ABSTRACT: Grain yield, which is mainly contributed by tillering capacity as well as kernel number and weight, is the most important traits to plant breeders and agronomists. Label-free quantitative proteomics was used to analyze yield-contributing organs in wheat. These were leaf sample, tiller initiation, spike initiation, ovary, and three successive kernel development stages at five, ten, and fifteen days after anthesis. We identified 3,182 proteins across all samples. The largest number was obtained for spike initiation (1673), while the smallest was kernel sample at fifteen days after anthesis (709). Of the 3,182 proteins, 296 of them were common to all seven organs. Organ-specific proteins ranged from 148 in ovary to 561 in spike initiation. When relative protein abundances were compared to that of leaf sample, 347 and 519 proteins were identified as differentially abundant in tiller initiation and spike initiation, respectively. When compared with ovary, 81, 35, and 96 proteins were identified as differentially abundant in five, ten, and fifteen days after anthesis, respectively. Our study indicated that two argonaute proteins were solely expressed in spike initiation. Of the four expansin proteins detected, three of them were mainly expressed during the first 10 days of kernel development after anthesis. We also detected cell wall invertses and sucrose and starch synthases mainly during the kernel development period. The manipulation of these proteins could lead to increases in tillers, kernels per spike, or final grain weight, and is worth exploring in future studies.
Dr. Mohsen Mohammad 
