Abiotic stresses, such as drought, salinity, extreme temperatures, chemical toxicity and oxidative stress are threats to agriculture and it is the primary cause of crop loss worldwide (Wang et al. (2003) Planta 218(1) 1-14).
In the art, several reports are available dealing with the biochemical, molecular and genetic background of abiotic stress (Wang et al. (2003) Planta 218(1) 1-14 or Kilian et al (2007) Plant J 50(2) 347-363). Plant modification to deal with abiotic stress is often based on manipulation of genes that protect and maintain the function and structure of cellular components. However, due to the genetically complex responses to abiotic stress conditions, such plants appear to be more difficult to control and engineer. Wang (Wang et al. (2003) Planta 218(1) 1-14), inter alia, mentions that one of the strategies of engineering relies on the use of one or several genes that are either involved in signalling and regulatory pathways, or that encode enzymes present in pathways leading to the synthesis of functional and structural protectants, such as osmolytes and antioxidants, or that encode stress-tolerance-conferring proteins.
Although improvements in providing abiotic stress tolerant plants have been reported, the nature of the genetically complex mechanisms underlying it provides a constant need for further improvement in this field. For example, it has been reported that genetically transformed drought tolerant plants generally may exhibit slower growth and reduced biomass (Serrano et al (1999) J Exp Bot 50:1023-1036) due to an imbalance in development and physiology, thus having significant fitness cost in comparison with plants that are not transformed (Kasuga et al. (1999) Nature Biot. Vol. 17; Danby and Gehring (2005) Trends in Biot. Vol. 23 No. 11).
Several biotechnological approaches are proposed in order to obtain plants growing under stress conditions. Plants with increased resistance to salt stress are for example disclosed in WO03/020015. This document discloses transgenic plants that are resistant to salt stress by utilizing 9-cis-epoxycarotenoid dioxygenase nucleic acids and polypeptides.
Plants with increased drought tolerance are disclosed in, for example, US 2009/0144850, US 2007/0266453, and WO 2002/083911. US2009/0144850 describes a plant displaying a drought tolerance phenotype due to altered expression of a DR02 nucleic acid. US 2007/0266453 describes a plant displaying a drought tolerance phenotype due to altered expression of a DR03 nucleic acid and WO 2002/083911 describes a plant having an increased tolerance to drought stress due to a reduced activity of an ABC transporter which is expressed in guard cells. Another example is the work by Kasuga and co-authors (1999), who describe that overexpression of cDNA encoding DREB1A in transgenic plants activated the expression of many stress tolerance genes under normal growing conditions and resulted in improved tolerance to drought, salt loading, and freezing. However, the expression of DREB1A also resulted in severe growth retardation under normal growing conditions (Kasuga (1999) Nat Biotechnol 17(3) 287-291). There remains a need for new, alternative and/or additional methodology for increasing resistance to abiotic stress, in particular abiotic stress like drought.
It is an object of the current invention to provide for new methods to increase drought resistance in a plant. With such plant it is, for example, possible to produce more biomass and/or more crop and plant product derived thereof if grown under conditions of low water availability/drought in comparison with plants not subjected to the method according to the invention.