The bHLH1-DTX35/DFR module regulates pollen fertility by promoting flavonoid biosynthesis in Capsicum annuum L.

Abstract

High pollen fertility can ensure the yield and efficiency of breeding work, but factors that affect the fertility of pepper pollen have not been studied extensively. In this work, we screened the reduced pollen fertility 1 (rpf1) mutant with reduced pollen fertility and yellow anthers from an EMS-mutagenized pepper population. Through construction of an F2 population, followed by BSA mapping and KASP genotyping, we identified CabHLH1 as a candidate gene for control of this trait. A G→A mutation at a splice acceptor site in CabHLH1 causes a frameshift mutation in the mutant, and the translated protein is terminated prematurely. Previous studies on CabHLH1 have focused on the regulation of flavonoid synthesis. Here, we found that CabHLH1 also has an important effect on pollen fertility. Pollen vigor, anther flavonoid content, and seed number were lower in CabHLH1-silenced pepper plants, whereas anther H2O2 and MDA contents were higher. RNA-Seq analyses showed that expression of the flavonoid synthesis genes DFR, ANS, and RT was significantly reduced in anthers of CabHLH1-silenced plants and rpf1, as was the expression of DTX35, a gene related to pollen fertility and flavonoid transport. Yeast one-hybrid and dual-luciferase reporter assays showed that CabHLH1 can directly bind to the promoters of DTX35 and DFR and activate their expression. These results indicate that CabHLH1 regulates ROS homeostasis by promoting the synthesis of anther flavonoids and acts as a positive regulator of pepper pollen fertility.

Genome-wide analysis of genetic diversity in a germplasm collection including wild relatives and interspecific clones of garden asparagus

“…Also present near this SNP is a gene with a myb-related protein 305-like function ( AsparagusV1_10.1876 ). These myb-related genes are usually involved in response to abiotic stresses, as in Vigna unguiculata , where a myb-related protein 305-like gene has been found to be upregulated after exposure to salt stress ( Zhang et al., 2022 ); however, they can also be associated with fruit production, as in Vigna mungo , where a myb-related protein 305-like gene has been found to be associated with a quantitative trait locus (QTL) for yield ( Singh et al., 2022 ), or with the ability to produce giant (mammoth) fruits, as in Cucurbita maxima ( Reddy et al., 2022 ). Therefore, it could be reasonable to assume that they may also be involved in determining flowering time and not solely in fruit characteristics.…”

Genome-wide identification of CaWD40 proteins reveal a novel complex (CaAN1-CaDYT1-CaWD40-91) involved in anthocyanin biosynthesis and genic male sterility in pepper (Capsicum annuum)

“…Several structural genes of anthocyanin biosynthesis, including CHS, CHI, F3H, F3'5'H, DFR, ANS and UFGT, was basically conserved in most plants [43,45,46]. In recent years, an increasing number of reports suggested that avonoids are closely related to pollen fertility [32,44,[47][48][49].…”

“…Pepper, as a typical spicy vegetable, belong to the genus Capsicum of of the Solanaceae family and originated in South and Central America [30]. The Capsicum species have various morphological characteristics and several pepper species lack anthocyanins [17,31,32]. In recent years, several genes controlling anthocyanin synthesis have been identi ed in pepper.…”

“…In recent years, several genes controlling anthocyanin synthesis have been identi ed in pepper. Zhang et al [32] reported that a splice acceptor site in CabHLH1 lead to a frameshift mutation in a mutant of de cient anthocyanin and fertility reduction of anther (rpf1). Two gene, CaAN3 and Ca3GT, controlling anthocyanin biosynthesis in pepper fruit were reported in succession [33,34].…”

Multi-omics analysis reveals key regulatory defense pathways and genes involved in salt tolerance of rose plants

“…Flavonoids comprise more than 9000 compounds and constitute a substantial category of plant secondary metabolites [ 18 ]. They have diverse biological functions in the growth and development of plants, including improving pollen fertility, imparting color, and influencing seed dormancy and germination [ 19 , 20 ]. In addition, flavonoids have protective roles against biotic and abiotic stresses, such as pathogen infections, ultraviolet (UV)-B, cold, drought, and salinity [ 21–23 ].…”