Endosperm structure and Glycemic Index of Japonica Italian rice varieties

Filip Haxhari, Francesco Savorani, Mariangela Rondanelli, Enrico Cantaluppi, Luigi Campanini, Edoardo Magnani, Cinzia Simonelli, Gentian Gavoci, Alessandro Chiadò, Mattia Sozzi, Nicola Cavallini,  Angelica Chiodoni, Clara Gasparri, Gaetan Claude Barrile, Alessandro Cavioni, Francesca Mansueto, Giuseppe Mazzola, Alessia Moroni, Zaira Patelli, Martina Pirola, Alice Tartara, Davide Guido, Simone Perna, Roberto Magnaghi

Front Plant Sci.; 2024 Jan 5: 14:1303771. doi: 10.3389/fpls.2023.1303771.

 ABSTRACT

Given that rice serves as a crucial staple food for a significant portion of the global population and with the increasing number of individuals being diagnosed with diabetes, a primary objective in genetic improvement is to identify and cultivate low Glycemic Index (GI) varieties. This must be done while ensuring the preservation of grain quality.

25 Italian rice genotypes were characterized calculating their GI "in vivo" and, together with other 29 Italian and non-Italian genotypes they were studied to evaluate the grain inner structure through Field Emission Scanning Electron Microscopy (FESEM) technique. Using an ad-hoc developed algorithm, morphological features were extracted from the FESEM images, to be then inspected by means of multivariate data analysis methods.

Large variability was observed in GI values (49 to 92 with respect to glucose), as well as in endosperm morphological features. According to the percentage of porosity is possible to distinguish approximately among rice varieties having a crystalline grain (< 1.7%), those intended for the preparation of risotto (> 5%), and a third group having intermediate characteristics. Waxy rice varieties were not united by a certain porosity level, but they shared a low starch granules eccentricity. With reference to morphological features, rice varieties with low GI (<55) seem to be characterized by large starch granules and low porosity values. Our data testify the wide variability of Italian rice cultivation giving interesting information for future breeding programs, finding that the structure of the endosperm can be regarded as a specific characteristic of each variety.

See https://pubmed.ncbi.nlm.nih.gov/38250450/

Figure 6 Scores plot (A) with the distribution of 45 of the 54 Italian varieties and IRRI accessions analyzed by PCA on starch granules characteristics and endosperm average porosity, and the corresponding loadings plot (B) with starch granules features. The physical structure of nine of the 54 varieties could not be analyzed by the ad hoc developed algorithm, due to the strongly prevalent presence of compact structures, thus causing some missing values in the data table.