Mutations in two pollen self-incompatibility factors in geographically marginal populations of Solanum habrochaites impact mating system transitions and reproductive isolation
Mutations in two pollen self-incompatibility factors in geographically marginal populations of Solanum habrochaites impact mating system transitions and reproductive isolation
复制标题
DOI：
10.3732/ajb.1600208
复制
发表时间：
2016-10-01
影响因子：
3
通讯作者：
Chetelat, Roger T.
中科院分区：
文献类型：
--
作者：
Markova, Dragomira N.;Petersen, Jennifer J.;Chetelat, Roger T.
研究前提：自交不亲和性（SI）是一种防止许多植物物种近交的机制。 SI的突变崩溃经常发生，但对于雌蕊和花粉SI功能逐渐丧失的进化步骤知之甚少。方法：在茄科植物中，SI是基于S-RNase的配子体类型。我们使用野生番茄品种 Solanum habrochaites 的 SI 和 SC 群体来研究两种花粉 SI 因子的自然变异：Cullin1 (CUL1) 蛋白和 S 位点 F-box 蛋白 (SLF-23)。在编码 SLF-23 识别的 S-RNase 的异源三倍体测试品系上评估花粉相容性。两种花粉因子对于该测试仪系列的兼容性都是必需的。使用互补测试和基因测序来鉴定 CUL1 或 SLF-23 中的突变。 主要结果：我们在该类群自然范围的北部和南部地理边缘附近收集的 SC 种群中检测到 CUL1 和/或 SLF-23 的功能丧失突变。非边缘 SC 和所有 SI 种质主要表达这些花粉因子的功能等位基因。 CUL1 序列的比较发现了北缘和南缘 SC 种质中存在的几个共享缺失突变。结论：CUL1 和 SLF-23 中的功能丧失突变可能在 SI 向 SC 转变期间相对较晚、雌蕊 SI 功能丧失后固定。 CUL1 突变导致与 SI 群体单方面不相容并加强生殖隔离。北部和南部 SC 生物型常见的点突变可能源自在更中部的 SI 人群中发现的共享祖先变异。
PREMISE OF THE STUDY: Self-incompatibility (SI) is a mechanism that prevents inbreeding in many plant species. The mutational breakdown of SI occurs frequently, yet relatively little is known about the evolutionary steps involved in the progressive loss of pistil and pollen SI function.METHODS: In Solanaceae, SI is the S-RNase-based gametophytic type. We used SI and SC populations of the wild tomato species Solanum habrochaites to study natural variation for two pollen SI factors: a Cullin1 (CUL1) protein and an S-locus F-box protein (SLF-23). Pollen compatibility was assessed on an allotriploid tester line encoding an S-RNase recognized by SLF-23. Both pollen factors are required for compatibility on this tester line. Complementation tests and gene sequencing were used to identify mutations in CUL1 or SLF-23.KEY RESULTS: We detected loss-of-function mutations in CUL1 and/or SLF-23 in SC populations collected near the northern and southern geographic margins of this taxon's natural range. Nonmarginal SC and all SI accessions expressed mostly functional alleles of these pollen factors. Comparison of the CUL1 sequences identified several shared deletion mutations present in both northern and southern margin SC accessions.CONCLUSIONS: Loss-of-function mutations in CUL1 and SLF-23 likely became fixed relatively late during SI to SC transitions, after loss of pistil SI function. Mutations in CUL1 establish unilateral incompatibility with SI populations and strengthen reproductive isolation. Point mutations common to northern and southern SC biotypes likely derive from shared ancestral variants found in more central SI populations.