Student/presenter: Avinash Shrestha, Ph.D student, Plant breeding and molecular genetics
Format: Oral presentation
Title: Novel genetic variation for reduced glanding identified in the cotton landrace Hopi
Avinash Shrestha1, Puneet Kaur Mangat1, Junghyun Shim1, 2, Lakhvir Kaur Dhaliwal1 and Rosalyn Shim1
1Plant and Soil Science Department, Texas Tech University, Lubbock, Texas, 79409
2Olam International Limited, Rukubi, Doma, Nassarawa 962, Nigeria
The presence of the toxic chemical gossypol in cotton glands limits the use of seed byproducts for edible oil and meal production. The landrace Hopi has sparse glands which can be exploited to potentially reduce gossypol levels in cotton seeds. In this study, we performed quantitative trait loci (QTL) analyses on an F2 population generated from crosses between Hopi and TM-1 to identify genetic variation for reduced glanding. A high-density genetic map spanning 2253.11 and 1932.21 cM for A and D sub-genome, respectively, with an average marker interval of 1.14 cM was generated using CottonSNP63K array. The linkage map showed a strong co-linearity with the physical map of cotton in terms of marker order. A total of five QTLs regulating the target trait were identified, three of which have not been previously reported. The new QTLs qGC_A11.1 and qGC_A11.2 in chromosome A11 spanned 380 and 570 kb, respectively, whereas qGC_D11 from chromosome D11 covered a 2010 kb region. In silico analysis of the novel QTLs regulating gland formation in cotton identified a total of 13 candidate genes. Tissue-specific, comparative expression analysis of the candidate genes showed significant downregulation of the transcription factors bHLH1, MYB2 and ZF1 in Hopi but not in TM-1. Sequence analysis identified early stop codons in the coding region of the transcription factors in Hopi, which likely caused the downregulation in the expression of the genes. This, consequently, translated to reduced gland formation in the landrace. The results of the study provide basis for the cloning and functional validation of genes regulating glanding in cotton towards applications in breeding for this target trait in cotton. The successful reduction of gland formation in cotton has important implications in our ability to reduce gossypol content in cottonseeds that will allow its widespread utilization for meal and oil production.