IAC 2561 Tiger - a colored type commercial bean cultivar with a non-darkening trait

Abstract

The cultivar IAC 2561 Tiger is a colored pinto-type common bean, derived from the cross IAC Tigre × Vibrante, has a type II indeterminate growth habit, a mean 1000-seed weight of 350 grams, an average 85-day cycle, and a yield potential of 3,978 kg ha^-1.

Keywords:
Grain darkening; yield; Phaseolus vulgaris

INTRODUCTION

Common bean (Phaseolus vulgaris L.) is an important legume crop consumed worldwide due to its protein potential and nutritional value (Zia et al. 2022). In Brazil, it is a staple food, especially in combination with rice, as this combination enhances its nutritional value. It is produced in the five regions of Brazil and in nearly every state (CONAB 2024).

In addition to its nutritional qualities, common bean has specific agronomic features; notably, it is an annual crop with a short phenological cycle, allowing the grower to better fit its cultivation into shorter crop seasons without compromising the production of other crops in the same crop year. In this regard, Brazil has three crop seasons: the first, August to December (rainy season); the second, January to February (dry season); and the third, May to July (winter season) (CONAB 2024). Bean breeding programs focus on traits essential for better crop quality and disease control throughout the year with the aim of releasing new cultivars on the market (Bezerra et al. 2021).

The plant growth habit, length of crop cycle, yield potential, disease resistance, seed coat darkening, and cooking time are essential breeding traits for development of seeds with high technological and nutritional quality (Chiorato et al. 2020).

Based on crop surveys for the first crop season of 2023-2024, the planted area for common bean with a colored seed coat was 36.34% greater than the area for growing black beans (CONAB 2024). Cultivation choices are affected by Brazilian consumption preferences regarding the colored bean types. Breeding programs have worked to develop cultivars of both seed coat types, black and colored seed, which is reflected by the comparable yield potential of these cultivars available on the market (Chiorato et al. 2020). Furthermore, according to CONAB, total production of common bean in the first crop season of 2023-2024 was 924.3 thousand tons, of which 571.4 thousand tons were of colored common bean, with a mean yield of 1,665 kg ha^-1.

In this context, the Common Bean Breeding Program of the Instituto Agronômico (Programa de Melhoramento Genético de Feijoeiro do Instituto Agronômico - PMGF-IAC) has played a key role in developing superior genotypes for the traits of grain quality, slow seed coat darkening, and resistance to diseases such as Fusarium wilt and anthracnose. It has also contributed to diversifying the cultivar portfolio, leading to better alignment with the demands of the production chain (Bezerra et al. 2021).

The grower’s choice of a bean cultivar goes beyond yield, involving traits such as resistance to biotic and abiotic stresses, nutritional quality, and technological aspects, including the rate of seed coat darkening and cooking time, and other post-harvest properties (Chiorato et al. 2020). From the consumers’ perspective, post-harvest quality is important, especially in regard to seed darkening during storage, as darker beans tend to be associated with longer cooking time and more difficult preparation (Silva et al. 2008).

In light of the above, the aim of this study is to present the cultivar IAC 2561 Tiger (Gen 18-100-2-100-2 advanced line), which has a pinto bean type seed coat. The cultivar produces bean seeds of medium to large size, has high yield, exhibits resistance to seed coat darkening after 60 hours of UV exposure, and is resistant to anthracnose.

GENETIC ORIGIN AND DEVELOPMENT

The PMGF-IAC has released cultivars with high yield potential to the Brazilian market (Chiorato et al. 2010, 2020, Carbonell et al. 2010, Carbonell et al. 2021, Bezerra et al. 2021).

Hybridization, followed by selection of superior plants, is a routine practice in breeding programs aimed at developing improved cultivars. Several hybrid combinations are obtained, and those with the most favorable traits are selected (Chiorato et al. 2020). The IAC 2561 Tiger cultivar, derived from the Gen 18-10-2-100-2 line, has been registered with the Brazilian Ministry of Agriculture (Ministério da Agricultura, Pecuária e Abastecimento - MAPA). Breeding work began in 2018 based on the double cross between the IAC Tigre genotype (because of its yield potential and disease resistance) and Vibrante genotype (because of its disease resistance and slow seed coat darkening) to obtain F₁ seeds. It received the designation Gen 18-100, where 18 refers to the year of obtaining the cross, and 100 refers to the number of the cross combination.

