Sucrose and starch catabolism in the anther of Lilium during its development: a comparative study among the anther wall, locular fluid and microspore/pollen fractions

Abstract

In order to better understand the various pathways of sucrose and starch catabolism in the anther of lily (Lilium hybrida var. "Enchantment"), invertase (EC 3.2.1.26) and amylase (EC 3.2.1.1, EC 3.2.1.2) activities were measured separately in different fractions (anther wall, locular fluid and microspore/pollen) and correlated with the sugar content during anther development. Our findings showed significant differences among the fractions analyzed, suggesting that the regulation of sucrose and starch catabolism could follow distinct pathways in each fraction. Glucose and fructose amounts progressively decreased from anther wall to fluid and from fluid to microspore/pollen. Thus, the developing pollen could act as a sink for the carbohydrates that reach the anther. In this sense, cell wall-bound invertases seem to play a major role in soluble sugar partitioning in the different fractions of the anther. Sucrose concentration was found to be substantially higher in the locular fluid than in the other fractions, indicating a probable site for storage. On the other hand, the anther wall tissues could have a buffering function, storing nutrient surplus in starch grains and thus regulating the availability of soluble sugars in the whole anther. All these results proved the advantages of the experimental model proposed here, as well as its usefulness to investigate sugar metabolism in Lilium anthers.

Starch distribution in anthers, microspores and pollen grains in Aechmea recurvata (Klotzsch.) L.B.Sm., Dyckia racinae L.B.Sm. and Tillandsia aeranthos (Loisel.) L.B.Sm. (Bromeliaceae)

“…The accumulation and mobilization of sugars, lipids and proteins are common during sporangia development and were demonstrated by microscopy, histochemistry, and biochemical, physiological and molecular assays (Pacini & Viegi 1995;Oliver et al 2005;Lora et al 2012;Konyar et al 2013). Regarding to the sugars, their importance was demonstrated for maturation of the epidermis, endothecium and tapetum (Clément & Audran 1995;Clément et al 1998;Castro & Clément 2007). In this subject, was also demonstrated that the middle layers also act in the access of sugars to the loculus (Clément & Audran 1995).…”

“…PAS-positive polysaccharides were found in the mature pollen grains cytoplasm in Mercurialis annua and Ricinus communis (Franchi et al 1996), and in Trachycarpus fortunei . Soluble polysaccharides are also found in mature starchless pollen grains, but they are only detected using other methodologies, especially biochemical analyses (O'Brien & McCully 1981;Pacini 1996;Castro & Clément 2007;Speranza et al 1997;Jain et al 2007). Speranza et al (1997) and Clément & Pacini (2001) demonstrated that, for different species, the PAS-positive cytoplasm of the vegetative cells is closely related to pollen grains dehydration at the time of their release, which presents a great viability after they are released, and are always associated with a dry environment.…”

Identification of metabolites involved in heat stress response in different tomato genotypes

“…Koch 2004 reviewed the role of acid invertase in plants; Three different acid invertases can be identified according to their location: vacuolar invertase (VIN), cytoplasmic invertase (CIN) and cell wall invertase (CWIN). The function of acid invertases in reproductive tissues has been intensely studied in different species such as lily Knox 1984, Castro andClement 2007), tobacco (Goetz et al 2001, Le Roy et al 2013, tomato (Pressman et al 2012) and chilli pepper (García et al 2013). …”

“…This was also found by Pressman et al 2002 in tomato. In addition, Castro andClement 2007 studied the content of carbohydrates in different fractions of lily anthers, such as anther wall, locular fluid and pollen. The accumulation of soluble sugars in the locular fluid suggested that this tissue may play a role in sugar storage during pollen development, which is especially useful once the tapetum is degraded.…”

“…In lily, soluble sugars also accumulated in mature pollen, mainly in the form of hexoses, while in tomato sucrose represented 80% of the carbohydrate fraction in mature pollen (Pressman et al 2012). Although we cannot exclude that the differential accumulation of hexoses vs. sucrose may be species specific, Castro and Clement 2007, notified that the lily pollen used for sugar analyses were hydrated. Using tomato pollen, we observed that hydrated pollen grains have a higher abundance of hexoses than dried pollen grains, due to the action of acid invertase upon (re-)hydration.…”