Alternatively spliced BobCAL transcripts alter curd morphotypes in a collection of Chinese cauliflower accessions

The curd of cauliflower(Brassica oleracea L.var.botrytis)is a modified inflorescence that is consumed as a vegetable.Curd formation is proposed to be due to a mutation in the BobCAULIFLOWER(BobCAL)gene,but the genetic relationship between BobCAL variation and curd morphotypes remains obscure.To address this question,we collected and classified a collection of 78 cauliflower accessions into four subpopulations according to curd surface features:smooth,coarse,granular,and hairy curd morphotypes.Through the cDNA sequencing of BobCAL alleles,we showed that smooth and coarse accessions characterized by inflorescence meristem arrest presented a strong association with the 451T SNP(BobCAL_T),whereas granular and hairy accessions marked with floral organ arrest presented an association with 451G(BobCAL_G).Interestingly,all BobCAL alleles were alternatively spliced,resulting in a total of four alternative splice(AS)variants due to the retention of the fourth and/or seventh introns.Among accessions with BobCAL_G alleles,the total expression of all these AS variants in granular plants was almost equal to that in hairy plants;however,the expression of the individual AS variants encoding intact proteins relative to those encoding truncated proteins differed.Hairy accessions showed relatively high expression of the individual variants encoding intact proteins,whereas granular accessions displayed relatively low expression.In smooth cauliflower,the overexpression of the BobCAL_Ga variant caused an alteration in the curd morphotype from smooth to hairy,concurrent with an increase in the expression levels of downstream floral identity genes.These results reveal that alternative splicing of BobCAL transcripts is involved in the determination of cauliflower curd morphotypes.

Phenotypic diversity of rapeseed accessions from different geographic locations

It is essential to evaluate agronomic and quality traits when using elite lines in rapeseed （Brassica napus L. ） breeding. 92 rapeseed accessions （44 Chinese, 22 European, 16 USA and 10 Ca-nadian） were evaluated by 16 agronomic and quality traits in Northern China. Analysis of variance among the 92 accessions revealed significant differences on 13 traits. The 13 traits were plant height, setting po-sition of the first primary branch, silique number （ on terminal raceme） , silique density, siliques per plant, seeds per silique, thousand seed weight, seed yield per plant, flowering time, final flowering, ma-turity time, cold mortality, and oil content. Other 3 traits were not significant （primary branches per plant, terminal raceme length and seed protein） . Cluster analysis revealed that 92 accessions were clus-tered into 3 major groups. The 1st group had 10 Canadian and 5 Chinese. The 2nd group had 33 acces-sions from China and 5 from Europe. The 3rd group had 39 accessions from Europe and the USA. For ag-ronomy and quality traits, 45. 73% genetic variation attributed to differences among populations of geo-graphic regions, and 54. 27% attributed to differences within geographic regions. In summary, the a-broad accessions were distinguished from domestic ones, and could be used as important germplasm re-sources for enriching the genetic background of Chinese rapeseed, and vice versa.