Metabolization of carbohydrates and invertases activities during in vitro pollen tube growth in a chili pepper

CARRIZO GARCÍA C.

Bristol

Congreso; XXI International Congress on Sexual Plant Reproduction; 2010

International Association of Sexual Plant Reproduction Research

The pollen tube growth is fast and requires a high level of sugar import as source of material and energy. Sucrose is considered the main nutrient for the developing pollen tubes and is usually supplied in artificial culture media. Invertases are important enzymes that regulate sucrose partitioning and then glucose and fructose availability. Pollen germination and pollen tube growth in media with and without sucrose were studied in a chili pepper (Capsicum annuum) to analyze the relationship between the fluctuations of some carbohydrates (soluble sugars, starch and callose) and the invertases activities. The purpose of the study was try to identify key processes that may affect pollen tube performance. Percentages of pollen germination were similar in both conditions, but pollen tubes were more vigorous when exogenous sucrose was supplied. The metabolization of soluble carbohydrates followed different pathways in both growing conditions, given that the presence/absence of exogenous sucrose has influenced in different degrees the three forms of invertase analyzed. The presence of exogenous sucrose was critical for the later development of pollen tubes. Callose wall deposition may be a key factor for the pollen tube integrity. Starch reserves were not relevant for pollen tube growth. Pollen tubes could grow autotrophically; however, autotrophy may not be an exclusive condition since exogenous sucrose was immediately metabolized when it was present. Soluble invertases would be the most relevant forms of the enzyme as regards sucrose hydrolysis, being decisive for the progress of downstream metabolic pathways where glucose and/or fructose are used.