Avaliação da endogamia e morfologia de grânulos de amido em progênies s1 de mandioca

Abstract

The objective of the present work was to use marker assisted selection (MAS) to select individuals with high inbreeding, evaluate morphological alterations in starch grains and estimate genetic gains with selection of transgressive individuals in self-fertilized (S1) cassava (Manihot esculenta Crantz) populations. Three accessions were self-fertilized (BGM0222, BGM1378 and BGM1662) generating a total of 274 S1 individuals. The genitors (S0) and their respective progenies (S1), were evaluated in the seedlings and clonal phases (CP). In order to determine the inbreeding coefficient (f) of the S1 individuals, 27 microsatellite and five minisatellite primers, were used. Starch of accessions S0: BGM0222, BGM1378 and BGM1662 and of their self-fertilized progênies S1: F0222, F1378 and F1662, were evaluated in the phase of seedlings for the following characteristics: granule area (GA, μm²), granule perimeter (GP, μm), granule length (GL, μm) and number of starch granules (NG). During the clonal phase (CP), the plants were evaluated for: plant height (PH), root dry matter content (DM), productivity of aerial part (PAP), productivity of roots (PR) and starch (PS). The inbreeding coefficient (f) of the S1 individuals varied from 0.11 to 0.89 within the same progeny with average of f = 0.50. The selection of S1 individuals with f ≥ 0,60, resulted in an increase of 38% of inbreeding in comparison to the average of the S1 progenies. The average size of the starch granule varied from 9 to13 μm among the individuals in an S1 progeny. The presence of transgressive individuals as to the characteristics related to morphology of the starch granules enabled expressive selection gains in the S1 individuals, 52%, 31%, 11% and 10%, for number of granules, area, length and perimeter, respectively. Individuals with high inbreeding levels will be selected for new cycles of inbreeding decreasing time for obtaining inbred lines. Individuals which presented differential characteristics for morphology of the starch granule have potential for exploring important differences in the properties of starch paste, which define many industrial applications of starch.