ViPS Invited Seminar August 2019
Hiroshi Wada, NARO, Japan

Date: 28th August 2019

Time: 13:15

Title: New approaches combined with environmental control for promoting heat tolerant rice breeding

Location: Seminar room 172, Korona Info Centre, Viikinkaari 11

Host: Kurt Fagerstedt

Abstract: The occurrence of heat-related damages, such as rice chalkiness and spikelet sterility that reduce quality and yield, is a major problem for global rice production under global warming. In Japan, multiple heat tolerant cultivars have been developed to reduce the occurrence of chalky rice using conventional breeding, although there have not been any cultivars developed for heat-induced spikelet sterility. Tremendous efforts have been made to examine the causes of each phenomenon; however, most analyses have remained at tissue level due to the technical limitations. While a laser microdissection method has been used to study chalky formation site-specifically, what exactly occurred in the endosperm cells prior to chalky formation remains unknown. Recently, a single cell metabolomics, called ‘picolitre pressure-probe electrospray-ionization mass spectrometry (picoPPESI-MS)’, has been combined with environmental control in order to directly analyze the metabolites in the single cells in intact plants growing in controlled environments. The use of picoPPESI-MS under heat conditions, together with time-course transmission electron microscopy, has extended the scope of our understandings of heat-induced chalky formation. When considering the predicted increase in heat risk, development of more superior heat tolerant cultivars is strongly desired, particularly for ensuring spikelet fertility at extremely high temperature to maintain yield. However, evaluating heat tolerance of multiple lines/cultivars is not a straightforward matter in the fields, because flowering dates differ among cultivars and the reproducibility of heat treatments applied is often not as reproducible. To accelerate breeding for developing new cultivars, we have built two sets of an artificial rice paddy fields placed in a growth chamber to simultaneously conduct two temperature treatments at flowering. By using this robust high-throughput screening method, it has become possible to reproducibly evaluate heat tolerances across multiple specimens of plants at the same time. And consequently, varietal differences in heat stress tolerance at flowering have been identified successfully. In this seminar, our recent progress using these techniques and prospects will be presented.

Hiroshi Wada is an environmental plant physiologist focusing on basic and applied research as well as the dissemination of any technologies his group develops. His research group aims to contribute to the development of agricultural technologies, promote related industries and create new food cultures for the Kyushu-Okinawa region.

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