The F₁ seeds were multiplied in a greenhouse (GH) in Campinas, SP, in the 2018 rainy crop season (September to December) to obtain F₂ seeds. In the 2019 winter crop season, the F₂ seeds were sown in Campinas, SP, in 3-meter rows, and 727 segregating progenies were selected in the field to advance to the F_2:3 generation. Of these, 269 progeny plants were selected in April 2020 based on their grain traits. In the Gen 18-100 cross, 4 progenies (1 to 4) were selected, and progeny 2 was approved and designated Gen 18-100-2.

In the 2020 rainy crop season, 50 seeds from each of the 269 F_2:4 progenies were pre-germinated and transplanted into boxes containing vermiculite and a sterilized substrate. At seven days after transplanting in a controlled laboratory environment (temperature, humidity, and photoperiod), the plants were artificially inoculated with three physiological races of anthracnose (Colletotrichum lindemuthianum: 65, 81, and 89). The resistant plants were individually selected, transplanted into pots, and grown in a greenhouse (GH) using the genealogical selection method. In the 2021 rainy crop season, F_2:5 plants were sown and evaluated for resistance to the three physiological races of anthracnose, as previously described. The seeds were harvested in January 2022 and selected based on seed coat color for the pinto bean commercial group with resistance to seed coat darkening. These seeds were assigned the progeny number 100-2 (Gen 18-100-2-100-2).

The seeds from the F_2:6 generation were sown in the 2022 dry crop season, having passed through a preliminary evaluation of lines with seed coats other than carioca and black. These lines composed the new Value for Cultivation and Use (VCU) trials for the periods of 2022, 2023, and 2024, and the line under evaluation achieved a mean yield of 2,350 kg ha^-1. This Gen 18-100-2-100-2 line was once more evaluated by applying the mixture of anthracnose pathogen races in the laboratory under controlled conditions, and it showed resistance to races 65, 81, 89, and 521.

The VCU trials began in the 2022 winter crop season and were conducted for a period of two years over six crop seasons (Winter/2022, Rainy/2022, Dry/2023, Winter/2023, Rainy/2023, Dry/2024), fulfilling the requirements established by MAPA for setting up and conducting trials. Lines with seed coats other than carioca and black were evaluated, and the trials were called VCU-OTG (other types of grain) by the PMGF-IAC. The trials included 23 lines and 3 check cultivars (IAC 2153, IAC 2154, and IAC 2156) for Region I (Rio Grande do Sul, Santa Catarina, Paraná, São Paulo, and Mato Grosso do Sul).

The VCU trials were conducted in Capão Bonito, SP, in the 2023 rainy crop season; in Mococa, SP, in the 2022 rainy and dry crop seasons; in Campinas, SP, in the 2022 and 2023 rainy crop, 2023 winter crop, and 2023 and 2024 dry crop seasons; in Tatuí, SP, in the 2022 winter and rainy and 2023 dry crop seasons; and in Votuporanga, SP, in the 2022 and 2023 winter crop seasons.

YIELD POTENTIAL

The IAC 2561 Tiger cultivar showed good performance, with mean yields of 1,858 kg ha^-1, 1,548 kg ha^-1, and 2,724 kg ha^-1 in the rainy, dry, and winter crop seasons, respectively (Table 1). Its yield performance in comparison with the mean yields of the check cultivars (IAC 2153, IAC 2154, and IAC 2156) was -0.59%, +17.72%, and +17.21% in the rainy, dry, and winter crop seasons, respectively, and it was resistant to physiological races 65, 81, 89, and 521 of the anthracnose pathogen, leading to its recommendation by the common bean breeding program of IAC as a high-quality pinto bean cultivar. The name was assigned with the following components: i) IAC - Instituto Agronômico de Campinas; ii) 25 - year of registration in the RNC (National Cultivar Registry) - Brazilian Ministry of Agriculture (Ministério da Agricultura, Pecuária e Abastecimento - MAPA); iii) 61 - corresponds to the 61st common bean cultivar developed by PMGF-IAC; and iv) Tiger: commercial name that alludes to the mottled seed coat and resistance to anthracnose.

