Somatic embryogenesis and peroxidase activity of desiccation tol-erant mature somatic embryos of loblolly pine

火炬松体细胞胚胎发生和干化体细胞的氧化物酶活性(英文)

White, translucent, glossy mucilaginous callus was initiated from the mature zygotic embryos explants on callus induction medium with 2,4-D, BA, and kinetin in the 3-9th week of culture. This type of callus induction occurred at a lower fre-quency with either a-naphthaleneacetic acid (NAA) or IBA (both 8 mg/L). White, translucent, glossy mucilaginous callus was embryogenic and mainly developed from the cotyledons of the mature zygotic embryo. Somatic embryos were formed on dif-ferentiation medium. Desiccation tolerance can be induced by culturing somatic embryos of loblolly pine (Pinus taeda L.) on medium supplemented with 50 mm abscisic acid (ABA) and/or 8.5% polyethylene glycol (PEG6000). Scanning electron micros-copy of desiccated somatic embryos showed that the size and external morphology of the desiccation tolerant somatic embryos recovered to the pre-desiccation state within 24-36 h, whereas the sensitive somatic embryos did not recover and remained shriveled, after the desiccated somatic embryos had been rehydrated. Peroxidase activity of desiccated somatic embryos in-creased sharply after 3 days of desiccation treatment, and desiccation tolerant somatic embryos had higher peroxidase activity compared to sensitive somatic embryos. Higher peroxidase activity of desiccation tolerant somatic embryos was possibly ad-vantage of catalyzing the reduction of H2O2 which was produced by drought stress, and protecting somatic embryos from oxida-tive damage.

培养于附加2,4-D、BA和KT的愈伤组织诱导培养基上的火炬松成熟合子胚在培养3-9周后形成白色、半透明、有光泽的粘性愈伤组织。这类愈伤组织形成于成熟合子胚的子叶,但当用NAA或者IBA代替愈伤组织诱导培养基中的2,4-D时,它的诱导频率明显降低。这种粘性愈伤组织在分化培养基上形成体细胞胚。体细胞胚经过去50μm ABA和8.5%PEG600处理后成为耐干化胚。扫描电镜观察表明,萌发处理36小时后,耐干化胚恢复到干化处理之前的状态且大小和形态正常,而不耐干化胚不能恢复到干化处理之前的状态且表面撕裂。过氧化物酶活性的分析结果表明,耐干化胚有更高的过氧化物酶活性。耐干化胚的高过氧化物酶活性可能与催化H2O2的分解和保护体细胞胚免受氧化的伤害有关。