School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban, 4041, South Africa.
Physiol Plant. 2010 Jun 1;139(2):205-19. doi: 10.1111/j.1399-3054.2010.01358.x. Epub 2010 Jan 25.
Cryopreservation is the most promising long-term storage option for recalcitrant (i.e. desiccation-sensitive) seed germplasm; however, its effects on the vigor of recovered seedlings are unclear. This study looked at the vigor of seedlings recovered from partially dried (D) and cryopreserved (C) recalcitrant zygotic embryos (ZEs) of Amaryllis belladonna. Seedlings recovered from fresh (F), D- and C-embryos were regenerated in vitro, hardened-off ex vitro and then exposed to 12 days of watering (W) or 8 days of water deficit (S), followed by 3 days of re-watering. Seedling vigor was assessed in terms of physiological and growth responses to the imposed water stress. Compared with F-embryos, partial dehydration and cryopreservation reduced the number of embryos that produced seedlings, as well as the subsequent in vitro biomass of these seedlings. DW- and CW-seedlings (i.e. seedlings recovered from dried and cryopreserved ZEs that were watered for 12 days) exhibited lower CO(2)-assimilation rates and abnormal root growth. Stomatal density was also lower in C-seedlings. DS- and CS-seedlings were exposed to persistent low leaf water and pressure potentials and unlike FS-seedlings, displayed signs of having incurred damage to their photosynthetic machinery. CS-seedlings were less efficient at adjusting leaf water potential to meet transpirational demands and more susceptible to persistent turgor loss than DS- and FS-seedlings. DS-seedlings performed slightly better than CS-seedlings but drought-induced seedling mortality in both these treatments was higher than FS-seedlings. These results suggest that seedlings recovered from partially dried and cryopreserved embryos were less vigorous and more susceptible to hydraulic failure than those from fresh ZEs.
冷冻保存是保存顽拗性(即干燥敏感)种子种质最有前途的长期储存方法;然而,其对恢复幼苗活力的影响尚不清楚。本研究观察了部分干燥(D)和冷冻(C)保存的孤挺花合子胚(ZE)的顽拗性种子幼苗活力。从新鲜(F)、D 和 C 胚胎中回收的幼苗在体外再生,然后在室外进行硬化处理,然后暴露于 12 天浇水(W)或 8 天水分亏缺(S),然后再浇水 3 天。根据对施加水分胁迫的生理和生长反应来评估幼苗活力。与 F 胚胎相比,部分脱水和冷冻保存减少了产生幼苗的胚胎数量,以及这些幼苗随后的体外生物量。DW 和 CW 幼苗(即从干燥和冷冻 ZE 中回收并浇水 12 天的幼苗)表现出较低的 CO2 同化率和异常的根生长。C 幼苗的气孔密度也较低。DS 和 CS 幼苗暴露于持续的低叶片水和压力势中,与 FS 幼苗不同,表现出其光合作用机制受损的迹象。CS 幼苗在调节叶片水势以满足蒸腾需求方面效率较低,比 DS 和 FS 幼苗更容易发生持续膨压损失。DS 幼苗的性能略好于 CS 幼苗,但这两种处理的干旱诱导的幼苗死亡率均高于 FS 幼苗。这些结果表明,与从新鲜 ZE 中恢复的幼苗相比,从部分干燥和冷冻保存的胚胎中恢复的幼苗活力较低,更容易发生水力故障。