REVISIÓN BIBLIOGRÁFICA
6. OSTEOARTROSIS Y MARCADORES BIOQUÍMICOS
6.1. Clasificación de los marcadores bioquímicos de OA
The most important biotic factors limiting chickpea production are fungal diseases such as Ascochyta blight and Fusarium wilt. Other fun- gal diseases such as botrytis grey mould or, in a minor extent, rust have increased in importance
in the last decade. Evaluations for resistance reaction have been done infield and under con- trolled conditions. It is required to include in the experiments resistant and susceptible check genotypes as well as differential lines in the case that they have been described. For aerial fungus in field experiments, highly susceptible lines should be used as disease spreaders to get homogenous infections.
A large proportion of QTL analysis for dis- ease resistance has been focused on Ascochyta blight (AB), caused by the fungus Ascochyta rabiei (Pass.) Labr, that affects all aerial parts of the plant. The pathogen is favoured by cool (15– 25 °C) and moist conditions (Bayaa and Chen
2011). Evaluation of AB resistance depends on several crucial factors including the choice of appropriate isolates for screening, methodology and the sources of resistance. The attempts to classify virulence in A. rabiei have been incon- clusive because of the variable number of cate- gories proposed by different studies, the lack of reproducibility of disease phenotypes among laboratories and the lack of comparable standard check cultivars or pathotypes (Peever et al.
2007). Field screening for AB usually consists of planting a susceptible genotype every two or four tested entries, which serves as an indicator/spreader line, scattering infected plant debris collected in the previous season and maintaining high humidity through sprinkler irrigation. If needed, entries could be sprayed with a spore suspension in the evening of a cloudy day (Pande et al. 2005). It could be interesting to include in the trial reported differ- ential lines for different pathotypes. Usually, nonparametric methods are employed for quan- tifying host response and the phenotype is grouped into discrete classes. The scale devel- oped by Singh et al. (1981) is one of the most widely employed. It is based on the severity of the infection on leaves, stems and pods, and host response is classified as: 1 = no infection, 2 = highly resistant (1–5%), 3 = resistant (6– 10%), 4 = moderately resistant (11–15%), 5 = intermediate (16–40%), 6 = moderately susceptible (51–75%) and 9 = plants dead. Area under the disease progress curves (AUDPC) of
each line (Campbell and Madden 1990) is fre- quently calculated in order to study the progress of the disease in each line. Genotypes can be scored weekly from the week when the suscep- tible check genotypes show the first disease symptoms to the week the check genotypes reach a score of 9.
Methods for screening AB under controlled environment require high level of relative humidity during the first 24-h post-inoculation (Udupa and Baum2003; Chen et al.2005). Also, spore concentration in the inoculum is a signifi- cant factor. Conidia of individual isolates are harvested from two-week-old cultures, and spore concentration is adjusted to the lowest that cau- ses sufficient disease in a majority of host genotypes (proposed 2 105 pycnidiospores mL−1). Two-week-old plants are sprayed with this conidial suspension to run-off and immedi- ately incubated 24 h at 20 °C and 100% relative humidity (RH) to facilitate infection. There are several methods for scoring AB phenotype (Chen et al.2004). The nonparametric 1–9 rating scale of Reddy and Singh (1984) is the method most commonly used for controlled condition evalua- tions. The lesions are scored as follows: 1 = healthy plant—no disease, 2 = lesions pre- sent but small and inconspicuous, 3 = lesions easily seen but plant is mostly green, 4 = severe lesions clearly visible, 5 = lesions girdle stems, most leaves show lesions, 6 = plant collapsing, tips die back, 7 = plant dying but at least three green leaves present, 8 = nearly dead plant (vir- tually no green leaves left) but still with a green stem and 9 = dead plant (almost no green parts visible).
Fusarium wilt (FW) caused by Fusarium oxysporum f. sp. ciceris is a soil fungus and chickpea plants may be infected at any growth stage. Different evaluation methods have been developed for screening under controlled and field conditions (Sharma and Muehlbauer2007; Li et al.2015). The level of resistance and sus- ceptibility of each line is usually calculated as percentage of wilt incidence (number of wilted plants/total number of plants 100). Based on wilt incidence, the data can be converted into categorical records. Sharma et al. (2005)
proposed the following scores range: 0–10% wilting = resistance, 11–89% wilting = interme- diate, 90% wilting = susceptible. In order to search for Fusarium wilt resistance genes, most studies have treated the character as a qualitative trait (see Chap.3), and only few considered the disease as a quantitative trait (Table8.1).
Botrytis grey mould (BGM) caused by Botrytis cinerea Pers.ex.Fr. is widely distributed and is the second most important disease in
tropical areas (Pande et al.2006; Davidson et al.