Table 1
Mean grain yield, in kg ha^-1, of the cultivar IAC 2561 Tiger compared to the mean of the check cultivars, by site, crop season, and year

Site	Season/Year	IAC 2561 Tiger cultivar (kg ha-1)	Check cultivars (kg ha-1)			Mean of the checks	CV (%)	F value
			IAC 2153	IAC 2154	IAC 2156
Votuporanga, SP	Winter 2022	2,121	871	1,775	1,142	1,263	22.54	10.52*
Tatui, SP	Winter 2022	2,363	2,398	2,496	1,829	2,241	16.66	15.17*
Campinas, SP	Rainy 2022	2,145	2,248	2,985	1,107	2,113	20.11	4.63*
Tatui, SP	Rainy 2022	2,850	3,475	2,858	1,846	2,726	22.84	3.34*
Mococa, SP	Rainy 2022	2,442	1,759	1,951	1,539	1,750	21.34	5.09*
Campinas, SP	Dry 2023	1,167	300	1,001	679	660	21.17	25.03*
Tatui, SP	Dry 2023	1,900	1,171	1,508	1,241	1,307	21.21	2.57*
Mococa, SP	Dry 2023	1,741	1,808	1,585	1,365	1,586	16.71	4.44*
Votuporanga, SP	Winter 2023	3,978	3,514	4,196	2,834	3,515	13.78	5.94*
Campinas, SP	Winter 2023	2,436	1,851	3,036	1,950	2,279	23.86	3.03*
Campinas, SP	Rainy 2023	900	1,143	1,356	1,274	1,258	22.22	7.22*
Capão Bonito, SP	Rainy 2023	954	1,914	1,473	1,106	1,498	21.89	5.48*
Campinas, SP	Dry 2024	1,385	1,742	2,045	1,332	1,706	17.51	4.60*
Mean of rainy (1st crop)		1,858	2,108	2,124	1,374	1,869	23.49	1.66*
Mean of dry (2nd crop)		1,548	1,255	1,535	1,154	1,315	19.22	0.81
Mean of fall-winter (3rd crop)		2,724	2,158	2,875	1,938	2,324	18.71	5.99*
Overall mean (Combined)		1,952	1,861	2,174	1,480	1,838	21.14	4.06*

• * Significant at 5% in the F test.

OTHER CHARACTERISTICS

The IAC 2561 Tiger cultivar has a type II indeterminate growth habit, mean 1000-seed weight of 350 grams, and mean crop cycle of 85 days from emergence to physiological maturity (normal cycle). It has tendrils/vines, large dark green leaves, medium to tall plant height reaching up to 80 cm, and long pods that are green during morphological maturity and beige at physiological maturity with an average of 5 seeds. It produces uniform beans (Figure 1) with a mean cooking time of 31 minutes after pre-soaking. Mean protein content is 21% (Table 2), which is higher than that of the check cultivars.

Table 2
Mean cooking time and crude protein content of the cultivar IAC 2561 Tiger compared with the check cultivars (IAC 2153 and IAC 2154) evaluated in different crop seasons in the state of São Paulo, Brazil

Crop Season	IAC 2561 Tiger cultivar		Check cultivars
			IAC 2153		IAC 2154
	Cooking time (min)1	Protein content (%)2	Cooking time (min)	Protein content (%)	Cooking time (min)	Protein content (%)
Winter/2022	33.10	22.00	33.20	21.00	22.20	18.50
Rainy/2022	32.50	21.00	41.00	20.50	23.10	19.00
Dry/2023	29.00	20.50	35.20	22.00	22.50	19.32
Winter/2023	28.60	21.20	32.50	22.20	24.00	18.90
Rainy/2023	33.20	21.50	36.00	21.00	19.80	19.20
Dry/2024	31.90	22.10	34.80	22.00	20.00	21.00
Mean	31.38	21.38	35.45	21.45	21.93	19.32

• ¹
  Cooking time assessed with the Mattson Cooker (Proctor and Watts 1987). ² Crude-protein content determined by the micro-Kjeldahl method (AOAC 1980, Bataglia et al. 1983).

