Restoration of female fertility in Trichoderma reesei QM6a provides the basis for inbreeding in this industrial cellulase producing fungus.
Restoration of female fertility in Trichoderma reesei QM6a provides the basis for inbreeding in this industrial cellulase producing fungus.
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DOI：
10.1186/s13068-015-0311-2
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发表时间：
2015
影响因子：
6.3
通讯作者：
Kubicek CP
中科院分区：
文献类型：
--
作者：
Linke R;Thallinger GG;Haarmann T;Eidner J;Schreiter M;Lorenz P;Seiboth B;Kubicek CP
丝状真菌经常被用作工业生物技术中的生产平台。所涉及的大多数菌株被认为是完全无性繁殖的，从而阻止了传统菌株育种技术的应用。在过去的十年中，有证据表明，许多这些不完美的真菌也拥有性生活周期。里氏木霉（Trichoderma reesei）是用于食品、饲料和生物精炼目的的酶的工业生产者，其是异宗配合的，并且在工业利用的物种中占据特殊地位，因为所有工业菌株都来源于单一的MAT 1 -2分离株QM 6a。因此，在该品系内通过杂交进行品系改良是不可行的，因为这需要MAT 1 -1交配伴侣。然而，简单地将其中一个交配伴侣的交配类型转换为MAT 1 -1，不足以产生能够与QM 6a MAT 1 -2有性生殖的基因型。我们已经使用系统生物学方法来鉴定在QM 6a品系中恢复有性生殖的基因。为此，T。reesei QM 6a与MAT 1 -1野生型菌株CBS999.97杂交。后代在两个谱系中与QM 6a回交8次，以获得具有最小组CBS999.97特异性基因的交配能力MAT 1 -1菌株。比较基因组分析确定了总共73个基因，其中两个编码未知的C2 H2/锚蛋白和WD蛋白HAM 5的同源物被确定为子实体形成所必需的。在交配型转换T. reesei QM 6a与亲本菌株QM 6a有性杂交。里氏木霉即使在实验室条件下通常也能够进行有性繁殖的发现，为使用这种真菌的经典育种技术的适用性带来了希望，如已知的用于植物和某些酵母的。然而，野生型分离物QM 6a是雌性不育的发现排除了沿着该品系的任何进展沿着。随着雌性不育遗传原因的发现和工程可育菌株的创建，我们现在提供了在该真菌中建立有性杂交的基础，并预示着T. reesei。本文的在线版本（doi：10.1186/s13068-015-0311-2）包含补充材料，可供授权用户使用。
Filamentous fungi are frequently used as production platforms in industrial biotechnology. Most of the strains involved were known as reproducing exclusively asexually thereby preventing the application of conventional strain breeding techniques. In the last decade, evidence was obtained that a number of these imperfect fungi possess a sexual life cycle, too. Trichoderma reesei, an industrial producer of enzymes for food, feed and biorefinery purposes, is heterothallic and takes a special position among industrially utilized species as all industrial strains are derived from the single MAT1-2 isolate QM6a. Consequently, strain improvement by crossing is not feasible within this strain line as this necessitates a MAT1-1 mating partner. Simply switching the mating type in one of the mating partners to MAT1-1, however, is not sufficient to produce a genotype capable of sexual reproduction with QM6a MAT1-2. We have used a systems biology approach to identify genes restoring sexual reproduction in the QM6a strain line. To this end, T. reesei QM6a was crossed with the MAT1-1 wild-type strain CBS999.97. The descendants were backcrossed 8-times in two lineages with QM6a to obtain mating competent MAT1-1 strains with a minimal set of CBS999.97 specific genes. Comparative genome analysis identified a total of 73 genes of which two—encoding an unknown C2H2/ankyrin protein and a homolog of the WD-protein HAM5—were identified to be essential for fruiting body formation. The introduction of a functional ham5 allele in a mating type switched T. reesei QM6a allowed sexual crossing with the parental strain QM6a. The finding that Trichoderma reesei is generally capable of undergoing sexual reproduction even under laboratory conditions raised hope for the applicability of classical breeding techniques with this fungus as known for plants and certain yeasts. The discovery that the wild-type isolate QM6a was female sterile, however, precluded any progress along that line. With the discovery of the genetic cause of female sterility and the creation of an engineered fertile strain we now provide the basis to establish sexual crossing in this fungus and herald a new era of strain improvement in T. reesei. The online version of this article (doi:10.1186/s13068-015-0311-2) contains supplementary material, which is available to authorized users.