外源激素与内生真菌互作对醉马草低温胁迫下种子萌发的影响

Effects of interaction between exogenous hormones and Epichloё on germination of drunken horse grass( Achnatherum inebrians) under low temperature stress

低温是限制种子萌发的一个关键因子,而外源激素和内生真菌分别通过外部介导和内部调控的途径来提高低温环境下种子的萌发能力.本研究以感染内生真菌(E+)和未感染内生真菌(E-)醉马草(Achnatherum inebrians)种子为材料,利用不同浓度的水杨酸(SA)或脱落酸(ABA)溶液浸泡种子,测定10℃条件下醉马草种子的发芽率、发芽指数、胚芽长、胚根长和幼苗含水量,探讨外源激素与内生真菌互作对醉马草种子低温条件下萌发的影响.结果发现,SA或ABA处理能促进醉马草E+、E-种子的萌发;高浓度SA或ABA处理下则表现出抑制作用,其中高浓度(0.2 mmol/L)ABA对种子发芽抑制作用显著(P<0.05);SA与内生真菌互作对种子发芽率、发芽指数和胚根长有显著(P<0.05)促进作用;ABA与内生真菌互作对种子发芽指数、胚芽长、胚根长和幼苗含水量有显著(P<0.05)的促进作用.表明一定浓度范围的SA或ABA与内生真菌互作,能够促进醉马草种子在低温胁迫条件下的萌发力.

Temperature is a crucial abiotic factor impacting the germination of plant seeds. However, accumulating evidences suggest exogenous hormones and endophyte as important regulators to alleviate the damage of seed germination and seedling growth in low temperature environment. In this study, endophyte-infected （E ＋ ）and endophyte-free （E-）seeds of A. inebrians were tested under cold stress. Under 10 ℃, seed germination, seedling growth, embryo length, radical length and seeding moisture content of E ＋ and E- A. inebrians were examined when salicylic acid（SA） or abscisic acid（ABA） were applied,to explore the effects of endophytic fungi and exogenous hormones interaction on the germination of A. inebrians at low temperature. The results showed that SA or ABA treatment could promote the germination of E ＋ and E- A. inebrians, however, higher concentrations of SA or ABA showed inhibition （P 〈 0. 05 ）, and the highest concentrations of ABA showed the strongest （P 〈 0. 05 ） inhibition. The interactions between SA and Epichloe endophyte had significant（ P 〈 0. 05 ）effects on germination rate, germination index and root length. The interactions between ABA and Epichloe endophyte had significant （ P 〈 0.05 ） effects on germination index, seedling water content, shoot and root lengths. In conclusion, the interactions between a certain concentrations of SA or ABA and Epichlo endophyte could promote the germination of A. inebrians under cold stress.