[目的]研究水分胁迫和复水下马铃薯光合作用的变化及其响应机制,为提高马铃薯抗旱性提供科学依据.[方法]以“克新1号”原种脱毒种薯为材料进行田间试验,设置土壤相对含水量分别为40％(为田间持水率的40％,下同,T1)、55％(T2)、70％(T3)、85％(T4)和100％ (T5)5个处理,播种后各处理土壤相对含水量统一控制在75％左右,从马铃薯块茎形成期(7月1日)开始控水,连续处理21 d,水分胁迫结束后进行复水处理,保持各处理的土壤含水量均在80％以上直至块茎膨大期结束,淀粉积累期保持土壤含水量在65％以上,测定不同处理马铃薯叶片的叶绿素相对含量(SPAD值)、净光合速率(Pn)、蒸腾速率(Tr)、胞间CO2浓度(Ci)、气孔导度(Gs)及产量.以“克新1号”原原种脱毒种薯为材料,进行室内盆栽试验,设干旱处理(土壤相对含水量为40％)和对照(保持土壤相对含水量为70％)2个处理,水分胁迫14 d后,分别在干旱处理和对照的30个单株上采集马铃薯幼嫩叶片,进行基因表达以及差异基因KEGG(kyoto encyclopedia of genes and genomes)通路富集分析,分析水分胁迫后马铃薯的差异基因及代谢途径变化.[结果]随着水分胁迫时间的延长,马铃薯叶片SPAD值、Pn、Tr、Gs、Ci均下降;随着水分胁迫程度的增加,马铃薯叶片SPAD值、Pn、Tr、Gs、Ci和产量先增加后下降.随着复水时间的延长,马铃薯叶片SPAD值、Pn、Tr、Gs、Ci均增加,但不同水分胁迫处理各指标的恢复速度和恢复程度不同.复水21 d后,T3与T4处理SPAD值、Pn、Tr、Gs、Ci均明显高于其他处理,且二者之间无显著差异,说明T3处理SPAD值、Pn、Tr、Gs、Ci均能恢复到与T4处理相当的水平.盆栽试验结果显示,水分胁迫后马铃薯KEGG代谢差异显著的途径有类黄酮合成、二芳基庚和姜辣素的生物合成、甘油酯代谢、糖脂生物合成、光合作用-天线蛋白、维他命B6代谢6条,表明干旱胁迫对光合作用的影响较为显著.在KEEG通路中,水分胁迫对光合作用-天线蛋白通路以及捕光复合体Ⅰ和Ⅱ的叶绿素a/b结合蛋白相关基因的表达影响显著.水分胁迫后,KEEG通路中的植物病原体相互作用通路虽然没有显著性富集,但是环核苷酸门控离子通道相关基因PGSC0003DMG402017989和钙调素、钙调素类蛋白相关基因PGSC0003 DMG4000195 27表达显著下调,最终导致气孔关闭.[结论]水分胁迫对马铃薯光合作用影响显著,复水后光合作用均有所恢复,但仍对产量影响显著,其主要原因是马铃薯通过SPAD值、Gs、Ci变化来间接影响叶片Pn和Tr,从而影响光合作用机制,最终反映在产量上.遭受水分胁迫后,马铃薯会通过加强天线蛋白系统和关闭气孔来进行自我保护,从而适应缺水环境.%[Objective] This study investigated the photosynthetic characteristics changes and response mechanism of potato leaves under water stress and rehydration to provide basis for improving drought resistance of potato.[Method] Field experiments were conducted with the seed-detoxification seed of "Kexin 1" and five treatments with soil relative water contents of 40％ (40％ of the field water retention,T1),55％ (T2),70％ (T3),85 ％ (T4) and 100％ (T5) were set up while soil relative water content was controlled at about 75 ％ after sowing for all treatments.Water was controlled from potato tuber formation period (July 1) for 21 days,then water content was maintained more than 80％ until the end of bulking stage and above 65 ％ at starch accumulation period.The relative content of chlorophyll (SPAD),net photosynthetic rate (Pn),transpiration rate (Tr),CO2 concentration (Ci),stomatal conductance (Gs) and yield were measured.Indoor pot experiment was also conducted with drought treatment (soil relative water content of 40％) and control (keeping soil relative water content of 70％).After 14 days of water stress,young leaves of potato were collected from 30 plants,and the changes in differential genes and metabolic pathways after water stress were analyzed by proceeding gene expression and differential genes KEGG (kyoto encyclopedia of genes and genomes) enrichment analysis of pathways.[Result] With the extension of water stress,SPAD,Pn,Tr,Gs and Ci of potato leaves decreased.With the increase of water stress,SPAD,Pn,Tr,Gs and Ci of potato leaves as well as yield decreased after initial increase.With the extension of rehydration,SPAD,Pn,Tr,Gs and Ci of potato leaves increased,and recovery rate and recovery degree were different among treatments.SPAD,Pn,Tr,Gs and Ci of T3 and T4 were significantly higher than those of other treatments 21 days after rehydration,but without significant difference between them.The pot experiment showed that flavonoid biosynthesis,stilbenoid,diarylheptanoid and gingerol biosynthesis,glycerolipid metabolism,glycosphingolipid biosynthesis-globo series,photosynthesis-antenna and vitamin B6 metabolism were significantly different in KEGG metabolism after water stress,indicating that the effect of drought stress on photosynthesis was more significant.In KEGG pathway,the effect of water stress on gene expression of photosynthesis-antenna protein pathway and chlorophyll a/b binding protein related light harvesting complexes Ⅰ and Ⅱ was significant.After water stress,although there was no significant enrichment in plant-pathogen interaction pathway of KEEG pathway,cyclic nucleotide-gated ion channels related genes of PGSC0003DMG402017989 and calmodulin,calmodulin-binding proteins related genes of PGSC0003DMG400019527 were significantly down-regulated,eventually leading to stomatal closure.[Conclusion] Water stress significantly affected potato photosynthesis,although restored after rehydration,the effects on potato yield was significant.The main reason was that SPAD,Gs and Ci indirectly affected Pn and Tr,which affected photosynthesis mechanism and yield.When subjected to water stress,potato protected itself through strengthening antenna protein system and stomatal closure.
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