糜子根系与旗叶协同衰老的生理生化机理研究

以榆糜3号糜子为试验材料,测定了拔节至成熟期糜子根系与旗叶生长指标、保护酶活性、可溶性蛋白含量等变化,初步分析了其根系与旗叶协同衰老的生理生化机制.结果表明:从拔节期到成熟期,糜子根系活性、表面积和干物质重,旗叶绿叶面积和干物质重,以及根系与旗叶的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性均呈先升高后降低的趋势,并均在拔节后34~41 d(籽粒灌浆前期~中期)达到最大值;根系与旗叶的可溶性蛋白质含量逐渐降低,而丙二醛(MDA)含量却持续大幅度上升;糜子旗叶的保护酶(SOD、CAT、POD)活性、可溶性蛋白含量始终极显著高于同期根系,而其MDA含量却始终极显著低于同期根系.研究发现,在糜子生育后期,其光合产物分配中心转移,造成根系和旗叶中光合产物亏缺;同时其旗叶和根系中保护酶活性逐渐降低,清除活性氧的能力减弱,引起细胞内活性氧积累和膜氧化伤害逐渐加重,最终导致植株逐渐衰老;在植株衰老过程中,根系与叶片衰老密切相关,并且根系抗氧化酶的活性相对较弱.

Biochemical Mechanism of Synergistic Senescence between Root System and Flag Leaf in Broomcorn Millet(Panicum miliaceum L.)

Bio-chemical mechanism of synergistic senescence between root and flag leaf in broomcorn millet was studied with 'Yumi 3' employed as the experiment material.The investigation of root,growth index,protective enzyme activities,soluble protein contents from the jointing stage to maturing stage.The results showed that from the jointing stage to maturing stage the root vigor,root surface areas,root dry matters,leaf areas and flag leaf dry matters,the superoxide dismutase(SOD),catalase(CAT),and peroxidase(POD)activities of root and flag leaf initially increased from low to high and then declined.The soluble protein contents of root and flag leaf gradually declined;The results indicated that dry matter accumulation and allocation to all organs were maximum in 34~41 d after jointing(in the earlier period and middle of grain filling).The content of MDA gradually increased.The flag leaf SOD,CAT,POD protective enzymes activities,soluble protein contents were significantly higher than that of root the corresponding period,and the content of MDA significantly less than that of root the corresponding period.The results indicated that hindered carbohydrate was transfered from the flag leaf and the root during late stage.Moreover,the activities of oxygen protective enzyme in flag leaf and root gradually declined.The ability of reactive oxygen species metabolism was declined slowly.The reactive oxygen species accumulated in cell and resulted in its lipid membrane damage during the aging process.Therefore,improving rhizosphere nutrition and raising root vigor help delay leaf senescence.In the aging process,the relationship between root senescence and anti-oxygen enzyme activities was weaker than that in flag leaf.