The presence of seed color in common bean (Phaseolus vulgaris) requires the dominant-acting P (pigment) gene, and white seed is a recessive phenotype in all domesticated races of the species. P was classically associated with seed size, thus describing it as the first genetic marker for a quantitative trait. The molecular structure of P was characterized to understand the selection of white seeds during bean diversification and the relationship of P to seed weight. P was identified by homology searches, a genome-wide association study (GWAS) and gene remodeling, and confirmed by gene silencing. Allelic variation was assessed by a combination of resequencing and marker development, and the relationship between P and seed weight was assessed by a GWAS study. P is a member of clade B of subclass IIIf of plant basic helix-loop-helix (bHLH) proteins. Ten race-specific P alleles conditioned the white seed phenotype, and each causative mutation affected at least one bHLH domain required for color expression. GWAS analysis confirmed the classic association of P with seed weight. In common bean, white seeds are the result of convergent evolution and, among plant species, orthologous convergence on a single transcription factor gene was observed.

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Bean golden yellow mosaic virus (BGYMV), incited by a whitefly (Bemisia tabaci Gennadius) transmitted geminivirus, is an important disease that can limit common bean (Phaseolus vulgaris L.) production in Central America, the Caribbean, and southern Florida. Only a few genes are currently deployed in BGYMV-resistant common bean cultivars. The identification of novel sources of resistance would help bean breeders broaden the genetic base of resistance to this important virus. Phaseolus coccineus L. germplasm accession G35172 was found by International Center for Tropical Agriculture scientists to be resistant to BGYMV. Populations derived from an interspecific cross between P. vulgaris and P. coccineus were evaluated to study the inheritance of resistance to BGYMV. Segregation ratios of F2 plants and other populations suggest that BGYMV resistance from P. coccineus is controlled by two genes. A recessive gene, with the proposed symbol bgm-3, confers resistance to leaf chlorosis and a dominant gene, with the proposed name Bgp-2, prevents pod deformation in the presence of BGYMV. Results from allelism tests with previously reported BGYMV resistance genes (bgm, bgm-2, and Bgp) and the absence of the SR-2 sequence-characterized amplified region marker for bgm support the hypothesis that bgm-3 and Bgp-2 are different genes for BGYMV resistance.

Registration of 'Rosada Nativa' Pink Bean 'RosadaNativa' pink bean (Phaseolus vulgaris L.) (Reg. no. CV-164, PI 606250) was developed and released in 1998 by the Puerto Rico Agricultural Experiment Station in cooperation with the USD A-ARS. RosadaNativa, tested as PR9443-1, was derived from the cross DOR483/BelNeb Rust Resistant-1. DOR483 is a bean golden mosaic (BGMV) resistant small red breeding line from CI AT. BelNeb Rust Resistant-1 (2) is a great northern bean cultivar that has resistance to bean rust [caused by Uromyces appendiculatus (Pers.:Pers.) Unger] and common bacterial blight [caused by Xanthomonas axonopodis pv. phaseoli Starr & Garces 1950 emend. Vauterin et al. 1995; syn. X. campestris pv. phaseoli (Smith) Dye]. Crosses, field selections, and evaluations were made at the Isabela Substation in Puerto Rico. The F t was advanced in the field. Individual F 2 and F 3 plants were selected under field conditions for erect plant architecture, early maturity, and commercially acceptable pink seed type. The F 4 and F 5 were evaluated for plant type, relative maturity and rust resistance. The best plants from selected families were harvested in bulk. The F 6 was screened for BGMV resistance using a greenhouse inoculation technique (1). The BGMV resistance of the RosadaNativa was confirmed in field trials conducted in Puerto Rico and the Dominican Republic. Rosada Nativa has the recessive bgm-I allele for resistance to BGMV. The presence of bgm-1, a recessive resistance gene, was confirmed using the R2 57 o/s3o RAPD marker (3). Rosada Nativa represents the first release of a pink bean with BGMV resistance. Rosada Nativa is resistant to the bean rust races prevalent in Puerto Rico and the Dominican Republic. It also carries the / gene for resistance to BCMV. Rosada Nativa is moderately resistant to web blight (caused by Rhizoctonia solani Kiihn) and susceptible to common bacterial blight.

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