Plant Genomics

Biography

Biography: Rudy Dolferus

Abstract

Limited water availability during the reproductive stage reduces fertility and affects grain yield of wheat crops. The young microspore (YM) stage is particularly sensitive to water stress, causing pollen abortion and reduced spike grain number. Changing rainfall patterns as a result of climate change will negatively impact on crop yields in the future, necessitating breeding of wheat varieties with improved tolerance to drought and other abiotic stresses. Soil drought treatments are notoriously difficult to control. We therefore developed a controlled environment phenotyping method based on YM hyper sensitivity to drought stress but using osmotic stress and hydroponics as a surrogate for drought stress. NaCl was used as osmoticum and the use of hydroponics enabled us to accurately control timing, duration and severity of the stress treatments. Two major QTL associated with maintenance of spike grain number under osmotic stress conditions (SGNO), SGNO-5A.1 and SGNO-7A, were identified using a Cranbrook×Halberd DH population. SGNO-5A.1 and SGNO-7A explained 31% and 24% of the genetic variation respectively and both QTL act synergistically to control stress tolerance (5A.1) and spike grain number (7A). Tolerant and sensitive tails of the Cranbrook×Halberd population are currently evaluated under managed field drought conditions (rainout shelter). Controlled environment studies confirmed that osmotic stress tolerant and sensitive tail lines are tolerant or sensitive to soil drought and heat stress, suggesting that osmotic adjustment is essential for maintaining grain number under other abiotic stress conditions. We are currently fine-mapping the SGNO-5A.1 and SGNO-7A QTL using MAGIC lines and F2 backcross lines.