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Abstract

Plants accumulate abscisic acid (ABA) under droughted conditions. Genetic variation in the accumulation of ABA in deteched and partially dehydrated leaves of rice has previously been reported, and this was found to be associated with variation in leaf size (smaller leaves made more ABA). Correlation analysis failed to distinguish clearly between a causal relationship between the two traits and close genetic between loci controlling the traits. Here we present a detailed genetic analysis of ABA accumulation in detached and partially dehydrated rice leaves. using a population of F2 plants generated from the lowland x upland cross IR20 (high-ABA) x 63-83 (low-ABA) which was mapped with RFLP and AFLP markers. Several highly significant quantitative trait loci (QTLs) for ABA accumulation and leaf weight were identified. Only one of the minor QTLs for ABA accumulation (accounting for only 4% of the phenotypic variance) was coincident with any QTLs for leaf size such that the high-ABA allele was associated with smaller leaves. This analysis, therefore, showed that the association previously found between ABA accumulation and leaf size was probably largely due to genetic linkage and not to a direct effect of leaf size on ABA accumulation or vice versa. Because of the importance of ABA accumulation in regulating responses of plants to drought stress and the effects of plant size on the rate of development of stress, QTLs for drought-induced ABA accumulation, leaf size and tiller number were compared between rice and wheat. In particular, a possible location in rice was sought for a homoeologue of the major wheat vernalization responsive gene, Vrn1, as this gene is also associated with major effects on leaf size, tiller number and ABA accumulation in wheat. The likelihood of homoeologous loci regulating ABA accumulation, leaf size and tiller number in the two crops is discussed.

AB-QTL analysis reveals new alleles associated to proline accumulation and leaf wilting under drought stress conditions in barley (Hordeum vulgareL.)

“…Abscisic acid (ABA) is one major factor implicated for leaf drying (senescence) under severe drought [47]. Quarrie et al [48] made a QTL analysis to dissect the genetics behind ABA accumulation and found ten QTL for low and high ABA accumulation in rice under drought stress conditions. In a previous study, they found a QTL for ABA accumulation on 5A of wheat in the region of vernalization gene Vrn1 [49].…”

Identification of QTLs for Yield and Drought-Related Traits in Maize: Assessment of Their Causal Relationships

“…quarrie et al (18) used qtl analysis for establishing relationships between physiological and morphological traits across cereals. in maize, mainly experiments on relationships between ABA, yield and other drought related traits have been conducted (12,18,22).…”

Chromosomal regions controlling seedling drought resistance in Israeli wild barley, Hordeum spontaneum C. Koch

“…multiqtl.com/). QTLs for drought resistant traits have been identified in many studies: for pre-and postflowering resistance to drought in sorghum (Tuinstra et al 1996(Tuinstra et al , 1997Crasta et al 1999); for anthesis-silking interval and yield components under drought in maize (Ribaut et al 1996(Ribaut et al , 1997; for OA in rice (Lilley et al 1996), barley (Teulat et al 1998), and wheat (Morgan and Tan 1996); for relative water content in barley (Teulat et al 2001(Teulat et al , 2003; for abscisic acid (ABA) accumulation in wheat (Quarrie et al 1994), maize (Lebreton et al 1995;Tuberosa et al 1998), and rice (Quarrie et al 1997); for stomatal behavior in maize (Lebreton et al 1995) and rice ; for root morphology and root penetration ability in rice (Champoux et al 1995;Ray et al 1996;Price and Thomas 1997;Yadav et al 1997;Zheng et al 2000). These QTLs were identified using the recombinant inbred lines (RILs), doubledhaploid population (DH), F 2 population, and F 3 or F 4 families.…”