Figure 1
Evaluation of seed coat darkening of beans from the cultivars IAC 2561 Tiger and IAC Tigre. A and B) Shelf darkening after more than 90 days of storage, for IAC 2561 Tiger and IAC Tigre, respectively. C and D) Accelerated darkening under ultraviolet light at 0 hour, for IAC 2561 Tiger and IAC Tigre, respectively. E and F) Accelerated darkening under ultraviolet light after 40 hours, for IAC 2561 Tiger and IAC Tigre, respectively.

The IAC 2561 Tiger cultivar showed resistance to anthracnose in artificial inoculations with Colletotrichum lindemuthianum races 65, 81, 89, and 521. It showed moderate resistance to Fusarium wilt (Fusarium oxysporum, race 6), common bacterial blight (XAP 19 of Xanthomonas axonopodis), and bacterial wilt (IBSBF 2869 of Curtobacterium flaccumfaciens pv. flaccumfaciens). Moderate resistance to angular leaf spot was observed under field conditions (Table 3).

Table 3
Reaction of the common bean cultivar IAC 2561 Tiger to anthracnose (Colletotrichum lindemuthianum races 65, 81, 89, and 521), Fusarium wilt (Fusarium oxysporum race 6), angular leaf spot, common bacterial blight (isolate XAP 19 of Xanthomonas axonopodis), and bacterial wilt (isolate IBSBF 2869 of Curtobacterium flaccumfaciens pv. flaccumfaciens)

Cultivar	Anthracnose1	Fusarium oxysporum 2	Angular Leaf Spot3	Bacterial Blight4	Bacterial Wilt5
IAC 2561 Tiger	R	MR	MR	MR	MR
IAC 2153	R	R	R	MR	MR
IAC 2154	S	S	S	S	R

• R: resistant, MR: moderately resistant, S: susceptible. ¹ Evaluated using the scoring scale described by Rava et al. (1993), ranging from 1-9 (1-3 = resistant and 4-9 = susceptible). ² Evaluated using the Schoonhoven and Pastor-Corrales (1987) scale (1-3 = resistant and 4-9 = susceptible). ³ Evaluated under field conditions. ⁴ Evaluated according to the Rava (1984) scale, ranging from 0-6 (0-2.0 = resistant and 2.1-6.0 = susceptible). ⁵ Evaluated using a scale ranging from 1-9, where scores from 1-3 indicated resistant, 4-6 moderately resistant, and 7-9 highly susceptible.

Anthracnose resistance was assessed under controlled environmental conditions, regulating temperature, humidity, and photoperiod. The evaluations were carried out with an inoculum density of 10⁶ spores mL⁻¹, with five replicates. In the VCU trials, plants were inoculated with races 65, 81, 89, and 521. Disease severity was assessed using the scale proposed by Rava et al. (1993), where plants scoring between 1 (absence of symptoms) and 3 (lesions restricted to veins on the abaxial surface of the primary leaf, affecting up to 3% of the veins) were classified as resistant. Plants with scores from 4, indicating initial symptoms on the adaxial veins (approximately 1% affected), to 9 (plant death) were classified as susceptible.

To assess resistance of the cultivar to Fusarium wilt, Fusarium oxysporum race 6 was inoculated at the same spore concentration and with the same number of replicates as in the VCU assessments. Disease severity was determined following the scale proposed by Schoonhoven and Pastor-Corrales (1987), based on hypocotyl symptoms. Scores from 1 to 3 indicated resistance, while scores from 4 to 9 indicated susceptibility.

