Genome sequencing identified novel mechanisms underlying virescent mutation in upland cotton Gossypiuma hirsutum

Jin Gao,Yong-Hui Wang,Li-Wang Cai,Hua Yang,Qing-Hua Shi,Wei Wang,Yang Shi,Yan-Ru Sun,Jian-Ping Chen

doi:10.1186/s12864-021-07810-z

Abstract

BackgroundVirescent mutation broadly exists in plants and is an ideal experimental material to investigate regulatory mechanisms underlying chlorophyll synthesis, photosynthesis and plant growth. Up to date, the molecular mechanisms in two virescent mutations have been clarified in cottons (Gossypiuma hirsutum). A virescent mutation has been found in the cotton strain Sumian 22, and the underlying molecular mechanisms have been studied.MethodsThe virescent mutant and wild type (WT) of Sumian 22 were cross-bred, and the F1 population were self-pollinated to calculate the segregation ratio. Green and yellow leaves from F2 populations were subjected to genome sequencing and bulked-segregant analysis was performed to screen mutations. Real-time quantitative PCR (RT-qPCR) were performed to identify genes in relations to chlorophyll synthesis. Intermediate products for chlorophyll synthesis were determined to validate the RT-qPCR results.ResultsThe segregation ratio of green and virescent plants in F2 population complied with 3:1. Compared with WT, a 0.34 Mb highly mutated interval was identified on the chromosome D10 in mutant, which contained 31 genes. Among them, only ABCI1 displayed significantly lower levels in mutant than in WT. Meanwhile, the contents of Mg-protoporphyrin IX, protochlorophyllide, chlorophyll a and b were all significantly lower in mutant than in WT, which were consistent with the inhibited levels of ABCI1. In addition, a mutation from A to T at the -317 bp position from the start codon of ABCI1 was observed in the genome sequence of mutant.ConclusionsInhibited transcription of ABCI1 might be the mechanism causing virescent mutation in Sumian 22 cotton, which reduced the transportation of protoporphyrin IX to plastid, and then inhibited Mg-protoporphyrin IX, Protochlorophyllide and finally chlorophyll synthesis. These results provided novel insights into the molecular mechanisms underlying virescent mutation in cotton.

Highlights

Virescent mutation broadly exists in plants and is an ideal experimental material to investigate regulatory mechanisms underlying chlorophyll synthesis, photosynthesis and plant growth
Virescent mutant plants together with wild type (WT) plants provide ideal experimental materials for investigations of mechanisms regulating the expression of genes in relation to chlorophyll synthesis, which are important to photosynthesis and plant growth
The virescent mutation is a recessive gene in Sumian 22 The young leaves of mutant were clearly distinguished by a yellowish leaf color (Fig. 1A), significantly different from the WT (Fig. 1C)

Summary

Introduction

Virescent mutation broadly exists in plants and is an ideal experimental material to investigate regulatory mechanisms underlying chlorophyll synthesis, photosynthesis and plant growth. The molecular mechanisms in two virescent mutations have been clarified in cottons (Gossypiuma hirsutum). A virescent mutation has been found in the cotton strain Sumian 22, and the underlying molecular mechanisms have been studied. Investigation of the molecular mechanisms underlying plant growth and production of cotton may facilitate the molecular breeding process. Virescent mutant plants together with wild type (WT) plants provide ideal experimental materials for investigations of mechanisms regulating the expression of genes in relation to chlorophyll synthesis, which are important to photosynthesis and plant growth

Methods

Results

Discussion

Conclusion