Self-Incompatibility System of Ipomoea trifida, a Wild-Type Sweet Potato

Abstract

Diploid Ipomoea trifi da (Convolvulaceae) is a close relative of the cultivated hexaploid Ipomoea batatas , the cultivated sweet potato. These plants have sporophytic self-incompatibility that is regulated by a single multiallelic locus, designated as the S -locus. Genetic analyses of I. trifi da plants collected from Central America identifi ed about 50 different S -haplotypes with a linear dominance hierarchy having some codominance relationships. A linkage map of DNA markers around the S -locus indicated that the S -locus is delimited to 0.23 cM. Within the S -locus genomic region, a hypervariable genomic region of 35-95 kbp was identifi ed, and we designated this region SDR ( S -locus-specifi c divergent region). Of the several genes located within the SDR, one anther-specifi c gene, AB2 , and three stigma-specifi c genes, SE1 , SE2 , and SEA , are candidate S -genes that may encode male and female S -determinants of self-incompatibility.Keywords Ipomoea trifi da • Self-incompatibility • Sweet potato IntroductionSelf-incompatibility (SI) is a genetic mechanism to prevent self-fertilization (and thus encourage outcrossing) in angiosperms. In self-incompatible plants, when a pollen grain is recognized as the same type as self, some stage of pollen germination, pollen tube elongation, ovule fertilization, or embryo development is halted, and no seeds are produced. SI is classifi ed into several groups: homomorphic SI, heteromorphic SI, cryptic SI (CSI), and late-acting SI. Heteromorphic SI is classifi ed into two groups: distyly is determined by a single locus, which has two alleles, and tristyly is determined by two loci, each with two alleles. Heteromorphic SI is sporophytic, in that both alleles in the male plant determine the SI response in the pollen. CSI exists in a limited number of taxa (for example, there is evidence for CSI in Silene vulgaris in the Caryophyllaceae; Glaettli 2004 ). In this mechanism, the simultaneous presence of cross-and self-pollen on the same stigma results in higher seed set from cross-pollen (Bateman 1956 ). Late-acting SI is also termed ovarian SI. In this mechanism, self-pollen germinates and reaches the ovules, but no fruit is set (Seavey and Bawa 1986 ;Sage et al. 1994 ).Homomorphic SI is classifi ed into sporophytic SI (SSI) and gametophytic SI (GSI) . The SSI system is found in species of several plant families, such as the Brassicaceae, Asteraceae, Malvaceae, Betulaceae, Sterculiaceae, Polemoniaceae, and Convolvulaceae (de Nettancourt 2001 ; Allen and Hiscock 2008 ). In the plants in these families, SI is genetically regulated by a single multi-allelic locus, the S -locus . Within the S -locus, a pair of genes (named S -genes ), one encoding the male-determinant molecules and the other the female-determinant molecules, is localized. These genes are essential for the SI reaction, because these gene products contribute to self/non-self recognition. The sets of S -genes are tightly linked at the S -locus, and the S -locus (also called S -haplotype : Nasrallah and Na...

Comparative analysis of the root transcriptomes of cultivated sweetpotato (Ipomoea batatas [L.] Lam) and its wild ancestor (Ipomoea trifida [Kunth] G. Don)

“…tabascana species [19–22]; these wild relatives do not form SRs. Previous transcriptome analyses investigating SR formation examined only the hexaploid cultivated species [2, 23, 24].…”

Variasi Struktur Morfologi Umbi dan Daun Ubi Jalar (Ipomoea batatas (L.) Lam.) Hasil Persilangan Alami Asesi Antin 1 dengan Beta 2

“…Jumlah kromosom ubi jalar adalah heksaploid (Tsuchiya, 2014) dan bunganya mengalami self incompatibility (Baafi et al, 2016;Kowyama et al, 2016;Tsuchiya, 2014). Kedua hal tersebut menyebabkan terjadinya variasi genetik yang tinggi dan berdampak pada tingginya variasi fenotipik pada tanaman yang ada di alam.…”