In the case of bacterial blight caused by Xanthomonas axonopodis, the trials used an inoculum concentration of 10⁸ CFU mL⁻¹, with five replicates per treatment. Evaluations followed the scale proposed by Rava (1984), ranging from 0 to 6. Plants with scores between 0.0 and 2.0 were classified as resistant, while those with scores between 2.1 and 6.0 were considered susceptible. Disease progression was monitored at the leaf inoculation site, where cuts had been made to facilitate bacterial penetration. In contrast, angular leaf spot was assessed under natural field conditions.

Resistance to Curtobacterium flaccumfaciens pv. flaccumfaciens was evaluated following the method described by Maringoni (2002) using plants grown under controlled conditions. Plants were inoculated at the first trifoliate leaf stage by injecting a bacterial suspension (10⁸ CFU mL⁻¹) into the hypocotyl. The pathogenic isolate was cultured in Nutrient Broth (NB) medium at 28 °C for 48 hours, and the suspension was prepared in sterile distilled water. Plants were maintained at an average temperature of 25-28 °C and high relative humidity to favor disease development. Disease severity was assessed 7 to 15 days after inoculation using a 1-9 scale, where scores from 1-3 indicated resistance, 4-6 moderate susceptibility, and 7-9 high susceptibility, based on symptom intensity, including wilting, vascular necrosis, and plant death.

Resistance to seed coat darkening (Table 4) was tested under controlled lighting conditions, following the methodology described by Spitti et al. (2019) using a colorimeter (Minolta, model CR-410), which measures color in a 3-parameter system (L*, a*, b*). For this study, only the L* axis (Lightness) was used, which ranges from 0 (black) to 100 (white). After exposing bean samples of the cultivars IAC 2561 Tiger, IAC 2053, and IAC 2054, in triplicate, to 40 hours of light, IAC 2561 Tiger exhibited the best tolerance index.

Table 4
Seed coat darkening of the cultivar IAC 2561 Tiger compared with the check cultivars IAC 2153 and IAC 2154, measured by L* values over 40 hours of light exposure

Cultivar	L* value at exposure time (hours)
	0	16	24	40
IAC 2561 Tiger	59.6	57.655	57.34	56.21
IAC 2153	57.58	51.2	47.77	46.05
IAC 2154	67.37	66.21	66.86	66.69

• ¹
  Evaluated in triplicate across three municipalities: Tatuí, Capão Bonito, and Adamantina.

Sowing recommendations include a between-row spacing of 50 cm and 9-12 plants per linear meter, depending on soil fertility, temperature, and other crop climatic conditions, resulting in 180,000 to 240,000 plants per hectare. The yield of the IAC 2561 Tiger cultivar depends on the crop season, growing region, and technological level of the grower. Waterlogged soils and areas not included in common bean cultivation zones should be avoided.

TECHNICAL RECOMMENDATIONS AND SEED PRODUCTION

Considering its high mean yield, 1000-seed weight, and slow seed coat darkening (Table 4), the IAC 2561 Tiger cultivar is recommended for growing in the three crop seasons (rainy, dry, and winter) in the states comprising Region I (RS, SC, PR, SP, and MS) and Region II (RJ, ES, MG, MT, MA, TO, GO, BA, and DF) of the MAPA Recommendation Zones. Thus, this cultivar contributes to the availability of certified high-quality and high-yielding pinto bean seeds, offering growers a new option without relying on saved seeds.

The IAC 2561 Tiger cultivar was registered in the Brazilian National Cultivar Registry (Registro Nacional de Cultivares - RNC) of the Ministry of Agriculture (Ministério da Agricultura, Pecuária e Abastecimento - MAPA) on 18 September 2024 under registration number 57687. Foundation seed is available for seed production at the seed production center of the Instituto Agronômico - IAC.

Data Availability

The datasets generated and/or analyzed during the current research are available from the corresponding author upon reasonable request.

REFERENCES

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Publication Dates

• Publication in this collection
  16 Feb 2026
• Date of issue
  2025

History

• Received
  04 June 2025
• Accepted
  24 June 2025
• Published
  01 Oct 2025