Lotus (Nelumbo) is perennial aquatic plant, which can be used for food, ornamentation and medicine. Lotus rhizome is a storage organ derived from modified subterraneous stem, which acts as an important nutritional vegetable and the areproductive tissue for asexual production. The rhizome enlargement ensures its winter survival and sprouting in the coming spring season. Therefore, it is significant to study the mechanisms of rhizome enlargement in lotus.
Researchers from Wuhan Botanical Garden used quantitative trait loci (QTLs) mapping to uncover the genetic determinants of lotus rhizome enlargement, and predicte a candidate gene that putatively controls rhizome enlargement, and functionally validated in transgenic potato.
This study constructed a high-density genetic linkage map with 2935 markers binned from 236,840 SNPs. Mapping analysis for number of enlarged rhizome (NER) and rhizome enlargement index (REI) identified 14 signifcant QTLs. Three QTL regions (cqNER-LG1, cqREI-LG1 and cqREI-LG2) were repeatedly identified in at least two years. Among them, cqREI-LG2 explained about 20% of the phenotypic variation, and was considered as a major QTL for REI.
NnBEL6 was identified as the putative candidate gene underlying cqREI-LG2. The role of NnBEL6 in rhizome enlargement in lotus was validated through gene expression analysis, sequence comparison and transgenic overexpression in potato.
This work elucidates the genetic basis of rhizome formation and provides a foundation for future new cultivars breeding.
It was funded by the National Natural Science Foundation of China, Biological Resources Programme of CAS and Key Research Program of Frontier Science of CAS.
