Image facilitated assessment of intra-spike variation in grain size in wheat under high temperature and drought stress.

Abstract

In wheat (Triticum aestivum L.), the grain size varies according to position within the spike. Exposure to drought and high temperature stress during grain development in wheat reduces grain size, and this reduction also varies across the length of the spike. We developed the phenomics approach involving image-based tools to assess the intra-spike variation in grain size. The grains were arranged corresponding to the spikelet position and the camera of smart phone was used to acquire 333 images. The open-source software ImageJ was used to analyze features of each grain and the image-derived parameters were used to calculate intra-spike variation as standard deviation (ISVAD). The effect of genotype and environment were highly significant on the ISVAD of grain area. Sunstar and Raj 4079 contrasted in the ISVAD of grain area under late sown environment, and RNA sequencing of the spike was done at 25 days after anthesis. The genes for carbohydrate transport and stress response were upregulated in Sunstar as compared to Raj 4079, suggesting that these play a role in intra-spike assimilate distribution. The phenomics method developed may be useful for grain phenotyping and identifying germplasm with low intra-spike variation in grain size for their further validation as parental material in breeding.

Plant phenotyping relevance

画像取得とImageJ解析による穀粒サイズおよび穂内変異の表現型評価手法を開発し、遺伝子型・環境比較に適用しており、表現型取得・抽出法が中心である。

Code and data availability

No paper-specific public phenotyping assets are identified. The paper's grain-image analysis used generic open-source ImageJ, and plotting used the generic gplots R package—neither is an authors' deposited asset. The only deposited data is RNA-seq (PRJNA918542), which is molecular omics, not a phenotyping asset. Phenot

No evidence-backed public reproduction asset is currently recorded.