Fig. 8. Phenotypic analysis of double versus single mutants and COM2 transcript levels in com1.a.

a SEM-based view of an immature spike of Wt cv. Bowman, single mutant com1.a (b), single mutant com2.g (c) and those of a DM mutant (d). In d upper panel shows basal nodes of a DM spike at GP stage with elongated CSM (as compared to Wt in Fig. 1g) and unusually enlarged glume primordia (in purple). Numbers 1–5 denote five IM-like branch meristems of a DM spike that eventually represents a putative ten-rowed spike. The lower panel is rotated by ~45° to the left while imaging. Please note IM-like branches 1 and 2 are invisible in the lower panel. Immature spikes (except d upper panel) are at similar developmental stages of early/advanced stamen primordium. Immature spikes in (b, c) represent typical SBS while d corresponds to the immature CBS spike class. e–h Showing mature spikes with Wt cv. Bowman depicted in (e), single mutant com2.g shown in (f) (reproduced from Poursarebani et al.¹³ with the kind permission from Genetics Society of America), single mutant com1.a shown in (g), and the mature spike in a DM plant displayed in (h). f, g Represent a frequent phenotype of the SBS class at maturity while d represents a mature CBS phenotype. i–n Grain characters of the DM plants, and the corresponding single mutant com1.a and com2.g in comparison to the Wt cv. Bowman. Data are based on a single greenhouse experiment and on averages of 20 plants (390–540 spikes) per phenotypic class. Per box plot, plus signs show the means while center bold-lines show the medians; box limits indicate the 25th and 75th percentiles; whiskers extend 1.5 times the interquartile range, outliers are represented by circles. o Depicts COM2 transcript levels in the com1.a mutant compared to Wt cv. Bowman. Data are generated from three biological replicates from 15–25 plants per experiment; mean ± SE of three biological replicates. Genotype differences were tested at a significance level of P > 0.05 using the two-tailed paired Student’s t-test. Source data underlying (i–n) are provided as a Source data file.