Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, University Paris-Sud, University of Evry, University Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, 91405, Orsay, France.
InBioS, PhytoSYSTEMS, Laboratory of Plant Physiology, University of Liège, Sart Tilman Campus Quartier Vallée 1, Chemin de la Vallée 4, B-4000, Liège, Belgium.
Sci Rep. 2017 Jun 30;7(1):4402. doi: 10.1038/s41598-017-04556-1.
Abscission is the mechanism by which plants disconnect unfertilized flowers, ripe fruits, senescent or diseased organs from the plant. In tomato, pedicel abscission is an important agronomic factor that controls yield and post-harvest fruit quality. Two non-allelic mutations, jointless (j) and jointless-2 (j-2), controlling pedicel abscission zone formation have been documented but only j-2 has been extensively used in breeding. J was shown to encode a MADS-box protein. Using a combination of physical mapping and gene expression analysis we identified a positional candidate, Solyc12g038510, associated with j-2 phenotype. Targeted knockout of Solyc12g038510, using CRISPR/Cas9 system, validated our hypothesis. Solyc12g038510 encodes the MADS-box protein SlMBP21. Molecular analysis of j-2 natural variation revealed two independent loss-of-function mutants. The first results of an insertion of a Rider retrotransposable element. The second results of a stop codon mutation that leads to a truncated protein form. To bring new insights into the role of J and J-2 in abscission zone formation, we phenotyped the single and the double mutants and the engineered alleles. We showed that J is epistatic to J-2 and that the branched inflorescences and the leafy sepals observed in accessions harboring j-2 alleles are likely the consequences of linkage drags.
离层是植物将未受精的花朵、成熟的果实、衰老或患病的器官从植株上分离的机制。在番茄中，花梗脱落是控制产量和采后果实品质的重要农艺因素。已经记录了两个非等位突变体，即 jointless（j）和 jointless-2（j-2），它们控制花梗离层区的形成，但只有 j-2 被广泛用于育种。j 被证明编码一个 MADS 框蛋白。我们使用物理图谱和基因表达分析相结合的方法，鉴定了一个与 j-2 表型相关的位置候选基因，Solyc12g038510。使用 CRISPR/Cas9 系统对 Solyc12g038510 进行靶向敲除，验证了我们的假设。Solyc12g038510 编码 MADS 框蛋白 SlMBP21。对 j-2 自然变异的分子分析揭示了两个独立的功能丧失突变体。第一个结果是插入了一个 Rider 反转录转座子。第二个结果是一个导致截短蛋白形式的终止密码子突变。为了深入了解 J 和 J-2 在离层形成中的作用，我们对单突变体、双突变体和工程等位基因进行了表型分析。我们表明 J 对 J-2 是上位的，并且在携带 j-2 等位基因的品系中观察到的分枝花序和多叶萼片很可能是连锁拖曳的结果。
