外源脱落酸对醉马草内生真菌共生体幼苗建植过程的影响

Effect of exogenous abscisic acid on seedling establishment of Epichloё gansuensis-Achnatherum inebrians symbiont

醉马草为多年生禾本科草本植物,广泛分布于我国西北干旱-半干旱草原,其与内生真菌形成的互惠共生体具有较强的抗逆性,在自然生境中具备一定的竞争力。种子萌发及幼苗生长是植物生活史最重要的时期,决定植物未来的竞争力。通过发芽和盆栽试验,以携带(endophyte-infected,E+)和未携带(endophyte-free,E-)内生真菌的醉马草为材料,设置5个不同脱落酸(ABA)浓度,研究外源喷施ABA对醉马草内生真菌共生体幼苗建植过程的影响。结果表明:2.0 mg·L^-1的ABA浓度对醉马草种子的发芽率、胚芽长、胚根长有显著的促进作用;1.0 mg·L^-1的ABA浓度较CK组对醉马草的净光合速率、根冠比、根表面积、根直径、根体积和根头数有显著的促进作用,但当ABA浓度为4.0 mg·L^-1时表现为抑制作用。上述结果说明内生真菌具有对外源ABA的利用能力,但这与外源ABA的浓度有很大关系。

Achnatherum inebrians is a perennial bunchgrass of the Poaceae family,widely dispersed in the arid and semi-arid grasslands of northwest China.It forms a reciprocal symbiosis with Epichloёendophyte.The presence of the endophyte provides A.inebrians strong resistance to various stresses,making it more competitive.Both seed germination and seedling growth are important stages of plant growth,determining the future competitiveness of plants.In the present study,a gradient of five different abscisic acid(ABA)concentrations was set up to explore how exogenous ABA affects endophyte-infected(E+)and endophyte-free(E-)A.inebrians seed germination and seedling growth.It was found that the germination rate,embryo length and radicle length of both E+and E-A.inebrians seeds were significantly promoted when treated with 2.0 mg·L^-1 ABA solution.The net photosynthetic rate,root∶shoot ratio,root area,root diameter,root volume and number of roots of the seedlings were higher when treated with 1.0 mg·L^-1 ABA than those in the CK group.In contrast,the germination A.inebrians seeds and seedling growth were inhibited when treated with 4.0 mg·L^-1 ABA solution.These results indicate that the interaction between Epichloёendophyte and an appropriate concentration of ABA improves seeds germination and seedling growth,and enhances the photosynthetic capacity of A.inebrians.