Benech-Arnold Roberto L, Rodríguez María V
Cátedra de Cultivos Industriales, Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.
Instituto de Fisiología y Ecología Vinculado a la Agricultura, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.
Front Plant Sci. 2018 Jun 15;9:811. doi: 10.3389/fpls.2018.00811. eCollection 2018.
The possibility of obtaining sorghum grains with quality to match the standards for a diversity of end-uses is frequently hampered by the susceptibility to pre-harvest sprouting (PHS) displayed by many elite genotypes. For these reasons, obtaining resistance to PHS is considered in sorghum breeding programs, particularly when the crop is expected to approach harvest maturity under rainy or damp conditions prevalence. As in other cereals, the primary cause for sprouting susceptibility is a low dormancy prior to crop harvest; in consequence, most research has focused in understanding the mechanisms through which the duration of dormancy is differentially controlled in genotypes with contrasting sprouting behavior. With this aim two tannin-less, red-grained inbred lines were used as a model system: IS9530 (sprouting resistant) and Redland B2 (sprouting susceptible). Redland B2 grains are able to germinate well before reaching physiological maturity (PM) while IS9530 ones can start to germinate at 40-45 days after pollination, well after PM. Results show that the anticipated dormancy loss displayed by Redland B2 grains is related reduced embryo sensitivity to abscisic acid (ABA) and increased levels of GA upon imbibition. In turn, transcriptional data showed that ABA signal transduction is impaired in Redland B2, which appears to have an impact on GA catabolism, thus affecting the overall GA/ABA balance that regulates germination. QTL analyses were conducted to test whether previous candidate genes were located in a dormancy QTL, but also to identify new genes involved in dormancy. These analyses yielded several dormancy QTL and one of them located in chromosome 9 (qGI-9) was consistently detected even across environments. Fine mapping is already in progress to narrow down the number of candidate genes in qGI-9.
许多优良基因型高粱易受收获前发芽（PHS）影响，这常常阻碍了获得符合多种最终用途标准的高粱籽粒的可能性。因此，高粱育种计划中考虑培育抗PHS的品种，特别是当作物预计在多雨或潮湿条件下接近收获成熟时。与其他谷物一样，发芽易感性的主要原因是作物收获前休眠期短；因此，大多数研究集中在了解不同发芽行为基因型中休眠期长短差异控制的机制。为此，使用了两个无单宁、红粒自交系作为模型系统：IS9530（抗发芽）和Redland B2（易发芽）。Redland B2籽粒在达到生理成熟（PM）之前就能很好地发芽，而IS9530的籽粒在授粉后40 - 45天，即PM之后很久才开始发芽。结果表明，Redland B2籽粒预期的休眠丧失与胚对脱落酸（ABA）的敏感性降低以及吸水后赤霉素（GA）水平升高有关。反过来，转录数据显示Redland B2中ABA信号转导受损，这似乎对GA分解代谢有影响，从而影响调节发芽的整体GA/ABA平衡。进行了QTL分析，以测试先前的候选基因是否位于休眠QTL中，同时也识别参与休眠的新基因。这些分析产生了几个休眠QTL，其中一个位于9号染色体上（qGI - 9），甚至在不同环境中都能持续检测到。目前正在进行精细定位，以减少qGI - 9中的候选基因数量。