2007). Different screening techniques have been used for germplasm under controlled and field conditions (Pande et al. 2006). Here, we will describe scale employed by Anuradha et al. (2011) to phenotype a RIL population for BGM. The authors determined QTLs associated with BGM. The severity of the disease was recorded following a 1–9 rating scale, where 1 = no infection on any part of the plant; 2 = minute
Table 8.1 QTLs linked to biotic stresses in different genetic backgrounds
Trait LGa QTL R2 (%)b Tightly linked markers Source of resistancec References
Ascochyta blight (AB)
LG2 QTLAR3 44.3 GA16, TA194,
TR19, Ein3
ILC3279, ILC72
Udupa and Baum (2003), Cobos et al. (2006), Iruela et al. (2007), Anbessa et al. (2009), Madrid et al. (2014) LG3 QTLAR4 18 STMS28, TS12, TA64, TR58 ICC1, CDC Frontier, Amit Flandez-Galvez et al. (2003), Ta’ran et al. (2007), Anbessa et al. (2009), Kottapalli et al. (2009)
LG4 QTLAR1 16.9 GAA47, GA24,
H3C041, CaETR
FLIP84-92C, Hadas, ILC3279
Santra et al. (2000), Tekeoglu et al. (2002), Lichtenzveig et al. (2006), Madrid et al. (2013)
QTLAR2 29.4 SCAR733b, TA2,
TA146, TA72, TA130, TA132, TS54, H1G20, SCY17 FLIP84-92C, ILC3279, Hadas, CDC Frontier
Santra et al. (2000), Udupa and Baum (2003), Cho et al. (2004), Iruela et al. (2007), Lichtenzveig et al. (2006), Ta’ran et al. (2007), Anbessa et al. (2009), Kottapalli et al. (2009)
LG6 QTLAR5 11.6 TA176, TA80,
TA22, TA40
CDC Frontier Ta’ran et al. (2007), Anbessa et al. (2009)
LG8 QTLAR6 16 TA3, H3C11a, TS46,
TS45
CDC Corinne Flandez-Galvez et al. (2003), Lichtenzveig et al. (2006), Anbessa et al. (2009) Fusarium (Foc)
LG5 QTLFoc01 37.8 TR59, TS35 JG62 Cobos et al. (2005)
LG2 QTLFoc02/Foc5 46.5 TA59 ICCL81001 Cobos et al. (2009)
LG6 FW-Q-APR-6-1 (race1)
16.4 CaM1402, CaM1101 WR315 Sabbavarapu et al. (2013) Botrytis grey mould (BGM)
LG6 QTL1 12.8 SA-14, TS71 ICCV2 Anuradha et al. (2011)
LG8 QTL2/QTL3 9.5–
48
TA25, TA144 TA159, TA118 Rust
LG7 QTLUca 73.7 TA18, TA180 Cr5-10 Madrid et al. (2008)
Only QTLs with LOD 3 were considered
aLinkage groups;bMaximum value published;cCr Cicer reticulatum
water-soaked lesions on emerging tender leaves, usually not seen; 3 = minute water-soaked lesions on 1–5% emerging and upper-most ten- der leaves, usually seen after careful examina- tion; 4 = water-soaked lesions on 6–10% upper-most tender leaves and tender shoots; 5 = water-soaked lesions, soft rotting of 11–25% of tender leaves and shoots; 6 = water-soaked lesions and soft rotting of 26–40% of top leaves and shoots; 7 = soft rotting and fungal growth on 41–55% of the leaves and branches; 8 = soft rotting, fungal growth on 56–70% of the leaves, branches and stems; 9 = extensive soft rotting, fungal growth on above 70% of the leaves, branches and stems (Pande et al.2006; Anuradha et al.2011).
Rust caused by the fungus Uromyces ciceris- arietini has been reported to be affecting chick- pea production in the Mediterranean region, South Africa, Mexico, Australia, Italy and the USA (Li et al.2015). Till now, only one QTL related to rust resistance has been published (Madrid et al. 2008; Table8.2). The evaluation of plant material was carried out underfield and controlled conditions. Field evaluations were performed inoculating the plants by spraying with a spore suspension (200 mg spores/l). Dis- ease severity (DS) was rated as a percentage of the host tissue covered by pustules at weekly intervals following (Sillero et al. 2012). Inocu- lations in growth chamber were carried out spraying the seedlings at the fourth leaf stage with an aqueous suspension of urediospores (2 mg per plant) diluted in pure talcum powder (1:10). Infection type (IT) under controlled con- ditions was rated using the scale proposed by Stakman et al. (1962) where 0 = no symptoms, “;” = necrotic flecks, 1 = minute pustules barely sporulating, 2 = necrotic halo surrounding small pustules, 3 = chlorotic halo, 4 = well-formed pustules with no associated chlorosis or necrosis.