ISHS Acta Horticulturae 800: X International Pear Symposium
IDENTIFICATION OF GENES CODING FOR NH4+ TRANSPORTERS IN 'ROCHA' PEAR/BA29 |
| Authors: | M. Mota, C. Neto, C.M. Oliveira |
| Keywords: | ammonium uptake, AMT1, nitrogen, Pyrus communis, quince BA29 |
| Abstract:
In most soils, NH4+ and NO3- are the predominant sources of nitrogen (N) that are available for plant nutrition. Uptake may take place as either NO3- or NH4+ but plants preferentially take up NH4+ when both forms are present. Plant genes encoding NH4+ transporters (AMT1) have been characterized mainly in herbaceous crops, but there are no studies at the genetic level regarding ammonium uptake in fruit species. Portuguese pear production is concentrated in the Oeste region of Portugal and relies on one main cultivar, 'Rocha'. Quince BA29 is the most frequent rootstock used in orchards of 'Rocha' pear in this region. To elucidate the role of NH4+ transporters in N nutrition of 'Rocha'/BA29 trees, we set out to identify genes encoding ammonium transporters expressed in the roots of this combination and to investigate their diversity. Fine roots of 'Rocha'/BA29 combination were sampled in different phases of the growth cycle (48DAFB, 110DAFB and six weeks after the harvest) and total RNA was extracted and reverse transcribed. Synthesized cDNA was subjected to PCR amplification with primers hybridizing with conserved regions of AMT1 genes already identified in different species and PCR products were cloned and sequenced. Sequences analysis and comparison with genes stored in genetic databases confirmed the identification of partial sequences of four different AMT1 genes, that show highest homology with four HATS (high-affinity transport system) transporter genes (LjAMT1;1, LjAMT1;2, LjAMT1;3 and LeAMT1;3). Simultaneous accumulation of the different transcripts was observed at the different stages analysed. The relative abundance of each of these transcripts during the growth cycle and in response to different doses of N is currently under investigation, in order to gain knowledge about the N uptake pattern by the trees, towards a more efficient N use. | |
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