Exploring naturally existing genetic variation in grain chalk formation in response to temperature and carbon dioxide

Authors: Barnaby, Jinyoung; McClung, Anna; KIM, WOOJAE - National Institute Of Crop Science, Iksan, South Korea; Ziska, Lewis; Fleisher, David; Reddy, Vangimalla

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/15/2020
Publication Date: 1/6/2021
Citation: Barnaby, J.Y., McClung, A.M., Kim, W., Ziska, L.H., Fleisher, D.H., Reddy, V. 2021. Exploring naturally existing genetic variation in grain chalk formation in response to temperature and carbon dioxide. Proceedings of 38th Rice Technical Working Group Meeting, February 24-27, 2020, Orange Beach, Alabama. Pp 103-104. Electronic Publication.

Interpretive Summary:

Technical Abstract: Climatic factors such as increased atmospheric CO2 levels are associated with global warming which is projected to dramatically impact the production and quality of food crops. Specifically, heat stress is known to significantly increase grain chalkiness in rice which reduces milling quality, cooking properties, and grain appearance. Over the last several years, the USA rice industry has been concerned about the increasing prevalence of undesirable chalky rice which has resulted in a loss of some international markets, particularly in South America and Central America. However, research has shown that some rice cultivars are more susceptible to heat induced grain chalk development than others. This indicates that there is a genetic component that could be used in breeding to mitigate the negative effects of climate change on rice grain quality. Using a KZ RIL mapping population from KBNT-1-1, a translucent, low phytic acid (LPA) mutant derived from the US long grain variety Kaybonnet, crossed with Zhe733, a chalky, long grain variety from China, Edwards et al (2017) identified 10 QTLs impacting grain chalk. In this study, the two parents and seven KZ-RILs selected based presence and/or absence of 4 major chalk QTLs were evaluated to understand the impact of genotype and environment interactions on heat-induced chalk formation as well as rice yield production. Plants were grown under ambient and elevated atmospheric CO2 levels (i.e. 400 and 600 ppm, respectively) in controlled growth chambers and half of the plants were subjected to heat treatment during anthesis. The genotypes were evaluated for 1) photosynthetic adjustment, A, gs, A/Ci, grain yield, in response to heat, 2) agronomic traits (i.e. yield, grain length, width, etc), 3) % chalk, and 4) grain elements (i.e. P, K, Ca, Mg, S, Na, Fe, Mn, Zn, Cu, B, As, C, and N). Our results showed natural genetic variation in heat-induced chalk formation and grain elemental contents in response to a changing climate, i.e. high temperature with elevated atmospheric CO2.