Map-based cloning and characterization of a QTL (quantitative trait loci) network underlying growth responses to drought in Arabidopsis thaliana
Final Report Abstract
In the framework of the project, the relationship of flowering time and growth responses to mild drought stress and its genetic bases were studied in detail. Using Arabidopsis thaliana natural variation, we demonstrated that late flowering might be advantageous under moderate drought. A late floral transition allows drought acclimatization over time and enables the plant to compensate partially for an early growth deficit response and, thus, to maintain its fitness under drought. In our study, the strong association between late flowering and low growth response to drought was partially due to the complex interaction of three QTL (Quantitative Trait Loci), which were putatively underlay by known and newly identified flowering time genes. Our results could be applied for breeding new crop cultivars with delayed floral transition that are able to cope with moderate soil water deficit. The well-known flowering time gene FRIGIDA (FRI) was identified as being causal for one of our QTL. By analyzing two widespread alleles of FRI, we demonstrated for the first time the existence of a new class of Arabidopsis accessions with an intermediate phenotype between slow and rapid cycling types. Accessions of this intermediate class carry the FRI allele of the commonly used lab strain Landsberg erecta (Ler), which so far had been thought to be non-functional. Disproving this assumption, our results show that this allele retains some functionality and results in a delay of flowering when compared to true FRI null alleles. The use of the new classification into three FRI functional groups will increase the accuracy of adaptive studies in A. thaliana. Furthermore, during the course of the project, we validated a new QTL underlying differences in flowering time in several early flowering A. thaliana mapping populations. Fine-mapping and cloning resulted in the identification of the causal gene and suggest a specific mutation underlying a delay of flowering in the Ler accession. If confirmed, our results associate for the first time the causal gene with the transcriptional regulation of FLOWERING LOCUS C (FLC), another well-studied flowering time gene in Arabidopsis.
Publications
- (2014) Functional analysis of the Landsberg erecta allele of FRIGIDA. BMC Plant Biology 14:218
Schmalenbach I, Zhang L, Ryngajllo M, Jiménez-Gómez JM
(See online at https://doi.org/10.1186/s12870-014-0218-2) - (2014) The relationship between flowering time and growth responses to drought in the Arabidopsis Landsberg erecta x Antwerp-1 population. Frontiers in Plant Science 5:609
Schmalenbach I, Zhang L, Reymond M, Jiménez-Gómez JM
(See online at https://doi.org/10.3389/fpls.2014.00609)
