Near infrared spectroscopic evaluation of starch properties of breeding populations of grain sorghum

Authors: Peiris, Kamaranga; Wu, Xiaorong; Bean, Scott; Perez-Fajardo, Mayra; Hayes, Chad; YERKA, MELINDA - University Of Nevada; JAGADISH, KRISHNA - Kansas State University; OSTMEYER, TROY - Kansas State University; Aramouni, Fadi; TESSO, TESFAYE - Kansas State University; PERUMAL, RAMASAMY - Kansas State University Agricultural Research Center-Hays; ROONEY, WILLIAM - Texas A&M University; KENT, MITCHELL - Texas A&M University; BEAN, BRENT - United Sorghum Checkoff

Submitted to: Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2021
Publication Date: 10/29/2021
Citation: Peiris, K.H., Wu, X., Bean, S.R., Perez-Fajardo, M.A., Hayes, C.M., Yerka, M., Jagadish, K.S., Ostmeyer, T., Aramouni, F.M., Tesso, T., Perumal, R., Rooney, W.L., Kent, M., Bean, B. 2021. Near infrared spectroscopic evaluation of starch properties of breeding populations of grain sorghum. Processes. 9(11). Article 1942. https://doi.org/10.3390/pr9111942.
DOI: https://doi.org/10.3390/pr9111942

Interpretive Summary: Starch is the major component of sorghum grain and is made up of two separate types of starch, amylose and amylopectin. The amount of starch in sorghum grain is an important end-use quality trait and the ratio of amylose to amylopectin is important for the end-use quality of sorghum and impacts functionality in foods as well as nutrition for both humans and as animal feed. Traditional laboratory methods for measuring starch content and composition are laborious and expensive, which limits their utility for screening large numbers of sorghum grain samples for these important traits. This project focused on developing near infrared spectroscopy (NIRS) calibrations for determining starch content and amylose content. NIRS is a rapid, non-destructive technique which scans whole sorghum grains allowing for large sample populations to quickly be analyzed. NIRS was able to predict both starch content and amylose content with r-square values of 0.87 for starch content and 0.84 for amylose content and can be used to rapidly screen sorghum grain for these important traits. This research will benefit sorghum breeders, genetists, and the seed industry.

Technical Abstract: Starch, mainly composed of amylose and amylopectin, is the major nutrient in grain sorghum. Amylose and amylopectin composition affects the starch properties of sorghum flour which in turn determine the suitability of sorghum grains for various end uses. Partial least squares regression models on near infrared spectra were developed to estimate starch and amylose levels in intact grain sorghum samples. Sorghum starch calibration model with a coefficient of determination (R2) = 0 .87, root mean square error of cross validation (RMSECV) =1.57% and slope = 0.89 predicted the starch content of validation set with R2 = 0.76, root mean square error of prediction (RMSEP) = 2.13%, slope = 0.93 and bias = 0.20%. Amylose calibration model with R2 = 0 .84, RMSECV=2.96% and slope = 0.86 predicted the amylose levels in validation samples with R2 = 0.76, RMSEP = 2.60%, slope = 0.98 and bias = -0.44%. Final starch and amylose cross validated calibration models were con-structed combining respective calibration and validation sets and used to predict starch and am-ylose levels in 1337 grain samples from two breeding populations. Protein and moisture levels of the samples were also determined using previously tested NIR spectroscopy models. The dis-tribution of starch and protein levels in the lines of low amylose (<5%) and normal amylose (>15%) and the overall relationship between starch and protein levels of sorghum population were in-vestigated. Percent starch and protein were negatively correlated, and low amylose lines tended to have lower starch and higher protein levels than lines with high amylose. The results showed that NIR spectroscopy of whole grain can be a high throughput prescreening method to identify sorghum lines with specific starch quality traits for developing lines for various end uses.