Modifications to a LATE MERISTEM IDENTITY1 gene are responsible for the major leaf shapes of Upland Cotton (Gossypium hirsutum L.)”.
Title: Modifications to a LATE MERISTEM IDENTITY1gene are responsible for the major leaf shapes of Upland Cotton:
On October25, Dr. Vasu Kuraparthy presented seminar on topic entitled:” Modifications to a LATE MERISTEM IDENTITY1gene are responsible for the major leaf shapes of Upland Cotton (Gossypium hirsutum L.)”.
Dr. Kuraparthy started his seminar by bringing into light economic importance of Cotton. He discussed about evolution of Cotton. Cotton is an allotetraploid (AADD) and was evolved from cross between Gossypium arboreum (AA) and Gossypium raimondii(DD).
Dr. Kuraparthy discussed that leaf shapes play an important role in increasing Cotton productivity. There are four major leaf shapes namely Normal, Sub-Okra, Okra and Super-okra. An ideal cultivar ideotype will be such which have normal leaves at vegetative leaves and okra type leaves at flowering stage.
He explained the morpho-metric experiments performed to separate out four leaf shapes. He described how they have cloned the gene controlling leaf shape. They have crossed Normal type with Okra type to produce the genetic map. Orthologous mapping to D-genome donor narrowed down the region to 34 putative genes. Further on, shuttle mapping with A-genome donor reduces the region to 10 putative genes. Mapping with association mapping panel and two near-isogenic lines brings them to region having 4 genes only.
Dr. Kuraparthy and his team performed expression analysisusing qRT-PCR. They found two genes (GhHRA1 and GhRLK) were expressing late in contrast to gene controlling leaf shapeexpresses at early stages. GhLMI1-D1awas expressing at same level in all leaf shapes; However, GhLMI1-D1b was upregualted in Okra and Super-Okra leaf types indicating that D1b is our potential gene.
They sequenced this gene in all the four leaf types and detected two major polymorphisms. He mentioned Sub-okra is the ancestral type. An 8-bp deletion in the third exon produces normal leaf type and tandem 133 bp duplication in the promoter region produces okra and super-okra leaf types.
Then, his team also performed VIGS (Virus Induced Gene Silencing) on the gene D1b to functionally characterize and validate the gene. They have designed construct specific to D1b. Silencing of D1b induces normal leaf (however, only temporarily). There was no change in expression of D1a validating specificity of VIGS construct.
They also looked for transcriptome wide changes in different leaf shapes by looking into RNA-seq data. They discovered that photosynthetic genes and developmental regulators areup-regulated whereasMicro-tubule and kinesin processes are down-regulated in okra type.
Dr. Kuraparthy and his team were able to conclude to leaf shape plays a crucial role in productivity and D1b is the gene controlling leaf shapes. The future studies will be on developing an ideal cultivar ideotype and understanding the mechanism of functioning of D1b gene.
Edited by Bhavit Chhabra
