Genotype by Environment Interaction: The Greatest Obstacle in Precise Determination of Rice Sheath Blight Resistance in the Field

Abstract

Rice sheath blight (SB) is the most serious rice disease in China. Resistance of rice to SB is a quantitative trait that is easily influenced by the environment; however, the extent of environmental influence on SB field resistance is still poorly understood. To identify rice genotype by environment interactions for SB resistance, 211 rice genotypes originating from 15 countries were planted and evaluated for SB field resistance in six different environments between 2012 and 2016 after inoculation with the SB pathogen isolate ZJ03. In addition, 65 rice genotypes were evaluated for SB field resistance in another four environments between 2013 and 2016 using ZJ03. Variations in SB field resistance were observed in different genotypes in different environments using objective and subjective rating methods. Two-way analysis of variance indicated that the interaction between the genotype and environment had a highly significant effect on SB field resistance. This analysis indicated that the environment had more of an influence than the genotype itself on SB field resistance, and the genotype by environment interaction was the greatest obstacle in obtaining a precise determination of SB field resistance in rice. The most resistant genotype, GD66, is a good candidate for genetic studies and breeding.

Genome-Wide Association Study of Sheath Blight Resistance within a Core Collection of Rice (Oryza sativa L.)

“…Moreover, our previous study [36] observed that the phenotypic diversity of several agronomic traits was comparable to that of populations with larger population sizes [48][49][50], or even higher for some agronomic traits. Ting's core collection consists of rice landraces that are considerably easier to utilize than wild rice in rice breeding because they have more abundant genetic diversity and remain in an intermediate stage between wild rice and cultivars in their domestication histories [37]. Ting's core collection shows a less complicated population structure, a shorter LD decay distance, and a lower kinship value than other populations utilized in rice GWAS [33].…”

“…In the present study, ShB resistance was estimated by one trait, i.e., lesion length/plant height (LL/pH), which had been utilized in previous studies [20,30,37]. It appears that LL/pH is the most applicable method for phenotyping ShB resistance within Ting's core collection because pH can affect the development of ShB pathogens in rice plants and influence eventual phenotypic outcomes [14].…”

“…Previous QTL regions were sufficiently wide such that they could be detected in different years and multiple locations in previous studies (QTLs were summarized in a review by Molla et al ( 2020)) [3]. It was indicated that the environment had more influence than the genotype on ShB resistance in the field, which might explain the lack of identical significant SNPs found in the two years [37]. Due to the wide range in QTL regions for rice ShB resistance, 13 gene-based SNPs that were significantly related to ShB resistance were supported by previous studies.…”

“…Moreover, pesticides were not utilized before 7 d when inoculated. The inoculation was conducted following the study of Zeng et al (2017) [37] with minor revisions. Rhizoctonia solani isolate ZJ03 was donated from Dr. Yuxiang Zeng at the China National Rice Research Institute.…”

Identification of promising resistance sources against sheath blight from the annual wild species of riceOryza nivara(SharmaetShastry)

“…Zeng et al . (2017) studied the environmental effect on disease progression among 169 genotypes and observed a highly significant ( P < 0.0001) effect. A positive correlation between RLH and DS was observed.…”