Temporal transcriptomics reveal the molecular mechanism of dormancy and germination regulated by temperature in Paris polyphylla seed

The mature seed of Paris polyphylla var.chinensis(PPC)is morphophysiologically dormant and develops differently under warm and cold temperatures.To elucidate the molecular mechanisms underlying temperature-dependent regulation of PPC seed dormancy and germination,we investigated the dynamic changes in PPC seed transcript levels under warm and cold temperature stratifications(WS and CS,respectively)by time-resolved RNA sequencing,focusing on genes related to hormone metabolism and signaling and cell wall remodeling(CWRM)and encoding transcription factors/regulators(TFs/TRs).A total of 48765 and 47836 differentially expressed genes(DEGs)were associated with WS and CS,respectively.Of these,17581 and 16652 DEGs,respectively,unique to WS and CS,and 5386 were common to both temperature stratifications across nine analyzed growth stages.The expression of hormone metabolism and signaling,TF/TR,and CWRM genes were closely associated with temperature.More genes related to gibberellin(GA),cytokinin,auxin,and brassinosteroid biosynthetic were upregulated in WS as compared to CS seeds,while genes related to dormancy release and germination were downregulated in WS seeds.However,only GA and abscisic acid levels were altered in PPC seeds breaking morphophysiological dormancy(MPD).Overall,37 TF and five TR families were upregulated whereas 24 TF and 16 TR families were downregulated in WS as compared to CS seeds.Most CWRM families were highly expressed under WS as compared to CS,suggesting that they promote endosperm weakening and embryo growth of WS seeds and facilitate MPD release and germination.A coexpression analysis revealed positive correlations between TFs/TRs and DEGs involved in hormone metabolism and signaling and CWRM.These results provided a basis for investigating the interaction between the endosperm and underdeveloped embryo in the regulation of PPC seed germination and seedling emergence.

四川地区华重楼(Paris polyphylla var.chinensis)主要病害调查及病原菌鉴定

华重楼是重要的中药材,近年来,华重楼病害已成为制约四川华重楼产量和品质提高的重要因素之一。本研究对四川种植区华重楼病害进行了调查,共调查到主要危害华重楼病害有4种。通过组织分离法对相应的病原菌进行分离,并对病原菌进行致病性测定、形态学观察和分子生物学鉴定。试验结果显示,结合病原菌形态特征及r DNA-ITS、HSP60、G3PDH、RPB2、TEF、ACT、LSU、Alt琢1、TUB基因序列分析,并构建多基因分子系统发育树,鉴定出引起华重楼4种真菌病害病原菌,分别为华重楼叶枯病(Epicoccum sorghinu)、褐斑病(Alternaria tenuissima)、灰霉病(Botrytis cinerea)和黑斑病(Alternaria alternata)。目前,危害华重楼的最为严重的病害是灰霉病、褐斑病和叶枯病。华重楼主要病害的调查及病原菌种类的鉴定为华重楼病害的防治提供理论依据。