Qualidade fisiológica e expressão de genes durante o desenvolvimento de sementes de pimenta habanero (Capsicum chinense JACQUIM.)

Abstract

The demand for habanero pepper seeds has increased considerably due to the expansion of peppers agribusiness. However, seeds of this species have low physiological quality constituting one of the main problems faced by farmers. The objective of this research was to evaluate the physiological quality of habanero pepper seeds during development as well as the expression of genes involved in seed germination. The trial was conducted in the experimental area and at Central Seed Laboratory of the Agriculture Department - Federal University of Lavras. Fruits were harvested at 14, 21, 28, 35, 42, 49, 56, 63 and 70 days after anthesis (DAA). It also was used seeds from fruits harvested at 70 days after anthesis and subjected to rest for seven days. Part of seeds harvested at different stages was subjected to drying at 35 °C until the seeds reach 8% of water content. For the physiological quality evaluation was used the germination test, first germination count, T50 and seedling emergence. The expression of alpha-amylase enzymes, Isocitrate lyase and endo β mannanase were analyzed by electrophoresis technique. The genes expression α amylase (B73), Isocitrate lyase (ICL6) and Endo β mannanase MAN2, Abscisic acid (NCED) and Gibberellin (GA3ox1) was determined using qRT-PCR technique in seeds not dried and subjected to drying. Higher values of germination and seed vigor were observed in habanero pepper seeds extracted from fruits harvested at 70 DAA and submitted to rest for seven days regardless of the drying process. Increased expression of alpha amylase enzyme and gene AmyB73 was observed in seeds harvested at 63 DAA and not subjected to drying. Increased expression of the enzyme endo β mannanase was observed in seeds extracted from fruits harvested at 70 DAA and subjected to seven days of rest, whether or not subject to drying. MAN2 gene expression was increased with the development until 70 DAA, in those seeds not subjected to drying. NCED greater gene expression was observed in seeds at a later stage of development (70DAA), independently of the drying. For gene GA3ox1, from 42 DAA, there was observed a decrease expression and the increased expression of this gene was observed in seeds not subjected to drying.