Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA.
Rijk Zwaan Iberica S.A., Carretera Viator Paraje El Mamí S/N, La Cañada, 04120 Almería, Spain.
Int J Mol Sci. 2021 Dec 2;22(23):13067. doi: 10.3390/ijms222313067.
Tomato clade species ( sect. ) display multiple interspecific reproductive barriers (IRBs). Some IRBs conform to the SI x SC rule, which describes unilateral incompatibility (UI) where pollen from SC species is rejected on SI species' pistils, but reciprocal pollinations are successful. However, SC x SC UI also exists, offering opportunities to identify factors that contribute to S-RNase-independent IRBs. For instance, SC LA0716 pistils only permit SC pollen tubes to penetrate to the top third of the pistil, while pollen penetrates to ovaries. We identified candidate LA0716 pistil barrier genes based on expression profiles and published results. CRISPR/Cas9 mutants were created in eight candidate genes, and mutants were assessed for changes in pollen tube growth. Mutants in a gene designated (), which encodes a small cysteine-rich protein, permitted pollen tubes to grow to the bottom third of the style. We show that SpDIR1L protein accumulation correlates with IRB strength and that species with weak or no IRBs toward pollen share a 150 bp deletion in the upstream region of . These results suggest that contributes to an -RNase-independent IRB.
番茄族（sect.）物种表现出多种种间生殖障碍（IRB）。一些 IRB 符合 SI x SC 规则，该规则描述了花粉从 SC 物种在 SI 物种柱头上被拒绝，但相互授粉成功的单向不亲和（UI）。然而，SC x SC UI 也存在，为鉴定有助于 S-RNase 独立 IRB 的因素提供了机会。例如，SC LA0716 柱头只允许 SC 花粉管穿透柱头的上三分之一，而花粉穿透子房。我们根据表达谱和已发表的结果鉴定了候选的 LA0716 柱头屏障基因。在八个候选基因中创建了 CRISPR/Cas9 突变体，并评估了突变体对花粉管生长的变化。指定为 () 的基因中的突变体，该基因编码一种小的富含半胱氨酸的蛋白质，允许花粉管生长到花柱的底部三分之一。我们表明，SpDIR1L 蛋白积累与 IRB 强度相关，并且对花粉表现出弱或无 IRB 的物种在 基因的上游区域共享 150 bp 的缺失。这些结果表明 有助于 S-RNase 独立的 IRB。
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