Increasing the rate of drying reduces metabolic imbalance, lipid peroxidation and critical water content in radicles of garden pea (Pisum sativum L.)

Abstract

Orthodox seeds become desiccation-sensitive as they undergo germination. As a result, germinating seeds serve as a model to study desiccation sensitivity in plant tissues. The eff ects of the rate of drying on the viability, respiratory metabolism and free radical processes were thus studied during dehydration and wet storage of radicles of Pisum sativum. For both drying regimes desiccation could be described by exponential and inverse modifi ed functions. Viability, as assessed by germination capacity and tetrazolium staining, remained at 100% during rapid (< 24 h) desiccation. However, it declined sharply at c. 0.26 g g -1 dm following slow (c. 5 days) drying. Increasing the rate of dehydration thus lowered the critical water content for survival. Rapid desiccation was also associated with higher activities and levels of malate dehydrogenase and the oxidized form of nicotinamide adenine dinucleotide. It was also accompanied by lower hydroperoxide levels and membrane damage. In addition, the activitiy of glutathione reductase was greater during rapid drying. Ageing may have contributed to increased damage during slow dehydration, since viability declined even in wet storage after two weeks. The results presented are consistent with rapid desiccation reducing the accumulation of damage resulting from desiccation-induced aqueous-based deleterious reactions. In addition, they show that radicles are a useful model to study desiccation sensitivity in plant tissues.

The Role - Activity and/or Processing - Of (Re) Active Oxygen Species in Desiccation Sensitivity and/or Tolerance, Development, Dormancy and/or Germination in Seeds

“…The role of free radical activity in seed deterioration in germinating orthodox and recalcitrant seeds as a result of drying has been supported by evidence from studies over a period of two decades [3][4][5][6][7][8][9][10]. Berjak and Pammenter [11] suggested that the recent interest may be a result of implication of (re)active oxygen species (ROS and/or AOS) in an intracellular signaling network.…”

Increased rate of drying reduces metabolic inequity and critical water content in radicles of Cicer arietinum L.

“…2a), Li and Sun (1999) and Parkhey et al (2012) also perceived increased accumulation of ⋅ O 2 − during storage/ desiccation of seeds. During RD, radicles were exposed for a while towards stress condition, hence resulted in low levels of ⋅ O 2 − (Ntuli et al 2013). In contrast, during both SD and WS, it was overproduced chiefly due to age related imbalance in cellular metabolism and not desiccation (Wesley-Smith et al 2001;Berjak and Pammenter 2008).…”

“…components, was considered as one of the potent requirements conferring DT to seeds (Berjak and Pammenter 2008). However, above protective system might become impaired during desiccation or hydrated storage and certainly are inefficient in removal of ROS, resulting oxidative injury in seed tissues (Chaitanya and Naithani 1994;Ntuli et al 2013).…”

“…Further, wet storage (WS) has been suggested to be one of the longterm, low intensity desiccation protocols, applicable for seeds/ seedlings (Pammenter et al 1994). It is very much obvious that detrimental metabolic reactions (metabolic imbalance, lipid peroxidation, antioxidant impairment) participating during hydrated storage are very much similar (Ntuli et al 2013).…”

“…Radicles of orthodox seeds become desiccation sensitive once they undergo the process of germination (Ntuli et al 2013). Therefore, germinated radicles can be exploited as a popular model to study the underlying mechanisms of desiccation sensitivity in seeds (Ntuli et al 2013).…”