New genotypes for productive and sustainable agriculture
- UK team: Davies, Forde
- Chinese team: Wensuo Jia, Laihua Liu, Yinbo Gan
Increased nutrient use efficiency in agriculture:
Fertilizers, particularly N fertilizers, are expensive and highly demanding of energy in their production and distribution. Large amounts of fertilizer applied to fields is lost from the cropping system (often > 50%), which is wasteful and leads to environmental problems. It is recognized that there is considerable potential to improve the N-use efficiency of major crop species. While conventional breeding has gone a long way towards optimizing the efficiency of N-use once the N is absorbed by the plant, there has historically been little emphasis on breeding for the ability to capture a higher proportion of the N applied (Lynch, 2007 Aust. J. Bot. 55, 493-512). The efficiency of nutrient capture is largely determined by the root architecture, a trait that is difficult for breeders to select for. Lancaster researchers have a strong record in plant-nutrient relationships (Forde) and see an opportunity to make a major contribution to improving crop yields per unit of N fertilizer applied by using genetic approaches to improve root architecture. Pioneering work at Lancaster has identified the existence of a gene regulatory net work at the root tip of the model species Arabidopsis that is responsible for modulation the growth and branching of the root system in response to variations in the external (and internal) supply of N. This network provides an ideal target for the manipulation of root architecture. Two of the genetic components of the network have already been identified (1, 2, 3) and we have shown that by down– or up-regulating the expression of one of them (ANR1) it is possible to produce plants with either increased or decreased amounts of root branching (4).
Consolidating the established collaborations with our Chinese partners (CAU) will, via the ability to conduct field scale trials and produce transgenics, enable us to transfer the knowledge we have gained from our extensive Arabidopsis work to a major monocot crop species (rice). Via the same regulatory network in rice to determine their ability to modify root architecture in this heterologous plant species and identify rice orthologues of ANR1 and of other components of the regulatory network and establish their ability to modulate root architecture in transgenic rice. In both cases the transgenic rice lines will be evaluated for their effects on N-use efficiency under field conditions.
Increased drought resistance of crop plants:
Recent Lancaster work (in collaboration with CAU) has highlighted the increases in plant water uses efficiency that can be achieved by modifying chemical root signaling that can limit yield when soil dries(5). By exploiting the opportunity to conduct field scale GM trials in China (CAU) we propose to exploit novel opportunities provided by rootstock-mediated plant improvement. We will do this by exploiting natural genetic variation and targeted gene expression. The surgical procedure of grafting allows production of a chimeric plant with different genotypes for root (rootstock) and shoot (scion). Modifying the root genotype then can allow us to target particular signaling pathways highlighted in our recent work as being of particular importance in drought resistance(6), without modifying the genotype of the whole plant (which may have additional unwanted effects). For a crop where the shoot is consumed as a foodstuff, modifying the genotype of a root system by transgenesis and grafting this to a wild-type shoot might confer the desirable drought resistance character to the crop while allowing us to overcome objections held by the public to eating transgenic food. Increased water use efficiency could be improved by transgenically enhancing the production and supply to the shoot of cytokines synthesized in roots. These hormones can delay leaf senescence with resulting increases in productivity under drought in ‘staygreen’ crops. This hypothesis is supported by the results reported recently by Rivero et al. (2007 Proceedings of the National Academy of Sciences, USA.104, 19631-19636). Proposed collaboration with CAU (Liu and Jia) will give us access to facilities and expertise for plant transformation and field-based phenotype analysis of transgenic plants that are not available to us in the UK. This will deliver: a programme of applied development and the generation of novel genes and IPR to regulate crop root architecture (to) increase resource use efficiency and productivity under drought.
(Click cited number link to relevant background pubulish paper list, or click here.)
