外源5-氨基乙酰丙酸对NaCl胁迫下黑果枸杞幼苗生理及生长的影响

Effect of Exogenous ALA on Physiological Characteristics and Growth of Lycium ruthenicum Seedlings under Salt Stress

5-氨基乙酰丙酸(ALA)是植物血红素、叶绿素等四吡咯化合物的关键生物合成前体,对植物适应非生物胁迫至关重要。为验证外源ALA对黑果枸杞幼苗生理生长的影响,该研究用300 mmol·L^(-1)NaCl和不同浓度(0、5、10、15、20、25 mg·L^(-1))的ALA共同处理黑果枸杞幼苗,并测定其相关的生理指标和生长指标,综合评价各处理幼苗的耐盐性。结果表明:(1)NaCl胁迫使黑果枸杞幼苗总生物量和叶片总叶绿素、类胡萝卜素、可溶性糖含量以及过氧化物酶(POD)活性较CK分别显著降低了33.39%、19.06%、24.38%、39.57%和47.91%(P<0.05),使黑果枸杞幼苗脯氨酸和丙二醛的含量较CK分别显著增加了165.74%和49.16%。(2)当外源ALA和NaCl同时处理时,黑果枸杞幼苗叶片类胡萝卜素和丙二醛含量、POD和过氧化氢酶(CAT)活性以及株高、总生物量均恢复至对照水平,叶片总叶绿素和脯氨酸含量以及SOD活性较CK显著增加。(3)黑果枸杞幼苗叶片叶绿素和脯氨酸含量以及抗氧化酶活性、生物量等指标随ALA浓度增加均呈先上升后下降的趋势,隶属函数综合评价发现,叶面喷施15 mg·L^(-1)ALA缓解盐胁迫伤害的效果最佳。研究认为,适宜浓度ALA可通过促进叶绿素和血红素的积累来调节黑果枸杞幼苗光合作用能力和抗氧化酶活性,增加体内脯氨酸的积累,有效缓解盐胁迫对植物的毒害作用,从而促进植株生长。

5-aminolevulinic acid(ALA),a key biosynthetic precursor of tetrapyrroles,is vital for plants adaptation to abiotic stress.To verify the effects of different concentrations of ALA,we applied exogenous ALA with different concentrations(0,5,10,15,20,25 mg·L^(-1))to the leaves of Lycium ruthenicum seedlings subjected to 300 mmol·L^(-1) NaCl.Then,the physiological and growth indexes of L.ruthenicum seedlings were determined,and comprehensively evaluated the salt tolerance of the seedlings under each treatments.Results revealed that:(1)compared with the control,the plant biomass,the contents of chlorophyll,carotenoid and soluble protein,the activity of POD were significantly decreased by 33.39%,19.06%,24.38%,39.57%and 47.91%(P<0.05)in L.ruthenicum leaves under the salt stress,but the contents of proline(Pro)and malondialdehyde(MDA)were significantly increased by 165.74%and 49.16%,respectively.(2)When exogenous ALA and NaCl were treated at the same time,the contents of carotenoid and malondialdehyde(MDA),the activities of CAT,POD,the plant height and total biomass were restored to the control level,and the contents of chlorophyll and proline(Pro)were significantly increased compared with the control in L.ruthenicum seedlings.(3)The contents of carotenoid and proline,the activities of antioxidant enzymes and biomass of the leaves of L.ruthenicum seedlings performed a trend that first increased and then decreased with the add of ALA concentration.The evaluation by membership function analysis indicated that 15 mg·L^(-1) ALA had the best effects on alleviating salt stress in L.ruthenicum seedlings under 300 mmol·L^(-1) NaCl stress.These findings suggested that ALA of appropriate concentration can regulate photosynthesis and antioxidant enzyme activities of L.ruthenicum seedlings by promoting the accumulation of chlorophyll and heme,and increase the accumulation of proline in vivo,thus effectively alleviating the toxic effect of salt stress on plants and promoting plant growth.