大田遮荫对紫心甘薯块根中酶活性的影响

ENZYMATIC ACTIVITY OF ROOT QUALITIES IN PURPLE-FLESHED SWEETPOTATO UNDER FLIED SHADING STRESS

在大田条件下,采用人工遮荫的方法探讨光照不足导致紫心甘薯块根品质下降的酶学机制。研究结果表明:在遮荫条件下,2个甘薯品种济薯18和Ayamurasaki叶片RUBPCase活性显著降低;叶片和块根中ATPase活性下降;块根ADPGPPase和UDPGPPase活性均显著降低,降低幅度随胁迫强度而增加;遮荫对块根可溶性淀粉合成酶(soluble starch synthase,SSS)和淀粉粒结合态淀粉合成酶(granulebound starch synthase,GBSS)活性的影响存在品种间差异,济薯18块根SSS活性显著降低,GBSS活性则不同程度高于对照,而Ayamurasaki的SSS活性却高于对照,GBSS活性则随遮光胁迫强度而降低;遮荫对花青素合成的关键酶苯丙氨酸解氨酶(Phenglalanine Ammonia Lyase,PAL)活性影响则很小。因此,遮荫胁迫从源库流各环节影响了紫心甘薯品质合成相关酶,其中RUBPCase、ATPase、ADPGPPase和UDPGPPase活性显著降低是导致紫心甘薯块根品质下降的主要原因。

Artificial shading treatments were adopted to study the enzymatic mechanism of root qualities decrease under insufficient light in different genotypes of purple-fleshed sweetpotato.Results showed that leaf RUBPCase activity in cv.Jishu18 and Ayamurasaki remarkably decreased under shading treatment.ATPase activity decreased in leaf and root of purple sweetpotato after shading.ADPGase and UDPGase activities in root of two cultivars decreased significantly with the increasing of shading intensity.Effects of shading on soluble starch synthase（SSS） and granule bound starch synthase（GBSS） activity were different in two verities,（SSS） activity in root of JiShu18 significantly decreased,but GBSS activity was inordinately higher than the control.In Ayamurasaki,SSS activity was significantly higher than its control and GBSS activity decreased with the increasing of shading intensity.Phenglalanine Ammonia Lyase（PAL） activity,as key enzyme of anthocyanin biosynthesis,changed little under shading stress.Shading could affect the enzyme related to root quality synthesis in purple-fleshed sweetpotato from source,sink and flow and the decrease of RUBPCase,ATPase,ADPGPPase and UDPGPPase activities,might be the main reason for the decrease of sweetpotato storage quality.