M9interstock. The dwarfing of M9rootstocks was due to the weak zeatin synthesis in roots. The dwarfing effect was initiated by inherently lower expression of MdPIN8in the M9interstem phloem, which limited IAA basipetal transport and caused poor root IAA supply.更多还原