Gen dan QTL Pengendali Umur pada Kedelai

<p>Traits that control time of flowering and<br />maturity in soybean determine harvesting time of a soybean<br />cultivar. In Indonesia, early maturing soybean cultivars are<br />important at short period growing seasons due to the water<br />shortage in dry planting season. Shorter period of growing<br />season would increase the crop harvest index. Genetic<br />diversity of the present soybean germplasm collection is<br />low. Diversity improvement through introduction from<br />countries with four seasons faced difficulty due to<br />differences in growth adaptability. Technology for developing<br />germplasm with a broader adaptation will facilitate<br />germplasm movement from a more diverse environmental<br />growth. The objective of this review was to describe how<br />the time of flowering and maturity are controlled in soybean.<br />The review is supported by flowering time mechanism of<br />the model plant Arabidopsis thaliana as the genetics of<br />flowering time has been intensively studied in this model<br />plant. Transition from vegetative to reproductive development<br />is the outcome of the activation of genes responsible<br />for floral organ formation. Initial activation is generally the<br />result of environmental cues indicating the appropriate time<br />to flower. Studies from Arabidopsis showed that transition<br />from vegetative to reproductive stage is complex involving<br />many genes and several genetic pathways. In soybean, time<br />of flowering and maturity are controlled by at least nine<br />genes, E1 to E8 and Dt1. The genes interact with daylength<br />and temperature. Major and minor QTLs controlling the<br />traits were identified using various mapping populations.<br />The major QTLs were detected at various populations with<br />diverse genetic backgrounds tested at diverse environmenttal<br />conditions. Some of the QTLs were associated with the E<br />genes and some others were not. Several Arabidopsis<br />flowering gene homologous sequences were also mapped<br />on the soybean genome. The E gene markers and the QTLs<br />with large effect for reproductive traits are breeder targets<br />for breeding and development of soybean photoperiod<br />insensitive germplasm. Genes for flowering time isolated<br />from Arabidopsis can be used to develop transgenic<br />soybean with broader adaptation. Technology for development<br />of soybean germplasm with broader adaptation will<br />facilitate the soybean germplasm movement from diverse<br />environmental growth conditions to support systematic and<br />sustainable national soybean breeding programs.</p>