Study On A Member SPL12 Of SQUAMOSA Promoter Binding Protein-Like Gene Family In Regulating Seed Dormancy In Rice

During rice(Oryza sativa L.)planting,pre-harvesting sprouting(PHS)often results in loss of grain yield and reduced quality.Enhanced seed dormancy could inhibit PHS to a certain extent and improve seed longevity.Seed dormancy is mainly regulated by abscisic acid(ABA)and/or gibberellin(GA)signaling pathways.Ole]8 is a seed-specific promoter.In this study,POle18:SPL12,POle18:IPA1 and P35S:SPL12:FLAG overexpression vectors were constructed to obtain transgenic plants.A series of experiments were conducted in the T1 generation after field planting.The main research results were as follows:1.Seed germination and field phenotype observation showed that POle18:SPL12 and POle18:IPA1 overexpression enhanced seed dormancy,but had no significant effect on plant types of rice.In addition,POle18:IPA1 overexpression also increased seed length,1000-grain weight,and plot yield2.Hormone measurement showed that compared with ZH11,the levels of ABA in fresh seed embryos of POle18:SPL12 and POle18:IPA1 overexpression lines decreased,and the expression levels of two biologically active gibberellins(GA3 and GA4)decreased.This result showed that SPL12 and IPA1 did not enhance seed dormancy through the ABA pathway3.The results showed that POle18:SPL12 overexpression lines compared with ZH11 differentially expressed genes(DEGs),a key GA related The synthetic gene KO2 and 4 putative GA-related receptor genes(Os07g0162900,Os08g0475100,Os09g0462200 and Os03g0790500)decreased in expression,and three important GA-related degradation genes(GA2ox3,GA2ox10 and HOX12)and SLR1(a negative regulator of GA signaling pathway)increased in expression.These results indicated that compared with ZH11,the GA signaling pathway in POle18:SPL12 overexpression lines was weakened4.ChIP-qPCR analysis further showed that SPL12 interacted with the promoters of a GA-related synthetic gene KO2,4 putative GA-related receptor genes(Os07g0162900,Os09g0462200,Os03g0790500 and Os08g0475100),3 GAs degradation genes(GA2ox3,GA2ox10,and HOX12)and SLR1,indicating that SPL12 weakened the GA signaling pathway through direct regulating many genes in the GA signaling pathway to enhance seed dormancyTherefore,we found that SPL12 and IPA1 enhanced seed dormancy and inhibited PHS.